Bottom Bracket Drag
HarryB
Sheldon Brown's advice on adjusting a cone-and-cup BB as a reference:
"Make a mental note of how easily the spindle turns when the bearing
is too loose-it should turn just as freely when you have finished
adjusting it." Does this same comparison apply to cartridge bearings -
IOW, the spindle's drag should not increase when the cartridge is
properly tightened?
I posted a question a few days ago about problems with tight BB's
("Bottom Bracket Question") on a tandem. I followed the advice given
and had both shells faced and chased. This really improved the BB that
was very tight and marginally improved the other. But, there is still
more drag after the BB's have been torqued than when they are loose.
In fact, the drag increases as soon as the drive side of the BB is
tightened and increases even more when the adjustable cup is
tightened.
The BBs in question are TruVativ GigaPipes and only have a couple of
thousand miles on them.
TIA,
Harry
Werehatrack
>How much drag is considered normal for a cartridge bearing BB?
Very damn little. A new unit will feel a little stiff at first for a
variety of reasons, but a used one should spin freely.
>I note
>Sheldon Brown's advice on adjusting a cone-and-cup BB as a reference:
>"Make a mental note of how easily the spindle turns when the bearing
>is too loose-it should turn just as freely when you have finished
>adjusting it." Does this same comparison apply to cartridge bearings -
>IOW, the spindle's drag should not increase when the cartridge is
>properly tightened?
If the unit is properly constructed *and* the BB shell in the frame is
faced and threaded correctly, then tightening it down should make no
difference.
>I posted a question a few days ago about problems with tight BB's
>("Bottom Bracket Question") on a tandem. I followed the advice given
>and had both shells faced and chased. This really improved the BB that
>was very tight and marginally improved the other. But, there is still
>more drag after the BB's have been torqued than when they are loose.
>In fact, the drag increases as soon as the drive side of the BB is
>tightened and increases even more when the adjustable cup is
>tightened.
>
>The BBs in question are TruVativ GigaPipes and only have a couple of
>thousand miles on them.
It sounds like the threads on one side are not cut squarely.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
Qui si parla Campagnolo
Cart BBs are just that, cartridge bearings with rubber seals that
automatically are more draggy than loose ball BBs. Some lower end BBs
DO get more sluggish when installed, shimano UN-series is a good
example. Never been a big fan of ISIS in general or Truvativ
specifically. BUT if they are smooth, not notchey or crunchy, best it's
gonna be.
Pete Biggs
> How much drag is considered normal for a cartridge bearing BB? I note
> Sheldon Brown's advice on adjusting a cone-and-cup BB as a reference:
> "Make a mental note of how easily the spindle turns when the bearing
> is too loose-it should turn just as freely when you have finished
> adjusting it." Does this same comparison apply to cartridge bearings -
> IOW, the spindle's drag should not increase when the cartridge is
> properly tightened?
Perhaps drag shouldn't increase theory, but it always does in my
experience - with several different BBs in several bikes.
~PB
* * Chas
"Werehatrack" <rau...@earthWEEDSlink.net> wrote in message
news:8352n290jb08cfmos...@4ax.com...
My thoughts too.
The BB should be faced and the threads chased using a BB tool like one
from VAR, Campy, Park etc. that has a pilot that goes through the BB
into a mating part to keep the cutting tools aligned.
If some used a single sided tool to face, tap or chase the threads the
two sides could be out of alignment.
Chas.
Jim Higson
> How much drag is considered normal for a cartridge bearing BB?
Don't know about normal, but if I give my cranks a good push with no chain
connected they continue to spin for several minutes.
Veloce cartridge BB (2006 model I think)
--
Jim
Lou Holtman
Tim McNamara
Lou Holtman <lholrem...@planet.nl> wrote:
The Veloce bottom brackets are pretty smooth turning- smoother than most
of Campy's other BBs including (the last ones I tried) Chorus and Record.
Lou Holtman
We are talking of minutes. That is a very loooong time. I can't believe
that.
Last week I installed a Shimano XT hollotech II crankset (outboard
bearings). I gave it a swing and it wouldn't turn even one revolution,
but that's just the drag of the seals and you don't notice that while
riding.
carl...@comcast.net
Dear Lou,
For fun, I tested a 1998 Schwinn Le Tour triple with 170 mm cranks,
pretty much unused and bought for spares, a ten-year-old bottom of the
line example of a crank.
With no pedals, the level crank will support two dimes over the left
pedal eye, but it starts to turn under the weight when a third dime is
added.
According to the US Mint, a dime is around 2.268 grams, plus or minus
a smidgen for grime and wear:
http://www.usmint.gov/about_the_mint/index.cfm?flash=yes&action=coin_specifications
So the initial bearing resistance (higher than the moving resistance)
is a bit less than 170 mm / 6 grams of torque, which works out to the
surprisingly high value of about 0.1 foot-lbs of torque.
Bracing the frame and giving the pedals a brisk turn produces about 13
seconds of spin on average.
Adding some light pedals increases the inertia and angular momentum
more than the wind drag and produces about 20 seconds of spin on
average.
So maybe really smooth modern bearings can spin for minutes. I'd love
to see some quick and dirty tests involving how many coins (or half or
quarter coins) a level crank can support before it starts to turn.
It's difficult to compare how hard one poster's hand twirls a crank,
so that's probably not as good a measure as weights on the ends of
pedals, even though it's fun. But a few spin-down times would be
interesting.
Since we're talking about at most the downward force of 3 dimes on a
motionless horizontal pedal, I suspect that in real life random air
current variations are more important. There just isn't much drag
available to reduce.
Cheers,
Carl Fogel
Dave Lehnen
I think your arithmetic is a little off. I get .00738 ft-lb, which at
90 RPM takes .094 watt. While pedaling, seal drag may be lower, but
bearing drag higher due to the load. It isn't going to be much power
loss unless the bearings are really awful.
>
> Bracing the frame and giving the pedals a brisk turn produces about 13
> seconds of spin on average.
>
> Adding some light pedals increases the inertia and angular momentum
> more than the wind drag and produces about 20 seconds of spin on
> average.
>
> So maybe really smooth modern bearings can spin for minutes. I'd love
> to see some quick and dirty tests involving how many coins (or half or
> quarter coins) a level crank can support before it starts to turn.
>
> It's difficult to compare how hard one poster's hand twirls a crank,
> so that's probably not as good a measure as weights on the ends of
> pedals, even though it's fun. But a few spin-down times would be
> interesting.
>
> Since we're talking about at most the downward force of 3 dimes on a
> motionless horizontal pedal, I suspect that in real life random air
> current variations are more important. There just isn't much drag
> available to reduce.
>
> Cheers,
>
> Carl Fogel
Dave Lehnen
* * Chas
"Lou Holtman" <lholrem...@planet.nl> wrote in message
news:45733de2$1...@news.nb.nu...
Well, it depends on how heavy your chainrings are, just like the
flywheel on a car. If you used nice heavy steel chainrings not the
flimsy alloy crap you see today, then yes they could possibly keep
spinning for quite some time.
Chas.
carl...@comcast.net
<dcle...@worldnet.att.net> wrote:
>carl...@comcast.net wrote:
[snip]
>> So the initial bearing resistance (higher than the moving resistance)
>> is a bit less than 170 mm / 6 grams of torque, which works out to the
>> surprisingly high value of about 0.1 foot-lbs of torque.
>
>I think your arithmetic is a little off. I get .00738 ft-lb, which at
>90 RPM takes .094 watt. While pedaling, seal drag may be lower, but
>bearing drag higher due to the load. It isn't going to be much power
>loss unless the bearings are really awful.
[snip]
>Dave Lehnen
Dear Dave,
You're right--I goofed.
When I went back to my spreadsheet, I found that I'd used the newtons
column instead of the pounds column and then multiplied instead of
dividing.
Now I think I've caught up with you.
We're converting 6 grams * 0.17 meters to X lbs * 1 foot.
6 grams x (1 lb/454 grams) = 6/454 lbs = 0.0132 lbs
0.170 meters x (39.4 inches/meter) = 0.17 x 39.4 = 6.7 inches
6.7 inches / (12 inches/foot) = 6.7/12 feet = 0.5583 feet
0.0132 lbs * 0.5583 feet = Dave's 0.0074 foot-lbs
So the force of 2~3 2.6 gram dimes on a 170 mm horizontal lever is
pleasantly smaller than the goofy figure that surprised me.
The really embarrassing part is that I made my careful miscalculations
while feeling fine, not after I woke up feeling fuzzy just now and had
to creep through things while feeling even dimmer than usual.
Thanks for checking the idle rumors from Fogel Labs.
Cheers,
Carl Fogel
HarryB
After the mechanic had finished the work and I was discussing with him
that I was disappointed that the BB's still seemed tight, he said that
he used a tool that cost upwards of $400. When I called back to find
out exactly which tool had been used, the mechanic had gone home, but
the person who answered the phone said it was a Park Tool.
When I screw the BB into the shell, I can turn it in with my fingers
until it bottoms out against the shell. The same for the other side
(although it apparently bottoms out against a ridge in the BB, not
against the BB shell.) It seems to me that if one of the threads was
not cut square relative to the centerline of the BB or concentric
relative to the other threads, that I wouldn't be able to screw both
sides of the BB all the way in with my fingers.
Harry
Lou Holtman
Carl, I gave my front wheel (with tire) with a recently overhauled and
very smooth running Record hub a very firm spin (I hurt myself) and it
stopped after 45 seconds. So I think 'several' minutes is a ridiculous
claim.
Lou Holtman
Oh please, alloy chainrings are fine. For several minutes spin time
those clunky chainrings must be very heavy and large in diameter.
* * Chas
"HarryB" <No...@none.net> wrote in message
news:qp88n2lc9cgecsbje...@4ax.com...
There is a possibility that the BB cartridge is contacting a tube or tubes
or a lump of braze protruding into the BB shell that doesn't get fully
cleaned up with the thread chasers. When you tighten the BB cup this could
be applying pressure to the OD of the BB cartridge causing a slight
deflection. Look inside the BB shell to rule this out.
BB tools like those made by Park are designed to work with a pilot and
bushings or both chasing taps together to keep the tool aligned . I've
seen guys who were lazy (I've done it myself) or didn't know better use
the BB threading tool with one side only. Also, one side of the BB threads
could be mis-aligned from the factory and the "mechanic" found it too hard
to use both sides on the of the Park thread chasers to correct the
problem... DOH!
Check out the Park BB tools at these links to Park's web site:
Facing Tool - there are detailed instructions on how to use both of these
tools at this site:
http://www.parktool.com/products/detail.asp?cat=25&item=BFS%2D1
Threading Tool:
http://www.parktool.com/products/detail.asp?cat=25&item=BTS%2D1
I would take your tandem back to the shop and request to watch while they
run the chasers through again.
One other thing is the possibility of over torquing the cups. IRD
recommends tightening their BBs to 24 to 30 Foot Lbs. of torque, Shimano
21.6 to 29 Foot Lbs. of torque and Phil 25 Foot Lbs.
If you don't have a torque wrench maybe you can borrow or rent one with
the proper sized socket. A "good" bike shop should have a torque wrench
since many of the newer BBs and crank arm need to be accurately tightened.
Chas.
carl...@comcast.net
<lholrem...@planet.nl> wrote:
Dear Lou,
Since a front wheel is not a bottom bracket, the two may behave
differently.
For one thing, the wheel has considerably greater wind drag from all
the spokes--you can feel the fan effect off to the side of a spun
front wheel.
The drag is partly due to the area of the spokes, which is
surprisingly large. With ~275 mm of exposed spoke at mostly 1.8 mm for
a butted spoke, each spoke has ~500 mm^2 of area. At 16 spokes, that's
8,000 mm^2. For 32 spokes, it's 16,000 mm^2.
The two 170 mm pedal arms on the crank that I tested are about 15 mm
wide by 160 mm exposed length, so 2 x 15 x 160 = 4,800 mm^2. So the
crank has considerably less raw fan surface than any normal spoked
wheel.
The other aspect of the wheel's increased wind drag is that the wheel
is much larger in diameter and therefore spins the spokes at a much
higher speed. About half the spoke length sticks out further than the
crank, so at the same rpm the spoke travels faster--and wind drag
rises wildly as speed increases.
So wheels may not compare very well to cranks.
In any case, your 45 second front wheel hand-spin turns out to be well
under what can be achieved:
"In one test, the wheel is accelerated to 70km/h before being
released; time is recorded until it comes to a complete standstill.
The best performing Cometes, used by Meares for her record, can spin
for over 12 minutes."
http://www.cyclingnews.com/tech.php?id=tech/2006/features/meares_bt_stealth
So some front wheels can go over 720 seconds when spun up to about 43
mph.
Sorry that you hurt yourself, but it's unlikely that your hand-spin
for 45 seconds reached even 20 mph.
When I tested hand-spinning of front wheels, I found that about 15 mph
was the maximum, due to the extremely limited span and awkward angle
at which our arms engage wheels. Your hand must change direction 90
degrees in only a quarter-turn of the wheel, so your hand comes off
the wheel long before you reach even the speed of a casual
stone-throw:
http://groups.google.com/group/rec.bicycles.tech/msg/9b36efb8133cd8a7
The current RBT record for hand-spinning a 700c front wheel [modest
cough] still stands at 16.2 mph.
Anyway, my initial reaction was disbelief when a crank was said to
spin for minutes, but I'm willing to be convinced. A 2006 crank,
beautifully finished and designed and so forth, with heavy pedals,
should certainly be able to beat my cheap 1998 test crank's 20 seconds
with light pedals.
I'd love to have someone with a nice new crank give it a whirl without
the chain and report actual seconds.
Cheers,
Carl Fogel
carl...@comcast.net
Dear Lou,
Actually, heavy pedals would probably be more helpful, since they're
further out and provide more angular momentum.
When I attached some light pedals to my test crank, spin time
increased about 50%, from around 13 seconds to over 20 seconds. The
extra mass overwhelmed the increased wind drag.
As always, I'm amused by the willingness of RBT posters to argue
yes-it-does and no-it-can't without taking the trouble to do something
as simple as testing how long a crank will spin.
Surely someone out there must want to take the current 20-second
crank-spin record away from me and my 1998 Shimano triple.
(Be warned that the record-holder craftily performed the test at
nearly 5,000 feet to take advantage of thinner air and reduced wind
drag.)
Cheers,
Carl Fogel
Lou Holtman
OK I'm challenged. I now go back to my garage, remove the chain and spin
my 2006 Campagnolo Carbon Compact crank, with smooth running Record BB.
I'll be back..
Lou Holtman
OK I'm back. 25 seconds the first attempt and 26 seconds the second. The
crankarm with the magnet for my cadence sensor ended up in the down
position twice. Pedals: speedplay zero's. I'm not a gorilla so there are
people who can spin a crankarm faster than I but 26 seconds is far
enough of 'several' minutes. I'm done.
Now I have dirty hands...
Lou Holtman
Yeah, yeah. We are talking about several MINUTES.
>
> As always, I'm amused by the willingness of RBT posters to argue
> yes-it-does and no-it-can't without taking the trouble to do something
> as simple as testing how long a crank will spin.
I did.
carl...@comcast.net
<lholrem...@planet.nl> wrote:
[Carl wrote]
Dear Lou,
Probably no one can improve much on your spin. The distance from a
standing start to where your hand comes off the pedal is so short that
it's hard to improve the initial speed.
You had pedals, so the extra mass was helping, and it sounds like the
same year and company for the bottom bracket as the original claim of
several minutes spin time, so 26 seconds seems to be a reasonable
figure.
Frankly, I'm relieved. Your 2006 Campy is a little better than my 1998
Shimano, 26 seconds to 20 seconds, but there's apparently been no
order of magnitude improvement in drag reduction for conventional
bottom brackets.
(Which would still be too small to matter.)
Barring exciting developments from other competitors, you've convinced
me that our initial skepticism was well founded. Maybe some outboard
bearing design with ceramics and lead-weighted pedals would spin for
minutes, but normal pedals seem to be closer to 0 than to 60 seconds.
Thanks for taking the time to test the kind of silly thing that
fascinates me. The local bike shops are idle right now, with the snowy
streets, but they'd still probably refuse to let me remove chains on
their new bikes just to test modern cranks.
Cheers,
Carl Fogel
Donald Gillies
>Carl, I gave my front wheel (with tire) with a recently overhauled and
>very smooth running Record hub a very firm spin (I hurt myself) and it
>stopped after 45 seconds. So I think 'several' minutes is a ridiculous
>claim.
I have found that I can get the BEST possible bearing adjustment by
using a set of unbrazed dropouts I own, and adjusting the cones with
the QR installed installed using standard tightness (finger tight on
dropout faces at 90 degree angle) and tightened on the (solo)
dropouts.
In fact, people just cannot believe how far and how well my bike can
coast when I am out on club rides with this 1970 bike.
Perhaps Carl is doing something similer to get 100% perfect on-bike
cone adjustment, yielding minutes of spinning time ??
- Don Gillies
San Diego, CA, USA
Pete Biggs
> Carl, I gave my front wheel (with tire) with a recently overhauled and
> very smooth running Record hub a very firm spin (I hurt myself) and it
> stopped after 45 seconds. So I think 'several' minutes is a ridiculous
> claim.
I just got 3.5 minutes from an Avanti hub + MA2 + light tyre, without trying
very hard. Record hubs have /more/ drag, despite the higher cost, thanks to
tighter seals (and maybe smaller balls as well?).
I can't imagine any cranks spinning that long, though.
~PB
jobst....@stanfordalumni.org
>> Carl, I gave my front wheel (with tire) with a recently overhauled
>> and very smooth running Record hub a very firm spin (I hurt myself)
>> and it stopped after 45 seconds. So I think 'several' minutes is a
>> ridiculous claim.
> I have found that I can get the BEST possible bearing adjustment by
> using a set of unbrazed dropouts I own, and adjusting the cones with
> the QR installed installed using standard tightness (finger tight on
> dropout faces at 90 degree angle) and tightened on the (solo)
> dropouts.
You're wasting your time. Adjust the wheel bearing a hair on the
loose side and not that when you close the QR, it doesn't rattle.
That's good enough.
> In fact, people just cannot believe how far and how well my bike can
> coast when I am out on club rides with this 1970 bike.
You are dreaming! Wind drag (your cross section to mass ratio) has
many times more effect on coasting. 1970 has noting to do with that,
nor does bearing adjustment. Even tires are lost in the wind assuming
they are reasonably inflated and smooth.
> Perhaps Carl is doing something similer to get 100% perfect on-bike
> cone adjustment, yielding minutes of spinning time ??
I see religion everywhere. Have faith!
Jobst Brandt
* * Chas
My precision counterbalanced heavy steel Astabula cranks and chainrings
ride really smooth. Once you get the cadence up over 120 RPM, it keeps
going and going and going, just like the Duracell Bunny!
Chas.
Lou Holtman
> Lou Holtman wrote:
>
>
>>Carl, I gave my front wheel (with tire) with a recently overhauled and
>>very smooth running Record hub a very firm spin (I hurt myself) and it
>>stopped after 45 seconds. So I think 'several' minutes is a ridiculous
>>claim.
>
>
> I just got 3.5 minutes from an Avanti hub + MA2 + light tyre, without trying
> very hard. Record hubs have /more/ drag, despite the higher cost, thanks to
> tighter seals (and maybe smaller balls as well?).
I just overhauled the hub. So lots of grease and 15 small balls. 3.5
minutes is a long time for a front wheel though. Any grease and seals in
there?
Lou Holtman
> Lou Holtman <lholrem...@planet.nl> writes:
>
>
>>Carl, I gave my front wheel (with tire) with a recently overhauled and
>>very smooth running Record hub a very firm spin (I hurt myself) and it
>>stopped after 45 seconds. So I think 'several' minutes is a ridiculous
>>claim.
>
>
> I have found that I can get the BEST possible bearing adjustment by
> using a set of unbrazed dropouts I own, and adjusting the cones with
> the QR installed installed using standard tightness (finger tight on
> dropout faces at 90 degree angle) and tightened on the (solo)
> dropouts.
You can adjust a Record/Chorus/Centaur hub with the wheel installed. You
only need a 2.5 mm hex key. Nice feature.
Lou Holtman
I'm sure they do.
Pete Biggs
My Avanti hub contains a normal amount of grease. The only seals are metal
dustcaps that don't contact any moving part, unlike Record's gaskets.
I also have wheels with Chorus hubs (similar to Record). They have never
spun as freely. But they spin freely enough, and are lighter, easier to
adjust and keep water out better.
~PB
Donald Gillies
>Donald Gillies writes:
>> In fact, people just cannot believe how far and how well my bike can
>> coast when I am out on club rides with this 1970 bike.
>You are dreaming! Wind drag (your cross section to mass ratio) has
>many times more effect on coasting. 1970 has noting to do with that,
>nor does bearing adjustment. Even tires are lost in the wind assuming
>they are reasonably inflated and smooth.
You are not on those rides. I'm the youngest guy, aged 44 !! So,
your contention that wind resistance is such a big factor going from
15 mph to 0 mph is really rather silly, as are more and more of your
recent posts ...
carl...@comcast.net
wrote:
Dear Don,
There may be some misunderstanding. My crank spin time is the lowest
mentioned so far in this thread.
Jim Higson said that he got several minutes of spin from his Veloce
cartridge BB (2006 model, he thought).
Intrigued by his claim and Lou Holtman's you-gotta-be-kidding
reaction, I descended to the Bat Cave and performed exhaustive
experiments for several minutes.
I got only 13 seconds of pedal spin out of an untouched and almost
unused no-pedal 1998 Schwinn Le Tour purchased for parts on eBay.
Adding light pedals increased my spin time about 50% to 20 seconds or
so.
I did cite some wheel tests by a race team, who spun wheels up to 70
kph and timed the spindown to find the best wheel, which spun for over
720 seconds:
http://www.cyclingnews.com/tech.php?id=tech/2006/features/meares_bt_stealth
But I've never timed front wheel spin-down time and doubt that my bike
coasts particularly well. Its axle cones are cruelly neglected.
However, I do [modest cough] hold the RBT record for pure speed
produced by slapping, spinning, or heaving on a 700c front wheel, 16.2
mph.
I suspect that the race team testing front wheels produced their 70
kph (43 mph) spin-speed either by using illegal substances or--even
more shocking!--a power assist.
In pursuit of the truth about bottom bracket spin time, Lou Holtman
hurt himself and even got his hands dirty. His hand-spun 2006 Campy
crank revolved for only about 25~26 seconds with pedals in place.
This suggests that claims for several minutes of crank spin may be
exaggerated and that Lou can make a 2006 Campy crank spin about 6
seconds longer than I can make a 1998 Shimano crank spin.
Maybe someone with an outboard bearing crank and ceramic bearings will
astonish everyone with several minutes of spin time, but until it
happens, Lou's test is the best data that we have in this crucial
matter.
Cheers,
Carl Fogel
Donald Gillies
stronglight) spinning for a LONG time (minutes) with a perfectly
adjusted loose-ball bottom bracket. I think I have done that
experiment myself, maybe 30 years ago. When the mood takes me, i mix
phil grease and oil 50-50 to get something a lot more slippery than
standard bearing grease, but not usually for the bottom bracket ...
I doubt that ANYTHING with a cartridge bottom bracket will last more
than a minute. You can spin a cartridge in your finger to see why. I
wouldn't be surprised if a standard cartridge bearing had 5x - 10x
more friction than an oiled loose-ball bearing.
Since wind resistence would play a small part in stopping a spinning
crank arm, I'd guess that the weight of the chainwheel (angular
momentum) and bearing friction could give a 10x - 20x advantage to a
vintage steel crankset vs. a modern aluminum sealed one.
As we all know, cartridge bearings can be used to make a cheaper
bottom bracket but not a better bottom bracket.
Jay Beattie
Unless you consider a "better bottom bracket" to be one that you do not
have to repack every time it rains hard. Not that all cartridge bearing
BB are that good at sealing out water, but most are better than my old
NR BBs (even with those plastic sleeves). I also like not having to
dick around with a pin spanner and toothed lock-ring wrench. I like the
plug an play approach to BBs these days. Any seal drag is probably
lost in the drive train drag -- but then who knows. Maybe I am burning
up extra calories. Aha! A weight loss opportunity. Extra seals
please! -- Jay Beattie.
HarryB
<verkt...@aol.spamski.com> wrote:
>
>"HarryB" <No...@none.net> wrote in message
>news:qp88n2lc9cgecsbje...@4ax.com...
>
[snip]
Chas,
I checked inside the shell and there is nothing protruding that could
contact the BB.
I called SRAM and talked with a tech support person who said that if
the shell has been faced and chased that the drag I described is
probably not unusual. He also said that if I spin the cranks and they
continue to revolve one or two revolutions that may well be the best
I'll get from this BB.
I am also concerned about the proper torque. The BB tool that I have,
a Park BBT8, is an eight sided socket that needs a crow's foot to work
with a torque wrench - and although I have a couple of torque
wrenches, I don't have a crow's foot. I have intentionally tightened
the BB to what I think is a low torque and will see how it goes. If
it's too loose I can always tighten it some more.
I've decided to live with this amount of drag for the time being. For
one thing, the "LBS" where I had the work done is about an
hour-and-a-half's drive from my house. So, to return it there would
consume a complete morning. And the other reason is that this tandem
(a recumbent) is an experiment to see if we like it better than our
present upright one. If we decide to keep it, I'll probably upgrade
the BB in the future and deal with this issue at that time.
Thanks for your help.
Cheers,
Harry
HarryB
>On Sun, 03 Dec 2006 23:48:19 +0100, Lou Holtman
><lholrem...@planet.nl> wrote:
>
>>Tim McNamara wrote:
>>> In article <45733de2$1...@news.nb.nu>,
>>> Lou Holtman <lholrem...@planet.nl> wrote:
>>>
>>>
>>>>Jim Higson wrote:
>>>>
>>>>>HarryB wrote:
>>>>>
>>>>>
>>>>>>How much drag is considered normal for a cartridge bearing BB?
>>>>>
>>>>>Don't know about normal, but if I give my cranks a good push with no chain
>>>>>connected they continue to spin for several minutes.
>>>>>
>>>>>Veloce cartridge BB (2006 model I think)
>>>>
>>>>
>>>>Several minutes??? That's not normal.
>>>
>>>
>>> The Veloce bottom brackets are pretty smooth turning- smoother than most
>>> of Campy's other BBs including (the last ones I tried) Chorus and Record.
>>
>>
>>We are talking of minutes. That is a very loooong time. I can't believe
>>that.
>>Last week I installed a Shimano XT hollotech II crankset (outboard
>>bearings). I gave it a swing and it wouldn't turn even one revolution,
>>but that's just the drag of the seals and you don't notice that while
>>riding.
>>
>>Lou
>
>Dear Lou,
>
>For fun, I tested a 1998 Schwinn Le Tour triple with 170 mm cranks,
>pretty much unused and bought for spares, a ten-year-old bottom of the
>line example of a crank.
>
>With no pedals, the level crank will support two dimes over the left
>pedal eye, but it starts to turn under the weight when a third dime is
>added.
>
[snip]
>
>Cheers,
>
>Carl Fogel
>
Carl,
That's an interesting way of checking the drag. Here are the results
of one of the BB's in question using your method. "Tight" means
tightened to guestimated torque while "loose" means finger tight:
1) Both sides of BB tight: about 16 grams
2) Drive side tight, adjustable cup loose: 6 grams
3) Drive side loose, adjustable cup tight: 6 grams
4) Both sides loose: 2.3 grams
5) Both sides tight, but an extra spacer added to the non-drive side
so that the adjustable cup bottoms out on the shell rather than the on
the BB: 10 grams.
I called SRAM and asked them about this. The tech person sort of said
the same thing that the mechanic at the LBS said, namely that it
really shouldn't be this way, but sometimes it just is. He also said
that if I give the cranks a good push with the chain off, that if they
continue to rotate for one-to-two revolutions that would not be
abnormal.
And, oh yes, he also said one other thing: he reminded me that this
wasn't Campy equipment we're talking about.
Cheers,
Harry
Johnny Sunset
Pete Biggs wrote:
> Lou Holtman wrote:
>
> > Carl, I gave my front wheel (with tire) with a recently overhauled and
> > very smooth running Record hub a very firm spin (I hurt myself) and it
> > stopped after 45 seconds. So I think 'several' minutes is a ridiculous
> > claim.
>
> I just got 3.5 minutes from an Avanti hub + MA2 + light tyre, without trying
> very hard. Record hubs have /more/ drag, despite the higher cost, thanks to
I managed to get about 70 seconds out of a wheel with a Phil Wood
single-sided hub, 36-spoke, Alesa 219 rim with 35-305 tire. The
"stroke" when spinning the wheel is so short that I could only get the
speedometer up to about 8.5 mph.
--
Tom Sherman - Post Free or Die!
Jay Beattie
Those BBs also have o-rings and spacers between the flange and the BB
shell. Are any of those missing/needed? If one is needed and missing,
that might account for some end loading. Also, some BBs can get binding
at low torque when the bearings don't seat in to the left cup/ring.
Make sure that area is greased. BTW, I hate that notched retaining
ring BBT8, which I am going to have to buy to work on my POS Truvativ
BB - which is creaking, groaning and snapping all of the time, although
it still spins O.K. -- Jay Beattie.
Michael Press
"Pete Biggs"
<p...@pomegranateremovehighlyimpracticalfruitbiggs.tc>
wrote:
Campagnolo NR, D-ring, cup and cone hub.
630x28 slick tire.
17 km/hr. 160 sec.
--
Michael Press
Jim Higson
> Jim Higson wrote:
>> HarryB wrote:
>>
>>
>>>How much drag is considered normal for a cartridge bearing BB?
>>
>>
>> Don't know about normal, but if I give my cranks a good push with no
>> chain connected they continue to spin for several minutes.
>>
>> Veloce cartridge BB (2006 model I think)
>>
>
>
> Several minutes??? That's not normal.
I must admit, I hadn't timed it. Now it has caused all this (unexpected!)
response I will do.
--
Jim
Jim Higson
HarryB
wrote:
>
>HarryB wrote:
[snip]
>> I am also concerned about the proper torque. The BB tool that I have,
>> a Park BBT8, is an eight sided socket that needs a crow's foot to work
>> with a torque wrench - and although I have a couple of torque
>> wrenches, I don't have a crow's foot. I have intentionally tightened
>> the BB to what I think is a low torque and will see how it goes. If
>> it's too loose I can always tighten it some more.
>>
>> I've decided to live with this amount of drag for the time being. For
>> one thing, the "LBS" where I had the work done is about an
>> hour-and-a-half's drive from my house. So, to return it there would
>> consume a complete morning. And the other reason is that this tandem
>> (a recumbent) is an experiment to see if we like it better than our
>> present upright one. If we decide to keep it, I'll probably upgrade
>> the BB in the future and deal with this issue at that time.
>>
>> Thanks for your help.
>
>Those BBs also have o-rings and spacers between the flange and the BB
>shell. Are any of those missing/needed? If one is needed and missing,
>that might account for some end loading. Also, some BBs can get binding
>at low torque when the bearings don't seat in to the left cup/ring.
>Make sure that area is greased. BTW, I hate that notched retaining
>ring BBT8, which I am going to have to buy to work on my POS Truvativ
>BB - which is creaking, groaning and snapping all of the time, although
>it still spins O.K. -- Jay Beattie.
Jay,
The Park Tool's BB tool is the one my LBS sold me. When I looked at it
I did notice that there were flats on one side, but hadn't noticed
that there were eight of them rather than six. I had just assumed that
I could have used a regular socket between the tool and my torque
wrench. If I were to do it over again I would probably purchase
TruVativ's BB-02-SPL tool since it has a 1/2" drive that would have
allowed me to use one of my torque wrenches.
Cheers,
Harry
Solvang Cyclist
4ax.com:
> performed exhaustive
> experiments for several minutes.
>
LOL (really).
But I question your results. After all, you knew which crank you were
testing so it wasn't a blind test. Also, did you kick up any dust or check
the trees before performing your tests? <grin>
Cheers,
David
Solvang Cyclist
@cascade.cs.ubc.ca:
> As we all know, cartridge bearings can be used to make a cheaper
> bottom bracket but not a better bottom bracket.
>
>
Well I certainly don't know that!
First, how can cartridge bearings be cheaper than equivalent quality
loose bearings? I can't imagine anything cheaper than the steel cup
bearings on an old Huffy.
Second, I don't see a value in the ability to spin a bottom bracket when
there's no load. Once you add the lateral force of pressing on the
pedals, any difference in friction due to the cartridge seals becomes
completely meaningless. Therefore, the maintenance free attribute of high
quality sealed bearings earn a ranking of "better" in my book.
Cheers,
David
Donald Gillies
>> As we all know, cartridge bearings can be used to make a cheaper
>> bottom bracket but not a better bottom bracket.
- cheaper to use a commercial sealed bearing whose manufacturing
quantity is in the zillions, than to mess around with bearing
retainers and grinding and hardening your own cups.
- cheaper to install because it takes less time to get it perfect and
the bottom bracket doesn't have to be faced - as well - for it to
work - acceptable.
cheaper? yes.
better? never.
Solvang Cyclist
@cascade.cs.ubc.ca:
>>gil...@cs.ubc.ca (Donald Gillies) wrote in news:el2d35$dlj$1
>>@cascade.cs.ubc.ca:
>
>>> As we all know, cartridge bearings can be used to make a cheaper
>>> bottom bracket but not a better bottom bracket.
>
> - cheaper to use a commercial sealed bearing whose manufacturing
> quantity is in the zillions, than to mess around with bearing
> retainers and grinding and hardening your own cups.
What you define as cheaper, I see as a better value: You get much higher
quality cartridge bearings that are manufactured in high quantities as
compared to equally priced custom made open cup versions.
>
> - cheaper to install because it takes less time to get it perfect and
> the bottom bracket doesn't have to be faced - as well - for it to
> work - acceptable.
>
> cheaper? yes.
> better? never.
>
> - Don Gillies
> San Diego, CA
>
You place zero value in the concept of lower maintenance for sealed
bearings?
Also, in what way are conventional open cup bottom brackets superior? Do
you value their slight advantage in unloaded free spinning? This would
have a minuscule (if any) advantage once the lateral forces of pedaling
is added. Or is there something else I'm missing?
Cheers,
David
John Thompson
>> How much drag is considered normal for a cartridge bearing BB?
>
> Don't know about normal, but if I give my cranks a good push with no chain
> connected they continue to spin for several minutes.
>
> Veloce cartridge BB (2006 model I think)
One thing to keep in mind is that a bearing can behave very differently
under load than when unloaded. That fact that your cranks spin for
several minutes when unloaded has very little relevence to how they will
perform under load.
--
John (jo...@os2.dhs.org)
jobst....@stanfordalumni.org
>>> How much drag is considered normal for a cartridge bearing BB?
>> Don't know about normal, but if I give my cranks a good push with
>> no chain connected they continue to spin for several minutes.
>> Veloce cartridge BB (2006 model I think)
> One thing to keep in mind is that a bearing can behave very
> differently under load than when unloaded. That fact that your
> cranks spin for several minutes when unloaded has very little
> relevence to how they will perform under load.
Let's not go off fear mongering. Explain where you believe there are
hidden aspects of bearing drag that would not be apparent in the
no-load test. Assuming the bearing isn't loose and nothing is broken,
where do you see relevant differences under load?
Jobst Brandt
Solvang Cyclist
$742e...@news.sonic.net:
> Let's not go off fear mongering. Explain where you believe there are
> hidden aspects of bearing drag that would not be apparent in the
> no-load test. Assuming the bearing isn't loose and nothing is broken,
> where do you see relevant differences under load?
>
>
I think the point was the opposite. Some in this thread are claiming that
open cup bearings are superior to sealed cartridge based on the
comparison of no-load spinning. The point about that not being relevant
to loaded conditions is that this difference, while substantial without a
load, is insignificant under loaded conditions. Under a load, you will
not notice any difference in drag caused by the bearing seals.
At least that's the point that I've been trying to make here. <grin>
Cheers,
David
Ted P.
controversial threads except maybe to inject a little humor here and
there. Laughter really is the best medicine.
I've seen many references to the weight of the bicycle versus the weight
of the rider when attempting to gain or lose just a smidgen more or less
of this or that. A 20 lb bike under a 200 lb rider with say 300 watts
power input. 220 lbs ... 300 watts. A 19.5 lb bike under a 200 lb
rider with 300 watts. 219.5 lbs ... 300 watts.
I haven't the means (or the want to) of measuring the drag of seals on a
BB. I think we can agree it's a small amount. What effect does that
drag have on a rotating mass of ? (how much does the BB, cranks, etc.
weigh? A couple/three or four lbs?) with 0 watts input versus 300 watts
input?
Besides, we need that drag to help stop the pedals when we want to rest.
(yeah, pretty lame)
--
Ted P.
Don't forget to take out the trash
Donald Gillies
garage. When I spin (twist is a more apt word) the bottom bracket,
not only is it smooth and quiet, but when I stop twisting it with my
fingers, the spindle goes for 0 mm before halting. There is even some
amount of stiction to get it going.
With a similar cup & cone bearing sitting properly aligned on the
washing machine, i can get some actual coasting out of the raw
bearing.
Solvang Cyclist
@cascade.cs.ubc.ca:
I don't see the point here. You have a single, currently bad, cartridge
bearing (or perhaps misaligned BB, who knows?) and you are comparing that
to a single open cup bearing under no load conditions. Is that your basis
for your statement that cartridge bearings are always worse than open cup
bearings?
First, not having any idea as to why the Ultegra BB doesn't spin freely,
we don't know it's due to the fact that the bearings have seals. Second,
regardless of the reason, a single sample can't be extrapolated to the
general statement that sealed bearings are inferior to open cup bearings.
Finally (and most importantly) I still fail to understand how these
"tests" (while perhaps entertaining when the weather is cold outside) are
at all useful in determining which design is "better".
You have made the claim that cartridge bearings are never better than
sealed bearings, but you still have not explained why. Is it because,
when the chain is off, you can spin the crank arms for a longer time?
That just isn't the way my bikes get used. I tend to ride them.
When riding, I defy you to tell the difference between a clean, greased
and properly adjusted open cup bearing and a "decent quality" cartridge
bearing. If that's the case, then for their use on a bike, both designs
are equal in quality.
On the other hand, keeping an open cup bearing "clean, greased and
properly adjusted" requires regular maintenance, while a "decent
quality" cartridge bearing requires none. Therefore, unless I'm missing
some qualities of open cup bearings, it would seem to me that all things
considered, sealed bearings are the superior design for bicycle
applications.
Please help me to understand why this is not so.
Cheers,
David
Lou Holtman
Cartridge BB are a blessing especially on a ATB. Who wants to take
apart, clean, grease and adjust his BB after every couple of wet and
dirty rides. Not me.
Donald Gillies
promoted and sold by the manufacturers. do you ??
Lou Holtman
Enlighten us, the ignorant, please. Let me guess. It's a marketing
scheme to let us buy more of their stuff?
Johnny Sunset
Donald Gillies wrote:
> You guys really don't have a clue why Cartridge bottom brackets are
> promoted and sold by the manufacturers. do you ??
The installation of a cartridge bottom bracket (BB) takes less time and
skill than a cup and cone BB. A manufacturer specifying cup and cone
BB's will be at a competitive disadvantage.
I suspect that the above is the reason Shimano has been moving away
from square taper BB's, as installation is more dependent on user skill
than their more recent designs.
Solvang Cyclist
@cascade.cs.ubc.ca:
I'm certain it's to make more money, since that's why (successful)
companies promote and sell anything. But why they are sold is not
relevant to this discussion.
You continue to claim that cartridge bearings are inferior to open cup
and cone bearings, yet you don't explain the reason. I have given an
explanation for why I disagree. That is: Sealed bearings offer lower
maintenance and *no* appreciable difference in feel "under normal usage
conditions."
Can you please explain the advantages of open cup and cone bearings to
me? If it's only that you can spin them longer when the chain is off, as
I've stated, that's not how I use my bike so it's of no advantage to me
given the extra maintenance required. If there are other advantages, you
have yet to state them.
Cheers,
David
Ozark Bicycle
I supect that the reasons Shimano has been moving away from square
taper are:
1) Marketing (New! Different!! Better!!!)
2) Proprietary designs mean they have a captive market when the crappy
originals wear out, assuming the buyer is unwilling to replace the
crank as well as the BB.