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Old 11-06-05, 08:37 AM
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TandemGeek
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Originally Posted by R900
...we'll wait until the Spring check up and have it corrected. The LBS is about 80 miles away, I might look into it later myself, but I haven't noticed a big problem in our couple short rides.
Since the tandem is new, adjusting the eccentric "should" be relatively easy. Trek uses a wedge-type eccentric similar to Cannondale. There is a hex-head expander bolt on the drive-side of the eccentric that releases the tension holding the small wedge tight against the eccentric body. You use a t-handle hex driver (4mm? perhaps 5mm, I forget but it's in that size range) to loosen the expander bolt and then, per the Trek manual, you "tap it" to drive apart the two pieces of the eccentric. If it doesn't come loose, there are some other tricks that can be used to persuade it to come loose. The more frequently you service the eccentric -- basically pulling one of the cranks (very easy as Trek uses self-extracting crank bolts on the tandem +++), then loosening & removing the eccentric, followed up with a cleaning & relube -- will ensure it will always be easy to remove and adjust. If left untouched for thousands of miles grit and grime can work into the eccentric making it really tough to remove.

On the crank timing, the only thing to keep in mind is that who ever is "leading" will encounter a bit more resistance with each turn of the cranks. Some stokers like this as provides them with positive pedal feedback that can sometimes be lost if the cranks are in perfect phase or if the captain is leading. The down side can be that stokers may tire faster. Just something to consider and experiment with... which harkens back to why its a good idea to master adjusting your own eccentric. As you'll find in the archives, once you know how to adjust the tension you can even figure out how much tension to use that ensures the chain won't have too much slack, but enough to let you "roll it off" the timing rings without loosening the eccentric... a handy "trick" for adjusting phase when experimenting or off-bike chain cleaning.

The in-line adjuster isn't all that awful and it's the lessor of two evils vs. not having the brake blocks as close to the rim as possible for maximum braking power. It's just one of those things that has a specific purpose that some bike shops who sell the Trek tandems don't even understand and, as a result, the rear brakes don't get adjusted to provide optimum rear brake power OR owners who have a need to remove their rear wheels find themselves having to deflate the tire to get past what appears to be a brake that does not have a release mechanism.

Last edited by TandemGeek; 11-06-05 at 08:43 AM.
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