At 3/12/2005 07:06 AM -0800, Jerome Moos wrote:
>Maybe I'm a little dense, but it isn't obvious to me so I'll ask. What is
>it about the tandem setup that led TA to manufacturer this adapter for tandems?
Jerry, I can think of some possibilities.
For non-crossover (same side) tandem drivetrains you would need to offset the front connecting ring by quite a bit, to line up with it's mate at the rear. When they went to crossover drive they probably just kept the technology. Keeping the chain close to the bike reduces stress on the frame and bearings.
I've seen French tandems with connecting rings as small as 26t. The Etoile allowed any size (up to 52t) ring to be used as a connecting ring without tooling up for small size "outer" rings.
I rode a Gitane with 26s that had crossover drive w/steel cranks, without the chainring offset provided by the Etoile. The bottom tube appeared to be only about 32-35mm dia. Connecting chain tension was so high, and the frame so flexy that the left arm would hit the chain, when pedalling hard with the right foot. From the wear on the crankarm I'd say this was a common occurrence. And yes, I did check to see if the RH threaded fixed cup had worked loose.
Mark Stonich;
Minneapolis Minnesota
http://mnhpva.org
http://bikesmithdesign.com