Bicycle Mechanics - Shimano bottom bracket life
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I have been experiencing problems with the service life of Shimano bottom brackets on my road bike. I have had two Dura-Ace units that began "ticking" within 200 miles, and were totally shot in less than 500 miles. When dismantling the units, I could see very noticeable scoring on the spindles.
I am now trying an Ultegra BB, and during the FIRST ride I have detected slight ticking starting with this unit.
Has anyone else had these problems? I am larger than the average road rider (230 lbs) but have had no real problems over the years with any other bottom brackets.
As far as I know, there are no aftermarket bottom brackets that are compatible with the new style Shimano cranks, so I don't know where else to turn.
Anyone have any similar experience of advise to share?
10-14-01, 02:15 PM
yes, i've known people with dura ace b.b's have a similar problem, although it was more a groan than i tick. i use dura ace myself and have had no problems. i know it might sound stupid but are you sure it's your b.b? check your chain too for a stiff link, this can cause a ticking noise. i thought i had the problem with my dura ace b.b, i heard a ticking noise i thought the b.b was shot. but i'd only assembled he bike weeks before and knew the b.b couldn't be shot so soon. in the end it turned out to be the cradle on the dura ace seat post clicking under the pressure of my weight as i pedalled! it just needed tightening up a little. the thing with transmission noises is, you can never be too sure where it's coming from, as you can't get your ear down there to identify where exactly it's coming from, as you ride. and then when you put it on a workstand, you can't apply enough pressure on the affected area to create the ticking noise! just have a check of the chain, put the bike on a workstand if you can and watch the chain go round to see if you can see a stiff link. if it's not that then i've no idea. you can't keep on buying b.b's for ever until the noise stops!
Good advice. I know from my first two Dura-Ace bottom brackets that they were the problem, because when I took them apart I could plainly see that they were totally worn out. There were actually small shoulders worn into the spindles, on each end at 180 degrees from each other, corresponding I guess with where the unit received the most pedal torque.
With my current Ultegra unit, I may be overly paranoid and the clicking may not be the bottom bracket. I am going to try swapping chains and see if that helps. I have tried swapping pedals, but it made no difference.
You are right about trying to diagnose these noises....it is maddening.
Supposedly Dura-Ace has a three year warranty and the other Shimano stuff has a two year. I was wondering if these problems would be covered under that. Has anyone tryed to get warranty replacement on a Shimano part?
A clicking sound may also be loose chainring bolts.
The Dura Ace BB with the large splined spindle is notorious for wearing out quickly. The reason is the bearings are very small -compared to regular BB's- and therefore have a very short life span. They just can't take the abuse of a regular unit. And Shimano won't give a license for anyone else to make them.
ISIS makes a similar unit, but it is not interchangeable with Shimano.
I have heard that the Ultegra unit actually lasts much longer than the Dura-Ace. Anyone have any experience that backs this up?
I've had experience with D/A, Ultegra, 105, and UN72 BB's. The D/A BB was great, while it lasted. After one time riding in the rain, it was shot. Had all of 400 miles on it. I replaced it with an ultegra, and it's been fine ever since. Lance Armstrong actually uses Ultegra BB's on all but his TT bikes. Most racers use them whenever there is a lot of climbing, due to the notorious fraqgility of the D/A BB.
I've also used a 105 BB, but was not impressed. It ran a bit rough even when new. Even the UN72 runs smoother.
10-15-01, 07:19 AM
the people i know, who had the problem with dura ace b.b's, switched to ultegra and found that model to be better. it seems i'm a lucky one, i've done thousand of miles on my dura ace b.b and it's still super smooth, never had any problems at all with it.
As a retrogrouch, I have reservations about bearing cartridge mania. Other than the maintenance time savings, do sealed bearing systems offer any tangible benefit, such as reduced friction, reduced weight, or increased reliability? The first-generation SunTour wheel bearings on my mountain bike have held up very well, and so far my son's Shimano UN-72 BB cartridge seems to work, although the [Shimano!] cranks do not seat all the way onto the spindles.
(My other problem is the Swiss BB threading on my two touring/commuting bikes, for which the only cartridge option of which I am aware is the pricey Phil Wood.)
FWIW, these newer sealed bearing BB's don't last as long as the older style BB's, and they cost more, also!
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