Chain jump problem

Joel said:

I have tandem that I ride with my wife.
Frequently when we are standing usually uphill the chain will jump on
the rear cassette and my wife being in the back feels the crank arm
jump. This is a very unpleasent experience for her. The cassette is a
12-28 shimano XTR 8 speed and the chain is a Shimano 8 speed. The
derailluer seems to be adjusted ok and works fine otherwise. I am
thinking of just replaing the cassette and chain thinking something is
worn. Anything alse I should check for?

Sounds like the frame is flexing when you really apply some torque on
hills and this is causing the chain to jump as it tries to move to a
different gear. This certainly happens to me on my tandem.
Best wishes,
Nigel Grinter

Joel said:

I have tandem that I ride with my wife.
Frequently when we are standing usually uphill the chain will jump on
the rear cassette and my wife being in the back feels the crank arm

Do you not feel the crank arm jump? Do the two cranksets keep in synch? If
not, it's the sync chain, not the drive chain.

Quoted message said:

jump. This is a very unpleasent experience for her. The cassette is a

Quoted message said:

12-28 shimano XTR 8 speed and the chain is a Shimano 8 speed. The
derailluer seems to be adjusted ok and works fine otherwise. I am
thinking of just replaing the cassette and chain thinking something is
worn. Anything alse I should check for?

Determine if the chain is worn, then replace if necessary. If it's an old
chain on a tandem where you guys regularly stand to pedal, it might very
well be worn too far, and have taken the cassette with it. Inspect the
sync chain and the various chainrings as well.

Jasper

1) Misalignment of the rear wheel or frame bending.

2) Wear on the chain and/or cassette.

3) A really STRONG or FAT wife with more leg strength than Cippolini.

4) A klutz pilot who hits the shift lever when he's working hard.