rim life.. questions...
Ravi
my road bike is a '04 Trek 2100, which came with Bontrager Select
Rims. Recently, when fixing a flat, i noticed there were cracks on the
rear rim near the spoke holes. the rim surface looks like:
===============================================
--o-- o --o-- o
===============================================
'o' is the spoke hole. and '--' is the crack and '==' is the braking
surfaces. This wheel is a 24 spoke wheel and has paired spokes.
The cracks are all on the drive side spokes only. And of the 12 total
drive side spokes, 9 of them had cracks around them (on the rim). I have
put on 10k miles on this wheel.
About me: 6'3" ~190lbs. sometimes i like mash up over small hills, but
usually spin up long grinding hills. i do not race, this is just a
recreational/long distance riding bike.
The LBS examined the wheel and said it was stress related cracks. At the
LBS, I found a '05 Bontrager Select wheel for $120. I would have bought
it, if i had my credit card with me. I decided to return later to buy
it. During this time it got me thinking and few questions:
why failure and why now:
* at ~10k miles, i have 9 cracks on the rims (i wonder when was the
first crack appeared - approx 1000 miles ago ?? probably) in that case
if i were to get a new set of wheels, probably will last only 8k or 9k
miles.
* the rims has no eyelets is that a possible cause for this failure ?
* from the time i bought this bike, only once a spoke came loose and got
it fixed by the LBS and two or three times went out of true and got it
trued by the LBS. Other than that nothing special was made to the Wheel.
Also the rim is offset to accomodate the cassette - so the tension on
the non-drive side wouldn't be as high - to cause this kind of failure.
* paired-spokes is it helping or not helping or hurting the life of wheels.
answers to the above concerns will help me choose one of the following
options:
* buy the '05 Bontrager Select wheel
* get a rim and build up the wheel myself - i haven't examined the
condition of the hub well to see what state it is in. In such a case, i
would have to hunt for a 24h sturdy rim to start with.
recently there has been lots of threads on wheels etc.. i am trying to
catchup on those, but some of my concerns aren't addressed in those.
please provide me your inputs so as to help me decide which way to go...
thanks,
ravi
carl...@comcast.net
wrote:
>Hi Wheel gurus,
> my road bike is a '04 Trek 2100, which came with Bontrager Select
>Rims. Recently, when fixing a flat, i noticed there were cracks on the
>rear rim near the spoke holes. the rim surface looks like:
>
>===============================================
> --o-- o --o-- o
>===============================================
>
>'o' is the spoke hole. and '--' is the crack and '==' is the braking
>surfaces. This wheel is a 24 spoke wheel and has paired spokes.
>
>The cracks are all on the drive side spokes only. And of the 12 total
>drive side spokes, 9 of them had cracks around them (on the rim). I have
>put on 10k miles on this wheel.
[snip]
Dear Ravi,
The spoke tension on the drive side was too high.
Cracks like these are not uncommon when wheels are built to
the highest tension that they can stand without immediately
deforming, a value that can be higher than the rim
manufacturer expects and recommends.
Either get a sturdier rim or reduce the tension.
Carl Fogel
jim beam
rim cracks are usually either defective rims [not so common] or excess
spoke tension. sounds like your lbs was over-tensioning if it had been
trued multiple times.
eyelets can be effective local stress mitigation, but even eyeletted
rims crack if spoke tension is still too high.
regarding repair/replacement, replacement is probably the way to go. i
believe you can get rims to repair this wheel, but the economics may not
make a lot of sense. standard rims are not usually available in paired
spoking but you could try a 36h rim skipping every 3rd hole, but spoke
length may be an issue, not to mention drilling offset.
Sniper Anon
On 28-Aug-2005, carl...@comcast.net wrote:
> Dear Ravi,
>
> The spoke tension on the drive side was too high.
>
> Cracks like these are not uncommon when wheels are built to
> the highest tension that they can stand without immediately
> deforming, a value that can be higher than the rim
> manufacturer expects and recommends.
>
> Either get a sturdier rim or reduce the tension.
So Carl, did you perform experiments and analysis to support your argument,
or did you decide to take jim beam's side just to rankle Jobst Brandt?
--
Sniper Anon
----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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carl...@comcast.net
<s_a...@mouse-potato.com> wrote:
>
>On 28-Aug-2005, carl...@comcast.net wrote:
>
>> Dear Ravi,
>>
>> The spoke tension on the drive side was too high.
>>
>> Cracks like these are not uncommon when wheels are built to
>> the highest tension that they can stand without immediately
>> deforming, a value that can be higher than the rim
>> manufacturer expects and recommends.
>>
>> Either get a sturdier rim or reduce the tension.
>
>So Carl, did you perform experiments and analysis to support your argument,
>or did you decide to take jim beam's side just to rankle Jobst Brandt?
Dear Snip,
Er, what other explanation besides the spoke tension being
too high for the rim do you offer when the rim cracks around
the base of 9 out of 12 of the higher-tension drive-side
spokes after a few thousand miles?
It's not as if this is a new complaint on this newsgroup.
Jobst's approach of increasing the tension until the wheel
deforms and then backing off was developed with sturdy
36-spoke rims back in the 1980's.
When applied to flimsier, lower-count modern rims, this
practice can lead to cracks around the spoke holes.
To produce the same overall drive-side tension of 18*T that
will cause local yielding with only 12 spokes instead 18,
each spoke has to be tightened to 1.5*T.
Hmmm . . . a 50% increase in tension, cracks appear around
the spoke holes in a few thousand miles, and someone starts
a thread to ask what to do.
This is why Jim Beam keeps suggesting that wheel-builders
should use a tensiometer and tension the spokes to the rim
manufacturer's recommendation.
Carl Fogel
jobst....@stanfordalumni.org
> My road bike is a '04 Trek 2100, which came with Bontrager Select
> Rims. Recently, when fixing a flat, I noticed there were cracks on the
> rear rim near the spoke holes. the rim surface looks like:
> ===============================================
> --o-- o --o-- o
> ===============================================
> 'o' is the spoke hole. and '--' is the crack and '==' is the braking
> surfaces. This wheel is a 24 spoke wheel and has paired spokes.
> The cracks are all on the drive side spokes only. And of the 12
> total drive side spokes, 9 of them had cracks around them (on the
> rim). I have put on 10k miles on this wheel.
> About me: 6'3" ~190lbs. sometimes I like mash up over small hills,
> but usually spin up long grinding hills. I do not race, this is
> just a recreational/long distance riding bike.
> The LBS examined the wheel and said it was stress related cracks.
That's self evident. What else causes metals to crack in service.
> At the LBS, I found a '05 Bontrager Select wheel for $120. I would
> have bought it, if I had my credit card with me. I decided to
> return later to buy it. During this time it got me thinking and few
> questions:
> why failure and why now:
> * at ~10k miles, I have 9 cracks on the rims (I wonder when was the
> first crack appeared - approx 1000 miles ago ?? probably) in that case
> if I were to get a new set of wheels, probably will last only 8k or 9k
> miles.
> * The rims has no eyelets is that a possible cause for this failure
> ? * from the time I bought this bike, only once a spoke came loose
> and got it fixed by the LBS and two or three times went out of true
> and got it trued by the LBS. Other than that nothing special was
> made to the Wheel. Also the rim is offset to accomodate the
> cassette - so the tension on the non-drive side wouldn't be as high
> - to cause this kind of failure. * paired-spokes is it helping or
> not helping or hurting the life of wheels.
There are several effects coming together that cause these failures.
One is too few spokes another is no steel sockets or eyelets, another
is hard anodizing together with excess tension caused by using too few
spokes. In addition, to accommodate 10-speed gear clusters, rear hubs
have gotten narrower to reduce offset (and the required difference in
tension from left to right). Just the same rear wheels, carry at
least 2/3 the load with the right side spokes. No wonder the rims
develop fatigue cracks.
Before the equipment fad got rolling in the present mode, low spoke
count wheels were used for special events like time trials. Then
professional teams, sponsored by component manufacturers, began using
them on a regular bases, to hell with the expense of frequent
replacement. So here we are with no market for reliable and durable
wheels, most riders being convinced that if Lance Armstrong does it,
it must be what I need.
I am at a loss to suggest what rims you should get but with the hubs
and spokes you have, there is no alternative to shelling out yet more
for the same. Paired spoking, patented by Lovelace in 1890, had no
benefits then and has none now.
For recreational bicycling (oops, that's not PC, we are all on
training rides for our next competition) 36-spoke wheels are still the
reasonable compromise between rim weight and number of spokes. With
low spoke count, one spoke failure will make the wheel unridable but
to make up for that, the spoke cannot be replaced in the field because
such wheels require special fixturing to be tensioned and trued. I
suppose the cell phone has absolved people of touring with tools and
equipment to be self sufficient, so wheels will probably continue to
be as fragile and excessively expensive as most currently are.
It was not long ago that a rider was assured of finding a replacement
rim at most any bicycle shop in the USA or overseas, the standard
being the 36-spoke Mavic MA-2 and other rims that had the same
effective dimensions. I recall rolling into a shop in Italy where we
bought a new MA-2 rim to replace a severely dinged one and no one
thought it was unusual to expect to find one. Most every bicycle
shop had these on the overhead rack.
Jobst Brandt
jobst....@stanfordalumni.org
>>> The spoke tension on the drive side was too high.
>>> Cracks like these are not uncommon when wheels are built to the
>>> highest tension that they can stand without immediately deforming,
>>> a value that can be higher than the rim manufacturer expects and
>>> recommends.
>>> Either get a sturdier rim or reduce the tension.
>> So Carl, did you perform experiments and analysis to support your
>> argument, or did you decide to take jim beam's side just to rankle
>> Jobst Brandt?
> Er, what other explanation besides the spoke tension being too high
> for the rim do you offer when the rim cracks around the base of 9
> out of 12 of the higher-tension drive-side spokes after a few
> thousand miles?
> It's not as if this is a new complaint on this newsgroup.
> Jobst's approach of increasing the tension until the wheel deforms
> and then backing off was developed with sturdy 36-spoke rims back in
> the 1980's.
> When applied to flimsier, lower-count modern rims, this practice can
> lead to cracks around the spoke holes.
Ah yes, "modern" rims. How much e have progressed
> To produce the same overall drive-side tension of 18*T that will
> cause local yielding with only 12 spokes instead 18, each spoke has
> to be tightened to 1.5*T.
> Hmmm... a 50% increase in tension, cracks appear around the spoke
> holes in a few thousand miles, and someone starts a thread to ask
> what to do.
> This is why Jim Beam keeps suggesting that wheel-builders should use
> a tensiometer and tension the spokes to the rim manufacturer's
> recommendation.
That makes little difference. What comes from that is the need for
Loctite on the spoke threads because spokes are now so loose (to not
crack rims) that they slacken in use. It is not unusual to hear spoke
rattle over rougher pavement and that is what unscrews spoke nipples.
At first it was machine built wheels, ones that machines could not
true if made tight as they should be, that introduced thread locking
compounds. Now that we have them, wheels have taken the next step,
that of requiring loose spokes to prevent rims failure and thereby
making thread-lock a necessity. Thread-lock has become the norm in
lieu of reasonably tight wheels because so many have so few spokes.
Jobst Brandt
carl...@comcast.net
jim beam
using the correct tension makes little difference? it may not make much
difference to wind resistance or stiffness or strength, but it most
definitely makes a difference to fatigue life and rim cracking.
> What comes from that is the need for
> Loctite on the spoke threads because spokes are now so loose (to not
> crack rims) that they slacken in use.
so what about the self-locking nipples that are so easily available?
they don't need loctite. what about the nylock variety used in so many
pre-builts? they don't need loctite either. and even if we /did/ use
loctite, what's wrong with that? it does the job, and judicious use of
a cigarette lighter renders the wheel completely maintainable. if not
more so because the threads are not gummed up with road grit and don't
sieze.
> It is not unusual to hear spoke
> rattle over rougher pavement and that is what unscrews spoke nipples.
i've never heard that. all i hear is the wind in my ears.
>
> At first it was machine built wheels, ones that machines could not
> true if made tight as they should be, that introduced thread locking
> compounds. Now that we have them, wheels have taken the next step,
> that of requiring loose spokes to prevent rims failure and thereby
> making thread-lock a necessity. Thread-lock has become the norm in
> lieu of reasonably tight wheels because so many have so few spokes.
an observation of a changing practice is not an observation of a
problem. if you hadn't been advocating spoke tension "as high as the
rim will bear" for so long, we might never have even /had/ pre-built
wheels today because rim manufacturers wouldn't have been so anxious to
get out from under the yoke of frivolous [excess tension] warranty claims.
>
> Jobst Brandt
carl...@comcast.net
Dear Mr. Peabody,
Posts asking if the MA-2 had been discontinued first
appeared in 1996.
By 1999, some people were even hoarding them:
http://groups.google.com/group/rec.bicycles.tech/msg/d0051b6795e93287?dmode=source
It's hard to buy rims that haven't been made in this
century.
http://www.timetravelreviews.com/tv_reviews/peabodyandsherman.html
Sherman
jim beam
excess tension comes /way/ above anodizing. and why does low spoke
count equate to excess tension? my mavic cosmos wheels are tensioned to
90kgf out of the box. that's not high.
> In addition, to accommodate 10-speed gear clusters, rear hubs
> have gotten narrower to reduce offset (and the required difference in
> tension from left to right). Just the same rear wheels, carry at
> least 2/3 the load with the right side spokes. No wonder the rims
> develop fatigue cracks.
to clarify, rear /wheels/ carry roughly 2/3 of the riders weight, and
drive-side spokes have roughly twice the pre-tension of non-drive side.
>
> Before the equipment fad got rolling in the present mode, low spoke
> count wheels were used for special events like time trials. Then
> professional teams, sponsored by component manufacturers, began using
> them on a regular bases, to hell with the expense of frequent
> replacement. So here we are with no market for reliable and durable
> wheels, most riders being convinced that if Lance Armstrong does it,
> it must be what I need.
i use low-count wheels on my commuter currently, and i notice
substantial benefits when dealing with strong cross winds on golden gate
bridge. right there is sufficient reason to "go low" - it's safer.
>
> I am at a loss to suggest what rims you should get but with the hubs
> and spokes you have, there is no alternative to shelling out yet more
> for the same. Paired spoking, patented by Lovelace in 1890, had no
> benefits then and has none now.
the "benefit" is that cross-bracing loads are minimzed - just consider
every 3 holes-worth of rim as a beam in 3-point loading if you want to
do the math. the "benefit" may be small, but it's not zero.
>
> For recreational bicycling (oops, that's not PC, we are all on
> training rides for our next competition) 36-spoke wheels are still the
> reasonable compromise between rim weight and number of spokes. With
> low spoke count, one spoke failure will make the wheel unridable but
> to make up for that, the spoke cannot be replaced in the field because
> such wheels require special fixturing to be tensioned and trued.
eh? they can be trued in the normal way, if you carry a spoke tool.
reality is, wheels with straight-pull spokes are much less likely to
suffer broken spokes than those with elbowed spokes. elbowed spokes are
subject to bending on any load and therefore are much more prone to fatigue.
> I
> suppose the cell phone has absolved people of touring with tools and
> equipment to be self sufficient, so wheels will probably continue to
> be as fragile and excessively expensive as most currently are.
>
> It was not long ago that a rider was assured of finding a replacement
> rim at most any bicycle shop in the USA or overseas, the standard
> being the 36-spoke Mavic MA-2 and other rims that had the same
> effective dimensions. I recall rolling into a shop in Italy where we
> bought a new MA-2 rim to replace a severely dinged one and no one
> thought it was unusual to expect to find one. Most every bicycle
> shop had these on the overhead rack.
where does nostalgia for a heavy, soft alloy, non-machined, non-welded,
eyelet rusting, flat spot prone rim get us?
>
> Jobst Brandt
41
carl...@comcast.net wrote:
> Cracks like these are not uncommon when wheels are built to
> the highest tension that they can stand withou t immediately
> deforming, a value that can be higher than the rim
> manufacturer expects and recommends.
>
> Either get a sturdier rim or reduce the tension.
Dear Mr Peabrain,
That's great advice. By how much exactly should he reduce the tension?
And how did you know what it was to begin with, and that it was
overspec? Are you guaranteeing that if tensioned to the low tension
that you recommend but don't specify, or for that matter to the
manufacturer's spec, if it is available, that the rim won't crack, even
though it has no eyelets, a low spoke count, and maybe is anodized?
And once this rim with few spokes is low-tensioned as per your legal
advice, what are you going to do for him when his spokes go slack and
his rim is therefore unsupported and he gets a sudden collapse upon a
slight lateral load?
I think I smell a lawsuit in the making.
Sniper Anon
On 28-Aug-2005, jobst....@stanfordalumni.org wrote:
> I am at a loss to suggest what rims you should get but with the hubs
> and spokes you have, there is no alternative to shelling out yet more
> for the same. Paired spoking, patented by Lovelace in 1890, had no
> benefits then and has none now.
Selling high profit margin boutique wheels certainly benefits the bottom
line of the manufacturer.
diann...@yahoo.com
> Hi Wheel gurus,
> my road bike is a '04 Trek 2100,
Nice bike, very similar to my Trek 2300!
> which came with Bontrager Select
> Rims. Recently, when fixing a flat, i noticed there were cracks on the
> rear rim near the spoke holes. the rim surface looks like:
>
> ===============================================
> --o-- o --o-- o
> ===============================================
>
> 'o' is the spoke hole. and '--' is the crack and '==' is the braking
> surfaces.
Classic rim cracks. Caused by fatigue (miles), sometimes made worse by
various conditions such as high spoke tension.
> This wheel is a 24 spoke wheel and has paired spokes.
The low number of spokes contributes to larger tension changes as the
wheel rolls. That acellerates fatigue, unless Bontrager designed the
rim for that (e.g. thicker wall). More on the paired spokes below...
> The cracks are all on the drive side spokes only.
Right side spokes have higher tension, so will normally crack sooner
than left side holes.
> And of the 12 total
> drive side spokes, 9 of them had cracks around them (on the rim). I have
> put on 10k miles on this wheel.
Sounds like you've just about used it up! In my experience most wheels
die an earlier death, either by violent trauma (e.g. hitting a kerb,
crashing, etc.), or by wearing out the rim sidewalls by braking.
> About me: 6'3" ~190lbs.
Not excessively heavy, I'd say.
> sometimes i like mash up over small hills, but
> usually spin up long grinding hills. i do not race, this is just a
> recreational/long distance riding bike.
Sounds like perfectly normal use to me.
> The LBS examined the wheel and said it was stress related cracks.
Precisely, the stress in the rim drops as each spoke comes to the road
contact point, then rises again as it passes. Eventually the changing
stress cracks the rim. That's metal fatigue.
> At the
> LBS, I found a '05 Bontrager Select wheel for $120. I would have bought
> it, if i had my credit card with me. I decided to return later to buy
> it.
Not a bad option! Would the '05 be a close enough match to your '04
front wheel?
> During this time it got me thinking and few questions:
> why failure and why now:
> * at ~10k miles, i have 9 cracks on the rims (i wonder when was the
> first crack appeared - approx 1000 miles ago ?? probably) in that case
> if i were to get a new set of wheels, probably will last only 8k or 9k
> miles.
Those are probably good assumptions.
> * the rims has no eyelets is that a possible cause for this failure ?
I'd expect Bontrager has designed the rim to tolerate that; I'd expect
the Bontrager rims that have eyelets are thinner (so might have about
the same life).
> * from the time i bought this bike, only once a spoke came loose and got
> it fixed by the LBS and two or three times went out of true and got it
> trued by the LBS. Other than that nothing special was made to the Wheel.
Fairly typical life of a wheel -- except you managed to avoid the usual
violence that often can end a wheel's life before fatigue cracks show
up. ;-)
> Also the rim is offset to accomodate the cassette - so the tension on
> the non-drive side wouldn't be as high - to cause this kind of failure.
Actually, the rim offset tends to *increase* the left side spoke
tension, to better help support the load. But still not to the higher
level of the right side spokes.
> * paired-spokes is it helping or not helping or hurting the life of wheels.
Trek's US patent (number 6,679,561) claims the spokes in your wheel are
far enough apart "so that, spoke imposed radial loads on the spoke bed
are unconcentrated"
> answers to the above concerns will help me choose one of the following
> options:
>
> * buy the '05 Bontrager Select wheel
Quick and easy, known performance.
> * get a rim and build up the wheel myself - i haven't examined the
> condition of the hub well to see what state it is in. In such a case, i
> would have to hunt for a 24h sturdy rim to start with.
If the hub is okay, another Bontrager rim would be the obvious choice
(few others will have the same drilling pattern). Re-use the old spokes
if none have broken; they're proven performers.
> thanks,
> ravi
Your Bontrager Select might be powder coated (not anodized). Some will
say this may have an effect on rim life, but I'm skeptical: cosmetic
anodizing is quite thin.
High spoke tension and mileage are the main killers when rims crack.
Don't back off the miles ;-) , but do ensure the spokes are tensioned
within the specs. Bontrager supply dealers with a table including your
Select wheel.
There's a third option, especially if your Bontrager hub isn't in good
shape: a new wheel with more spokes.
HTH!
carl...@comcast.net
wrote:
>
>carl...@comcast.net wrote:
>
>> Cracks like these are not uncommon when wheels are built to
>> the highest tension that they can stand withou t immediately
>> deforming, a value that can be higher than the rim
>> manufacturer expects and recommends.
>>
>> Either get a sturdier rim or reduce the tension.
>
>
>Dear Mr Peabrain,
>
>That's great advice. By how much exactly should he reduce the tension?
[snip strange legal fantasy]
Dear 4,
Rim manufacturers usually mention recommended tensions.
People usually ignore them.
Unless it's specifically mentioned that a tensiometer was
used to build the wheel, it's reasonable to assume that
someone used the seat of his pants.
Why do lawyers love to fantasize about becoming what they
despise and know next to nothing about?
Carl Fogel
carl...@comcast.net
wrote:
Aaargh!
Accidentally deleted "non-" in front of "lawyers".
(Possibly 41 will file suit?)
CF
Mike Jacoubowsky
>
> The spoke tension on the drive side was too high.
>
> Cracks like these are not uncommon when wheels are built to
> the highest tension that they can stand without immediately
> deforming, a value that can be higher than the rim
> manufacturer expects and recommends.
>
> Either get a sturdier rim or reduce the tension.
>
> Carl Fogel
Carl: A few further data points may enlighten you, as the customer is one of
ours and I personally inspected the rim.
First, the rim is worn down to the "wear indicators" on the sidewalls. Why,
after only 12k miles (which I believe was what we were originally told,
although he states here 10k, so I might have been confused) would the
sidewalls be worn that much? Primarily from riding in the rain. Ravi is
quite an enthusiastic rider and has taken to cycling in a big way, which is
great! We need more Ravis! But riding in the rain is hell on rims; it grinds
the sidewalls to pieces in no time. This isn't anything new; our commuters
commonly wear through sidewalls, sometimes literally exploding them. That's
why the newer rims have "wear indicators" (little square indentations in one
or two places on the sidewall which, when the rim is worn down to them, are
an indication it's time to replace).
Second, spoke tension on those wheels in not particularly high; in fact,
it's lower than many, due to the offset spoke bed. I have a theory, which
Jobst might disagree with, that rims ridden in the rain are more susceptible
to wear & cracks at the nipple/rim interface, due to abrassive action. I
have certainly seen the effects of this, but cannot say for sure of the
cause.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
<carl...@comcast.net> wrote in message
news:5004h15f6fc6g5pl4...@4ax.com...
Ron Ruff
Mike Jacoubowsky wrote:
> I have a theory, which
> Jobst might disagree with, that rims ridden in the rain are more susceptible
> to wear & cracks at the nipple/rim interface, due to abrassive action. I
> have certainly seen the effects of this, but cannot say for sure of the
> cause.
>
"Stress corrosion cracking (SCC) is the formation of brittle cracks in
a normally sound material through the simultaneous action of a tensile
stress and a corrosive environment."
I don't know if this is what is going on... but maybe the water (mixed
with a little salt?) would qualify as a "corrosive environment".
Still, the spoke holes of a rim should be designed to last if it is
ridden in the rain. Poor design or manufacture is the likely place to
look for a cause... unless the mechanic overtensioned the wheel by a
significant amount.
carl...@comcast.net
Dear Mike,
Are you saying that these spokes were actually checked with
a tensiometer and found to be low?
If so, was the tension check performed before or after the
cracking?
If the spokes were checked after the rim cracked and found
to have low tension, this isn't exactly surprising--any
cracking would tend to release tension.
Or are you saying that this particular brand of wheel is
supposed to have its spokes at what would be a low tension?
If so, how much?
As for the idea that rain is causing the cracks, I'm
skeptical, but willing to entertain almost any interesting
notion.
However, I suspect that someone will be throwing cold water
on that idea pretty soon.
Carl Fogel
jim beam
> Mike Jacoubowsky wrote:
>
>>I have a theory, which
>>Jobst might disagree with, that rims ridden in the rain are more susceptible
>>to wear & cracks at the nipple/rim interface, due to abrassive action. I
>>have certainly seen the effects of this, but cannot say for sure of the
>>cause.
>>
>
>
> "Stress corrosion cracking (SCC) is the formation of brittle cracks in
> a normally sound material through the simultaneous action of a tensile
> stress and a corrosive environment."
that's a possibility, and is a theory that's been proposed here a couple
of times in the past. it's hard to conclude one way or another in the
absence of some serious microscopy, but if the nipps are brass and the
rim is not eyeletted, that increases probability as copper compounds can
be an scc agent in some of these alloy systems.
carl...@comcast.net
wrote:
>Hi Wheel gurus,
Dear Ravi,
People seem interested in your plight, so here are
Bontrager's Select road wheels:
http://www.bontrager.com/Road/Wheelworks/Wheels/5754.php
The recommended tension seems to be higher than the 90-110
kgf often mentioned in this newsgroup.
According to the table on page 9 of this pdf . . .
http://www.bontrager.com/assets/File_Listings/asset_upload_file325_970.pdf
. . . all the various Select spokes (drive-side and also
non-drive-side) are supposed to be tensioned to 110-150
(presumably kgf) for loads in the 110 to 290 lb range
(presumably the rider's weight on both wheels).
Page 10 of the same pdf mentions that "We have worked with
Hozan to make a special gauge that is more accurate at the
higher spoke tensions used on Bontrager Wheelworks wheels."
Again, higher tension, fewer spokes, and cracks appearing on
the drive side spoke holes indicate that the tension is too
high for the rims, so getting rid of future cracks will
likely require either lower tension or else sturdier rims.
Carl Fogel
carl...@comcast.net
Dear Jim,
Brass locking nipples:
http://www.bontrager.com/Road/Wheelworks/Wheels/5754.php
Mike Jacoubowsky will know about the eyelets.
Carl Fogel
Mike Jacoubowsky
>
> Are you saying that these spokes were actually checked with
> a tensiometer and found to be low?
No, neither I nor my former service manager (he's now our "operations
manager", a bit of a change, but we still consider him our best service guy
in our Redwood City location) checked the tension with a tensiometer, but
unless Ravi had deliberately increased the tension himself (which is a
question I didn't think to ask), those wheels are set relatively-low by the
factory. The use of the offset spoke bed was specifically for that purpose.
There is no need on such a wheel to have really high tension on one side,
and much lower on the other. I should have pointed that out earlier.
> If so, was the tension check performed before or after the
> cracking?
Neither, not using a tensiometer anyway.
> If the spokes were checked after the rim cracked and found
> to have low tension, this isn't exactly surprising--any
> cracking would tend to release tension.
That would be true in the event of rim deformation, but typically the type
of cracking we see around spoke holes doesn't cause the wheel to go out of
true, which implies that it's not doing much to change the shape of the
spoke bed, at least not initially. I should also point out (or maybe I
shouldn't!) that I've experienced such cracks in a rim myself, and rather
than immediately replace the rim, continued to ride on it for a great many
mile afterward, to see what would happen. Specifically, I was wondering what
the eventual failure mode would be. When I told one of my tech reps about
this, he was horrified, to say the least. Sigh. I've seen enough wheels
where someone has broken a spoke in a crash or whatever and continued on,
that I really wasn't that worried about what would happen if a spoke
completely pulled out of the rim. My bad. Kids, don't try this one at home.
> Or are you saying that this particular brand of wheel is
> supposed to have its spokes at what would be a low tension?
> If so, how much?
Pretty much already gone over a few paragraphs above.
> As for the idea that rain is causing the cracks, I'm
> skeptical, but willing to entertain almost any interesting
> notion.
There could be two reasons why rims that are ridden in the rain fail more
often. One, people like me who ride nice wheels in icky weather end up
subjecting them to a lot more abuse (in terms of road hazards, because
there's a lot more bad stuff out there, including more stuff that you don't
see, when the weather's nasty). And second, the possiblity that gritty water
isn't a pleasant environment for the nipple/rim interface.
> However, I suspect that someone will be throwing cold water
> on that idea pretty soon.
At this point I should also point out that *many* bigger guys (Ravi & I are
either 6' or taller, and I'm not super light at 168, er, ok, 172 lately,
although Ravi, while taller, is pretty darned thin) go through rear rims at
a rate of 10k miles or less. Many get greater mileage than that too! But
those who ride hard, aren't superlight, and ride in the rain will often find
rear rims failing from cracks at the spoke holes, eyelets or not, and not
just on reduced spoke count wheels. We've had some Mavic 32 & 36-spoke rims
that were notorious for this; Jobst appears to believe it's from hard
anodization, and it just might be.
If one wants to greatly reduce the likelihood of rim cracking, my advice
would be to go to a much-heavier rim. Simply adding more material by itself
can result in reduction of this tendency. In my perfect world, the ultimate
rim would be a heavy rim with an offset spoke bed. That way you have more
even tension between the two sides of the wheel (which can only be a good
thing), plus greater resistance to cracking (because it's flexing less?).
> Carl Fogel
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
<carl...@comcast.net> wrote in message
news:4sp4h1tj6ca09e8n8...@4ax.com...
jobst....@stanfordalumni.org
> Posts asking if the MA-2 had been discontinued first appeared in
> 1996.
> By 1999, some people were even hoarding them:
> http://groups.google.com/group/rec.bicycles.tech/msg/d0051b6795e93287?dmode=source
> It's hard to buy rims that haven't been made in this century.
The way you say that, you make 10 years sound like eons. However, I
am not suggesting the OP try to use an unavailable MA-2 on a 24-spoke
paired spoke hub as you imply. My comments were directed toward the
pursuers of the latest in fadish equipment to the exclusion of the
reasonable and durable, so much so that reliable components are no
longer available. The wannabe racer has thus shot himself in the foot
when it comes to reliable components.
Jobst Brandt
jim beam
it's extraordinarily unlikely to be anodizing, given that the anodizing
cracks that radiate from a spoke hole are not always aligned with the
actual rim crack.
______
/ \ <--- extrusion crack
| |
| | <--- "anodizing" crack
| |
\______/ <--- extrusion crack
examination of a rim with a magnifier will show that anodizing cracks,
[and almost always present], are /strictly/ radial in nature, focusing
on the dead center of the rim hole. if subsequent rim cracking was
/only/ ever at the dead center of a hole, it could support the anodizing
theory by being exactly aligned with the anodizing cracks. trouble is,
rim cracks frequently initiate at the edge of a hole but still follow
the circumferential path, i.e. their initiation is /not/ influenced by
the orientation of the anodizing cracks present. following a strictly
circumferential path indicates a much stronger influence from a rims
extrusion characteristics. long cracks even progress some distance in
one circumferential path, jump sideways, then continue in a
circumferential path again. again, this indicates /classic/ extrusion
crack propagation.
jim beam
like drillium?
jobst....@stanfordalumni.org
>> I have a theory, which Jobst might disagree with, that rims ridden
>> in the rain are more susceptible to wear & cracks at the nipple/rim
>> interface, due to abrasive action. I have certainly seen the
>> effects of this, but cannot say for sure of the cause.
> "Stress corrosion cracking (SCC) is the formation of brittle cracks
> in a normally sound material through the simultaneous action of a
> tensile stress and a corrosive environment."
> I don't know if this is what is going on... but maybe the water
> (mixed with a little salt?) would qualify as a "corrosive
> environment".
> Still, the spoke holes of a rim should be designed to last if it is
> ridden in the rain. Poor design or manufacture is the likely place
> to look for a cause... unless the mechanic over-tensioned the wheel
> by a significant amount.
When I read how frail these wheels seem to be I don't see how riders
who have more the 10 years experience don't step up an mention that
other than crashing, side wall break wear was formerly the only death
of rims. Cracks are something hard anodizing introduced before any
changes in spoke count or rim cross section were made. Although the
first hard anodized models of formerly durable rims were touted as
being far stronger yet they separated in use so that some had the
spokes attached to the inner wall and the tire to the now separate
outer wall and bead. It was that bad. Mike should recall those days.
After that, anodizing was made thinner and the claim of greater
strength faded as fancier extrusions were brought to market. Used
rims of that time were sectioned and polished so that microscope
pictures of the cross section on end showed cracks in the anodizing
and cracks that propagated into the base aluminum. Non anodized rims
of the same kind and of similar age, discarded for crash trauma, were
similarly analyzed and showed no such cracks.
Marketing can do wonders:
Benefits:
Its new brilliant silver color has ensured its status as the most
talked about wheel in the peloton; and the new composite front hub
reduces the weight thanks to Mavic's expertise.
Lightweight
Lighter front hub (composite bonded to aluminum)
Rim manufactured using the ISM process
High ratio closure skewers
Zicral spokes/FTS-L hub
Efficiency
Ispoulse concept
Lateral rigidity due to Fore concept
FTS-L hub
Mavic quality bearings
Aerodynamic
Semi-profiled rims
Bladed spokes
Reduced spoke count
Great buzzwords, however...
They didn't mention overall weight and how much machining these rims
get to leave a thicker wall at spoke sockets.
Jobst Brandt
jim beam
> Ron Ruff writes:
>
>
>>>I have a theory, which Jobst might disagree with, that rims ridden
>>>in the rain are more susceptible to wear & cracks at the nipple/rim
>>>interface, due to abrasive action. I have certainly seen the
>>>effects of this, but cannot say for sure of the cause.
>
>
>>"Stress corrosion cracking (SCC) is the formation of brittle cracks
>>in a normally sound material through the simultaneous action of a
>>tensile stress and a corrosive environment."
>
>
>>I don't know if this is what is going on... but maybe the water
>>(mixed with a little salt?) would qualify as a "corrosive
>>environment".
>
>
>>Still, the spoke holes of a rim should be designed to last if it is
>>ridden in the rain. Poor design or manufacture is the likely place
>>to look for a cause... unless the mechanic over-tensioned the wheel
>>by a significant amount.
>
>
> When I read how frail these wheels seem to be I don't see how riders
> who have more the 10 years experience don't step up an mention that
> other than crashing, side wall break wear was formerly the only death
> of rims. Cracks are something hard anodizing introduced before any
> changes in spoke count or rim cross section were made.
funny. seems you don't recall the cracked silver ma2's. one of which
was shown here:
http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPG
pic from:
http://groups.google.com/group/rec.bicycles.tech/msg/a205b677a9954ada?hl=en&
so, not only do we have the cracked ma2, we also have circumferential
cracking that does /not/ follow the hole's radial anodizing crack
pattern. this rim /is/ [silver] anodized.
jobst....@stanfordalumni.org
> Brass locking nipples:
> http://www.bontrager.com/Road/Wheelworks/Wheels/5754.php
> Mike Jacoubowsky will know about the eyelets.
http://www.dtswiss.com/data/files/DAT_EN_30430225861.pdf
It sound impressive but it is merely a spoke nipple with Spoke Prep.
So why do we need them. As I explained, this concept was introduced
to make up for low tension in machine built wheels... which most wheels
are today.
Fortunately many of these wheels are hand finished these days and I
hope Holland Mechanics and BMD incorporate the feature I have been
proposing for years so that this tension restriction vanishes for
their machines. Maybe Spoke Prep will gradually go away, but don't
get your hopes up. Just think how long wheels were tied and soldered
for no useful purpose... mainly because we've always done it that way.
In the old days wheel builders used the momentary tension relief
method regularly for tightening thin spokes on 24-spoke wheels for
road and Track TT's.
Jobst Brandt
Mike Jacoubowsky
> who have more the 10 years experience don't step up an mention that
> other than crashing, side wall break wear was formerly the only death
> of rims. Cracks are something hard anodizing introduced before any
> changes in spoke count or rim cross section were made. Although the
> first hard anodized models of formerly durable rims were touted as
> being far stronger yet they separated in use so that some had the
> spokes attached to the inner wall and the tire to the now separate
> outer wall and bead. It was that bad. Mike should recall those days.
Mike does, indeed, recall those days. However, Mike also has memories of
rims that were much more easily dented than is presently the case. Rims were
most definitely "softer" back in the day. More ductile would be the way to
present it in a positive fashion. From a manufacturing standpoint, I can
only speak of Bontrager, and they have cut back on the use of anodizing,
believing that it may cause cracks. However, the extent to which those
cracks cause failure varies from rim-to-rim. As I mentioned to Carl, I've
ridden extensively on a rear rim that exhibits cracks at the eyelets (yes,
eyelets... I'm not convinced that eyelets are a cure for all that ails
rims). I measured the speed of crack propagation by marking the end of the
cracks with a felt-tip pen, and remain puzzled by the extremely slow-speed
with which they progress. The question I thus have is, should we be
concerned primarily with cracks that detune (cause an out-of-true condition)
the wheel? Or is any visible evidence of a crack something that should
elicit immediate concern and replacement?
jobst....@stanfordalumni.org
I don't know where you get this diagram but if a rim is going to
crack, a hard crust (anodizing) will accelerate that process and do
so on the same axis as it would were there no anodizing. It is the
preferred stress alignment to the extrusion that is inherently weaker
across the axis of extrusion than in line with it.
Jobst Brandt
jobst....@stanfordalumni.org
>> I have a theory, which Jobst might disagree with, that rims ridden
>> in the rain are more susceptible to wear & cracks at the nipple/rim
>> interface, due to abrasive action. I have certainly seen the
>> effects of this, but cannot say for sure of the cause.
> "Stress corrosion cracking (SCC) is the formation of brittle cracks
> in a normally sound material through the simultaneous action of a
> tensile stress and a corrosive environment."
> I don't know if this is what is going on... but maybe the water
> (mixed with a little salt?) would qualify as a "corrosive
> environment".
> Still, the spoke holes of a rim should be designed to last if it is
> ridden in the rain. Poor design or manufacture is the likely place
> to look for a cause... unless the mechanic over-tensioned the wheel
> by a significant amount.
When I read how frail these wheels seem to be I don't see how riders
who have more the 10 years experience don't step up an mention that
other than crashing, side wall brake wear was formerly the only death
of rims. Cracks are something hard anodizing introduced before any
changes in spoke count or rim cross section were made. Although the
first hard anodized models of formerly durable rims were touted as
being far stronger yet they separated in use so that some had the
spokes attached to the inner wall and the tire to the now separate
outer wall and bead. It was that bad. Mike should recall those days.
After that, anodizing was made thinner and the claim of greater
jim beam
no. if the actual rim crack orientation is not aligned with the
anodizing crack orientation, you /cannot/ claim cause and effect.
"acceleration" just a red herring.
> It is the
> preferred stress alignment to the extrusion that is inherently weaker
> across the axis of extrusion than in line with it.
in fracture mechanics and fatigue, initiation sets the whole playing
field for propagation. since initiation is clearly not in the realm of
anodizing because the orientation is wrong, and propagation is clearly a
feature of extrusion, there is nothing you can wave at as some kind of
association.
>
> Jobst Brandt
Ravi
> Either get a sturdier rim or reduce the tension.
i am going to rebuild the hub using much more sturdier rims and will use
it either as a replacement wheel/rain wheels... being a newbie, i am
*awestuck* at the volume of research/science behind each and every
aspect of a simple machine we all call bicycle...
thanks,
ravi
>
> Carl Fogel
41
jim beam wrote:
> jobst....@stanfordalumni.org wrote:
> > When I read how frail these wheel s seem to be I don't see how riders
> > who have more the 10 years experience don't step up an mention that
> > other than crashing, side wall break wear was formerly the only death
> > of rims. Cracks are something hard anodizing introduced before any
> > changes in spoke count or rim cross section were made.
>
> funny. seems you don't recall the cracked silver ma2's. one of which
> was shown here:
>
> http://web.onetel.net.uk/~davidwgreen/rimpics/4.JPG
>
> pic from:
> http://groups.google.com/gro up/rec.bicycles.tech/msg/a205b677a9954ada?hl=en&
Funny but you don't seem to recall that in that thread Dianne proposed,
and a certain wheel book author independently proposed as well, that
the cause was a too-short socket. I suppose you also don't recall that
after that was explained, you couldn't even understand why, if that
were the case, the cracks were nevertheless only on the drive side. I'd
say funny that you would want to recall one of your many more
embarassing moments, but then you often link to things that discredit
what you say..
Ravi
>
>
> rim cracks are usually either defective rims [not so common] or excess
> spoke tension. sounds like your lbs was over-tensioning if it had been
> trued multiple times.
i haven't been riding on good roads either. Since this was my first
serious bike, i should take some guilt. I have learned few of the
techniques to take care of the wheels - like getting off the saddle when
going over potholes and such stuff. Also there were sometimes i would
ride down certain bumpy roads without trying to take it easy etc. --
this was all during my rookie period of cycling.
> eyelets can be effective local stress mitigation, but even eyeletted
> rims crack if spoke tension is still too high.
>
> regarding repair/replacement, replacement is probably the way to go. i
> believe you can get rims to repair this wheel, but the economics may not
> make a lot of sense. standard rims are not usually available in paired
> spoking but you could try a 36h rim skipping every 3rd hole, but spoke
> length may be an issue, not to mention drilling offset.
I am not going to be trying any thing that sophisticated yet. But if i
get a good sturdy 24h rim, will build up this hub. But as a replacement,
i am going with the new wheel approach - also because of time
constraints ;) i do not want to see my bike with a handicap - who would
want to...
thanks,
ravi
41
That does seem to be the operative phrase. Your advice was so
authoritative though! It was as if you had actually inspected the wheel
and had the experience to know just what to do.
Ravi
>
> There are several effects coming together that cause these failures.
> One is too few spokes another is no steel sockets or eyelets, another
> is hard anodizing together with excess tension caused by using too few
> spokes. In addition, to accommodate 10-speed gear clusters, rear hubs
> have gotten narrower to reduce offset (and the required difference in
> tension from left to right). Just the same rear wheels, carry at
> least 2/3 the load with the right side spokes. No wonder the rims
> develop fatigue cracks.
i understand the point you are making. I have read some of your posts
and others just blow past my head ;) and i am able to slowly appreciate
the value of good old, time proven method of wheel building. Using
sheldonbrown's website of wheel building, i have completed two such
wheels (front and rear) and they have held up pretty decently for
~200miles now. Your book is in my reading list for sure.
> Before the equipment fad got rolling in the present mode, low spoke
> count wheels were used for special events like time trials. Then
> professional teams, sponsored by component manufacturers, began using
> them on a regular bases, to hell with the expense of frequent
> replacement. So here we are with no market for reliable and durable
> wheels, most riders being convinced that if Lance Armstrong does it,
> it must be what I need.
Definitely that seems to be the case - just like in the fashion world,
the stars set new looks, same is true in cycling as well. But yes, we
need to definitely understand the basics and carry forward the essence
of the classical ways of wheel building.
> I am at a loss to suggest what rims you should get but with the hubs
> and spokes you have, there is no alternative to shelling out yet more
> for the same. Paired spoking, patented by Lovelace in 1890, had no
> benefits then and has none now.
thanks for attempting, i just outpoured some of my thoughts in the OP.
> For recreational bicycling (oops, that's not PC, we are all on
> training rides for our next competition) 36-spoke wheels are still the
> reasonable compromise between rim weight and number of spokes. With
> low spoke count, one spoke failure will make the wheel unridable but
> to make up for that, the spoke cannot be replaced in the field because
> such wheels require special fixturing to be tensioned and trued. I
> suppose the cell phone has absolved people of touring with tools and
> equipment to be self sufficient, so wheels will probably continue to
> be as fragile and excessively expensive as most currently are.
i understand what i gotten into. I am a newbie in terms of bicycling
science. I keep a good LBS supported bike and then there is this self
supported bike - which is kind of still in the process of learning and
stuff. i am slowly getting there... but thanks for letting us pick your
brains - all your efforts help people like us (newbies) get better
understanding of things....
I was reading http://yarchive.net/bike/index.html the other day and
found very useful and informative posts. Thanks Jobst !
BTW, on one of your pictures (in Bill Bushnell's) rides, i noticed
something different -
http://bushnell.homeip.net/~bill/bike/pictures/tailwinds_to_santa_cruz.2005.04.09/pages/page_26.html
you have the right hand operate the front brake ?? and left the rear ?
thanks for your insights,
+ravi
> It was not long ago that a rider was assured of finding a replacement
> rim at most any bicycle shop in the USA or overseas, the standard
> being the 36-spoke Mavic MA-2 and other rims that had the same
> effective dimensions. I recall rolling into a shop in Italy where we
> bought a new MA-2 rim to replace a severely dinged one and no one
> thought it was unusual to expect to find one. Most every bicycle
> shop had these on the overhead rack.
> Jobst Brandt
Bruce Graham
>
> i haven't been riding on good roads either. Since this was my first
> serious bike, i should take some guilt. I have learned few of the
> techniques to take care of the wheels - like getting off the saddle when
> going over potholes and such stuff. Also there were sometimes i would
> ride down certain bumpy roads without trying to take it easy etc. --
> this was all during my rookie period of cycling.
>
>
rims more than you did would have been a waste of time. Rims are
consumables like brake pads and chains and cassettes but they often last
a bit longer than the other parts. I think the Mavic website even says
to regard rims as consumables.
Ride down a few steep twisty mountain roads in the wet and see just how
fast you can wear your rims!
Bruce
Ravi
> Ravi wrote:
> Nice bike, very similar to my Trek 2300!
2300 is very nice bike. I came this close to buying it... but you know
the bugetary police didn't permit ;)
> Sounds like you've just about used it up! In my experience most wheels
> die an earlier death, either by violent trauma (e.g. hitting a kerb,
> crashing, etc.), or by wearing out the rim sidewalls by braking.
touch wood, i don't want any part to meet such a violent end.
>
> Not a bad option! Would the '05 be a close enough match to your '04
> front wheel?
i think they have similar patterns, so it will not too much of a
mismatch. fashion police cannot get me on this one.
>>During this time it got me thinking and few questions:
>>why failure and why now:
>>* at ~10k miles, i have 9 cracks on the rims (i wonder when was the
>>first crack appeared - approx 1000 miles ago ?? probably) in that case
>>if i were to get a new set of wheels, probably will last only 8k or 9k
>>miles.
>
> Those are probably good assumptions.
Ok, one question, when should i stop riding on a rim ? At the sign of
the first crack on any of the spokes ??
> Quick and easy, known performance.
*Quick and Easy* is the part i like it most. And with the old hub, i am
gonna rebuild with a much heavier rim for rain rides.
> If the hub is okay, another Bontrager rim would be the obvious choice
> (few others will have the same drilling pattern). Re-use the old spokes
> if none have broken; they're proven performers.
hub seems to have some reasonable amt. of life in it, but i haven't
taken it apart to examine the innards of it, but will try to give it new
life with a new rim, hopefully that will get me thru this winter.
thanks,
ravi
Ravi
> Dear Ravi,
>
> People seem interested in your plight, so here are
> Bontrager's Select road wheels:
thanks to all the posters who had jumped in to share their
thoughts/comments. I appreciate each of the response :)
> http://www.bontrager.com/Road/Wheelworks/Wheels/5754.php
>
> The recommended tension seems to be higher than the 90-110
> kgf often mentioned in this newsgroup.
>
> According to the table on page 9 of this pdf . . .
>
> http://www.bontrager.com/assets/File_Listings/asset_upload_file325_970.pdf
>
> . . . all the various Select spokes (drive-side and also
> non-drive-side) are supposed to be tensioned to 110-150
> (presumably kgf) for loads in the 110 to 290 lb range
> (presumably the rider's weight on both wheels).
Thanks carl for going to the extent of locating the page numbers... I
will keep this in mind with my new wheel.
>
> Page 10 of the same pdf mentions that "We have worked with
> Hozan to make a special gauge that is more accurate at the
> higher spoke tensions used on Bontrager Wheelworks wheels."
>
> Again, higher tension, fewer spokes, and cracks appearing on
> the drive side spoke holes indicate that the tension is too
> high for the rims, so getting rid of future cracks will
> likely require either lower tension or else sturdier rims.
sure, i am going to rebuild the hubs with a sturdier rim - as a quick
replacement, i am going to go with a new wheel and the sturdier rim
based on the outcome, i would either use it along with the new one.
Thanks for all of your replies,
+ravi
> Carl Fogel
carl...@comcast.net
jobst....@stanfordalumni.org wrote:
>Carl Fogel writes:
>
>>>> The spoke tension on the drive side was too high.
>
>>>> Cracks like these are not uncommon when wheels are built to the
>>>> highest tension that they can stand without immediately deforming,
>>>> a value that can be higher than the rim manufacturer expects and
>>>> recommends.
>
>>>> Either get a sturdier rim or reduce the tension.
>
>>> So Carl, did you perform experiments and analysis to support your
>>> argument, or did you decide to take jim beam's side just to rankle
>>> Jobst Brandt?
>
>> Er, what other explanation besides the spoke tension being too high
>> for the rim do you offer when the rim cracks around the base of 9
>> out of 12 of the higher-tension drive-side spokes after a few
>> thousand miles?
>
>> It's not as if this is a new complaint on this newsgroup.
>
>> Jobst's approach of increasing the tension until the wheel deforms
>> and then backing off was developed with sturdy 36-spoke rims back in
>> the 1980's.
>
>> When applied to flimsier, lower-count modern rims, this practice can
>> lead to cracks around the spoke holes.
>
>Ah yes, "modern" rims. How much e have progressed
>
>> To produce the same overall drive-side tension of 18*T that will
>> cause local yielding with only 12 spokes instead 18, each spoke has
>> to be tightened to 1.5*T.
>
>> Hmmm... a 50% increase in tension, cracks appear around the spoke
>> holes in a few thousand miles, and someone starts a thread to ask
>> what to do.
>
>> This is why Jim Beam keeps suggesting that wheel-builders should use
>> a tensiometer and tension the spokes to the rim manufacturer's
>> recommendation.
>
>That makes little difference. What comes from that is the need for
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Loctite on the spoke threads because spokes are now so loose (to not
>crack rims) that they slacken in use. It is not unusual to hear spoke
>rattle over rougher pavement and that is what unscrews spoke nipples.
>
>At first it was machine built wheels, ones that machines could not
>true if made tight as they should be, that introduced thread locking
>compounds. Now that we have them, wheels have taken the next step,
>that of requiring loose spokes to prevent rims failure and thereby
>making thread-lock a necessity. Thread-lock has become the norm in
>lieu of reasonably tight wheels because so many have so few spokes.
>
>Jobst Brandt
Dear Jobst,
In this case, tension does seem to make the difference.
The cracks in the rim are appearing around nine of the
twelve higher-tension drive-side spokes.
The cracks aren't appearing around the lower-tension
non-drive-side spokes.
If lack of tension caused the cracking, then the cracks
would have first appeared around the lower-tension spokes.
This again suggests that the problem is that the spokes were
over-tensioned for this particular rim.
The solution still sounds like either lower tension or a
different rim.
Carl Fogel
Paul Cassel
I'm new to this sport - only a few months, but did buy and read your
book as I thought I may have to equip my ride with new wheels. It turned
out I had to return that ride and buy a new one which came with working
wheels.
I think you are missing a very important point in the entire wheel
discussion. That's simply that folks don't mind buying new wheels every
few thousand miles and in fact may prefer to do so. You may disparage
such behavior as 'marketing' or that the riders are fools, but that's
what folks are like. Even very expensive wheels don't mean a severe
economic hardship to many riders if they're needed at even the short
interval of, say, 3-5k miles. Every rider isn't a poor student or a
racer getting by on a pittance.
For many years Checker made a car which would go hundreds of thousands
of miles w/o much work. Taxi companies bought these cars which would
have worked perfectly fine for 90% of consumers, but they didn't sell
much to individuals *despite being the right choice from a durability
view*.
If you doubt that folks don't WANT the equivalent of the Checker car in
wheels, just look around you or start offering 36 spoke 4 cross wheels
to folks riding 16 lb wonders. Use the selling point that the wheels
will outlast the bikes. Or maybe just envision what a 4 cross would look
like on a 16 lb wonder with carbon brake levers.
My new for me bike has wheels which you condemn. I won't debate your
points why these wheels aren't nearly as durable as the ones you prefer
because I know you are right. However, there are considerations aside
from durablity when it comes to desireablity.
-paul
Doug Huffman
and drives price inflation. We who ride as a 'lifestyle' - perhaps on a
fixed income - would prefer not to see the cost of cycling further inflated.
The conspiracy of ignorance masquerades as common sense.
"Paul Cassel" <pcasse...@comcast.net> wrote in small part in message
news:A9SdnZ2dnZ2uNRSnnZ2dn...@comcast.com...
Sandy
Doug Huffman <doug.h...@comcast.net> a réfléchi, et puis a déclaré :
> "Desirability", especially in a newbie, equals marketing or
> commercialism and drives price inflation. We who ride as a
> 'lifestyle' - perhaps on a fixed income - would prefer not to see the
> cost of cycling further inflated.
You live in the bastion of market-driven economy ; it is the economic
philosophy you are exporting and, at times, imposing in other cultures. So,
get used to it - your niche of the market is not where the momentum is. Big
noise versus little chirp.
> The conspiracy of ignorance masquerades as common sense.
Cool stuff, even if unrelated.
--
Bonne route !
Sandy
Verneuil-sur-Seine FR
Doug Huffman
What shall I accuse in return, hmm, M. Francophile?
And I consider my "cool stuff" on point.
"Sandy" <leu...@frree.fr> wrote in message
news:43130cc8$0$8242$626a...@news.free.fr...
Art Harris
> My new for me bike has wheels which you condemn. I won't debate your points why these wheels aren't nearly as durable as the ones you prefer because I know you are right. However, there are considerations aside from durablity when it comes to desireablity.
Please elaborate. What characteristics of these wheels make them more
desireable? If you're willing to pay more for a less durable wheel,
there must be some reason.
Art Harris
Jasper Janssen
They're PRETTY!
Why do people buy Barbies, after all?
Jasper
Rick
Mike Jacoubowsky wrote:
> > Dear Mike,
> >
> > Are you saying that these spokes were actually checked with
> > a tensiometer and found to be low?
>
> No, neither I nor my former service manager (he's now our "operations
> manager", a bit of a change, but we still consider him our best service guy
> in our Redwood City location)
If Bruno is now Ops manager, who is service manager?
>
> At this point I should also point out that *many* bigger guys (Ravi & I are
> either 6' or taller, and I'm not super light at 168, er, ok, 172 lately,
> although Ravi, while taller, is pretty darned thin) go through rear rims at
> a rate of 10k miles or less. Many get greater mileage than that too! But
> those who ride hard, aren't superlight, and ride in the rain will often find
> rear rims failing from cracks at the spoke holes, eyelets or not, and not
> just on reduced spoke count wheels. We've had some Mavic 32 & 36-spoke rims
> that were notorious for this; Jobst appears to believe it's from hard
> anodization, and it just might be.
Mike, 172 at 6' is not that big. I am 5'9" and run in the 160lb
category, and some folks think I am too thin.
Anyway, 10K miles on a rim is ridiculously low unless one is riding in
slop all the time. I ride all handbuilt wheels, 32 or 32 spoke. I
have a mix of rims, some on the lighter side, some heavy duty (Mavic
T520, e.g.). I ride on the same hills as you, in all weather, and Ravi
and I do a lot of the same route on our commutes. I would consider
10K unacceptable as an average for a rim. Somethings wrong if that's
all the life one is getting out of a hoop.
- rick
data...@yahoo.com
Mike Jacoubowsky
Art: It's not just wheels, it's everything. But for fun let's look at the
choices people make for their wives/husbands/life partners or whatever. How
much is based on practicality (low maintenance, less expensive, greater
compatibility) and how much is driven by appearance? Remember, we're not
talking about something as minor as a bike choice here, we're talking about
the person you might be spending your entire life with!
So I guess my point is this- if someone thinks a given wheel looks cooler,
or has some other benefit they like (maybe a bit lighter weight or more
aerodynamic perhaps)... well, what makes that such a terrible reason for
choosing a wheel? And how many of the people who demand little more from a
wheel than that's it's "workable" are consistent with that in other areas of
their lives, or is there almost a fetish about keeping the bicycle pure &
simple just because you can?
Fortunately, my own experience is that you can have it both ways, if you
wish (boutique and durable).
--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA
Ron Ruff
Sandy wrote:
>
> You live in the bastion of market-driven economy ; it is the economic
> philosophy you are exporting and, at times, imposing in other cultures. So,
> get used to it - your niche of the market is not where the momentum is. Big
> noise versus little chirp.
>
True, but...
I too live in "the bastion of market-driven economy", but I don't
subscribe to that philosophy nor many others that are tirelessly
promulgated here... and I have no plans to ever "get used to it".
Keep on chirping!
diann...@yahoo.com
> On Sun, 28 Aug 2005 11:07:23 -0700, Ravi <tor...@yahoo.com>
> wrote:
>
> The recommended tension seems to be higher than the 90-110
> kgf often mentioned in this newsgroup.
>
> According to the table on page 9 of this pdf . . .
>
> http://www.bontrager.com/assets/File_Listings/asset_upload_file325_970.pdf
>
> . . . all the various Select spokes (drive-side and also
> non-drive-side) are supposed to be tensioned to 110-150
> (presumably kgf) for loads in the 110 to 290 lb range
> (presumably the rider's weight on both wheels).
Wow Carl, kind of sloppy compared to your usual thoroughness! Here are
a couple of notes in response to your comment above:
1. Not all the spokes; only drive side are specfied in the rear wheel.
Look at the top of the column. There's a note indicating drive side.
2. The Bontrager manual gives the units at the top of each column. The
spoke tension is "Deflection [in] Gauge Units", not kilograms.
3. "Load" appears to refer to spoke tension in pounds. But I'm just
guessing here.
I'm guessing "gauge units" are a measure of the displacement of the
plunger in the tensiometer. On page 10, Fig. 24, you can see the
Bontrager/Hozan spoke tension gauge looks like it uses a fairly
ordinary dial indicator. Other spoke tensiometers also require
conversion from the gauge reading to spoke tension, so "gauge units"
should be no surprise.
> Page 10 of the same pdf mentions that "We have worked with
> Hozan to make a special gauge that is more accurate at the
> higher spoke tensions used on Bontrager Wheelworks wheels."
^^^^^^^^^^^^^^^^^^^^^
Perhaps the "higher tension" is refering to the aero wheels at the top
of the chart? Up to 400 pounds! (You and I discussed that some time
ago, I recall).
However, the Select rear wheel calls for more normal tension (on the
right side) between 110 and 290 pounds, which, if I've done the maths
right, convert to roughly 50 and 130 kilograms. Though it seems like
quite a spread, on average it's perhaps not exceptionally high.
> Again, higher tension, fewer spokes, and cracks appearing on
> the drive side spoke holes indicate that the tension is too
> high for the rims,
... or that the wheel has run its intended mileage?
Reminds me of the thread asking "How long should wheels last?" Maybe
10,000 miles is enough? ...Or not?!? :-)
diann...@yahoo.com
> >>* at ~10k miles, i have 9 cracks on the rims (i wonder when was the
> >>first crack appeared - approx 1000 miles ago ?? probably) in that case
> >>if i were to get a new set of wheels, probably will last only 8k or 9k
> >>miles.
> >
> > Those are probably good assumptions.
>
> Ok, one question, when should i stop riding on a rim ? At the sign of
> the first crack on any of the spokes ??
Replacing at the first crack is probably what the manufacturer might
advise, bout would be *very* conservative in my opinion.
You implied in your original post that the wheel seemed okay until you
happened to notice the cracks; also, Mike J has related his personally
riding a cracked rim with no immediate ill effects. Those experiences
should give you an idea that rim cracking is typically a graceful
failure.
Sniper Anon
On 29-Aug-2005, Paul Cassel <pcasse...@comcast.net> wrote:
> I think you are missing a very important point in the entire wheel
> discussion. That's simply that folks don't mind buying new wheels every
> few thousand miles and in fact may prefer to do so. You may disparage
> such behavior as 'marketing' or that the riders are fools, but that's
> what folks are like. Even very expensive wheels don't mean a severe
> economic hardship to many riders if they're needed at even the short
> interval of, say, 3-5k miles. Every rider isn't a poor student or a
> racer getting by on a pittance.
With a wasteful attitude like that, you must be a USian.
Steel frame bicycles are great because they will last (or the frames can be
repaired) practically forever, and the components can be replaced as they
wear out.
All the crap in stores that costs more to repair than replace disgusts me.
--
Sniper Anon
----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Sniper Anon
On 29-Aug-2005, "Doug Huffman" <doug.h...@comcast.net> wrote:
> "Desirability", especially in a newbie, equals marketing or commercialism
> and drives price inflation. We who ride as a 'lifestyle' - perhaps on a
> fixed income - would prefer not to see the cost of cycling further
> inflated.
Wow! Something sensible written by Doug Huffman.
carl...@comcast.net
>carl...@comcast.net wrote:
>> On Sun, 28 Aug 2005 11:07:23 -0700, Ravi <tor...@yahoo.com>
>> wrote:
>>
>> The recommended tension seems to be higher than the 90-110
>> kgf often mentioned in this newsgroup.
>>
>> According to the table on page 9 of this pdf . . .
>>
>> http://www.bontrager.com/assets/File_Listings/asset_upload_file325_970.pdf
>>
>> . . . all the various Select spokes (drive-side and also
>> non-drive-side) are supposed to be tensioned to 110-150
>> (presumably kgf) for loads in the 110 to 290 lb range
>> (presumably the rider's weight on both wheels).
>
>Wow Carl, kind of sloppy compared to your usual thoroughness! Here are
>a couple of notes in response to your comment above:
>
>1. Not all the spokes; only drive side are specfied in the rear wheel.
>Look at the top of the column. There's a note indicating drive side.
>2. The Bontrager manual gives the units at the top of each column. The
>spoke tension is "Deflection [in] Gauge Units", not kilograms.
>3. "Load" appears to refer to spoke tension in pounds. But I'm just
>guessing here.
Dear Dianne,
Er, look at the top of the table again and re-read what I
scribbled.
http://www.bontrager.com/assets/File_Listings/asset_upload_file325_970.pdf
The front and the rear drive-side spoke "deflection" for all
the Select wheels are indeed listed in two columns--and the
values are all the same, 110-150 gauge units.
Typically, spoke tensions are listed as front and rear
non-drive-side together, versus rear drive-side, which is
generally higher.
In this case, the broad range appears to include all
spokes--the front, the rear non-drive side, and the rear
drive side are all at 110-150 Hozan gauge units.
It was reasonable to presume that these gauge units are
intended to represent kgf, but not certain--that's why I
wrote "presumably kgf".
Finding the details about the Hozan readings is surprisingly
hard (a number of sites that used to carry Hozan have
dropped their tensiometers, possibly due to the much less
expensive and more popular Park tool), but here's a link to
a Mavic page that indicates that the Hozan "divisions" are
ridiculously close to kgf:
http://www.birota.ru/manuals/mavic/roadracing/coscarbonssc/CosCarbSSCSpareParts2001.pdf
At the bottom under "tension," Mavic recommends tensioning a
front wheel (not the one in this thread) at
110-130 kg or
100-120 divisions (Hozan tensiometer),
and the right rear at
130-150 kg or
120-150 divisions (Hozan tensiometer).
I also guessed that the 110 to 290 load for all columns and
versions of the Select wheel was intended to be the rider's
weight, so I'm not sure why you offered a note to the same
effect.
Frankly, the Bontrager table is poorly done, but I think
that I interpreted it accurately.
Carl Fogel
jim beam
since tensiometer reading is dependent on spoke gauge as well as spoke
tension, presumably hozan chose a scale that was convenient for the
commonest spoke gauge, 1.8mm in the butted section. for any other
gauge, conversion will be obligatory.
Ravi
> Carl: A few further data points may enlighten you, as the customer is one of
> ours and I personally inspected the rim.
thanks mike for jumping in. These doubts, i had of late and i shot an
email. I sense that there is a generation gap in the line of wheel
building. Newer generation wants to be trendy and flashy looking,
whereas the older generation is kind of based on sound values and
reliability. I kind of have to say it is natural, but things will
eventually go the righ way - even though the current trend isn't </end
philosophy mode>.
I got very useful inputs on the goodness of using the time proven
methods of wheelbuilding (including the components). Recently i built my
first wheel (actually built two). They are 36H and cross 3 for my fixie.
I will post pics soon. I would definitely need to read "The Bicycle
Wheel' to really grasp the basics. As far as replacement for this wheel
goes, i am going to have to resort to the newer generation method of
going for a new wheel. But i am going to build up that 24h hub with a
much heavier rim, and use for the rainy conditions.
thanks to all the responses, you have been very informative :)
happy riding,
+ravi
Mike Jacoubowsky
>> are
>> either 6' or taller, and I'm not super light at 168, er, ok, 172 lately,
>> although Ravi, while taller, is pretty darned thin) go through rear rims
>> at
>> a rate of 10k miles or less. Many get greater mileage than that too! But
>> those who ride hard, aren't superlight, and ride in the rain will often
>> find
>> rear rims failing from cracks at the spoke holes, eyelets or not, and not
>> just on reduced spoke count wheels. We've had some Mavic 32 & 36-spoke
>> rims
>> that were notorious for this; Jobst appears to believe it's from hard
>> anodization, and it just might be.
>
> Mike, 172 at 6' is not that big. I am 5'9" and run in the 160lb
> category, and some folks think I am too thin.
At 5'9 and 160lb, you're a compact model! At any rate you're below any sort
of threshold where we commonly see rapid wear on equipment due to weight. My
problem is not just the weight, but also my "style" (or lack thereof). I
love to sprint, I do lots of intervals (which I don't love, but they're good
for me), and I tend to attack hills out of the saddle, which most definitely
makes a difference.
Of course, I don't really have a baseline for how long my equipment will
last with the new, slightly-lighter me (I'm hovering between 168 & 172,
whereas a bit over a year ago I was in the 180-185 range). But, since I'm
still delivering the same power to the pedals, I'm not likely to see the
reduction in component stress I might otherwise.
> Anyway, 10K miles on a rim is ridiculously low unless one is riding in
> slop all the time. I ride all handbuilt wheels, 32 or 32 spoke. I
> have a mix of rims, some on the lighter side, some heavy duty (Mavic
> T520, e.g.). I ride on the same hills as you, in all weather, and Ravi
> and I do a lot of the same route on our commutes. I would consider
> 10K unacceptable as an average for a rim. Somethings wrong if that's
> all the life one is getting out of a hoop.
And on that we'll just have to disagree. A front wheel can go several times
that, but 10k miles is not a bad number for the average rider. Any number of
things can kill a wheel, as has been mentioned here. That you get greatly in
excess of that is great, but your experience (even on the same equipment as
others) is simply not typical. And, for every rider like yourself, we'll
have one (actually, usually more than one) who can kill just about anything
built for him, regardless of weight & spoke count. Typically it's a rider
who's on the larger side and rides in groups where he's somewhat outmatched,
always on the rivet (as Paul S would say), riding at the back of the pack
just barely hanging on. No time to maneuver out of the way of the pothole
suddenly appearing underneath.
That you can get such miles in the rain is strange though, as there really
isn't anything aside from increased sidewall thickness (heavy rims) that can
give rain wheels longer life. Unless you've got disc brakes, of course! :>)
But are you really as stupid as I am, and ride in the hills no matter what
the weather? I gave you more credit than that! Maybe someday my
Tuesday/Thursday ride will fall on a holiday with really nasty weather and
you can join me!
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
Mike Jacoubowsky
zillion other things going on at the time), you're missing the fact that a
tensiometer is going to deflect differently, for the same amount of tension,
based on the spoke's cross-section. Thus a true 100lb load is going to show
a much different number for a thin spoke than for a thicker one, as well as
different for a round spoke vs bladed. There's no way for the tensiometer to
know the difference, since all it's doing is measuring deflection...*not*
the actual load.
Ted Bennett
> since tensiometer reading is dependent on spoke gauge as well as spoke
> tension, presumably hozan chose a scale that was convenient for the
> commonest spoke gauge, 1.8mm in the butted section. for any other
> gauge, conversion will be obligatory.
Could you enlighten us as to how to do the conversion? Is it simply a
matter of ratio of r, or of r^2?
It would also seem that the design of the tensiometer could also be a
source of error, if the wire thickness varies. It seems at first glance
that the instrument must press on both sides of the wire.
--
Ted Bennett
carl...@comcast.net
Dear Mike
As Jim Beam points out, it's likely that Hozan's
calibrations were intended to be close to kgf for a fairly
common spoke size.
I'm aware of the difference in readings for different
spokes, but given the poor quality of the Bontrager and
Hozan sites, it's hard to do much more than point out that
the Hozan division readings are practically identical to kgf
on the link that I could find (a poor Mavic page).
I'm being unkind to Bontrager and Hozan, but the Bontrager
site assumes that everyone will not only use a Hozan
tensiometer, but a Bontrager version of a Hozan tensiometer.
This, again, is probably why Hozan tensiometers are so hard
to track down lately. The less willing you are to play
nicely, the fewer people you will find willing to play.
The much cheaper Park tool, for example, comes with a
calibration table for numerous spoke widths and
designs--flat, oval, and bladed--that translates its
readings into kgf. And it was designed so that there's
little chance of the user confusing its readings for direct
kgf--a 25 on the Park tensiometer is around 200 for a
straight 14 gauge, as I recall (irritated comment follows).
A surprising number of technical information pages cannot
pass the obvious test of whether they answer the obvious
questions--which is why this newsgroup attracts so many
frustrated questions addressed to knowledgeable bike dealers
like Sheldon Brown, Peter Chisholm, Andrew Muzi, John Dacey,
and others.
To be fair, the Mavic link that I gave isn't much
better--the Mavic page tells you the spoke length and part
number, but not whether they're round, butted, oval, or
bladed, much less their width.
The damned Park Tool site has just been changed, but it
still doesn't have that most basic feature, an option to
search the site.
And when you finally stumble over the damned table showing
how many kgf a reading of 25 means on a bladed spoke, there
is no table!
You have to download and view an XLS spreadsheet, which
could have been used to put the table on the screen.
http://www.parktool.com/repair/readhowto.asp?id=79
Aaaaargh! Why not just put the table in plain sight where
everyone can find it?
[Pause to wipe froth from trembling lip.]
You and Dianne strike me as being quite knowledgeable about
these wheels, but it doesn't sound as if either of you has a
handy table that indicates the recommended spoke tension in
kgf.
(You know, exactly what someone like the original poster
would like to know when he starts trying to work on his own
wheels.)
If anyone has a table that translates Bontrager-modified
Hozan tensiometer divisions into plain old kgf for various
spokes, it would help--we'd know what the recommended
tension actually was.
Until then, I'll continue to suspect that the original
poster (a nice fellow who can only marvel at the fuss)
needed lower spoke tension or a sturdier rim to avoid those
cracks around 9 out of 12 of his drive-side spoke holes.
Carl Fogel
Phil, Squid-in-Training
>>> My new for me bike has wheels which you condemn. I won't debate your
>>> points why these wheels aren't nearly as durable as the ones you
>>> prefer because I know you are right. However, there are
>>> considerations aside from durablity when it comes to desireablity.
>>
>> Please elaborate. What characteristics of these wheels make them more
>> desireable? If you're willing to pay more for a less durable wheel,
>> there must be some reason.
>>
>> Art Harris
>
> Art: It's not just wheels, it's everything. But for fun let's look at
> the choices people make for their wives/husbands/life partners or
> whatever. How much is based on practicality (low maintenance, less
> expensive, greater compatibility) and how much is driven by
> appearance?
Well said. It seems that many rims these days have undergone rim depth
augmentation surgery.
--
Phil, Squid-in-Training
Phil, Squid-in-Training
>> Dear Mike,
>>
>> Are you saying that these spokes were actually checked with
>> a tensiometer and found to be low?
>
> No, neither I nor my former service manager (he's now our "operations
> manager", a bit of a change, but we still consider him our best
> tensiometer, but unless Ravi had deliberately increased the tension
> himself (which is a question I didn't think to ask), those wheels are
> set relatively-low by the factory. The use of the offset spoke bed
> was specifically for that purpose. There is no need on such a wheel
> to have really high tension on one side, and much lower on the other.
> I should have pointed that out earlier.
>> If so, was the tension check performed before or after the
>> cracking?
>
> Neither, not using a tensiometer anyway.
>
>> If the spokes were checked after the rim cracked and found
>> to have low tension, this isn't exactly surprising--any
>> cracking would tend to release tension.
>
> That would be true in the event of rim deformation, but typically the
> type of cracking we see around spoke holes doesn't cause the wheel to
> go out of true, which implies that it's not doing much to change the
> shape of the spoke bed, at least not initially. I should also point
> out (or maybe I shouldn't!) that I've experienced such cracks in a
> rim myself, and rather than immediately replace the rim, continued to
> ride on it for a great many mile afterward, to see what would happen.
> Specifically, I was wondering what the eventual failure mode would
> be. When I told one of my tech reps about this, he was horrified, to
> say the least. Sigh. I've seen enough wheels where someone has broken
> a spoke in a crash or whatever and continued on, that I really wasn't
> that worried about what would happen if a spoke completely pulled out
> of the rim. My bad. Kids, don't try this one at home.
And people tend to freak out about bending MTB brake levers back... bending
derailleur hangers back... tweaking frames slightly... aluminum isn't a
needle standing on end; are lawsuits really the cause of all this mania
about bending or modifying aluminum?
--
Phil, Squid-in-Training
Phil, Squid-in-Training
> jobst....@stanfordalumni.org wrote:
>
>>
>> There are several effects coming together that cause these failures.
>> One is too few spokes another is no steel sockets or eyelets, another
>> is hard anodizing together with excess tension caused by using too
>> few spokes. In addition, to accommodate 10-speed gear clusters,
>> rear hubs have gotten narrower to reduce offset (and the required
>> difference in tension from left to right). Just the same rear
>> wheels, carry at least 2/3 the load with the right side spokes. No
>> wonder the rims develop fatigue cracks.
>
> i understand the point you are making. I have read some of your posts
> and others just blow past my head ;) and i am able to slowly
> appreciate the value of good old, time proven method of wheel
> building. Using sheldonbrown's website of wheel building, i have
> completed two such wheels (front and rear) and they have held up
> pretty decently for ~200miles now. Your book is in my reading list
> for sure.
>
>> Before the equipment fad got rolling in the present mode, low spoke
>> count wheels were used for special events like time trials. Then
>> professional teams, sponsored by component manufacturers, began using
>> them on a regular bases, to hell with the expense of frequent
>> replacement. So here we are with no market for reliable and durable
>> wheels, most riders being convinced that if Lance Armstrong does it,
>> it must be what I need.
>
> Definitely that seems to be the case - just like in the fashion world,
> the stars set new looks, same is true in cycling as well. But yes, we
> need to definitely understand the basics and carry forward the essence
> of the classical ways of wheel building.
>
>
>> I am at a loss to suggest what rims you should get but with the hubs
>> and spokes you have, there is no alternative to shelling out yet more
>> for the same. Paired spoking, patented by Lovelace in 1890, had no
>> benefits then and has none now.
>
> thanks for attempting, i just outpoured some of my thoughts in the OP.
>
>> For recreational bicycling (oops, that's not PC, we are all on
>> training rides for our next competition) 36-spoke wheels are still
>> the reasonable compromise between rim weight and number of spokes. With
>> low spoke count, one spoke failure will make the wheel
>> unridable but to make up for that, the spoke cannot be replaced in
>> the field because such wheels require special fixturing to be
>> tensioned and trued. I suppose the cell phone has absolved people
>> of touring with tools and equipment to be self sufficient, so wheels
>> will probably continue to be as fragile and excessively expensive as
>> most currently are.
>
> i understand what i gotten into. I am a newbie in terms of bicycling
> science. I keep a good LBS supported bike and then there is this self
> supported bike - which is kind of still in the process of learning and
> stuff. i am slowly getting there... but thanks for letting us pick
> your brains - all your efforts help people like us (newbies) get
> better understanding of things....
>
> I was reading http://yarchive.net/bike/index.html the other day and
> found very useful and informative posts. Thanks Jobst !
>
> BTW, on one of your pictures (in Bill Bushnell's) rides, i noticed
> something different -
> http://bushnell.homeip.net/~bill/bike/pictures/tailwinds_to_santa_cruz.2005.04.09/pages/page_26.html
>
> you have the right hand operate the front brake ?? and left the rear ?
For anybody but the occasional rider on right-hand-drive countries, the
right hand operating the front brake is always safer.
--
Phil, Squid-in-Training
Bruce Graham
carl...@comcast.net says...
> Until then, I'll continue to suspect that the original
> poster (a nice fellow who can only marvel at the fuss)
> needed lower spoke tension or a sturdier rim to avoid those
> cracks around 9 out of 12 of his drive-side spoke holes.
>
became noticeable, it seems that (for the rider's style and environment)
the wheel was a perfectly balanced design. A heavier rim would have just
been ballast (unless the extra material was on the brake cheeks) and
lighter spoke tension would have simply provided a wheel with less
ultimate lateral strength for all of those 10K miles. Now if one spoke
had just fatigued at the same time it would have been even better (using
old Colin Chapman's Lotus philosophy that if a component finishes the
race without breaking it is an opportunity for future weight reduction:-)
Bruce G
Antti Salonen
> Jobst's approach of increasing the tension until the wheel
> deforms and then backing off was developed with sturdy
> 36-spoke rims back in the 1980's.
>
> When applied to flimsier, lower-count modern rims, this
> practice can lead to cracks around the spoke holes.
The 36-spoke rims were often less sturdy than the modern rims used with
low-spoke-count wheels. In fact they were often lighter than any
aluminium rim available today. That's exactly why it was possible to
reach the maximum overall tension that the rim could take without an
exceedingly high tension for each spoke. The fact that rear wheels had
less dish also helped.
Today it's more common to have a heavy, stiff rim with only 16 to 24
spokes. Even with 36 spokes it would take a lot more tension for each
spoke to deform the rim, and with far fewer spokes it's impossible
without cracking the spoke holes, eyelets or no eyelets.
-as
Paul Cassel
> "Desirability", especially in a newbie, equals marketing or commercialism
> and drives price inflation. We who ride as a 'lifestyle' - perhaps on a
> fixed income - would prefer not to see the cost of cycling further inflated.
>
> The conspiracy of ignorance masquerades as common sense.
>
OK, I could retort that one solution is for you to unfreeze your income,
but I won't. Sure, marketing and image are a great deal of what makes up
desireablity - I'll agree. Now time for you to agree that what you take
as lifestyle choices is a stylistic choice too.
We're all the same, but we choose different styles to represent that.
-paul
Paul Cassel
way they look. Now to find out how long they last. The ratings reviews I
read on roadbikereview.com indicate that they are durable despite having
charcteristics that Jobst condemns (lightweight, blade spokes, etc.).
They seem to roll or something better than the wheels I had on my
borrowed bike based on my (admitedly) newbie tests of speed.
But I didn't say I rated them more highly based on my expertise (which
is non-existent). What I said is that since wheels of this style sell,
and sell for a brutal amount of money (in the case of my wheels, about
$800) many folks obviously have seen characteristics that THEY think is
worth the money.
My reply to Jobst is only that one size does not fit all. I didn't
disagree with his conclusions or mechanics.
-paul
Paul Cassel
> With a wasteful attitude like that, you must be a USian.
>
Nope. New Mexican.
Doug Huffman
false premise. Have you stopped spending too much on your bicycles yet?
Our three primary bikes', two singles and a tandem, total cost is alone of
more value than the US poverty level.
Reading again The Bell Curve: Intelligence and Class Structure in America by
Herrnstein and Murray (Free Press, 1994?) makes your statement "We're all
the same..." specious and quite politically correct.
"Paul Cassel" <pcasse...@comcast.net> wrote in message
news:QfmdnfIDZZQ...@comcast.com...
Art Harris
> They came on the bike so there was no marginal cost for me.
Of course there was. If you say these wheels normally sell for $800,
then the bike should have cost less with more conventional wheels.
> I like the way they look.
Ah, now we're getting to heart of the matter.
> The ratings reviews I read on roadbikereview.com indicate that they are durable despite having charcteristics that Jobst condemns (lightweight, blade spokes, etc.).
You previously said you weren't disputing Jobst as to
durability/reliability. Now it sounds like you are. How much lighter
are these wheels anyway, and how much improvement will they make to a
rider that has been in the "sport" for six months? Who are these people
on roadbikereview.com that are maiking these claims?
> What I said is that since wheels of this style sell, and sell for a brutal amount of money (in the case of my wheels, about $800) many folks obviously have seen characteristics that THEY think is worth the money.
Are you sure about that? Or are they just going with the trend? Hey,
these look like the wheels that Lance rides; they must be right for me.
Art Harris
Rick
Mike Jacoubowsky wrote:
>
> But are you really as stupid as I am, and ride in the hills no matter what
> the weather? I gave you more credit than that!
Don't give credit where it is not due. I do ride as often as I can,
including rain. I was just a bit ahead of Terry Morse when he bit it
on Page Mill on a fine rainy December day back a couple of years ago
when he slipped and broke his greater trochanter. Had the joy of
descending on the fresh snow a few times off the top of Page Mill and
Kings. Then it is not so out of the ordinary to climb Stelvio on a
fine June day in the snow, as we did last year :-) (not quite as much
snow on the ground as it had during this year's Giro, but the snow was
actually still falling on the top 1000' of the climb and then descent).
> Maybe someday my
> Tuesday/Thursday ride will fall on a holiday with really nasty weather and
> you can join me!
We've crossed a few times on those rides, mostly during the times I was
happily (albeit nervously) unemployed. We usually do OLH since we
live further south
(MV, Sunnyvale) but occasionally hit Kings. Teased you once about a
big shark wedge bag on your bike ;-)
- rick
carl...@comcast.net
Dear Bruce,
" . . . to avoid those cracks . . ."
I'm not saying that the cracks are good, bad, or part of
intentional design.
I'm just saying that the original poster needed less tension
or a sturdier rim to avoid them.
I'm impressed by the amount of argument such an obvious
observation has provoked.
Carl Fogel
Tom Nakashima
"Art Harris" <n2...@hotmail.com> wrote in message
news:1125408346.8...@z14g2000cwz.googlegroups.com...
Eight-Hundred Dollars, Oh, they MUST be good.....
-tom
Ron Ruff
Paul Cassel wrote:
>
> OK, I could retort that one solution is for you to unfreeze your income,
> but I won't. Sure, marketing and image are a great deal of what makes up
> desireablity - I'll agree. Now time for you to agree that what you take
> as lifestyle choices is a stylistic choice too.
>
> We're all the same, but we choose different styles to represent that.
>
Do you really think that it is the "same" to want durable and
inexpensive components vs. slavishly throwing money after the latest
fashion, then throwing it away after a few months and buying the next
"new thing"?
This is merely a "stylistic" choice? As though a wish for practical
items puts us in some sort of fringe league where we gather together to
ride our unstylish bikes and scoff at all the fashionable folk in the
"other" clique.
Did I mention that we also wear funny hats?
The money that you are spending to stay on top of the trend gives you a
certain pleasure... the false and extremely shallow sense that you have
purchased something "hot", therefore by association making yourself
"hot".
Of course there is also a thrill to simply getting something "new", and
this is easier to justify if the stuff you buy doesn't last... but this
is also part of a shallow and unfulfilling cycle.
Is this the best way to use this resource? Does this result in the
greatest benefit to *yourself*... let alone the rest of society?
I hope that you eventually run out of money, or the "pleasure" of being
trendy reaches it's inevitable conclusion and you can find something
better to live for.
Ron Ruff
carl...@comcast.net wrote:
>
> " . . . to avoid those cracks . . ."
>
> I'm not saying that the cracks are good, bad, or part of
> intentional design.
>
> I'm just saying that the original poster needed less tension
> or a sturdier rim to avoid them.
>
> I'm impressed by the amount of argument such an obvious
> observation has provoked.
>
I agree with your second point (sturdier rim), but "less tension" is
probably not a practical solution. The tension in the wheel was
probably per spec, and making it any lower would have compromised the
strength of the wheel... or maybe you mentioned that somewhere?
Poor design or manufacture IMO... general use rims should not exibit
cracking around eyelets after 10k miles, they should retire due to
braking wear, or dents from accidentally bottoming out on potholes or
other mishaps. Bontrager Selects are fairly low-end heavy wheels...
they are not lightweight racing models.
Jasper Janssen
>Of course there was. If you say these wheels normally sell for $800,
>then the bike should have cost less with more conventional wheels.
Hell, you could have sold them on ebay for two wheelsets worth of
conventional wheels[1] that are about *that* close in weight and *that*
far apart in durability.
Jasper
[1] Dura Ace/Open Pro or Velocity Aerohead (OC)/DT or Wheelsmith.
Jasper Janssen
wrote:
>Sniper Anon wrote:
>
>> With a wasteful attitude like that, you must be a USian.
>>
>Nope. New Mexican.
And New Mexico is part of what federal government again?
Jasper
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>And people tend to freak out about bending MTB brake levers back... bending
>derailleur hangers back... tweaking frames slightly... aluminum isn't a
>needle standing on end; are lawsuits really the cause of all this mania
>about bending or modifying aluminum?
I think people's observations of what happens when you bend sheet aluminum
manually (if you do it at a sharp angle, you inevitably get cracks in the
outer bend) have more to do with it. It only takes a little bending for
alu to be over the hill.
Jasper
carl...@comcast.net
<rruff...@yahoo.com> wrote:
Dear Ron,
The spokes may have been tensioned to the recommended value.
But I saw no one in this thread who actually checked the
tension with a tensiometer.
As Jim Beam pointed out, riders and mechanics are fond of
truing rims by tightening, often after first building the
wheel by raising the tension until the rim yields locally.
Repeated truing like this will lead to tension surprisingly
higher than recommended, particularly when coupled with the
local-yield approach.
(At least, I was surprised when Jim's patient nagging
finally led me to buy a tensiometer and check my wheels. I
lowered my spokes back to the recommended tension.)
Whatever the tension was, it was high enough on the drive
side to cause cracks around the spoke holes on these
particular rims, so it was too high for the rim.
I agree that they could be just poor rims, although people
are arguing that such cracks are not really a problem
because the sidewalls wore out at about the same time.
Carl Fogel
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>For anybody but the occasional rider on right-hand-drive countries, the
>right hand operating the front brake is always safer.
What do right hand drive countries have to do with it? Front brake, is
most important brake, and for anybody except left-handed people the right
hand is best in power and modulation. Since lefthanded people occur in RHD
countries as much as LHD, I don't see the reasoning for that mattering.
Jasper
jobst....@stanfordalumni.org
On that note, you might want to read about a guy that attended my HS
and lived in the SF Bay Area. He was amazingly good at staying ahead
of the trend:
http://tinyurl.com/b3w48 (1st)
http://tinyurl.com/azzok (2nd)
http://tinyurl.com/djblq (3rd)
What an enormous waste of talent. What a weird mind!
Jobst Brandt
jobst....@stanfordalumni.org
jim beam
> In article <16q7h1d12euuda14v...@4ax.com>,
> carl...@comcast.net says...
>
>>Until then, I'll continue to suspect that the original
>>poster (a nice fellow who can only marvel at the fuss)
>>needed lower spoke tension or a sturdier rim to avoid those
>>cracks around 9 out of 12 of his drive-side spoke holes.
>>
>
> Why... given that the sidewalls wore out at the same time as cracks
> became noticeable, it seems that (for the rider's style and environment)
> the wheel was a perfectly balanced design. A heavier rim would have just
> been ballast (unless the extra material was on the brake cheeks) and
> lighter spoke tension would have simply provided a wheel with less
> ultimate lateral strength for all of those 10K miles.
strength is /not/ /not/ /not/ a function of tension!!! the yield point
of the material remains unchanged. the modulus of the material remains
unchanged. all that tension achieves is longer term structural
stability by ensuring the spoke nipple is not loose enough to unscrew by
increasing the thread interface friction, but that is /not/ "strength".
jim beam
> jim beam <nos...@example.net> wrote:
>
>
>>since tensiometer reading is dependent on spoke gauge as well as spoke
>>tension, presumably hozan chose a scale that was convenient for the
>>commonest spoke gauge, 1.8mm in the butted section. for any other
>>gauge, conversion will be obligatory.
>
>
> Could you enlighten us as to how to do the conversion? Is it simply a
> matter of ratio of r, or of r^2?
not without sitting down to some homework, but it's a function of r^2
iirc. refer to the park tool tension table and different readings for
different spoke thicknesses if you want to see a quick & dirty demo.
>
> It would also seem that the design of the tensiometer could also be a
> source of error, if the wire thickness varies. It seems at first glance
> that the instrument must press on both sides of the wire.
>
correct, but i think you'll find that's taken into account with the
conversion table.
jim beam
> carl...@comcast.net wrote:
>
>>" . . . to avoid those cracks . . ."
>>
>>I'm not saying that the cracks are good, bad, or part of
>>intentional design.
>>
>>I'm just saying that the original poster needed less tension
>>or a sturdier rim to avoid them.
>>
>>I'm impressed by the amount of argument such an obvious
>>observation has provoked.
>>
>
>
> I agree with your second point (sturdier rim), but "less tension" is
> probably not a practical solution. The tension in the wheel was
> probably per spec, and making it any lower would have compromised the
> strength of the wheel
tension does /not/ affect strength of the wheel!
jobst....@stanfordalumni.org
>>> Until then, I'll continue to suspect that the original poster (a
>>> nice fellow who can only marvel at the fuss) needed lower spoke
>>> tension or a sturdier rim to avoid those cracks around 9 out of 12
>>> of his drive-side spoke holes.
>> Why... given that the sidewalls wore out at the same time as cracks
>> became noticeable, it seems that (for the rider's style and
>> environment) the wheel was a perfectly balanced design. A heavier
>> rim would have just been ballast (unless the extra material was on
>> the brake cheeks) and lighter spoke tension would have simply
>> provided a wheel with less ultimate lateral strength for all of
>> those 10K miles.
> strength is /not/ /not/ /not/ a function of tension!!! the yield
> point of the material remains unchanged. the modulus of the
> material remains unchanged. all that tension achieves is longer
> term structural stability by ensuring the spoke nipple is not loose
> enough to unscrew by increasing the thread interface friction, but
> that is /not/ "strength".
No no no, you can prove this to yourself by manually side loading a
newly laced wheel that has just had all its spoke slack taken up. It
will deflect sideways in collapse mode (spokes bowing out), while a
properly tensioned wheel can hold a many times larger load.
You are mistaking rigidity with strength. Once tensioned, the lateral
elasticity is independent of tension for small excursions.
>> Now if one spoke had just fatigued at the same time it would have
>> been even better (using old Colin Chapman's Lotus philosophy that
>> if a component finishes the race without breaking it is an
>> opportunity for future weight reduction:-) Bruce G
That doesn't do this subject or Chapman justice. These tales were
generated by his detractors who ignored similar failures on his
competitors cars. In those days computer modeling was not yet in.
Jobst Brandt
jim beam
your second paragraph is utterly contradictory of your first. and your
first is a deliberate fudge - slack spokes are not tensioned.
jobst....@stanfordalumni.org
> tension does /not/ affect strength of the wheel!
Are you sure you want to stand by that statement? There is a grace
period for retrieval and correction. After that, you're stuck.
Jobst Brandt
jim beam
i stand by it jobst. all the spoke tension tables in the back of your
book show is tension, not strength. you do not analyze the extent to
which increasing compressive hoop stress in a rim brings it nearer to
yield and you don't care to acknowledge that increasing tension in
spokes brings them nearer to yield also. but that's no a surprise given
that you're the guy that maintains that spokes only slacken in use,
despite the fact that lateral stress increases spoke tension and that
non-axial loading of elbowed spokes causes bending which is the cause of
fatigue.
jobst....@stanfordalumni.org
>>> tension does /not/ affect strength of the wheel!
>> Are you sure you want to stand by that statement? There is a grace
>> period for retrieval and correction. After that, you're stuck.
> I stand by it Jobst.
Let me make sure there is no semantic dodge in that statement. You
mean that tension affects neither radial nor lateral wheel strength.
> All the spoke tension tables in the back of your book show is
> tension, not strength. You do not analyze the extent to which
> increasing compressive hoop stress in a rim brings it nearer to
> yield and you don't care to acknowledge that increasing tension in
> spokes brings them nearer to yield also. But that's no a surprise
> given that you're the guy that maintains that spokes only slacken in
> use, despite the fact that lateral stress increases spoke tension
> and that non-axial loading of elbowed spokes causes bending which is
> the cause of fatigue.
In light of your claim, can you describe a model of how spoked wheels
support loads? I thought there was consensus that spokes cannot
support compressive loads, and that they must have tension greater
than distributed radial loads they are to support. How do you
reconcile this concept with your claim that tension does not define
wheel strength.
If your model is significantly different than the one I have
described, it may give insight to why you challenge much of what I
have written. On the other hand, how about leaving my writings out of
this and concentrate on what you said, nothing else. Trying to drag
your disagreement with "the Bicycle Wheel" into this is a diversion.
Jobst Brandt
jim beam
> Johnnie Walker writes:
>
>
>>>>tension does /not/ affect strength of the wheel!
>
>
>>>Are you sure you want to stand by that statement? There is a grace
>>>period for retrieval and correction. After that, you're stuck.
>
>
>>I stand by it Jobst.
>
>
> Let me make sure there is no semantic dodge in that statement. You
> mean that tension affects neither radial nor lateral wheel strength.
"i stand by it jobst." there's nothing ambiguous about that statement.
if you think you have a mine to explode, go right ahead.
>
>
>>All the spoke tension tables in the back of your book show is
>>tension, not strength. You do not analyze the extent to which
>>increasing compressive hoop stress in a rim brings it nearer to
>>yield and you don't care to acknowledge that increasing tension in
>>spokes brings them nearer to yield also. But that's no a surprise
>>given that you're the guy that maintains that spokes only slacken in
>>use, despite the fact that lateral stress increases spoke tension
>>and that non-axial loading of elbowed spokes causes bending which is
>>the cause of fatigue.
>
>
> In light of your claim, can you describe a model of how spoked wheels
> support loads? I thought there was consensus that spokes cannot
> support compressive loads, and that they must have tension greater
> than distributed radial loads they are to support. How do you
> reconcile this concept with your claim that tension does not define
> wheel strength.
this statement encompasses two things:
1. knowingly putting false words in other peoples mouths - a
particularly objectionable habit of yours jobst.
2. the utter misconception that a load calculation gives any indication
of strength! so the load on my kitchen table is 27lbs right now. you
want to tell me how strong my table is? red herrings suggesting i'm
talking compressive spoke load is utter bull.
>
> If your model is significantly different than the one I have
> described, it may give insight to why you challenge much of what I
> have written. On the other hand, how about leaving my writings out of
> this and concentrate on what you said, nothing else. Trying to drag
> your disagreement with "the Bicycle Wheel" into this is a diversion.
jobst, there are many material errors in your book, most of which i just
can't be bothered to repeat at this time of night, but they include the
confusion of load calculation with strength calculation, confusion
between strain aging material & non-strain aging material, the omission
of wire gauge from your tensiometer equation, etc. i live in hope that
one of these days, you'll be man enough to correct some of the worst
ones, but given that you don't seem to know what you don't know, maybe
i'm deluding myself.
>
> Jobst Brandt
Phil, Squid-in-Training
Brake levers and derailleur hangers are virtually no-stress cases. Why do
many believe they need to be replaced?
--
Phil, Squid-in-Training
Phil, Squid-in-Training
> On Tue, 30 Aug 2005 02:12:59 -0400, "Phil, Squid-in-Training"
> <phil_leeIHEA...@hotmail.com> wrote:
>
>> For anybody but the occasional rider on right-hand-drive countries,
>> the right hand operating the front brake is always safer.
>
> What do right hand drive countries have to do with it?
Signalling with the other (car side) hand.
--
Phil, Squid-in-Training
Sniper Anon
On 30-Aug-2005, Bruce Graham <jbgr...@nowhere.com.au> wrote:
> Now if one spoke
> had just fatigued at the same time it would have been even better (using
> old Colin Chapman's Lotus philosophy that if a component finishes the
> race without breaking it is an opportunity for future weight reduction:-)
That philosophy likely cost Jochen Rindt has life.
--
Sniper Anon
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Jasper Janssen
Scuse me? Brake levers are no stress cases? Whats that thing I do where I
pull on the brake lever with my whole hand to get the damn bike to stop,
again? As far as derailleur hangers go, mainly I think because if it does
fail, it does so fairly catastrophically, generally destroying a derailer,
chain, and wheel.
Jasper
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>Jasper Janssen wrote:
>> On Tue, 30 Aug 2005 02:12:59 -0400, "Phil, Squid-in-Training"
>> <phil_leeIHEA...@hotmail.com> wrote:
>>
>>> For anybody but the occasional rider on right-hand-drive countries,
>>> the right hand operating the front brake is always safer.
>>
>> What do right hand drive countries have to do with it?
>
>Signalling with the other (car side) hand.
Uhm.. in all cases you're going to have signal both left and right turns,
not just car side turns.
Jasper
Ron Ruff
>
> tension does /not/ affect strength of the wheel!
>
Spokes that become untensioned in use (not unscrewed, just untensioned)
tend to break ... at least that has been my experience. That is the
strength I am refering to... since IMO a wheel that breaks spokes is
"not strong".
There apparently is a balancing act here between getting the tension
high enough... but not too high... and it seems to get too high for the
rim before it gets too high for the spokes.
If there is no concern about spokes being too loose, why do the
manufacturers specify such high tensions? Why not cut the tension in
half to save the rims, and apply thread lock to keep the nipples from
unscrewing?