Bottom Bracket Problems

[redryder]

We have a 2004 Cannondale Road Tandem (with approx 1,000 miles). When we ride over 25 miles the front bottom bracket starts to make noise. It starts off with random noise and then increases with every rotation. Bike went to local LBS last week and they looked at it and stated a screw was loose in the bottom bracket (they tightened). Went for a 40 mile ride on Saturday and at the 25 mile mark it started up again. By the time we ended our ride, at 40 miles, the noise increased to where it sounded like someone was sawing a log. Should the bottom bracket be replaced? Is this a common problem with aluminum bikes? Is it tandem specific? Is there an upgraded bottom bracket available? Is this heat/friction related? We are taking the bike back to LBS next week. Just wanted to know if anyone had this same problem. Thanks.

[TandemGeek]

Unless there is a problem with the TruVativ ISIS bottom bracket -- not unheard of but certainly rare -- I would be more inclined to suspect a dry eccentric (the aluminum cylinder into which the captain's bottom bracket is installed).

Cannondales are notorious for noisy eccentrics and the only way to cure them is to fully disassemble, remove, clean, and then apply a generous amount of lubricant to the entire mechanism and contact surfaces on both the eccentric body and the frame's eccentric shell before reinstalling. It sometimes takes a lot of torque to get the eccentric tight enough to prevent creaking.

Of course, the other problem is getting the C'dale eccentrics loose -- particularly when they are dry. If you or your LBS ever have trouble removing the eccentric you'll find a "trick" to easy extraction here: http://hobbes.ucsd.edu/tandem/Maintenance.faq

The only other thing to check on would be the crank interface. ISIS and Shimano's Octalink spline interfaces require a healthy slathering of grease.

[zonatandem]

Cannondale was/is notorious for bottom bracket creaks. Years ago, friend with C'dale tandem had that problem; C'dale rep made the following suggestion: Remove pilot seatpost and pour a small amount of linseed oil down the tube. Miraculously, creaking ceased!

[Bill G]

ANOTHER METHOD FOR REMOVING A STUCK CANNONDALE ECCENTRIC

You can also remove a stuck eccentric on a cannondale by backing out the wedge bolts, take a rubber mallet and strike squarely againt the center of the crank arm on the opposite side of the wedge bolts dead center with the bolt that attaches the crank arm to the bottom bracket spindle. The eccentric will move to the side letting the wedged piece slide away from the eccentric body, therefore letting it slip or break loose enternally. This method will not leave any marks or dings if a good quality rubber mallet is used. Then grease the heck out of everything and reinstall the eccentric.

Good luck,:)
Bill G

[zonatandem]

Wedge bolt eccentrics have always been more problematic than others.

[Old Hammer Boy]

On my '05 'Dale, the factory used gobs of what appears to be Never Seez. I ocassionally loosen it up just to make sure it hasn't started to sieze up. It's been just fine so far. It may be that Never Seez has proven to be the best product for these wedge assemblies. You may want to use that in the future. Here's a link that describes the product's charteristics: http://anti-seizecompounds.com/product_02

Note that it resists galvanic action between dissimilar metals and also protects against road salt corrosion. I'm guessing these are the two main challenges with this type of bottom bracket eccentric. Good luck finding your phantom noise. OHB

[TandemGeek]

On my '05 'Dale, the factory used gobs of what appears to be Never Seez.

I previously recommend Anti-Seize compound... but most folks found it so messy to work with (your hands will look like the tin-man's from Wizard of Oz) that the added value vs. less aggressive lighter lubes was hard to justify.

Never Seez.. good stuff, but if you use it consider wearing disposable latex gloves and be prepared to clean the excess from your tandem following the install.

[stapfam]

I had to adjust the concentric at around 500 miles on my Dale and it took a bit of effort to adjust- Next time it had to be done was around 3,000 miles and that was difficult. Although I had greased it well- it had almost dried up. Since then I strip and rebuild it about every 1,000 miles and I put plenty of "Black Gold" grease on it. Wipe off the surplus, tighten it as tight as I can but at the 1K service it is very easy to free off.

[redryder]

Thanks for all of your replys. I printed off some copies for my LBS. The bike is in the shop and should be completed by Friday. We are planning a 50 mile ride Friday afternoon so I will see if the noise returns. Will keep you posted.

Thanks again :D

[gregm]

Creaks down there can also be attributed to chainring bolts or the pedal/crank interface. Something to keep in mind if the other possibilities don't pan out.

-Greg