3 speed Triumph bike problems, help!

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Hi All,
I'm new and just bought a used 3 speed Triumph bike. I love it however, either the chain keeps popping off the bike when I ride it. Maybe I'm not shifting the gears and peddling correctly. Although how hard could that be. But it keeps popping off. Any suggestions?
Henry Bemis

Your front chainring could be bent. If it is, some pliers should straighten it out.

Hi All,
I'm new and just bought a used 3 speed Triumph bike. I love it however, either the chain keeps popping off the bike when I ride it. Maybe I'm not shifting the gears and peddling correctly. Although how hard could that be. But it keeps popping off. Any suggestions?
Henry Bemis
A few ideas:

1. not enough chain tension

2. chainring and/or sprocket worn, chain worn

3. if you only experience the problem in high gear, what may be happening is the 3-speed (sturmey I assume) is popping into neutral and the sudden increase in chain speed coupled with loss of tension causes the chain to come off, but I feel this would not happen if the chain tension was correct. That is, the chain would stay on when the AW hub does what it is famous for and goes from 3rd to neutral by itself.