[marcusbandito]

Forgive me for not posting this in the mechanic's forum, but I thought I could benefit from your experience here. I have a customer with a Trek T-1000 and we are having a heck of a time eliminating a creak from the front bottom bracket on their bike. We have disassembled, cleaned, & re-greased without success. We have been talking to Trek's people and have just replaced the eccentric bottom bracket. It seems to be solved now, but the creak always returns after the first ride so I thought I would see if there are any tips you might have before I send them on their way. Maybe a dance I was supposed to do before reassembling everything or some hat I was supposed to be wearing.

Thanks

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[rjberner]

.......but the creak always returns after the first ride so I thought I would see if there are any tips you might have before I send them on their way.

Had this problem on my wife's new single bike -- with a non- Shimano or Campy BB. Turned out to be a sloppy, threaded sleeve on one side of the BB assbly. Some mechanics told me to wrap the threads in teflon tape before installing it; others suggested Loktite.

Instead, I s**t-canned it and bought a new premium Shimano crank and BB because I am a superstitious guy and I HATE CREAKS AND GROANS OF ANY KIND! The problem was solved.

You may want to try the thread lock methods first if you haven't already.

[Dennisj]

Got our T-1000 in late February of this year with the same problem. Dealer ended up replacing the entire front crank assembly and drive chain. 1300+ miles later, no problem.

[JohnC]

If the BB is eccentric then there are no threads per se. Correct? At least this is true for my two Burley's. I had a similay mystery "creak" on my road tandem this spring. Both my wife and I were absolutely convinced it was the front BB that was creaking. I removed the BB and the set bolts and no matter what I did the noise never went away. Finally while working on something unrelated I noticed that the stoker seat tube shock was squeaking. I lubricated it and the noise is completely gone now.

I have no idea how the physics work that move the perceived source of the noise from the stoker seat tube to the captain BB, but there it is.... It was a couple of months figuring out that one.

Not sure that this is related to your situation, but I thought it might help.

John

[TandemGeek]

If the BB is eccentric then there are no threads per se. Correct? At least this is true for my two Burley's.

Unlike nearly all other major tandem builders, Burley previously used proprietary, pressed-in bottom brackets on their tandems. Back around 2003(?) they adopted the more conventional threaded bottom brackets. Personally, I liked the pressed-in cartridge bearing bottom brackets: solid components that fit-up nicely. However, for the average consumer / home wrench they limited the options relative to aftermarket bottom bracket and crank upgrades.

[TandemGeek]

Maybe a dance I was supposed to do before reassembling everything or some hat I was supposed to be wearing.

No, no special dances...

Having a bike with two bottom brackets, two sets of cranks, and this thing called an eccentric provides the owner with significant number of additional sources for creaks and noises. As someone else noted, the large tandem tubesets also do a great job of migrating noises away from the source... often times a saddle, seatpost, clamp, or handlebar clamp, or a pedal which further complicates things.

Of these bits and pieces, the only truly tandem-specific part is the eccentric and they can be a bit touchy: The Trek and Cannondale wedge-type eccentrics seem to be more prone to creaking than the expanding eccentrics (Ventana, daVinci, custom builders), which are more prone to creaking than the solid eccentrics held in place by set screws (Santana), which are more prone to creaking than solid eccentrics held in place by split eccentric shells and pinch bolts (Burley & Co-Motion).

For all of these components, the key to getting them to not creak once it starts is to: disassemble, clean, grease, and then reassemble with proper torque. Also, it's a good idea to make a habit of retorquing the eccentric's bolts after the first ride following removal and reinstallation just to take up any slack that develops as the eccentric "beds back in" to the shell under a working load.

Now, I did find it interesting that Dennisj had a similar issue with his T-1000 that required a replacement part to fix. If Trek received a batch of eccentrics that were a bit out of spec, then all bets are off for getting rid of drive train noise: definitely something to check into if other newer Trek T-X000 owners chime in with similar problems on similar model year bikes.

Back to the rest of the drivetrain, as others have noted, teflon tape can be used for 'reinstallation' of threaded bottom brackets to ensure they are not the source of drive train noise. Personally, I like to use a layer of the thicker, yellow gas-pipe stuff when reinstalling BB's, noting that new ones usually have an equivalent treatment applied by the manufacturer. Anti-seize compound does a great job of eliminating BB thread creaks, but it makes a mess out of everything, and blue Loctite has it's place, but IMHO not on bottom bracket cups.

Cranks are no different than on 1/2 bikes: square taper spindles and crank holes need to be cleaned with rubbing alcohol before reassembly (use a thin film of grease if your BB cut sheet says to, e.g., Shimano says yes) or slather on the grease for Octalink/ISIS interfaces. I also grease the threads on the crank set screws... just not a fan of Loctite for that application either. Finally, before leaving the cranks, make sure all the chain ring bolts are tight: a loose one in the high load positions will give you a rythmic "click" that'll drive you nuts.

As for the rest of potential sources of noise, I pretty much use blue Loctite on every non-drive train bolt part on our tandems that connect a body part to the frame: handlebar stem clamp, seatpost seat clamp & rail slots, as well as the stoker boom & handlebar stem clamp bolts. By treating all of these bolts with blue Loctite most of the "nuisance" creaks that can masqurade as drive train noises are eliminated.

[mrfish]

Excellent post - Same as my general experience - my last mystery creak was dirt in between the A-headset spacers. After stripping most of the front end of the bike I noticed the spacer was slightly dull where it rests on the stem. A bit of cleaning and light greasing soon silenced it. Problem is generally finding the creak rather than silencing it.

Only difference is that I do like non-permanent Loctite on b/b threads, especially Italian threadings which naturally undo as you pedal. Advantage of non-permanent Loctite is that it doubles the torque required to undo the component without doubling the installation torque. Also vibration won't loosen them. On Campag b/bs this means you can back off the cups slightly so that everything runs silky smooth without worryng that the b/b will unscrew itself in the middle of nowhere. This also means the b/b lasts longer.

It's funny that bike mechanics don't use more loctite. I worked for a while in Mechanical Engineering on Chemical Plant machinery and loctite was used by the fitters on very frequently. That has also been my experience on model helicopters, where the rule is loctite everywhere, except if it's nyloc or something screwing into plastic.