Tandem Cycling - Chain length
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05-31-07, 09:04 AM
I have read two different methods of establishing chain length:
1) Chain should be just long enough that it can be shifted to big/big without damaging the rear derailler.
2) Chain should be just short enough that when shifted to small/small, the slack side of the chain won't drag against itself on the rear derailler.
If these are different lengths, which is the better way to go?
05-31-07, 10:04 AM
Big/big, chain ends should overlap by one link (an inch or so).
05-31-07, 10:46 AM
My current single came from the bike shop w/ a chain too short to shift into the big/big. Talk about a rude awakening the morning I discovered that. Needless to say, I added links so I could hit all combinations as soon as I had the chance. Now that I have the longer chain, I occasionally hear some "chain slap" as I hit bumps in the small/small combination, but have never had any issues w/ shifting or the chain dragging on it'self.
05-31-07, 02:38 PM
For tandems running triples, BIG / BIG. Small / Small isn't a usable gear combination as the chain starts rubbing against the lower part of the front derailleur and then up against the middle chainring before it ever gets to the smallest cog when running in the smallest chainring.
05-31-07, 04:18 PM
Now big/big or small/ small will cause that nasty thing called cross-chaining. That is where the chain will be stretching sideways to cover the two sprockets and will wear a chain out eventually- will wear on the front derailler and will annoy the stoker with the noise of everything rubbing so in theory will never be done.
Normal way to cut a chain to length is to set it up on the largest front and largest rear sprocket and cut it so it will be be just a link longer- Definitely not shorter. A few years ago I put a new chain on it was just a 1/2 link short but as we never cross- chain it will be fine. It wasn't and as we found out - we do crosschain. AND we are experienced riders that NEVER crosschain. That 30 mile ride was a nightmare.
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