Problems with DA BBs

[Lincoln]

So I've gone through two DA 7800 bottom brackets in way to short a time. I don't know how many miles but chains and tires last longer! I don't ride this bike in the wet and I would expect them to last many many years.

Any thoughts? Bad luck? Bad design? Should I just upgrade to the slightly improved (?) 7900 model? Upgrade to the Chris King (I don't want to spend that kind of dough but if the option is buying DA at regular intervals...)? Other thoughts or ideas?

Thanks!

[ThasFACE]

I had phil wood bearings pressed into a da bb and haven't had any kind of trouble in many thousands of miles. Not the cheapest option, but it's a good one.

[nahtnoj]

Define "way too short a time"?

Could be stating the obvious, but perhaps your frame is not faced properly, and mis-alignment is accelerating wear?

[Lincoln]

Define "way too short a time"?

Could be stating the obvious, but perhaps your frame is not faced properly, and mis-alignment is accelerating wear?

way to short: I don't keep track of miles or hours, but I've had them last fewer miles than a set of tires. A top-shelf BB should last many, many times longer than this.

Thanks, good idea on the facing, unfortunately I'm pretty sure this is not the problem and that it is correctly faced.

[rnhood]

I suspect you have something else amiss. The DA BB is super reliable. I have about 8K miles on mine. Are you riding a standard bike or a one-off custom? The comment about facing and alignment is a good one to consider.

[dvs cycles]

Sounds to me as like you are tightening the preload cap too tight and putting too much side pressure on the bearings. I've put over 25000 miles on mine and not a single tick or noise. :beer:

[weiwentg]

Sounds to me as like you are tightening the preload cap too tight and putting too much side pressure on the bearings. I've put over 25000 miles on mine and not a single tick or noise. :beer:

could be. the NDS bearing in mine is feeling a bit rough after a 3-4 thousand miles, probably because I overtightened the preload cap.

[chuckaw]

Any tips/guidance on just how tight the pre load cap should be? This has always been a gray area to me.

[alancw3]

from what i have read try a ultegra 6600 bb instead. much more durable.

[geoffm]

It does sound like a pre-load issue. The problem is that the pre-load recommended by Shimano is extremely light at 0.7 -1.5 Nm. Many torque wrenches do not have such a fine setting. That is the reason the tools for that job are made out of plastic. I have had good luck with just ensuring that the non-drive side crankarm is snugged-up properly to the bearing and pre-loading it just finger-tight.

[Lincoln]

Sounds like maybe I have been over tightening the preload. I just use the little plastic Shimano doo-hickey that provides no leverage but I did snug it firmly by hand.

Here's from Park Tool's site bold is theirs:

After bearing cups are installed, grease spindle surface and place right crank with spindle through the right side cup (drive side). Push from right side until spindle comes out left cup. Fit is snug, and in some cases gentle use of a mallet may help.

If spindle appears to catch and will not come out non-drive side cup, may be an indication that shell faces need machining. Grease splines of spindle and install left arm. Notice splines are keyed, and left arm will only install 180-degrees opposite of right arm. Grease threads of arm cap and thread cap into spindle. This cap acts only to push arm fully over to cup bearing. This cap does not tighten the arm onto the spindle. IMPORTANT NOTE: Secure cap gently. Use the eight sided stud a the end of the BBT-9 and tighten only 4 to 6 inch-pounds. Over tightening will side-load the bearing and cause premature wear. Spin arm to test.

[Lincoln]

I suspect you have something else amiss. The DA BB is super reliable. I have about 8K miles on mine. Are you riding a standard bike or a one-off custom? The comment about facing and alignment is a good one to consider.

Custom Strong. Facing/alignment is not the problem.

[dvs cycles]

Sounds like maybe I have been over tightening the preload. I just use the little plastic Shimano doo-hickey that provides no leverage but I did snug it firmly by hand.

Here's from Park Tool's site bold is theirs:I bet your next BB will last much longer then. :beer: