Tandem Cycling - Cannondale Eccentric Maintenance Instructions

For the archives:

Here are some resources for Cannondale tandem owners that will help them understand how to adjust their eccentric bottom brackets and, should they ever become "stuck", how to get them "unstuck":

This first link will take you to Cannondale's eccentric supplement. It's pretty clear-cut and the methods as described work well unless the wedge becomes stuck to the point where hammering away on the wedge bolt has no effect:

http://www.cannondale.com/asset/iu_files/techcenter/2003_eccentric_bb_chain_adjustment_owners_manual_supplement_en.pdf

FWIW, here's a link to the Cannondale Tandem supplement as well:
http://www.cannondale.com/asset/iu_files/techcenter/2005_tandem_owners_manual_supplement_en.pdf

Both of these files can be found on Cannondales Web site Tech support pages:
http://www.cannondale.com/tech_center/bikes/other_bike.html

If you find your Cannondale's eccentric's wedge will not release, you'll want to follow these instructions for "extracting" it. This is the only, sure-fire way to get it undone with minimal fuss and reliable results: http://hobbes.ucsd.edu/tandem/Maintenance.faq

The alternative is to buy a Trek as the wedge bolt is self extracting.

The alternative is to buy a Trek...

...or just about any other tandem since no one else uses the Cannondale eccentric. Actually, they aren't that bad if they're not assembled by a Gorilla and given some periodic maintenance. If left installed for several seasons or, again, over tightened to eliminate "creaking" the washer extraction method is very easy and effortless so long as you have the right tools.

Once I got it loose from the factory, it has been reliable and easy to use. I think they need to update their torque wrench specs or the lube for that unit. This is why God invented plastic hammers.

Just remember to take BOTH crank arms off when trying to adjust the timing chain. The cannondale supplement doesn't mention this. I've had good luck with mine, be sure to give it a good coat of anti-seize or grease though.

Am not at all impressed with C'dale's eccentric. Trek apparently uses a wedge type set up. Most others are more simplified.

I'm confused. I have the Cannondale double wedge eccentric. Did Cannondale change the design of the eccentric? First of all, it is a wedge design. Second, mine is self-extracting and the self-extracting method works fine. Third, why would you ever have to take off both crankarms to adjust the timing chain? How could you know how to adjust it without the crankarms on?

You don't have to take the crank arms off to adjust the eccentric- that is misinformation. Or at least I never have during my time owning a Cannondale tandem over the past 15 years.

I always release the wedge by loosening the bolt a bit, putting a punch in the bolt head and giving it a firm rap with a hammer (the punch, not the bolt). This has also worked really well for the past 15 years with no evident ill effects.

I recently bought a Ventana off-road tandem, and have had the opportunity to see the Bushnell eccentric up close- it is a fine piece of work, and I may buy one to put in the Cannondale since it works so well and is completely self-releasing.

Rick

I must have a newer eccentric like rmac. It's a double wedge design with which is also self extracting via a captive e-clip. I don't have to remove the cranks either. The eccentric has worked perfectly for me.

Sheldon