**Best Ti Bottom Bracket**
Jeffrey Peter Ziegler
I was wondering what people thought that the best Ti bottom bracket was?
I know that the stratics from sampson ahs gotten a lot of press lately,
but one of my firends had trouble with it. Has anyone else experienced
any difficulty? Are there other brands that should be looked at?
Thanks for the info!! Jeff -jpzi...@cats.ucsc.edu
Andrew St. J Mein
one word- SCHWEEET!
andrew =]
FISCHER DAVID ALEXANDER
Only two choices for DURABLE Ti BB's.
Phil Wood
Bontrager
Dave
Rachel McKay
>Only two choices for DURABLE Ti BB's.
>
>Phil Wood
>Bontrager
Do Royce b/bs live up to their reputation (and price tag)?
Rachel McKay <rm...@ntms.bt.co.uk>
Software Engineer, BT.
John Olsen
>
>
>I was wondering what people thought that the best Ti bottom bracket was?
I am biased because Glenn is a friend of mine, but the Ericson Ti BB is
the most elegant design I've seen. Union/Frondenburg is carrying them.
Big, hollow, Ti tube in the middle- as stiff as a conventional BB could
be.
Olsen
sjg...@vaxa.weeg.uiowa.edu
Kristan Roberge
over time, cuts little flakes outta the crank tapers and leads to
creaking noises). And a russian made Ti BB that's very similar to the
syncros (same size bearings, axle's are similar, somewhat heavier
since its ALL ti : axle, lockrings, cups, bolts, washers). I prefer
the russian model on my dual suspension bike since being all Ti it'll
take a pounding a bit better than one like syncros that relies on alot
of aluminum (cups / lockrings) to keep the weight down. The russian
model also costs about 40% less.
Email if your interested in purchasing one of the russian Ti BBs.
pag
jol...@techcenter.paccar.com says...
forever. This White Ind. spindle is hollow but if you are a heavy,
aggressive rider I would stick with a solid Ti spindle or Cro mo spindle
which are way stronger than Ti. I have a 88mm wide bottom bracket so the
sealed bearings are way outboard, and I way less than 140 so I am not
worried about spindle failure.
Michael Gabrielson
I have had alot of luck with my synchros Ti bottom bracket. I am only
160 pounds however. I have heard heavier riders can't ride on the
hollow Ti spindles. I like the adjustable chainline and low maintenance
of cartridge bearings. But above all the weight factor is most
important. "LIGHT IS RIGHT!!"
>
D. EISMAN
and the less expensive Sampson Colorado Ti BB on my training bike for the
past year with great results. For a heavier weight rider, I would have to
say
the Stratics BB is a must (over the Colorado) because it's a little
beefier, and
the fluted spindle gives it a lot more strength. For a lighter rider, like
myself,
the colorado works just fine.
Chris Gee
>I was wondering what people thought that the best Ti bottom bracket was?
>I know that the stratics from sampson ahs gotten a lot of press lately,
>but one of my firends had trouble with it. Has anyone else experienced
>any difficulty? Are there other brands that should be looked at?
>Thanks for the info!! Jeff -jpzi...@cats.ucsc.edu
FISCHER DAVID ALEXANDER (fisc...@ucsub.Colorado.EDU) wrote:
: Only two choices for DURABLE Ti BB's.
: Phil Wood
: Bontrager
:
jol...@techcenter.paccar.com wrote:
> ... Ericson Ti BB is the most elegant design I've seen. Union/Frondenburg
> is carrying them. Big, hollow, Ti tube in the middle- as stiff as a
> conventional BB could be.
p...@interramp.com wrote:
* I have been using White Industry Ti spindle, they have been making them
* forever. This White Ind. spindle is hollow but if you are a heavy,
I'd like to add my choice:
Paragon - in my Kestrel 200ems(Dura-Ace)
I wonder if Nuke Proof makes Ti BB's as well?
(I have NP Ti hubs on my MTB.)
chris
============================================================================
Christopher W Gee (ch...@fa.disney.com) |"...this program WORKS,
Walt Disney Feature Animation | it just doesn't compile..."
Glendale, CA 91221 (818)544-2505 |"...that's as white as it
Kestrel200ems/dura & trek7000/xt/scottshock | gets, all the bits are on..."
============================================================================
-={[foo]}=-
: >>I was wondering what people thought that the best Ti bottom bracket was?
: >
: >
Well, speaking from experience:
Syncros has one of the best products out there. Here's why I
think so:
1. It's well constructed and it shows.
2. It's really light.
3. It's really strong (haven't had a problem yet ~170lbs)
4. It's fully adjustable and serviceable <---YES!!
5. You can adjust the chain line verrrry easily.
6. It's not that expensive (it's 100+, but still...)
7. You need a red and blue "Spanner Wrenches" to
install it - prolly $8-10
(hey - that's what they're for!)
I have one on my mountain bike (i'm the third person to use it, too :))
and it's still silky smooth. I just lube up the bearings every couple of
months and no worries. It also has double bearings on the drive side
which makes it pretty damn close to bombproof.
I also have one on my road bike (I dont know why...it was impulsive, i'll
admit) and it is suuuuuper smooth and light (about 15 lbs lighter than
the one i replaced ;).
My vote goes to syncros: cool products, cool name.
--
===============================*boink*=============================
mrb...@phantom.com ''' mrb...@network-23.com
abra...@presto.cs.tufts.edu (o o) mabr...@jade.tufts.edu
===========================-oOOo-( )-oOOo-=========================
MANNIX IAIN RORY CAMPBELL
Chris Gee <ch...@fa.disney.com> wrote:
>jpzi...@cats.ucsc.edu (Jeffrey Peter Ziegler) writes:
>>I was wondering what people thought that the best Ti bottom bracket was?
>>I know that the stratics from sampson ahs gotten a lot of press lately,
>>but one of my firends had trouble with it. Has anyone else experienced
>>any difficulty? Are there other brands that should be looked at?
>>Thanks for the info!! Jeff -jpzi...@cats.ucsc.edu
>
>FISCHER DAVID ALEXANDER (fisc...@ucsub.Colorado.EDU) wrote:
>: Only two choices for DURABLE Ti BB's.
>: Phil Wood
>: Bontrager
>:
>jol...@techcenter.paccar.com wrote:
>> ... Ericson Ti BB is the most elegant design I've seen. Union/Frondenburg
>> is carrying them. Big, hollow, Ti tube in the middle- as stiff as a
>> conventional BB could be.
>
>p...@interramp.com wrote:
>* I have been using White Industry Ti spindle, they have been making them
>* forever. This White Ind. spindle is hollow but if you are a heavy,
>
>I'd like to add my choice:
>
> Paragon - in my Kestrel 200ems(Dura-Ace)
>
>I wonder if Nuke Proof makes Ti BB's as well?
>(I have NP Ti hubs on my MTB.)
>
>chris
I've been using a Syncros Gorilla (older dual drive side bearing) for a
couple of years now, no problems at all, and I weigh 215 pounds on a good
day. Kinda related - anyone out there have FIRST HAND experience with
broken ti bb spindles? Not steel, but TITANIUM!!!! (I got too many
'...broke an XT blah...') I have never seen one broken, and while I am
sure that they have, I'm not so sure that they are as fragile as some
say. Bye.
Mannix
Jobst Brandt
> I've been using the Sampson Stratics Ti BB on my racing bike for two
> years, and the less expensive Sampson Colorado Ti BB on my training
> bike for the past year with great results. For a heavier weight
> rider, I would have to say the Stratics BB is a must (over the
> Colorado) because it's a little beefier, and the fluted spindle
> gives it a lot more strength.
The fluted spindle is not stronger because the highest bending moment
and torque stress in any spindle occurs on the square taper, just
inside the press fit in the crank bore. All that gratuitous machining
on the midspan of the spindle doesn't even make it stiffer to ride
because it is primarily stressed in torsion there and the flutes
reduce that resistance to twisting. The resistance to torsional
deformation can be approximated by the largest inscribed circular
cross section within the outline of the shaft. In this case, flutes
reduce that diameter. The fins of the flutes carry practically no
stress in torsion.
When I see such designs I realize that there is little mechanical
knowledge at such companies and it is spooky to think of what other
foolish flaws are designed into their products. They certainly don't
do any measurements in tests or they would realize the errors of such
designs. You could also deduce that something is amiss when no one of
note makes fluted drive or axle shafts anywhere.
Jobst Brandt <jbr...@hpl.hp.com>
Gary Helfrich
: When I see such designs I realize that there is little mechanical
: knowledge at such companies and it is spooky to think of what other
: foolish flaws are designed into their products. They certainly don't
: do any measurements in tests or they would realize the errors of such
: designs. You could also deduce that something is amiss when no one of
: note makes fluted drive or axle shafts anywhere.
It is correct that the flutes are there just for looks, and contribute
nothing to the performance of the Sampson bb. On the other hand, how do
you know that this particular company is run by ignorant people that do
not measure or test their products? This is a competitive market, and
often styling is the only way to set one product apart.
You might be offended by engineering taking a back seat to marketing.
The fact that a company is market driven is not an accurate indicator of
the level of engineering behind its products, however. If you have any
FACTS about the competence of the designers at Sampson, please share
them with us all.
Gary Helfrich
Arctos Machine
Jeff Sweeney
>You might be offended by engineering taking a back seat to marketing.
>The fact that a company is market driven is not an accurate indicator of
>the level of engineering behind its products, however. If you have any
>FACTS about the competence of the designers at Sampson, please share
>them with us all.
Good design embodies elegant engineering and satisfies the more venal
desires of the corporation. They are not mutually exclusive, often
just the opposite. If a design is poorly engineered then it is a poor
design.
--
Jeff
swe...@dionheinz.uchicago.edu
Usenet: The information-sewerpipe.
Gary Helfrich
: Good design embodies elegant engineering and satisfies the more venal
: desires of the corporation. They are not mutually exclusive, often
: just the opposite. If a design is poorly engineered then it is a poor
: design.
My point was that putting some frills on a product to gain market
recognition is in no way related to the engineering expertise behind the
product. Jobst posted his personal opinion of Sampsons product
development process ("no measurement...no testing") as fact, which is
very misleading to others in this group. For all we know, the company
had done exhaustive testing, but wanted to do a product that was
different from the competition. Who knows but the people at Sampson?
Gary Helfrich
Arctos Machine
Jobst Brandt
> It is correct that the flutes are there just for looks, and contribute
> nothing to the performance of the Sampson BB. On the other hand, how do
> you know that this particular company is run by ignorant people that do
> not measure or test their products? This is a competitive market, and
> often styling is the only way to set one product apart.
There are two reasons that pop right out. Steel BB spindles fail in
fatigue as it is, although not often. Therefore, titanium is a
dangerous material to put to this use because it endangers riders and
the financial security of the company that makes them. The other
reason is that the gratuitous material and machining is bogus and I am
fairly certain that they truly believe there is some function to their
design besides making it heavier with non functional metal.
This is similar to oddball cranks that are on the market with I-beam
cross sections or ones with tiny cross sections at the pedal neck and
thread knuckle. In contrast, you must wonder what Campagnolo and
Shimano are doing with their absence of titanium spindles and scrawny
cranks. It reminds me of gas station (not dealer) garage mechanics
who believe engineers are a bunch of gnerds who don't understand what
makes things break in contrast to "use grease monkeys" who would do all
that designing a lot better... real guys with all the experience.
> You might be offended by engineering taking a back seat to marketing.
> The fact that a company is market driven is not an accurate indicator of
> the level of engineering behind its products, however. If you have any
> FACTS about the competence of the designers at Sampson, please share
> them with us all.
Maybe you could do the same. I see their output, but you seem to have
inside information to justify these weird designs. It's hard enough
to make a durable Ti spindle and these guys make it more difficult for
themselves with expensive machining and by adding material to make it
nearly as heavy as steel. It doesn't add up. Please throw some light
on this.
Jobst Brandt <jbr...@hpl.hp.com>
Todd C Pepling
*definitely* tok top priority at the expense of faulty design. Jobst is
correct in assuming that not all companies test products they market, and
the testing that is done in some cases is entirely biased and
inadequate. I know from testing I performed while employed at a certain
company that test results were sometimes entirely ignored. While I can't
speak for Sampson, I can recall an article in one of the major bicycle
magazines that suggested some sort of standardized testing for bicycle
products. Jobst, myself, and the author of that article aren't the only
ones who see problems with safety issues concerning the design and sale of
current MTB products, *primarily* in the high-end market, to which Sampson
is associated. And in that sense, while I feel Jobst stepped over the
line in this particular case, he raises (as usual) a valid point.
Gary, I *highly* respect your opinions, but I feel the heart of the issue
we users on the net should be disscussing now is the problems with and
the overcoming of issues surounding the establishment and standardizng of
testing to insure bicyclists aren't injured due to marketing taking priority
over design issues in the aftermarket segment of our industry. I submit
using Shimano's standards (since they already are the industry standard)
for strength testing, with a rating system relating a products relative
strength to a comparible Shimano product.
We've got a great opertunity to do something truly useful within this
newsgroup, beyond anything I've read here previously. Is it possible to
make our industry better/safer? I want you who is reading this right now
to put in your two cents. Jobst, Joshua, KB, Jim P., Trek, Specialized,
Gary, Cannondale, GT, Nashbar, and you other net-heads: can we
voluntarily establish a rating systembeneficial to both industry and
consumers?
Todd
--
"Life is a gamble and we're all placing our bets." - Spinal Tap
Todd Pepling (tcp...@Pitt.edu)
Unniversity of Pittsburgh
F Thomas Korsmeyer
>My point was that putting some frills on a product to gain market
>recognition is in no way related to the engineering expertise behind the
>product.
I don't think it is that simple in the case of boutique bike parts.
Because of the way they are marketed, the frills *are* related to the
engineering expertise behind the product. Most of the makers of these
parts create an aura of technical expertise around their products.
The message they try to get accross is that you should toss your
everyday shimano and replace it with this "high-tech, suitable-for-
your-favorite-racer, computer-generated" part. So although they
may not say so in particular, the idea created in the mind of the
buyer (intentionally, I claim) is that these flutes on the bb spindle,
or this I-beam cross section stem, are motivated by some technical
expertise which is lacking in run-of-the-mill parts.
Dan Empfield
swe...@dionheinz.uchicago.edu (Jeff Sweeney) wrote:
<<Good design embodies elegant engineering... [snip]
I don't think Gary was championing the Sampson product. I think he may
have been reacting to the following, very sweeping, statement by Jobst:
: When I see such designs I realize that there is little mechanical
: knowledge at such companies and it is spooky to think of what other
: foolish flaws are designed into their products. They certainly don't
: do any measurements in tests or they would realize the errors of such
: designs.
Here, Jobst has already decided, on the basis of a fluted bottom bracket,
that the engineers at Sampson have "little mechanical knowledge", their
other products will undoubtedly have "foolish flaws", and that they do not
"do any measurements in their tests." This is not only a reckless
statement, it borders on libelous.
I suspect that if I dug around Hewlett Packard's basement I could find
products which exhibit similar design eccentricities (perhaps something
designed by Jobst?). Were I to make statements the like of which I refer
to above, I wonder how long I would have to wait before I got a letter
from their attorney.
QRman
Dan Empfield
<<...gratuitous material and machining is bogus...
I wonder if you now do, or have recently, owned, or had reason to
otherwise appreciate, steel bikes with especially artistic and
"gratuitous" lugwork? I don't agree with you that needless stuff is
bogus. It's just needless, like the artistic nature of the lugs on the
bike you ride (as opposed to purely functional and boring lugs). It's
only when the marketing effort has a negative effect on the function that
your point is well taken.
<<In contrast, you must wonder what Campagnolo and Shimano are doing with
their absence of titanium spindles and scrawny cranks.
When I think of Campagnolo and Shimano, fluted seatposts immediately come
to mind (I digress from fluted BB spindles). Why would those companies
put flutes in their seatposts? There are no good reasons for such an
engineering change. Spooky. Makes me wonder about their testing
procedures.
As regards what they are doing with their absence of scrawny cranks, I
have it on good authority that they are busy scratching their heads and
wondering how to get their upper end crank market back.
QRman
Gary Helfrich
: I don't think it is that simple in the case of boutique bike parts.
: Because of the way they are marketed, the frills *are* related to the
: engineering expertise behind the product. Most of the makers of these
: parts create an aura of technical expertise around their products.
: The message they try to get accross is that you should toss your
: everyday shimano and replace it with this "high-tech, suitable-for-
: your-favorite-racer, computer-generated" part. So although they
: may not say so in particular, the idea created in the mind of the
: buyer (intentionally, I claim) is that these flutes on the bb spindle,
: or this I-beam cross section stem, are motivated by some technical
: expertise which is lacking in run-of-the-mill parts.
First, I should point out that I think the Sampson bb is a pretty silly
product, with no functional advantages over other bb's. What I objected
to is presenting personal opinion as fact. I would bet that no one in
this thread has any information as to the level of testing that goes on
at Sampson, or any of the other "boutique" companies in the bike
industry. I would agree with you that many parts are created with
engineering taking a back seat to marketing. What I fail to see is the
link between being a whore to the market, and being technicaly uneducated
and naive. Look at some of the styling excess in the automotive industry
that gets in the way of functionality. Does this mean that there is a
lack of engineering expertise, or just that the marketing and styling
guys have the final say?
Gary Helfrich
Arctos Machine
Robert Horvatich
>
> You might be offended by engineering taking a back seat to marketing.
> The fact that a company is market driven is not an accurate indicator of
> the level of engineering behind its products, however. If you have any
> FACTS about the competence of the designers at Sampson, please share
> them with us all.
Engineering and marketing have to be worked together hand in hand.
You could have Gods gift to BB design but if it doesn't look cool,
I don't think you are going to sell too many of them. Sounds stupid
I know but that is the products are sold. Both have their value on
the bike shop shelf.
Much of what goes into designing a car is market driven. Meeting
customer demands. We engineers then have to make sure that it meets
safety standards and design requirement. This makes for a very
challenging job. If no safety standards existed, a vehicle would
be a much easier to engineer and design.
Yes, standards for bicycle parts would be a big improvement over,
buy it and hope it works for you. The industry would be much better
off as a whole. Manufacturers would have the opportunity to compare
consistent numbers and possibly set up more realistic targets for
their products to meet. This would undoubtedly remove some of those
stupid light parts from the shelves.
Rob
email: |"You can't take life too seriously,
rho...@tbd161.tbd.ford.com | you don't get out alive." Bugs Bunny
rich...@cruzio.com
I don't know what Jobst knows about Sampson, but judging the design
on engineering principles it is not well thought out. At least the
one we saw a year ago. The "fluted" center section and small journal
diameters are not solutions to any mechanical problems and could be
construed as a design exercise. I think the test results back this
up clearly.
KB
L. Scott Harvell
All of the information that I read on the Sampson bottom bracket mentions
an oversized spindle for stiffness, a commonly accepted theory, not the fluted
design. The flutes are claimed as a weight savings, kind of like double butted
tubing (again a fairly well accepted theory). And as far as the weight issue
mentioned by Jobst the Sampson in question weighs in at 139g which is 61% of
a Campagnolo Record bottom bracket (225g) and 57% of a Shimano Dura-Ace bottom
bracket (240g), so as a percentage that seems fairly good to me.
Now I will agree that Ti bottom brackets are likely not the best idea for a
long lived use however neither are extralight handlebars or a number of other
light parts. That does not mean that they do not have their uses, If weight
means more to you then money then go for it and keep a close eye on the part
and change it often. The makers of extra light parts will love you for it.
I have never used any of these parts myself nor do I know anyone who does
but each one of the replies that I have seen has carried as much misinformation
in it as you are claiming of others. If you have specifics to counter a claim
them put it in. If you are guessing at what the actual claims might be get
more information before you reply.
Just trying to inject a little rational into the discussion.
--
L. Scott Harvell "America a great place to get your knickers
har...@cnfusd.enet.dec.com twisted"
Certainly no one would claim these opinions, other then me!
Jeffrey L. Bell
>...
>When I think of Campagnolo and Shimano, fluted seatposts immediately come
>to mind (I digress from fluted BB spindles). Why would those companies
>put flutes in their seatposts? There are no good reasons for such an
>engineering change. Spooky. Makes me wonder about their testing
>procedures.
Except that seat posts are under bending stresses.
The midsections of BB spindles are under torque.
While fluting does nothing for torque, it can inprove the
stiffness/gram in bending.
-Jeff Bell
John Olsen
>
My favorite example of a silly, non-functional frill on a boutique bike
part is the shear wall up the middle of the Control Tech seat post, a
clever feature that makes the post 8% weaker in bending than if they
simply distributed the same amount of material around the ID. Nothing
looks quite as HiTech as the fluted BB, though. That one is visually
the cake.
Olsen
Gordon D. Renkes
>I suspect that if I dug around Hewlett Packard's basement I could find
>products which exhibit similar design eccentricities (perhaps something
>designed by Jobst?). Were I to make statements the like of which I refer
>to above, I wonder how long I would have to wait before I got a letter
>from their attorney.
I have used Hewlett Packard scientific equipment for years in
various laboratories. With only a couple of exceptions, they are
built like nuke-proof brick outhouses. Reliable. Work as advertised.
Realistic specs. And when there are problems, I can get for free plenty
of assistance from their repair personnel over the phone. I have had
2 of their hard disc drives (which I believe is Jobst's area) running
day and night for 6 years on one system, with no need to repair and no
data lost due to hardware failure.
If bicycles were built to the same standards as HP equipment, I
doubt if we would hear as much discussion about creaks, wobbles, recalls,
catastrophic breaks, etc.
Did you ever think about starting your own bicycle company, Jobst?
?!
Gordon Renkes renk...@osu.edu
THE Ohio State University
120 West 18th Avenue
Columbus Ohio 43210
USA "Just the FAQ's, Ma'am"
ALAN FAIRLEY
>The midsections of BB spindles are under torque.
>While fluting does nothing for torque, it can inprove the
>stiffness/gram in bending.
If in fact, fluting does reduce the torsional resistance of the spindle, is
the torsional load on the spindle great enough for this
decrease in resistance to make any difference? (Of course, if the answer
is no, then the question becomes why not just have a smaller diameter
spindle in the first place).
Ericdw
collective opinion about that?
Also, is everyone forgetting the miserable Campagnolo Ti spindles from
the late 70's and the Ti spindled XTR BB's that adorn many of the pro's
factory bikes? Word from a friend is "Light, but you need to replace it
once a year."
To get back at an earlier statement, the highest stress riser on a
spindle is usually at the lip where the bearings seat. Every failed
spindle I have seen has failed at that shoulder. Although the fluted BB
spindle may be a classic case of tail fins, the bearing shoulder is a far
more agregious error. But then again what the hell do I know, I ride a
frame with fluted tubes, and I dare to like it.
Eric W
Keith Bontrager
I have used an HP plotter for the last 6 years. The first one died when
a mouse pissed on the main board. It was way obsolete and it would have
cost more to repair than to replace. It is gathering dust in my garage.
Anybody want a dead 9772s?
I moved up to a Draftmaster EXL. It crapped out after about 6 months.
Since I purchased it second hand, I don't know the exact milage. I
purchased it from a one man architechural office when the guy retired.
My bet is that it was not thrashed at the time. I was at the mercy
of the documentation and the repair staff.
The problem first problem ended up simple to repair using the documentation.
It was not inexpensive, but no one ever promised it would be. The
trouble shooting flow charts were pretty good.
It went down again 6 months later. The same procedures pointed to too
many possible components that I could not diagnose. I was then at the
mercy of a technician. He had to make a house call since they would
not accept a machine of that size in their repair facility. We called,
got a target date for the tech to arrive, and waited.
And waited. Then we got a call and the person at HP said that they
were too bust to get to our place at the original time, but that
for an upcharge we could get a higher priority and they would be
right out. Nope. Same thing 2 days later. Nope, we repeated.
The house call cost $400.00 for the first small increment of time,
and we didn;t think it was prudent to bump this up any higher. The
machines were fetching $2k to $2.5k used at the time. A long visit
or a liberal upcharge would spoil the day for us. Not for them.
The guy arrived finally. Most of the first 25 minutes was spent
in diagnosis. Got it solved in less than 30. Didn;t have the
parts and a return trip would be another $400. The replacement
was not that tough, but I would have to try it without testing
since I didn't have the appropriate equipment. No complaints -
if you have tricky stuff and you can't handle the repair, you're
taking chances. And this can go wrong sometimes.
The last 1/2 hour of the tech's $400 dollar visit was spent scamming me
for cheap bike parts. What the hell, he figured I'd paid for the
time and he had nothing better to do with the rest of the hour. He
was not a cyclist, and I imagine that it was common to try to add
swag like thjis along the way. He left me his card and suggested
that I call him directly next time. I made a note of this.
The bill came with the priority upcharge added on and we had to
argue for hours to get it backed out. The machine has performed
well since. If the analogous situation had occured with a bike
company, I would not get too carried away with the praise I heaped
on. It is clear that, with respect to customer service or after
the warrantee is over repair, that the personality of the
individuals that you deal with and the constraints applied by
the organization (no you must not try to scam customers) matter.
We've had our low points as well.
KB
Robert Horvatich
> Look at some of the styling excess in the automotive industry
> that gets in the way of functionality. Does this mean that there is a
> lack of engineering expertise, or just that the marketing and styling
> guys have the final say?
Just FYI, styling does govern much on how a car is shaped inside
and out. Packaging and safety drive much of the rest of the design.
If engineers where responsible for the shape of a vehicle, you
would have cars that would be easy to assemble and work on but most
likely ugly as sin. What you see and experience when you drive and work
on a car is the compromise between different areas of marketing, styling,
engineering, safety, manufacturablity, cost, weight, and probably a
couple of other area I forgot and some more I don't know about yet.
Michael O'Hair
>
>Here, Jobst has already decided, on the basis of a fluted bottom bracket,
>that the engineers at Sampson have "little mechanical knowledge", their
>other products will undoubtedly have "foolish flaws", and that they do not
>"do any measurements in their tests." This is not only a reckless
>statement, it borders on libelous.
>
>I suspect that if I dug around Hewlett Packard's basement I could find
>products which exhibit similar design eccentricities (perhaps something
>designed by Jobst?). Were I to make statements the like of which I refer
>to above, I wonder how long I would have to wait before I got a letter
>from their attorney.
>
Probably longer than the national magazine that reviewed the Sampson road bike
and found the crank arms so flexy that they were deemed to be dangerous and
replaced with another brand. Sampson has since changed their crank arms.
The question is: did they recall the earlier versions or issue a warning?
Jobst Brandt
>> When I see such designs I realize that there is little mechanical
>> knowledge at such companies and it is spooky to think of what other
>> foolish flaws are designed into their products. They certainly don't
>> do any measurements in tests or they would realize the errors of such
>> designs.
> Here, Jobst has already decided, on the basis of a fluted bottom bracket,
> that the engineers at Sampson have "little mechanical knowledge", their
> other products will undoubtedly have "foolish flaws", and that they do not
> "do any measurements in their tests." This is not only a reckless
> statement, it borders on libelous.
I-beam sections for a torsional element is a clear misunderstanding of
engineering and the size of the pedal eye of the crank is an
indication of failure to perform appropriate tests. Cranks break and
they break most often through the pedal eye. When a crank fails from
fatigue it is usually detectable before failure because the crack is
exposed. A spindle failure is not detectable, because it generally
occurs inside the press fit of the crank. When a crank or spindle
fails, when the rider is standing (the condition under which most such
failures occur) and moving more than 10 mph, it is a certain fall
toward the side of the failure. If a left crank or pedal comes off
while riding next to traffic, the rider will most likely fall into the
path of that traffic.
I believe that equipment on bicycles is not held to the safety
standards to which we are accustomed in most other products that we
buy because bicycling is viewed as a dangerous endeavor and a special
category of risk. I have seen my share of material failures and I am
not ready to try new components that are thinner lighter, made of
light weight metals and that do not measure up to the current best
hardware.
I learned the hard way about aluminum stem expander bolts, light
weight saddles, early single bolt seat posts, streamlined bar stem
clamps, non steel QR devices for wheels, aluminum handlebars, pedals
and other items that were claimed to be new and better but broke,
there where a skeptical and observant person should expect a failure.
> I suspect that if I dug around Hewlett Packard's basement I could find
> products which exhibit similar design eccentricities (perhaps something
> designed by Jobst?). Were I to make statements the like of which I refer
> to above, I wonder how long I would have to wait before I got a letter
> from their attorney.
That's pretty slick weaving of concepts. Now I'm speaking for Hewlett
Packard and they are suing whom?
Lets get back to the subject. I observe two components that violate
well understood engineering principles. One uses titanium in the same
dimensions that specially selected steel is already marginally strong
enough, and it uses a longitudinally fluted torsion shaft. The other
uses an I-beam as a torsion member and bending in the non-preferred
axis.
If you observe the mode of failure of most cranks, you will find that
they break (at or near the pedal eye) from bending. This occurs at
the bottom of the stroke when the rider's full weight steps off to the
other foot that is at the top of the stroke. The I beam structure
loaded 90 degrees from its preferred bending orientation is highly
susceptible to crack initiation on the edges of the "caps". I find
this worth commenting on and I am expressing my opinion. I represent
no one but myself. You are entitled to do the same, unless you have a
vested interest in the matter at hand, in which case it colors your
opinion and may also have other ramifications.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> All of the information that I read on the Sampson bottom bracket
> mentions an oversized spindle for stiffness, a commonly accepted
> theory, not the fluted design. The flutes are claimed as a weight
> savings, kind of like double butted tubing (again a fairly well
> accepted theory). And as far as the weight issue mentioned by Jobst
> the Sampson in question weighs in at 139g which is 61% of a
> Campagnolo Record bottom bracket (225g) and 57% of a Shimano
> Dura-Ace bottom bracket (240g), so as a percentage that seems fairly
> good to me.
How about comparing the spindle weight to a conventional steel spindle.
The weight savings advertised is assuming all the weight difference is
in the spindle and it is not.
Jobst Brandt <jbr...@hpl.hp.com>
John Olsen
>
> Boone Technologies makes a Ti spindle with spiral flutes. What is the
>collective opinion about that?
An open section in torsion will always have miserable specific stiffness
numbers. Always. The Boone BB is "cool" looking, and probably sells
pretty well. See above posts on marketing uber engineering!
> To get back at an earlier statement, the highest stress riser on a
>spindle is usually at the lip where the bearings seat. Every failed
>spindle I have seen has failed at that shoulder. Although the fluted BB
>spindle may be a classic case of tail fins, the bearing shoulder is a far
>more agregious error. But then again what the hell do I know, I ride a
>frame with fluted tubes, and I dare to like it.
>
Cool! Dare to be different! Actually, the fluted tubes are, at least,
closed sections, and they are probably only a LITTLE worse than plain ol'
round ones. Enjoy. Ride.
Don't forget there are two issues here- strength (as in avoiding outright
yielding or breaking, either outright or after many fatigue cycles)
and stiffness... The flutes don't help either much, but they sure don't
do much for the BB's torsional stiffness. They WOULD help in bending. To
those that own and love them, I say, "Enjoy. Ride. Go in peace."
Olsen
Dan Empfield
<<I-beam sections for a torsional element is a clear misunderstanding of
<<engineering and the size of the pedal eye of the crank is an
<<indication of failure to perform appropriate tests. Cranks break and
<<they break most often through the pedal eye.
You bring up a very interesting point, on a variety of levels. If I
understand you correctly, you are calling into question the viability of a
crank which is made with an I-beam design, and I will offer Kooka as an
example of what I think you're referring to.
Certainly there is a torsional element to the stress on a crankarm. I am
not a maker of cranks, but it would seem to me that the torsional element
is not the only, nor even necessarily the major, element.
In fact, it would seem to me, the torsional element changes relative to
both the mechanics of a rider's pedal stroke and his biomechanical
idiosynchrosies (i.e., I have no empirical data, but I can envision a
supinator applying a greater torsional component to the load than a
pronator). It could be that the torsional element for many riders is
slight enough so that an I-beam style crank could work well.
To continue Kooka as an example, the cranks are quite light, (identical to
Topline on my scale), and it seems I remember them testing quite well in
some stiffness tests that Velo News (or somebody) did.
I'm rambling, but my point is that you have a penchant for making syllogisms:
"I-beams are bad torsionally",
"crankarms must exhibit torsional strength", ergo
"I-beam crankarms are a bad idea."
"bad ideas are put forth by bad engineers"
"I-beam cranks are a bad idea", ergo
"a manufacture who makes an I-beam crank employs bad engineers."
<<I have seen my share of material failures and I am
<<not ready to try new components that are thinner lighter, made of
<<light weight metals and that do not measure up to the current best
<<hardware.
I have a non-rhetorical "no-agenda" question for you. Have you, in your
personal experience plus the firsthand experience of your friends,
exhibited a greater degree of failure in the newer, usually lighter,
generation of components vs. Campy, Shimano, etc.? The reason I ask is
that I have had at least as high a degree of failure in the latter as in
the former.
QRman
L. Scott Harvell
Jobst Brandt writes:
I was comparing products that I could buy. The only data point that I have
on a steel spindled bottom bracket of similar construction, ie not a sealed
unit, is a Cooks Brothers that weighs 264g which is heaver then both the
sealed units.
So I think what Gary is saying, correct me if I am wrong Gary, is that
there is nothing that prevents marketing and engineering from producing
something that they both feel is a good and worthwhile product. I doubt
that you know how much testing is done, or what the failure rate is for the
Sampson BB. You are basing you comments on a given design that you have not
studied enough to determine their own claims. I would expect you of all
sources on the net to at least have some information to back up their
statements. And the only comments that you have posted here would apply to
all Ti BB's so your original comments about Sampson should have been applied
to any maker of Ti BB's. Unless of course you have something that shows the
Sampson BB to be inferior to other Ti BB's, in which case please share it
with us.
I have no information about Sampson BB's at all so I am not going to comment
on the reliability of them. Certainly many people out there use Ti BB's so
its hard to say that everyone out there will "fall out into traffic" if they
use one. It pays to be well informed about good and bad uses for a material
and what precautions one should be prepared to take.
Me? I have a superlight Ti frame, 2.6 lbs made by Gary's ex partner (Mike
Augspurger), and I run 26 inch wheels with 28 14/15/14 spokes, also light.
However it has a stock Shimano bottom bracket and stock Ultegra cranks for
the vary reason that I believe that they are less likely to break. Light
even stupid light may have its purposes as long as the user understand what
they are getting into.
So please if you are going to blast an item for its design or material at
get the designers claims straight or go after the whole technical issue.
As in all Ti bottom brackets are a bad design!
Stephen Hynes
Jobst point deserves more emphasis than even he gives it. There are many intelligent
ways of saving weight on bikes, and the large companies - Shimano, etc. - have
found most of them. They have an obvious interest in both performance and
safety, the latter mostly because of their size and exposure to liability. Small, technically
challenged producers of light weight components abound. Some actually grow into
into reasonably large enterprises, and even develop enviable reputations. The fact that they
experience high failure rates does not appear to be news. The question
is never asked. Even bike shops, who get to see these parts coming in, injured
riders in tow, seem to shrug it off. "They'll replace it free" is accepted by too many
customers.
Everyone should report their failed components here. Perhaps a log could be made of
them. I have a long list, but I am afraid that I would be accused of sour grapes or
something were I to share it. Perhaps Jobst would share his obviously extensive list
of failures?
Steve Hynes
Jim Papadopoulos
> In article <3l0dhg$8...@newsbf02.news.aol.com>, eri...@aol.com (Ericdw) says:
> >
> > Boone Technologies makes a Ti spindle with spiral flutes. What is the
> >collective opinion about that?
>
> An open section in torsion will always have miserable specific stiffness
> numbers. Always. The Boone BB is "cool" looking, and probably sells
> pretty well. See above posts on marketing uber engineering!
>
Helical flutes change the torsional stiffness picture (better than
straight flutes, in BOTH torsional directions) and the bending stiffness
picture (worse). Paper/pencil analyses are not so simple but can be done.
Note that I am NOT 'approving' the above-mentioned spindle, but I do think
the torsional flexibility is not so clear.
JP
Jim Papadopoulos
> My favorite example of a silly, non-functional frill on a boutique bike
> part is the shear wall up the middle of the Control Tech seat post, a
> clever feature that makes the post 8% weaker in bending than if they
> simply distributed the same amount of material around the ID.
Ummm -- are you talking about a thin web in the centerplane of the
bicycle, joining the front to the back of the seatpost?
My impression was, that thinwall posts could have sufficient bending
strength, but that some kinds of frame clamps (steel bands around a
slotted tube-end) actually dimpled seatposts as the clamp heels pressed
inwards. Whether that was a cosmetic or more serious problem, I thought
the web was to prevent it.
???? JP
David Tan
Dan Empfield <QR...@cts.com> wrote:
>In article <D646F...@hpl.hp.com>, jbr...@hpl.hp.com (Jobst Brandt) wrote:
>
><<I-beam sections for a torsional element is a clear misunderstanding of
><<engineering and the size of the pedal eye of the crank is an
>
>Certainly there is a torsional element to the stress on a crankarm. I am
>not a maker of cranks, but it would seem to me that the torsional element
>is not the only, nor even necessarily the major, element.
>To continue Kooka as an example, the cranks are quite light, (identical to
>Topline on my scale), and it seems I remember them testing quite well in
>some stiffness tests that Velo News (or somebody) did.
Could you describe the testing procedure? The few tests I've seen
apply a dead load directly to the pedal eye of the crank (Winning
and Bullseye's ad) Now it seems to me that in a real world situation,
the load is applied to an extension of the crank which is orthogonal to
the crank and which has a dimension which is a fair fraction of the
crank length (even if you take just the mid-point of the pedal spindle
as an average.) Even if in-plane stiffness is the major element in total
deflection, it is not the only one. Jobst's pronouncements may be rather
sweeping in some respects, but I agree with his main point, namely that
there is a lot of unproven stuff out there which show egregiously poor
engineering (did I really see an ad for an I-beam section stem?!) and
which sells apparently on marketing hype and a different "look". Which
is alright by me so long as they make no unfounded performance claims
(and do not pose excessive risk to the user)
>[...]
>I have a non-rhetorical "no-agenda" question for you. Have you, in your
>personal experience plus the firsthand experience of your friends,
>exhibited a greater degree of failure in the newer, usually lighter,
>generation of components vs. Campy, Shimano, etc.? The reason I ask is
>that I have had at least as high a degree of failure in the latter as in
>the former.
The problem with this approach is that such a basis set is usually
too small to draw any statistically valid conclusions. A given
person may have better luck year-in, year-out with a Huret Jubilee
rear derailleur than another with Super Record. Still and all,
whether statistically valid conclusions and the most thorough of
stiffness tests should have anything to do with a person's decisions
are entirely up to the person, of course (fortunately, I suspect,
for many a boutique manufacturer) Biking is as much a matter of the
heart as anything. (This does not mean, of course, that I think that
a manufacturer ought to be able to claim something--stiffness, say--
without being able to back it up and state how they do so!)
Dave
Martin O'Toole
2 ounces probably, 3 tops, and what, $50-60 more AND potentially
unreliable? Not me. -Matt
Martin O'Toole
Good idea! I'll start with Shimano freehub bodies (every 6 months), all
brands of latex inner tubes, a Zoom 130 handlebar (what was I thinking
anyway), the original push-push Rapidfire shifters (thankfully
improved), and the locknuts on Shimano hubs (pot metal). I could keep
going, but I'll stick to the ones that almost killed me for a start.
Matt
Jobst Brandt
>> I-beam sections for a torsional element is a clear misunderstanding of
>> engineering and the size of the pedal eye of the crank is an
>> indication of failure to perform appropriate tests. Cranks break and
>> they break most often through the pedal eye.
> You bring up a very interesting point, on a variety of levels. If I
> understand you correctly, you are calling into question the viability of a
> crank which is made with an I-beam design, and I will offer Kooka as an
> example of what I think you're referring to.
> Certainly there is a torsional element to the stress on a crankarm. I am
> not a maker of cranks, but it would seem to me that the torsional element
> is not the only, nor even necessarily the major, element.
Torsional weakness is probably more a performance problem than a
failure problem. The material is not efficiently used so the crank is
more flexible than it could be. You'll notice that both Campagnolo
and Shimano, no longer put a beauty groove down the face of their
cranks. Although this feature made old Campagnolo Record cranks more
elegant looking it reduced the torsional rigidity by a perceptible
amount but had no apparent effect on its failures.
> In fact, it would seem to me, the torsional element changes relative to
> both the mechanics of a rider's pedal stroke and his biomechanical
> idiosyncrasies (i.e., I have no empirical data, but I can envision a
> supinator applying a greater torsional component to the load than a
> pronator). It could be that the torsional element for many riders is
> slight enough so that an I-beam style crank could work well.
That rings like a dodge and weave to me, with enough disclaimers to
defy disagreement. You and riders who want to believe this are
entitled to do so. I can't argue against what you prefer for whatever
reasons but I can say these reasons have no technical basis.
> To continue Kooka as an example, the cranks are quite light, (identical to
> Topline on my scale), and it seems I remember them testing quite well in
> some stiffness tests that Velo News (or somebody) did.
I don't know why Kooka cranks are the basis for this discussion. I
haven't mentioned them and haven,t seen any lately so I can't say what
they might do. If they are I-beam shaped cranks then they are not
using the metal to their best advantage, regardless of how well they
perform any of their functions. Do you believe that the major
manufacturers don't know why their cranks all look alike and why they
do not have I-beam cross sections?
> I'm rambling, but my point is that you have a penchant for making
> syllogisms:
> "I-beams are bad torsionally",
> "crankarms must exhibit torsional strength", ergo
> "I-beam crankarms are a bad idea."
> "bad ideas are put forth by bad engineers"
> "I-beam cranks are a bad idea", ergo
> "a manufacture who makes an I-beam crank employs bad engineers."
Hey I think he's got it. As Henry Higgins would say of Eliza Doolittle.
>> I have seen my share of material failures and I am not ready to try
>> new components that are thinner lighter, made of light weight
>> metals and that do not measure up to the current best hardware.
> I have a non-rhetorical "no-agenda" question for you. Have you, in
> your personal experience plus the firsthand experience of your
> friends, exhibited a greater degree of failure in the newer, usually
> lighter, generation of components vs. Campy, Shimano, etc.? The
> reason I ask is that I have had at least as high a degree of failure
> in the latter as in the former.
I found that Campagnolo C-Record cranks broke in about 1/5 the
distance that the prior Record cranks did and noticed that their pedal
eyes had a smaller cross section than the earlier cranks. It was this
and inspection of the Dura Ace crank that moved me to switch to them.
As I said, I don't use material that is visibly scrawnier in
dimensions than the best that I have tried so I have never put out the
extra money and risked injury to try off brand products.
Earlier I was given things like aluminum stem expander bolts (that
appear to be static devices once tightened) that broke at the threads
from the dynamic loading. I tried pedals whose aluminum cages broke
where even my old Campagnolo steel ones ultimately broke. I have
witnessed seat post clamps fail and know of one rider who will never
be the same from falling, locked in the cleats, onto the back tire
when his saddle separated from the post. He may yet need a colostomy
because his sphincter was severely damaged. Aluminum bars with
expanded center sections have also separated at the stem because
clamping forces crimp the thinner wall and cause a stress
concentration. Plenty of these fail.
I think the manufacturers owe themselves a return to basics and that
they must earn their own credibility. Over the long haul, credibility
cannot be built by advertising. The truth comes out, even if it takes
awhile. That cranks break was swept under the rug for a long time.
The bicycle press is one of the unwitting conspirators in this because
they fear what their advertisers' reactions might be if they were to
report factually and without omission.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
>> How about comparing the spindle weight to a conventional steel
>> spindle. The weight savings advertised is assuming all the weight
>> difference is in the spindle and it is not.
> I was comparing products that I could buy. The only data point that
> I have on a steel spindled bottom bracket of similar construction,
> ie not a sealed unit, is a Cooks Brothers that weighs 264g which is
> heaver then both the sealed units.
The point is that the fluted shaft is weaker in torsion, the principle
perceptible compliance while pedaling, than it would be as a straight
shaft of constant and smaller diameter. The bending stiffness affects
derailleur cage clearance and may be the reason they fattened the mid
section and then to counter the increased weight cut grooves that
compromised torsional strength. In any case, the failure point is most
likely still at the place where steel spindles break and that is inside
the press fit of the crank.
> So I think what Gary is saying, correct me if I am wrong Gary, is
> that there is nothing that prevents marketing and engineering from
> producing something that they both feel is a good and worthwhile
> product. I doubt that you know how much testing is done, or what
> the failure rate is for the Sampson BB. You are basing you comments
> on a given design that you have not studied enough to determine
> their own claims. I would expect you of all sources on the net to
> at least have some information to back up their statements. And the
> only comments that you have posted here would apply to all Ti BB's
> so your original comments about Sampson should have been applied to
> any maker of Ti BB's. Unless of course you have something that
> shows the Sampson BB to be inferior to other Ti BB's, in which case
> please share it with us.
Well, wasn't that what I said? As I pointed out, titanium has a
problem of material strength at a place where the cross section has
been defined by the industry for a steel part. This can only be
improved by going to non standard dimensions and maybe someone will do
it, as head bearings did awhile ago although this may not have been a
great leap forward.
> I have no information about Sampson BB's at all so I am not going to
> comment on the reliability of them. Certainly many people out there
> use Ti BB's so its hard to say that everyone out there will "fall
> out into traffic" if they use one. It pays to be well informed
> about good and bad uses for a material and what precautions one
> should be prepared to take.
As long as they are aware of the risk and believe that for their use
titanium is sufficiently strong, that's fine. I am concerned that the
idea that titanium is as strong or better than steel (at some expense)
is being put forth. At present this is untrue and odd and unusual
machining should not be misinterpreted as a solution to the materials
problem.
> Me? I have a super light Ti frame, 2.6 lbs made by Gary's ex partner
> (Mike Augspurger), and I run 26 inch wheels with 28 14/15/14 spokes,
> also light. However it has a stock Shimano bottom bracket and stock
> Ultegra cranks for the vary reason that I believe that they are less
> likely to break. Light even stupid light may have its purposes as
> long as the user understand what they are getting into.
That's great and if you present it in these terms, I have no
complaint. As you probably know you can get conventional 24 spoke
rims also and aero wheels often use 18 spokes. Many things work but
they have limitations that should not be ignored or hidden.
> So please if you are going to blast an item for its design or
> material at get the designers claims straight or go after the whole
> technical issue. As in all Ti bottom brackets are a bad design!
I think you jump to conclusions when you think I singled on maker out
for something that is widespread. Someone else presented Sampson as
an example and I took issue with their approach for the reasons that I
believe are valid.
From this exchange an apparent need for disclaimers seems to have
arisen. I have always found disclaimers at the end of every posting
to be ridiculous but now I find those who make assumptions about
responsibility for things posted here more ridiculous.
Jobst Brandt <jbr...@hpl.hp.com>
David Walker
>
>In article <3k77s1...@marvin.wdi.disney.com>,
>Chris Gee <ch...@fa.disney.com> wrote:
>>jpzi...@cats.ucsc.edu (Jeffrey Peter Ziegler) writes:
>>>I was wondering what people thought that the best Ti bottom bracket was?
>>>I know that the stratics from sampson ahs gotten a lot of press lately,
>>>but one of my firends had trouble with it. Has anyone else experienced
>>>any difficulty? Are there other brands that should be looked at?
>>>Thanks for the info!! Jeff -jpzi...@cats.ucsc.edu
>>
>>FISCHER DAVID ALEXANDER (fisc...@ucsub.Colorado.EDU) wrote:
>>: Only two choices for DURABLE Ti BB's.
>>: Phil Wood
>>: Bontrager
>>:
>>jol...@techcenter.paccar.com wrote:
>>> ... Ericson Ti BB is the most elegant design I've seen. Union/Frondenburg
>>> is carrying them. Big, hollow, Ti tube in the middle- as stiff as a
>>> conventional BB could be.
>>
>>p...@interramp.com wrote:
>>* I have been using White Industry Ti spindle, they have been making them
>>* forever. This White Ind. spindle is hollow but if you are a heavy,
>>
>>I'd like to add my choice:
>>
>> Paragon - in my Kestrel 200ems(Dura-Ace)
>>
>>I wonder if Nuke Proof makes Ti BB's as well?
>>(I have NP Ti hubs on my MTB.)
>>
>>chris
>
>
>I've been using a Syncros Gorilla (older dual drive side bearing) for a
>couple of years now, no problems at all, and I weigh 215 pounds on a good
>day. Kinda related - anyone out there have FIRST HAND experience with
>broken ti bb spindles? Not steel, but TITANIUM!!!! (I got too many
>'...broke an XT blah...') I have never seen one broken, and while I am
>sure that they have, I'm not so sure that they are as fragile as some
>say. Bye.
>Mannix
>
Yes, I have: the (in)famous Campy Super Record bb from the mid-'70s. At
that time, they made them out of CP (commercially pure) grade Ti, which
is less than 1/2 as strong as Ti6Al4V, which everyone uses today. Even
Campy figured out, though, that by making the axle solid rather than
hollow that they could stand up pretty well. I've been riding on a "Type
II" solid Super Record bb for 5 years with no problems. Maybe it IS out-
dated, but so is the rest of my Super Record-equipped Masi 3V... I weigh
160lbs., which helps. I agree with your comment, though, in that I've
seen quite a few steel axles broken over the years. Granted, they're
usually pot-metal variety, but nonetheless...
I've installed several Sampson Stratics bb's, and Jobst Brandt's comments
aside, they've been working fine. It IS important to make sure the bearings
are fully seated in the cups when installing--I had some problems initially
with lateral play developing because of this. The trick is not to tighten
one cup/lockring side until BOTH cups are fully seated, then carefully
tighten them together. Whether they are the best design is debatable, but
in response to Mr. Brandt's rantings, I would ask this: Does ANYBODY out
there know of a Stratics bb axle actually breaking in use (or anyone else's)?
wal...@boulder.nist.gov (Dave Walker)
Bruce Rowen
>
>Jobst Brandt writes:
>
>>L. Scott Harvell writes:
>>
>>> All of the information that I read on the Sampson bottom bracket
>>> mentions an oversized spindle for stiffness, a commonly accepted
>>> theory, not the fluted design. The flutes are claimed as a weight
>>> savings, kind of like double butted tubing (again a fairly well
>>> accepted theory). And as far as the weight issue mentioned by Jobst
>>> the Sampson in question weighs in at 139g which is 61% of a
>>> Campagnolo Record bottom bracket (225g) and 57% of a Shimano
>>> Dura-Ace bottom bracket (240g), so as a percentage that seems fairly
>>> good to me.
>>
>>How about comparing the spindle weight to a conventional steel spindle.
>>The weight savings advertised is assuming all the weight difference is
>>in the spindle and it is not.
>>
>>Jobst Brandt <jbr...@hpl.hp.com>
Sampson Stratics 130mm 103g (delrin cups)
Sampson Stratics 122mm 98g "
Sampson Colorado 108mm 161g (2024 Al cups)
Ritchey LogicPro 120mm 290g (includes bolts)
Ritchey LogicProWCS 123mm 269g (Ti bolts)
Ritchey LogicComp 120mm 289g (includes bolts)
Phil Carbon/Ti 119mm 164g
Phil Sealed 113mm 262g (w/o rings)
Shimano UN51 113mm 344g (complete)
Shimano UN71 115mm 273g (complete)
Shimano UN91 113mm 239g (complete)
MRC Ti BB/GUN 113mm 181g (w/bolts)
Lightspeed Ti 113mm 151g (w/o bolts)
ATB Ti 123mm 196g (w/bolts)
Grafton Speed Ti 125mm 175g (w/o bolts)
Cook Bros. Ti 120mm 212g (w/bolts)
.
.
.
.
.
.
.
(Many, many more source:Bike Pro Buyer's Guide)
Weights somtimes are for the complete BB including washers and bolts,
sometimes not.
Initial impressions are that the Sampson BB gets its weight advantage
from the Delrin (plastic) cups.
Most of the dimensional info given suggests that manufactures use the
same dimensions for both their Ti and CrMo spindles.
---
-------------------------------------------------------------------------------
Bruce Rowen National Radio Astronomy Observatory
Scientific Programmer Array Operations Center
bro...@aoc.nrao.edu P.O. Box O Socorro, NM 87801
(505)835-7329 (505)835-7000
-------------------------------------------------------------------------------
Jim Papadopoulos
>
> Everyone should report their failed components here. Perhaps a log could
be made of
> them. I have a long list, but I am afraid that I would be accused of
sour grapes or
> something were I to share it. Perhaps Jobst would share his obviously
extensive list
> of failures?
I'd love to see such a list, and could contribute a fair number of
examples myself. (If you're interested in outdated parts!)
Remember though that 0.1% failure rate on Shimano parts (say) would look
far worse than a 10% failure rate for a small manufacturer, in terms of
the numbers.
Straying pretty far from the subject: I need to get a range of examples of
field failures, so as to 'calibrate' my testing protocol by producing a
similar fracture initiation pattern. Anyone who would sell me (or 'rent'
me) broken handlebars, please email me. I'm not talking big $$$ here, say
$10 incl. shipping.
(I'll be getting into other parts later.)
Jim Papadopoulos
(normally at bicyc...@delphi.com )
Brad Anders
>On 23 Mar 1995, Gary Helfrich wrote:
>>
>> You might be offended by engineering taking a back seat to marketing.
>> The fact that a company is market driven is not an accurate indicator of
>> the level of engineering behind its products, however. If you have any
>> FACTS about the competence of the designers at Sampson, please share
>> them with us all.
>
>Engineering and marketing have to be worked together hand in hand.
>You could have Gods gift to BB design but if it doesn't look cool,
>I don't think you are going to sell too many of them. Sounds stupid
>I know but that is the products are sold. Both have their value on
>the bike shop shelf.
I have one of the aforementioned Sampson BB's. It is sitting up on a shelf
in my garage right now, after listening to a friend of mine tell me how he
broke his spindle while climbing in the Santa Cruz mountains and it took
him a couple of hours before he was able to get someone to help him get
home. I also have a very nice Topline crank sitting on the shelf, too.
Another friend of mine broke it out at the pedal eye.
I bought both of these products not because they "looked cool" but because
I race and was trying to find some very light components that I thought might
hold up for a while under racing and training conditions. When I see a rider
with identical equipment break these components in less than six months of
use, I make my own judgement call about their durability.
I have since switched to the "new" DA cranks and DA sealed BB. Surprisingly,
the combined weight of the two isn't that far off from my Sampson/Topline
combo, something on the order of 100 gm heavier. For about a 100 gm penalty,
I get a steel spindle, much better bearings that don't need critical and
constant re-adjusting, stiffer crank arms and spider, and two high-quality
DA chainrings included, all at a considerably lower cost.
--
*******************************
* Brad Anders / Sunnyvale, CA *
* ban...@netcom.com *
*******************************
John Terry
about them that has nothing to do with how well they are engineered.
Do all Ti BB's creek under hard pedaling?? There is nothing more anoying
than ascending a grueling climb and having to listen to a creek every
pedal stroke. I have tried everything to eliminate the nussance with no
luck. I even tried teflon on the BB spindle before assembly. At this
point, I'm back to my steel shimano XT BB. At least it is quiet.
________
/ / ~ Kick back...
/ __ /_ _ John Terry ~ Relax...
/ / / / / / / terr...@uidaho.edu ~ Play a game of solitaire...
\__/ /__/ / / / / ~ Watch Windows crash...
John Olsen
>
>In article <3kvfl0$1...@ender.techcenter.paccar.com>, jolsen wrote:
>
>
>> My favorite example of a silly, non-functional frill on a boutique bike
>> part is the shear wall up the middle of the Control Tech seat post, a
>> clever feature that makes the post 8% weaker in bending than if they
>> simply distributed the same amount of material around the ID.
>
>
>strength, but that some kinds of frame clamps (steel bands around a
>slotted tube-end) actually dimpled seatposts as the clamp heels pressed
>inwards. Whether that was a cosmetic or more serious problem, I thought
>the web was to prevent it.
That is certainly possible, but isn't it in the wrong direction if that is
the case? The clamping loads are primarily 90 degrees to the web, that
is, side to side. No, I think that the main reason that the web is there
is that the uninformed pick up the part in the bike shop, think "Oooh,
this looks strong!", and buy it over a simpler-looking (but possibly
stronger) part with a circular or elliptical inside shape.
That is to say, marketing triumphs, yet again. Shocking. Unprecedented.
Even better, I once had a company send me a post with a Y-shaped extrusion
up the middle. If 1 shear wall is good, 3 must be better, ne c'est pas?
In fact, let's put ALL the material on the neutral axis! We'll make a seat
post which is just a strip of material oriented sideways. Hmmm,
suspension! Egad. I'm on to something!
JO :)
-Unruh,J.D.
Brad Anders <ban...@netcom.com> wrote:
>
>I have since switched to the "new" DA cranks and DA sealed BB. Surprisingly,
>the combined weight of the two isn't that far off from my Sampson/Topline
>combo, something on the order of 100 gm heavier. For about a 100 gm penalty,
>I get a steel spindle, much better bearings that don't need critical and
>constant re-adjusting, stiffer crank arms and spider, and two high-quality
>DA chainrings included, all at a considerably lower cost.
>
One of the interesting things I have noted on may "lightweight" components
is that you cannot compare what is sold to the major brands easily. The
quoted weights on some lightweight components don't include all the pieces,
which tend to be part of the quoted weight for Campy of Shimano.
Examples are cranks which generally include rings and chainring bolts
from major manufacturers and usually don't for the superlight parts, and
hubs which include a QR from major manufacturers and don't from most of
the smaller companies. If you can find weight data and comapre exactly
the same things, many of the superlight parts suddenly don't seem to save
as much weight.
John Unruh
Robert Horvatich
> In article <3l8k8c$r...@fun.Direct.CA>, shy...@Direct.CA (Stephen Hynes) wrote:
>
> >
> > Everyone should report their failed components here. Perhaps a log could
> be made of
> > them. I have a long list, but I am afraid that I would be accused of
> sour grapes or
> > something were I to share it. Perhaps Jobst would share his obviously
> extensive list
> > of failures?
>
> I'd love to see such a list, and could contribute a fair number of
> examples myself. (If you're interested in outdated parts!)
>
> Remember though that 0.1% failure rate on Shimano parts (say) would look
> far worse than a 10% failure rate for a small manufacturer, in terms of
> the numbers.
Another complication to this issue is that most of these small companies
feed the high end aftermarket group. It may be accurate to say that
there are more mountain bikes with shimano stuff on them just sitting
in garages than bikes with aftermarket parts invested in them. Just
another data point to muddy the waters.
Rob
Joshua_Putnam
>JIS (Japan Industrial Standard) standard D 9415, section 4 subpart
>(4) states:
> _Drop impact strength for the crank in vertical position_ A weight
> of mass of 10kg (including the weight base) being dropped from a
> height of 1000 mm
Is a weight of only ~22lb dropped once from a height of about a
yard really comparable to the sort of loading in mountain biking?
I'm thinking of a ~200lb rider grinding up a hill at ~40 rpm,
putting well over 200lb force on the pedals with each stroke. Do
this for several thousand cycles and I suspect you'll break quite
a few cranks that survive this standard.
--
Jo...@WOLFE.net is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
"My other bike is a car."
Bike parts for sale: finger Joshua...@gonzo.wolfe.net for list.
Mike Locke
>In article <3kifqc$a...@ucsu.Colorado.EDU>, man...@ucsu.Colorado.EDU (MANNIX IAIN RORY CAMPBELL) says:
>>
>>I've been using a Syncros Gorilla (older dual drive side bearing) for a
>>couple of years now, no problems at all, and I weigh 215 pounds on a good
>>day. Kinda related - anyone out there have FIRST HAND experience with
>>broken ti bb spindles? Not steel, but TITANIUM!!!! (I got too many
>>'...broke an XT blah...') I have never seen one broken, and while I am
>>sure that they have, I'm not so sure that they are as fragile as some
>>say. Bye.
I have a two year old (about 12000 miles) White Industries TI BB. It's
about due for a bearing change, but no axle problems to date.
>Yes, I have: the (in)famous Campy Super Record bb from the mid-'70s. At
>that time, they made them out of CP (commercially pure) grade Ti, which
>is less than 1/2 as strong as Ti6Al4V, which everyone uses today. Even
>Campy figured out, though, that by making the axle solid rather than
>hollow that they could stand up pretty well. I've been riding on a "Type
>II" solid Super Record bb for 5 years with no problems. Maybe it IS out-
>dated, but so is the rest of my Super Record-equipped Masi 3V... I weigh
>160lbs., which helps. I agree with your comment, though, in that I've
>seen quite a few steel axles broken over the years. Granted, they're
>usually pot-metal variety, but nonetheless...
Pot-metal is a zinc alloy, usually selected because it casts easily.
It is too weak to make even an inferior quality BB axle from, the axle
would break immediately. The cheapest BB axles (ignoring 1 piece cranks)
are made from carbon steel (medium or high?).
>
>I've installed several Sampson Stratics bb's, and Jobst Brandt's comments
> ...
>there know of a Stratics bb axle actually breaking in use (or anyone else's)?
Something Jobst has admitted once before and I would like to point out again:
Some people can "get away" with using ultra light parts. Jobst can break a
C-Record crank in 6 months (5000 miles?). I doubt that I could break a
C-Record crank in a life time. Jobst can force a bike with 42-17 gearing
up a 35% grade (I may have the numbers off a little bit, but you get the idea),
I know I couldn't get up that grade in a 39-32.
The point here is that Jobst would probably break my TI BB in no time. Likely
as not, he could break my Kestrel 200EMS frame as well in what he would call
"normal usage". None-the-less, these parts are more than adequate for me,
and I will continue to use them. I weigh 145 lbs and am not particularly
strong. Jobst weighs 175 lbs and *is* particularly strong. You need to
decide for yourself if these light weight parts are adequate *for you*.
Of course, it would be nice if there was some reasonable way to quantify
adequate in advance...
--
--
S'later, Mike Locke
Mark Huie
a bit techy.]
In article <3laqia$9...@wegener.ems.psu.edu>,
David Tan <t...@essc.psu.edu> wrote:
>Could you describe the testing procedure? The few tests I've seen
>apply a dead load directly to the pedal eye of the crank (Winning
>and Bullseye's ad)
JIS (Japan Industrial Standard) standard D 9415, section 4 subpart
(4) states:
_Drop impact strength for the crank in vertical position_ A weight
of mass of 10kg (including the weight base) being dropped from a
height of 1000 mm (500 mm for the length of the crank is 140 mm or
less) to the test crank, which is fixed as shown in Fig. 4, and
the test crank shall not break. In the case of the crank is made
of steel, this test can be omitted.
Fig. 4 shows a fixture where the weight is dropped on a test pedal
spindle mounted to the crank. The weight loads the spindle 100mm
from the crank face.
Now, whether US manufacturers are actually doing it that way is a
different matter.
The other subparts are:
(1) Static load strength for pedal fitting point
(2) Chainwheel fixing strength
(3) Drop impact strength for crank in horizontal position [loading
along the pedal axis]
(4) [above]
(5) Repeated fatigue strength for the crank
[actual text and descriptions omitted 'cause I'm too lazy to
key them in- m.h.]
Many may contend that the numbers are not realistic for mountain bikes
because these standards were set before them (I assume) but at least
the basic testing aparatus and procedures are set. (And at least this
addresses Jobst's pet peeve of pedal eye strength. :)
>Now it seems to me that in a real world situation,
>the load is applied to an extension of the crank which is orthogonal to
>the crank and which has a dimension which is a fair fraction of the
>crank length (even if you take just the mid-point of the pedal spindle
>as an average.) Even if in-plane stiffness is the major element in total
>deflection, it is not the only one. Jobst's pronouncements may be rather
>sweeping in some respects, but I agree with his main point, namely that
>there is a lot of unproven stuff out there which show egregiously poor
>engineering (did I really see an ad for an I-beam section stem?!) and
>which sells apparently on marketing hype and a different "look". Which
>is alright by me so long as they make no unfounded performance claims
>(and do not pose excessive risk to the user)
These strength tests are relatively real world in that they account
for the cantelevered loading from the pedal (even if I can't spell
it correctly). They do not specify which construction method you
should use, but given the strength constraints, you can figure out
relative merits of various designs by trial and error at least.
Is there any strength aspect that has not been adequately addressed
by the JIS standard? ('course, it'd help if I gave a full description
of each test, but that's not going to happen now) Even out-of-plane
loading is addressed, though only in terms of breaking strength and
not stiffness.
-huie
Sutherland's Bicycle Shop Aids
--
Mark Huie After all is said and done,
mh...@netcom.com more is said than done.
Mark Huie
>In <mhuieD6...@netcom.com> mh...@netcom.com (Mark Huie) writes:
>
>>(4) states:
>> _Drop impact strength for the crank in vertical position_ A weight
>> of mass of 10kg (including the weight base) being dropped from a
>> height of 1000 mm
>
>yard really comparable to the sort of loading in mountain biking?
>I'm thinking of a ~200lb rider grinding up a hill at ~40 rpm,
>putting well over 200lb force on the pedals with each stroke. Do
>this for several thousand cycles and I suspect you'll break quite
>a few cranks that survive this standard.
(as I mentioned, some/many would doubt how well these tests
scale for mountain bike usage)
Maybe I should have included the text for (5) Fatigue strength....
(I'll try to remember to do that the next time I have the reference
in front of me)
And as I said, though the loads may not be realistic for a mountain
bike, the _application_ of the loads from a testing standpoint seems
to mimic general cycling styles well. Unless anybody wants to
disagree?
What I'm not sure of is if the hardness of the pedal spindle and weight
dropped onto it have any significant effect.
-huie
Andrew Cooke
>In <mhuieD6...@netcom.com> mh...@netcom.com (Mark Huie) writes:
>
>>JIS (Japan Industrial Standard) standard D 9415, section 4 subpart
>>(4) states:
>> _Drop impact strength for the crank in vertical position_ A weight
>> of mass of 10kg (including the weight base) being dropped from a
>> height of 1000 mm
>
>Is a weight of only ~22lb dropped once from a height of about a
>yard really comparable to the sort of loading in mountain biking?
>I'm thinking of a ~200lb rider grinding up a hill at ~40 rpm,
>putting well over 200lb force on the pedals with each stroke. Do
>this for several thousand cycles and I suspect you'll break quite
>a few cranks that survive this standard.
>
if the crank is fixed solid then the energy - about 100J -
is going to be `dissipated' within less than 10mm. that
requires an average force of 10000N or 1000kg static weight
(about a ton).
that's a fairly large cyclist. (i don't know how people
relate this sort of failure - from a big load - to fatigue from
many smaller loads, though; nor do i understand how or whether
it is fixed).
andrew
(don't forget that even if you jump, your legs flex
to take a lot of the peak load - it's not going to exceed what
you can apply by pushing, unless your bones lock up...)
--
A.C...@roe.ac.uk work phone 0131 668 8100 home phone/fax 0131 662 1594
institute for astronomy, royal observatory, blackford hill, edinburgh.
http://www.roe.ac.uk/ajcwww/home.html
Jobst Brandt
> JIS (Japan Industrial Standard) standard D 9415, section 4 subpart
> (4) states:
> _Drop impact strength for the crank in vertical position_ A weight
> of mass of 10kg (including the weight base) being dropped from a
> height of 1000 mm (500 mm for the length of the crank is 140 mm or
> less) to the test crank, which is fixed as shown in Fig. 4, and
> the test crank shall not break. In the case of the crank is made
> of steel, this test can be omitted.
> (And at least this addresses Jobst's pet peeve of pedal eye
> strength. :)
This does nothing in that respect because crank and spindle failures
are fatigue failures that would not show up in such a tests.
I think there is a distinct misunderstanding of the nature of these failures.
> Sutherland's Bicycle Shop Aids
> --
> Mark Huie After all is said and done,
> mh...@netcom.com more is said than done.
--
Jobst Brandt <jbr...@hpl.hp.com>
Dan Empfield
<<> In fact, it would seem to me, the torsional element changes relative to
<<> both the mechanics of a rider's pedal stroke and his biomechanical
<<> idiosyncrasies (i.e., I have no empirical data, but I can envision a
<<> supinator applying a greater torsional component to the load than a
<<> pronator). It could be that the torsional element for many riders is
<<> slight enough so that an I-beam style crank could work well.
<<
<<That rings like a dodge and weave to me, with enough disclaimers to
<<defy disagreement. You and riders who want to believe this are
<<entitled to do so. I can't argue against what you prefer for whatever
<<reasons but I can say these reasons have no technical basis.
Why is it a dodge and weave?
<<> To continue Kooka as an example, the cranks are quite light, (identical to
<<> Topline on my scale), and it seems I remember them testing quite well in
<<> some stiffness tests that Velo News (or somebody) did.
<<
<<I don't know why Kooka cranks are the basis for this discussion. I
<<haven't mentioned them and haven,t seen any lately so I can't say what
<<they might do. If they are I-beam shaped cranks then they are not
<<using the metal to their best advantage, regardless of how well they
<<perform any of their functions.
It is irrelevant how well they function? Isn't the point of a part how
well it functions?
<<Do you believe that the major manufacturers don't know why their cranks
all <<look alike and why they do not have I-beam cross sections?
All major manufacturers cold-forge their best cranks. Virtually all (but
not all) lightweight aftermarket cranks are machined. I suspect that a
forged crank made in the same profile as any popular machined crank would
have nasty consequences.
I also know that both Campy and Shimano have changed the profile of their
cranks considerably over the years, and regardless of what they do, they
have a hard time giving away after-market cranks.
[horror stories... snip]
<<I think the manufacturers owe themselves a return to basics and that
<<they must earn their own credibility. Over the long haul, credibility
<<cannot be built by advertising. The truth comes out, even if it takes
<<awhile. That cranks break was swept under the rug for a long time.
<<The bicycle press is one of the unwitting conspirators in this because
<<they fear what their advertisers' reactions might be if they were to
<<report factually and without omission.
I agree wholeheartedly. I think, though, that your exhortation must apply
to all manufacturers, not just the smaller ones. As you yourself related,
C-Record cranks are much stronger than previous Campy models (built when
they were a relatively young company with only 40 or 50 years of component
making under their belt). I've seen similar failure problems with other
large companies, and not just European ones. It is not a challenge to make
light stuff, but it is a challenge to make light strong stuff. I contend
that many, thought not all, of the smaller American companies do it much
better than the larger ones.
QRman
Mark Huie
>Mark Huie writes:
>
>> JIS (Japan Industrial Standard) standard D 9415, section 4 subpart
>> (4) states:
>> (And at least this addresses Jobst's pet peeve of pedal eye
>> strength. :)
>
>This does nothing in that respect because crank and spindle failures
>are fatigue failures that would not show up in such a tests.
>
>I think there is a distinct misunderstanding of the nature of these failures.
Oops. I meant the section: "(5) Repeated fatigue strength for the crank"
(which I'll try to remember to look up again tomorrow)
>Jobst Brandt <jbr...@hpl.hp.com>
-huie
Jobst Brandt
>>> In fact, it would seem to me, the torsional element changes
>>> relative to both the mechanics of a rider's pedal stroke and his
>>> biomechanical idiosyncrasies (i.e., I have no empirical data, but
>>> I can envision a supinator applying a greater torsional component
>>> to the load than a pronator). It could be that the torsional
>>> element for many riders is slight enough so that an I-beam style
>>> crank could work well.
>
> That rings like a dodge and weave to me, with enough disclaimers to
>> defy disagreement. You and riders who want to believe this are
>> entitled to do so. I can't argue against what you prefer for
>> whatever reasons but I can say these reasons have no technical
>> basis.
>
> Why is it a dodge and weave?
"I have no empirical data, but"..."I can envision a"... "It could be
that"... "could work well". If that isn't about as fuzzy wuzzy as
technical proof gets, I haven't seen it yet. As I said, it's a dodge
and a weave, there's not much to hold onto or refute.
>> I don't know why Kooka cranks are the basis for this discussion. I
>> haven't mentioned them and haven't seen any lately so I can't say
>> what they might do. If they are I-beam shaped cranks then they are
>> not using the metal to their best advantage, regardless of how well
>> they perform any of their functions.
> It is irrelevant how well they function? Isn't the point of a part
> how well it functions?
If they perform as well as, let's say DuraAce, and are I-beam in
cross section then they are substantially heavier than they could be
without the inappropriate cross section. However, I am certain they
do not achieve the same endurance.
>> Do you believe that the major manufacturers don't know why their
>> cranks all look alike and why they do not have I-beam cross
>> sections?
>
> All major manufacturers cold-forge their best cranks. Virtually all
> (but not all) lightweight aftermarket cranks are machined. I
> suspect that a forged crank made in the same profile as any popular
> machined crank would have nasty consequences.
Please be specific. What sort of nasty consequences and why. If
the cross section acn be forged, I see no reason why it should be
weak or otherwise unreliable.
> I also know that both Campy and Shimano have changed the profile of
> their cranks considerably over the years, and regardless of what
> they do, they have a hard time giving away after-market cranks.
Lets not worry about what they did ten years ago but what they are
doing today when these off-the-wall NC products are being made. The
aftermarket is largely made by esoteric equipment aficionados. My
replacement parts don't come from that source.
> I agree wholeheartedly. I think, though, that your exhortation must
> apply to all manufacturers, not just the smaller ones. As you
> yourself related, C-Record cranks are much stronger than previous
> Campy models (built when they were a relatively young company with
> only 40 or 50 years of component making under their belt).
I didn't say that. I said that the C-Record cranks that I used were
substantially weaker than the previous ones and, I believe, mainly
because they reduced the cross section of the pedal eye. My point was
that the vanity groove on the side of the mainline cranks disappeared
about ten years ago, I believe, because someone looked at the
resilliance of these cranks scientifically. It was not so much a
strength consideration as a rigidity one, since cranks rarely failed in
the zone of the weakening groove. To make up for that, the after
'burners' not only have a groove but chose and I-beam cross section.
> I've seen similar failure problems with other large companies, and
> not just European ones. It is not a challenge to make light stuff,
> but it is a challenge to make light strong stuff. I contend that
> many, thought not all, of the smaller American companies do it much
> better than the larger ones.
In opposition to your claim, I'll say that machined from bar is less
strong per unit weight than forging. Because the big manufacturers
have a larger population of products in test on the market and will
generally have numerically more failures than some company that makes
a couple of hundred parts. Campagnolo and Shimano are used on
hundreds of thousands of OEM bicycles. Besides, that's where the
market is, not in the after market. The aftermarket comes free if you
can get major OEM contracts.
Jobst Brandt <jbr...@hpl.hp.com>
Matt Bushore
|> All major manufacturers cold-forge their best cranks. Virtually all (but
|> not all) lightweight aftermarket cranks are machined. I suspect that a
|> forged crank made in the same profile as any popular machined crank would
|> have nasty consequences.
Unless I am amazingly stupid, the forged crank is probably going
to be stronger nearly every time, unless it fails due to some kind of funky
fatigue loading.
The forging process should leave residual compressive stresses in
the material that will help the cranks resist failure.
Someone who didn't nearly fail mat sci could expand on this?
Jobst Brandt
> Jobst, your arguments mainly seem to boil down to three:
> 1. You put a lot of confidence in what the big bike companies do,
> and believe that if the smaller companies knew what was good for
> them, they'd make 600+ gram cold-forged cranks as well (if they
> could afford to cold-forge).
> My answer: Shimano cold-forges cranks because they are a forging company.
> That they happen to be the world's largest bicycle and sport-fishing
> manufacturers are accidents of business.
They have probably become among other things a forging company
(although I suspect they have vendors who do the forging) because that
is the way one economically and reliably gets the strength necessary.
I see you think that they make the parts as heavy as they do because
they picked the weight from some arbitrary forging parameter. I have
noticed that both Campagnolo and Shimano parts got heavier as more and
more broken cranks came back. Mavic cranks are also about the same
weight. There must be more to it than what you seem to believe. I
for one use the stuff because it doesn't break as much as the stuff I
had before.
> Of all their adventures in cold-forging, bikes and reels rose to the
> top. They were a forging company before they got into the bike
> business, and if they drop bike parts they'll still be a forging
> company. Cold-forging is also incredibly cheap, if you're making
> 500,000 cranks, instead of 5000. Which is why Shimano's profits in
> 1993 were larger than Cannondales total sales, and 2/3 of Trek's
> total sales. This gives you an idea of the depth of Shimano's
> pockets, which should indicate why their cranks are, for liability
> reasons, built to be ridden by the defensive front of the Pittsburgh
> Steelers. But you know all this.
Maybe you can tell me what got them into the business and what they
made previously. In any case, cranks machined from the solid of the
same material cannot be as strong for the lack of grain continuity.
There is orientation in metal.
> 2. You appear to say that, because cold-forging is a better intrinsic
> process than CNC, that this is the way cranks should be made.
> My answer: Of course you're right, cold-forging is an intrinsically
> better process. However, nobody forges out of 7000 series. Shimano
> forges with 2024 or 6061, which means that what the CNC makers lack in
> process they make up for (maybe more than make up for) in material with
> much more impressive metallurgical properties. If there is a rap against
> CNC, it is that their product is more prone to dings turning into eventual
> failures, which means that, especially for MTB'ers, they must frequently
> inspect their equipment, which turns out to be a pretty good practice
> anyway, eh?
How about producing some fatigue test results if you are going to
claim that by better alloys (and I'm not convinced the material has
these advantages) you can make up for an inferior process.
> 3. You say that I-beams are bad designs, because cranks undergo torsional
> stress.
That's not what makes them break but is makes them springy when you
stand on them. The failures come at the stress concentrations at the
pedal eye and the junction to the spider. The torsional part makes
the crank springy and the failure occurs where its weakness is not
perceptible.
> My answer: Bike Magazine in Germany did do a survey of about 50 or so
> cranks last year. I have not re-discovered this article, but among the
> sub-400 gram cranks tested, an I-beam design had the least amount of
> deflection (their test did account for torsional deflection)....
[no fact but much guessing].
The German bike rags are no better than the US ones. In fact the
chief technical editor, who recently switched magazines, not long ago
had a series showing pictures of typical failed parts, saying that
these were primarily the fault of poor maintenance. He showed broken
cranks, spindles, pedals, and a fork among other things. If this
isn't pandering to the manufacturers, I don't know what to call it.
> If you're saying that the CNC community, who builds for real racers,
> should attach a set of parameters to their products, I'm all for it. But
> should your son race juniors on a crank built for William "Regrigerator"
> Perry?
I'm not sure what you mean by "attaching parameters". The way you
say that they sound like disclaimer tags that warn the rider.
Jobst Brandt <jbr...@hpl.hp.com>
Mark Huie
>In article <D6GvI...@hpl.hp.com>, Jobst Brandt <jbr...@hpl.hp.com> wrote:
>>I think there is a distinct misunderstanding of the nature of these failures.
>
>Oops. I meant the section: "(5) Repeated fatigue strength for the crank"
>(which I'll try to remember to look up again tomorrow)
>
>>Jobst Brandt <jbr...@hpl.hp.com>
Ah, here it is:
(5) _Repeated fatigue strength for the crank_ When the
crank is fixed to the test pedal spindle and the test crank
spindle, the crank lowering angle is made 35+-2 degrees
[the crankarm is lowered 35 degrees from horizontal. m.h.]
and the chainwheel is fixed with a chain as shown in Fig. 5,
and a load of 1200 N {120 kgf} (600 N {60 kgf} for cranks
which the length is 140 mm or less) is applied 100000 times
to the position 110 mm apart from the fitting part of the
crank of the test spindle at a rate of 60 times per minute,
there shall not occur fissures or breakage in the crank, nor
slackening in the fixing part of the crank and the crank
spindle. In the case of the crank made of steel, this test
can be omitted.
So, the test pedal spindle is loaded vertically 110mm from the crank
face with that arm 35 degrees below horizontal at 1200N at 60Hz for
100,000 cycles. The crankarm is held stationary with a chain around the
chainring. Both crankarms need to be mounted to the fixture when testing
the left crankarm. It does not mention whether the same right crankarm
is to be used when testing the left crankarm, but I assume it doesn't
need to be- the crankarms are tested separately (which allows you
to test that the spider also does not fatigue when you're testing
the right crank).
Again, whether 1200 Newtons is a realistic figure for mountain
bike appliactions isn't the question since it's easy to just
increase the load. At least there are standards for testing
such things as static load strength, impact strength, and fatigue
strength.
Given that there are these standards for testing, is it that great
of a leap to scale these up for mountain bikes? (okay, in some cases
the loading of a mountain bike component is going to be completely
different from a road bike as evidenced by the Control Tech recall
of their road stems a while back)
Um... what was the original thread anyway?
Brian Lee
<discussion of Jobst's conclusions...>
>3. You say that I-beams are bad designs, because cranks undergo torsional
>stress.
>My answer: Bike Magazine in Germany did do a survey of about 50 or so
>cranks last year. I have not re-discovered this article, but among the
>sub-400 gram cranks tested, an I-beam design had the least amount of
>deflection (their test did account for torsional deflection). Kooka, a
>crank roughly I-beam in shape, out-tested Topline, Grafton, and Cook
>Bros., if I remember right. On the face of it, this shouldn't have
>happened, as a Topline probably represents the best theoretical use of a
>crank machined out of 7075 bar stock.
I found a copy of a crank test, reportedly performed by "Bike" magazine
via a gopher through Velonet's web page (http://cycling.org). Not sure
if this is the same test you're referring to.
In the test, they subjected various cranks to 500,000 torsional
load cycles at 180N +/- 600N (to simulate an 80 kg biker). 3 cranks
in the test broke: Adventure Components (AC), Kooka, & Speed Tec
(a German mfg.) If I remember correctly, both AC & Kooka have a
roughly I-beam shaped cross-section.
---------------------------------------------------------------
Brian Lee | "Eschew Obfuscation"
|
bl...@cc.chiron.com | Disclaimer Datclaimer
---------------------------------------------------------------
Dan Empfield
[lots of really good stuff, most of which I snipped]
Jobst, your arguments mainly seem to boil down to three:
1. You put a lot of confidence in what the big bike companies do, and
believe that if the smaller companies knew what was good for them, they'd
make 600+ gram cold-forged cranks as well (if they could afford to
cold-forge).
My answer: Shimano cold-forges cranks because they are a forging company.
That they happen to be the world's largest bicycle and sport-fishing
manufacturers are accidents of business. Of all their adventures in
cold-forging, bikes and reels rose to the top. They were a forging company
before they got into the bike business, and if they drop bike parts
they'll still be a forging company. Cold-forging is also incredibly
cheap, if you're making 500,000 cranks, instead of 5000. Which is why
Shimano's profits in 1993 were larger than Cannondales total sales, and
2/3 of Trek's total sales. This gives you an idea of the depth of
Shimano's pockets, which should indicate why their cranks are, for
liability reasons, built to be ridden by the defensive front of the
Pittsburg Steelers. But you know all this.
2. You appear to say that, because cold-forging is a better intrinsic
process than CNC, that this is the way cranks should be made.
My answer: Of course you're right, cold-forging is an intrinsically
better process. However, nobody forges out of 7000 series. Shimano
forges with 2024 or 6061, which means that what the CNC makers lack in
process they make up for (maybe more than make up for) in material with
much more impressive metallurgical properties. If there is a rap against
CNC, it is that their product is more prone to dings turning into eventual
failures, which means that, especially for MTB'ers, they must frequently
inspect their equipment, which turns out to be a pretty good practice
anyway, eh?
3. You say that I-beams are bad designs, because cranks undergo torsional
stress.
My answer: Bike Magazine in Germany did do a survey of about 50 or so
cranks last year. I have not re-discovered this article, but among the
sub-400 gram cranks tested, an I-beam design had the least amount of
deflection (their test did account for torsional deflection). Kooka, a
crank roughly I-beam in shape, out-tested Topline, Grafton, and Cook
Bros., if I remember right. On the face of it, this shouldn't have
happened, as a Topline probably represents the best theoretical use of a
crank machined out of 7075 bar stock. However, since the torsional stress
on a crank is less than one-third of the bending stress, a design roughly
based on an I-beam could conceivably be the best design. So what you
believe theoretically to be true did turn out to be actually untrue.
My conclusion: Your reasons for relying heavily on the practices of large
component companies are bogus, because their reasons for doing what they
do have no real application for the high-end rider. Weightwise, Shimano
always has been, is now, and always will be very unconcerned about
building components specific for the best racers (although the mechanical
functionality of their parts is without equal). They have too much to
lose in profits by abandoning their extremely cheap manufacturing
processes, and too much to lose in a lawsuit if a huge goon jumps on a
product built for an elite racer.
If you're saying that the CNC community, who builds for real racers,
should attach a set of parameters to their products, I'm all for it. But
should your son race juniors on a crank built for William "Regrigerator"
Perry?
QRman
Dan Empfield
(Matt Bushore) wrote:
<< Unless I am amazingly stupid, the forged crank is probably going
<<to be stronger nearly every time, unless it fails due to some kind of funky
<<fatigue loading.
<<
<< The forging process should leave residual compressive stresses in
<<the material that will help the cranks resist failure.
<<
<<Someone who didn't nearly fail mat sci could expand on this?
You're right, for similar metals. There was one NC crank manufacturer
whose name I won't mention who, I heard, was slipped a 6061 micky, i.e.,
was mistakenly delivered 6061 bar instead of 7075 which was ordered. They
did have failures as a result.
But, I am neither a component maker nor a metallurgist. Unless someone
took the time to machine a replica of an extant cold-forged crank out of
7075 bar and tested them both, (or the much more expensive converse was
undertaken by a forging company), I'm not smart enough to determine the
answer. Except that I heard of a test performed on an NC company's 7075
downhill crank, against a major company's cold-forged (6061) road crank,
and the deflection numbers were about the same. Although that NC
company's road cranks were sub 400g, their downhill crank was @ or about
500 g (+ or -), still considerably lighter than the 600g cold-forged road
crank it was tested against.
QRman
Jobst Brandt
> So, the test pedal spindle is loaded vertically 110mm from the crank
> face with that arm 35 degrees below horizontal at 1200N at 60Hz for
> 100,000 cycles. The crankarm is held stationary with a chain around the
> chainring. Both crankarms need to be mounted to the fixture when testing
> the left crankarm. It does not mention whether the same right crankarm
> is to be used when testing the left crankarm, but I assume it doesn't
> need to be- the crankarms are tested separately (which allows you
> to test that the spider also does not fatigue when you're testing
> the right crank).
That sounds like someone gave it some thought. Now then who is
performing these tests? The only thin that I see right off is that
crank failure most often occurs at the pedal eye and it breaks off
from force on the pedal when the crank is straight down and the rider
steps off to the other pedal when standing. I don't think the two
tests can be combined. That is, the spider connection to the right
crank and the pedal eye strength.
Jobst Brandt <jbr...@hpl.hp.com>
Charles B. Musgrave
[discussion of cold forging, broken cranks, history of Shimano cold forging
snipped]
Maybe you can tell me what got them into the business and what they
made previously. In any case, cranks machined from the solid of the
same material cannot be as strong for the lack of grain continuity.
There is orientation in metal.
Jobst,
I am either misunderstanding what you are trying to say here or you are not
technically accurate. Could you elaborate on your point about the grain
continuity? Grain continuity is usually what you don't want for a strong
material. Yes, there is orientation in metal and that is what you often want to
get away from. Dislocations pinned at grain boundaries effectively increase
the moduli of the material.Cold forging allows for the creation of dislocations
(and stacking faults in Al) without the weakening effects of annealing out the
those dislocations or allowing for homogenization of the material (grain
growth, etc).
I think you could say that "cranks machined from the solid are usually not as
strong as cold forged cranks". The "cannot" and reasons for the strength
difference might be better left out.
have a good one,
Charles
Paul Robert Brown
>In article <mhuieD6...@netcom.com>, Mark Huie <mh...@netcom.com> wrote:
> (5) _Repeated fatigue strength for the crank_ When the
> crank of the test spindle at a rate of 60 times per minute,
^^ ^^^^^ ^^^ ^^^^^^
> [...]
>face with that arm 35 degrees below horizontal at 1200N at 60Hz for
^^^^
>100,000 cycles. The crankarm is held stationary with a chain around the
>[...]
Hz is cycles per second.... Sorry for the nit.
pb
Jobst Brandt
> I am either misunderstanding what you are trying to say here or you
> are not technically accurate. Could you elaborate on your point
> about the grain continuity? Grain continuity is usually what you
> don't want for a strong material. Yes, there is orientation in metal
> and that is what you often want to get away from. Dislocations
> pinned at grain boundaries effectively increase the moduli of the
> material.Cold forging allows for the creation of dislocations (and
> stacking faults in Al) without the weakening effects of annealing
> out the those dislocations or allowing for homogenization of the
> material (grain growth, etc).
Bar stock also has grain structure but when you machine it, this
structure is interrupted. Formed materials have flow and continuity
that ones cut from the solid do not. This is for instance what makes
drawn wire substantially stronger than bar stock and cutting threads
into a spoke destroys this continuity, making a uselessly weak spoke.
The same goes for screws and bolts. No one that has the option would
take a cut thread over a rolled thread. The same is generally true
for a forged or formed crank. A machined crank likewise cuts through
the preferred grain an particularly the denser surface that prevents
crack initiation.
> I think you could say that "cranks machined from the solid are
> usually not as strong as cold forged cranks". The "cannot" and
> reasons for the strength difference might be better left out.
The use of disclaiming euphemisms like "hardly ever" or "nearly
always" to cover unlikely exceptions is the mother of unwarranted
beliefs. Soft pedaling by not saying "cannot", keeps the possibility,
although not the probability, of the NC machined crank's superiority
alive. It isn't and I'm not going to encourage it.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> Why do you think most of the fatigue occurs at the very bottom of
> the pedal stroke? It seems to me this would vary from rider to rider.
> You're just speaking from your own experience, no?
No. I am speaking from all the broken cranks I have seen and those
that aothers have seen and reported. What may seem to vary from rider
to rider does not do so. Your conjecture is misplaced. Instead of
telling me that my experience and observations are probably wrong on
the basis your conjecture is the reason I occasionally use a less than
gracious tone in my responses. It is not as though I haven't given
reasons and explanations for how and why these failures occur.
Jobst Brandt <jbr...@hpl.hp.com>
Charles B. Musgrave
|> Charles Musgrave writes:
|>
|> > I am either misunderstanding what you are trying to say here or you
|> > are not technically accurate. Could you elaborate on your point
|> > about the grain continuity? Grain continuity is usually what you
|> > don't want for a strong material. Yes, there is orientation in metal
|> > and that is what you often want to get away from. Dislocations
|> > pinned at grain boundaries effectively increase the moduli of the
|> > material.Cold forging allows for the creation of dislocations (and
|> > stacking faults in Al) without the weakening effects of annealing
|> > out the those dislocations or allowing for homogenization of the
|> > material (grain growth, etc).
|>
|> Bar stock also has grain structure but when you machine it, this
|> structure is interrupted. Formed materials have flow and continuity
|> that ones cut from the solid do not. This is for instance what makes
|> drawn wire substantially stronger than bar stock and cutting threads
|> into a spoke destroys this continuity, making a uselessly weak spoke.
Kind of. Drawn wire has flow lines along the length of the wire making
for long hotdog-like grains. Drawing automatically lines up the grain
boundaries with the wire axis. It is the discontinuity of the grains
being maximized across the wire than makes it strong or in other words the
microstructural anisotropy of a forged part makes it strong. Much
stronger than if you had a single crystal part...which obviously has
the maximum continuity, but poor properties. Forged materials also give
you the chance for high dislocation densities...which is of course another
discontinuity which leads to stronger materials.
Anyway, it is the continuity (flowlines) of the discontinuity (grain
boundaries) that makes your original continuity comment not completely
accurate.
|> The same goes for screws and bolts. No one that has the option would
|> take a cut thread over a rolled thread. The same is generally true
|> for a forged or formed crank. A machined crank likewise cuts through
|> the preferred grain an particularly the denser surface that prevents
|> crack initiation.
This of course is assuming that the engineering was done properly so that
the forging flow lines are perpidicular to the maximum stress trajectories,
which is not always a good assumption. That grain continuity in the wrong
directon can lead to wonderful paths of crack propagation! Forged parts
usually do have better surface microstructures for preventing crack
initiation.
|>
|> > I think you could say that "cranks machined from the solid are
|> > usually not as strong as cold forged cranks". The "cannot" and
|> > reasons for the strength difference might be better left out.
|>
|> The use of disclaiming euphemisms like "hardly ever" or "nearly
|> always" to cover unlikely exceptions is the mother of unwarranted
|> beliefs. Soft pedaling by not saying "cannot", keeps the possibility,
Actually, the poor orientation of the forge flow lines is not totally
unlikely. Anyway, for a crank, machining the hole in for the pedals
is going to lead to one of the more likely failure spots. I would rather
have a well designed microstructure here, than the good flowline microstructure
of the forging which is going to be disrupted...like you said earlier.
|> although not the probability, of the NC machined crank's superiority
|> alive. It isn't and I'm not going to encourage it.
I wouldn't either if I hadn't seen exceptions myself.
|>
|> Jobst Brandt <jbr...@hpl.hp.com>
Anyway, I agree with you that overall I think forged is better than cast.
On the otherhand, I didn't agree with the explanation. I just like to
be technically accurate.
Charles
Eric Bazan
:Mark Huie writes:
:
:: So, the test pedal spindle is loaded vertically 110mm from the crank
:: 100,000 cycles. The crankarm is held stationary with a chain around the
:: chainring. Both crankarms need to be mounted to the fixture when testing
:: is to be used when testing the left crankarm, but I assume it doesn't
:: need to be- the crankarms are tested separately (which allows you
:: to test that the spider also does not fatigue when you're testing
:: the right crank).
:
:That sounds like someone gave it some thought. Now then who is
:crank failure most often occurs at the pedal eye and it breaks off
:from force on the pedal when the crank is straight down and the rider
:steps off to the other pedal when standing. I don't think the two
:tests can be combined. That is, the spider connection to the right
:crank and the pedal eye strength.
:
:Jobst Brandt <jbr...@hpl.hp.com>
Why do you think most of the fatigue occurs at the very bottom of
the pedal stroke? It seems to me this would vary from rider to rider.
You're just speaking from your own experience, no?
-Eric Bazan
Mark Huie
Paul Robert Brown <pbr...@asparagus.berkeley.edu> wrote:
>
>>In article <mhuieD6...@netcom.com>, Mark Huie <mh...@netcom.com> wrote:
>> (5) _Repeated fatigue strength for the crank_ When the
>> [...]
>> crank of the test spindle at a rate of 60 times per minute,
>>face with that arm 35 degrees below horizontal at 1200N at 60Hz for
>>100,000 cycles. The crankarm is held stationary with a chain around the
>
>Hz is cycles per second.... Sorry for the nit.
Oops. It really does say 60 times per minute (i.e. 1 HZ). I just
read it wrong. But somehow, I think it's a typo. Can you imagine
leaving the crank on the test bed for three months? 27 hours sounds
much more reasonable.
I just tried checking an older version of the JIS specifications, but
all we have is 1982 in Japanese. From the pictures, the test was
different.
Eric Bazan
>Eric Bazan writes:
>
>> Why do you think most of the fatigue occurs at the very bottom of
>> the pedal stroke? It seems to me this would vary from rider to rider.
>> You're just speaking from your own experience, no?
>
>that aothers have seen and reported. What may seem to vary from rider
>to rider does not do so. Your conjecture is misplaced.
So it is.
>instead of
>telling me that my experience and observations are probably wrong on
>the basis your conjecture is the reason I occasionally use a less than
>gracious tone in my responses.
Huh? I told you nothing, I merely questioned.
>It is not as though I haven't given
>reasons and explanations for how and why these failures occur.
>
Oh please, as if I'm supposed to be familiar with everything you've
ever written! My, my, but Jobst, you are turning into a crusty old turd!
I don't see what is so inflammatory in my original post. Sorry to have
disturbed you!
-Eric Bazan
>Jobst Brandt <jbr...@hpl.hp.com>
rich...@cruzio.com
> Eric Bazan writes:
>
> > Why do you think most of the fatigue occurs at the very bottom of
> > the pedal stroke? It seems to me this would vary from rider to rider.
> > You're just speaking from your own experience, no?
>
> No. I am speaking from all the broken cranks I have seen and those
> that aothers have seen and reported. What may seem to vary from rider
> telling me that my experience and observations are probably wrong on
> the basis your conjecture is the reason I occasionally use a less than
> reasons and explanations for how and why these failures occur.
>
Jobst,
Awhile back we went through this. At that time I asked a few
questions concerning your observations of crank failures of
this sort. The basic question was concerning the brand, type,
or year of manufacture of the cranks you've seen fail in this
way.
At that time, the incidents you could recount, and those that
others recalled, involved older road cranks, generally italian
or french with one or two lower quality japanese cranks. No
one (I asked whether anyone had seen a more recent design of
crank made specifically for off road riding fail in this
manner. As I recall, I asked a fairly specific question w/
respect to models and year manufactured at the time.) had
any information concerning a failure of one of these. The
reason I went to this effort was that our testing indicated
that this may be the case.
The sections on many of the production arms in the vicinity of
the pedal attachment is bigger on these cranks than it was
on the older road cranks, and our investigations reveal
improved fatigue strength on many in the loading case you
refer to as a source for failures. We haven't tested many of
the older road cranks since it is difficult to get them in
new condition.
We have only seen field failures of the newer
cranks in the vicinity
of the RH arm where it joins the spider. This area has been
improved on the latest Shimano arms. Of course, Ritchey sorted
this out on his cranks (with your input?), and the latest Sugino
cranks are good in this respect as well.
This comment refers only to
the better cranks in the lines. The materials and methods
employed to make the lower priced models do not show well in
rigorous fatigue tests and are probably not intended for
serious use. I do not have enough brand and model information
to make this useful information to riders except to say that
the best Sugino and Shimano XT and better are very good in fatigue.
One side note. We tetst bottom bracket spindles as well. Since the
test fixture requires a set of cranks to apply the load to the
spindle, we have to find some cranks that have good fatigue strength
or we just end up chewing through cranks to run the tests. We use
XTR cranks for this. I've done my share of bitching about the
durability of shimano's drivetrain components, cogs and rings
in particular, so I am not that careful about the politics of
this, but they execute their crank arms at a level that few
appreciate. No one else's parts that we've evaluated
comes close in this regard.
So, seems like a good time to ask the question again. Does anyone
have any experience with off road crank models, roughly newer than
1989 or so, Shimano Deore (LX?) or better (any brand of course) that
have failed, and if so, where on the crank did they fracture?
Anxiously awaiting your reply,
KB
PS
Jobst, is that really the reason for the tone of your postings? :>
Jobst Brandt
>>> Why do you think most of the fatigue occurs at the very bottom of
>>> the pedal stroke? It seems to me this would vary from rider to rider.
>>> You're just speaking from your own experience, no?
>>
>> No. I am speaking from all the broken cranks I have seen and those
>> that others have seen and reported. What may seem to vary from rider
>> to rider does not do so. Your conjecture is misplaced. Instead of
>> telling me that my experience and observations are probably wrong on
>> the basis your conjecture is the reason I occasionally use a less than
>> gracious tone in my responses. It is not as though I haven't given
>> reasons and explanations for how and why these failures occur.
> The sections on many of the production arms in the vicinity of the
> pedal attachment is bigger on these cranks than it was on the older
> road cranks, and our investigations reveal improved fatigue strength
> on many in the loading case you refer to as a source for failures.
You can safely use even well used cranks if your sample size is large
enough because most cranks are never operated near the loads that
cause failures. In that event, you'll need to throw out early failures
but at least you'll have some feeling for the state of cranks prior to
today.
> We have only seen field failures of the newer cranks in the vicinity
> of the RH arm where it joins the spider. This area has been
> improved on the latest Shimano arms. Of course, Ritchey sorted this
> out on his cranks (with your input?), and the latest Sugino cranks
> are good in this respect as well.
These cracks are common on most cranks that have five spider arms in
contrast to Ritchey and Campagnolo C-Record that have four. The cracks
in the web that looks like the skin between ones fingers is generally
benign, and unless it cuts across into the body of the crank extension,
remains a blemish. I have found that before this crack becomes source
for concern, the crank breaks off elsewhere.
> One side note. We test bottom bracket spindles as well. Since the
> test fixture requires a set of cranks to apply the load to the
> spindle, we have to find some cranks that have good fatigue strength
> or we just end up chewing through cranks to run the tests.
Avocet built such a testing machine when they were in the hardware
business and it used a steel crank manufactured for that purpose and a
block anchor for the other end of the spindle. A variable stroke
eccentric and strain gauge on the connecting rod allowed setting the
load. Using an aluminum crank makes me suspect that you will have
difficulty breaking any reasonably manufactured spindles since the
ones I broke survives several crank failures.
> We use XTR cranks for this. I've done my share of bitching about
> the durability of Shimano's drivetrain components, cogs and rings in
> particular, so I am not that careful about the politics of this, but
> they execute their crank arms at a level that few appreciate. No
> one else's parts that we've evaluated comes close in this regard.
You'll probably get some heat from the aftermarket crank adherents for
this remark but that's the way it is. It is common to believe that
major manufacturers are just making cheap junk while the small shop
knows all the tricks and is interested only in idealistic goals. The
market takes care of more policing than most riders believe... except
in the fashion business such as clothes and eyewear in particular.
> So, seems like a good time to ask the question again. Does anyone
> have any experience with off road crank models, roughly newer than
> 1989 or so, Shimano Deore (LX?) or better (any brand of course) that
> have failed, and if so, where on the crank did they fracture?
Much of my riding is off road to a greater degree than many dirt
bicycles experience. I also use hard road tires so there is an
additional shock loading. I have been using Dura Ace for the last ten
years or so with only two failures that I caught before separation.
Jobst Brandt <jbr...@hpl.hp.com>
Christopher W. Hanlon
So, seems like a good time to ask the question again. Does anyone
have any experience with off road crank models, roughly newer than
1989 or so, Shimano Deore (LX?) or better (any brand of course) that
have failed, and if so, where on the crank did they fracture?
Anxiously awaiting your reply,
KB
I've seen broken STX cranks. These were off a 1994 Gary Fisher
Hoo Koo E Koo (sp?). My friend broke them while track-standing
at a stop light (in other words they broke while he was standing
on them).
The right crank broke where the arm started to form the spider.
Looking at the break I noticed that half the break was dirty, signifying
(obviously) that the crank had a crack in for some time. The break was
fairly clean (broke clean through). Luckily he did not get hurt since
he was just standing.
This is a lower-end crank (below LX), however does not look too much
different than the LX. I would assume the majority of the difference
in cranks (of shimano's) occurs between the LX and XT cranks, this is
based soley on the price of the two though.
So, people if you have shimano cranks, check them for cracks...
--
christopher hanlon | the differences that we see
engineering animation, inc | are the ones that we concern
cwha...@eai.com | ourselves the most with
Michael W Wara
> In article <D6zDL...@cruzio.com> rich...@cruzio.com writes:
>
> So, seems like a good time to ask the question again. Does anyone
> have any experience with off road crank models, roughly newer than
> 1989 or so, Shimano Deore (LX?) or better (any brand of course) that
> have failed, and if so, where on the crank did they fracture?
>
> Anxiously awaiting your reply,
>
> KB
I broke the non-drive arm of a Grafton Joy-Stix crank last summer.
The crank broke without there being any visible cracks before hand. There
was no dirt in the break. The crack arm broke clean through where it sits
on the spindle on the side opposite from the arm.
Typically, Grafton was both extremely courteous and expeditious
about replacing the broken crank. They did it in under a week(now that's
service!). They informed me at the time that this crank was one of the
original Joy Stix that was recalled. At tht time of the recall I checked
to see that my crank was not one of these(they were labelled in a
distincitve fashion) so this came as some surptise to me.
Hope that helps.
Michael Wara
David Harrell
>In article <D6zDL...@cruzio.com> rich...@cruzio.com writes:
>
> So, seems like a good time to ask the question again. Does anyone
> have any experience with off road crank models, roughly newer than
> 1989 or so, Shimano Deore (LX?) or better (any brand of course) that
> have failed, and if so, where on the crank did they fracture?
>
> Anxiously awaiting your reply,
>
> KB
>
I bought a S-Works Steel bike from my mechanic, who is a trials rider.
He'd broken the left crankarm right at the pedal. It was a Grafton.
So, I've been riding a pretty nice bike with one LX and one Grafton
crank for a while, and I ran into some guys in the woods who said
something to the effect that they also ride Grafton cranks. I told
them this story, and that I was still waiting on the warranty part
to come in. They said that their Grafton cranks typically last about
one season. I don't care much for that, so I'd be glad to hear some
suggestions as to what a good replacement crank would be. (I still
haven't gotten the Grafton replacement.) My thoughts right now are
between Topline and XTorXTR.
David Harrell
har...@oasys.dt.navy.mil
Jason Krantz
David-
I have to question the wisdom of purchasing Topline
cranks over Graftons. They have several failings compared to Grafton.
(I am not an engineer and do not wish to incur Jobst's wrath... so what
I say comes only from experience, not empirical testing.)
The major flaw, in my opinion, is that Toplines have a spider which
is threaded and then bolted to the crankarm. While I haven't heard of
a failure at the spider-crankarm junction, it does cause creaking because
the spider and crankarm flex at different rates. I hate the idea of having
a ~$200 crank creak like a loose Exage crank. Also, it seems like there's
too much torque at the spider/crankarm junction to be resisted simply by
a bolt and loctite. This is entirely subjective, but if one could
design a crankarm with an _integral_ spider, then why not do it?
Yes, I know Topline used to machine for Grafton, but if I
understand what Jobst says about pedal eyes correctly, Topline's
lack of material there is far more likely to induce failure than Grafton's
relatively beefy design. However, if you want a strong crank, I would
suggest Syncros' chrome-moly offering, or, if light weight is that
important to you, maybe a Cook's E crank. I hear the White Industries
crank is cold-forged, so that might be a good idea. However, since
the only Shimano off-road crank which is still cold-forged is XTR,
there's not much of a reason to buy an XT over an LX.
(all manufacturing information courtesy of Bike-Pro's catalogue)
Hope it works out well for you.
Jason
Brian Lee
<various discussions re: Topline vs. Grafton...>
Just to muddy the waters a bit. I called Bike Pro yesterday,
and they said they no longer carry Grafton cranks because
Grafton just went out of business. I haven't heard this from
a second source yet so we'll see...
Mark Chandler
>In article <3nrp4d$r...@tierra.santafe.edu> jas...@kamakiriad.mit.edu (Jason Krantz) writes:
><various discussions re: Topline vs. Grafton...>
>Just to muddy the waters a bit. I called Bike Pro yesterday,
>and they said they no longer carry Grafton cranks because
>Grafton just went out of business. I haven't heard this from
>a second source yet so we'll see...
I spoke to John Grafton a week or so ago. We talked about his brakes
and levers (I'm finishing the brake buyer's guide for MTB Magazine).
He mentioned that he moved the entire company from Southern California
to Durango, CO. If you call the So Cal numbers, you'd think that
the company is no more. He sent samples of brakes and levers to
be photographed for the article, so I don't think he's dead yet.
>---------------------------------------------------------------
>Brian Lee | "Eschew Obfuscation"
> |
>bl...@cc.chiron.com | Disclaimer Datclaimer
>---------------------------------------------------------------
--
Mark Chandler Concord, California m...@crl.com