Chronic chain derailment
On my New World Tourist with Sachs Centera, my chain sometimes jumps off the front ring and gets stuck between the chainring and its protector. Obviously the distance between the two is too large, but my mechanic doesn’t think that we can whack the protector into a better form. What is your advice?
We must first determine why the chain is coming off the chainring. Inspect the chain and the chainring carfully for bent links or teeth. Either of these can cause the chain to jump. The other thing to check is the spring tension in the rear derailleur. As these springs wear out, the derailluer can no longer maintain chain tension and the chain will do as it wishes. I would also have the chainline checked by a professional bike mechanic.
The chain should not derail from the chainring under normal use. The chainring protector should function as a chain guard so you don’t catch pant legs in the chain. It should also function to keep the chainring from getting bent during folding or packing. If the chainring protector is damaged, we can provide a replacement.