Originally Posted by
jnbrown
We have been riding tandems for 40 years and never broke a chain.
I am not sure it is even possible to apply enough force to break one unless the force is coming from the side.
Maybe your chain line is severely off or some other problem with the bike.
Another possibility is defective or counterfeit chains.
Discovered due to the shortage there a lot of counterfeit chains out there.
We've also been riding tandems for over 36 years, and the only chain we've ever broken was due to a defective derailleur issue (a story in itself). I agree that something is likely problematic with the bike, whether it be in the chain alignment, bent derailleur hanger, worn freewheel, or possibly a combination of a few things. Perhaps some close-up pics of the drivetrain might help?