Originally Posted by
Bubba Zanetti
If the chain falls off when shifting to the smaller cogs, the rear deraileur is not applying enough tension on the chain as the cage swings back. Shift it to the smallest cog and bounce the bike up and down while observing the chain. If the chain looks really loose, you need more tension my adjusting the deraileur or taking chain links out.
I'll try to take one or two links out (or as many as possible when having it on the large cog back). The chain doesn't fall off immediately when shifting to smaller cogs but after some time when I put a bit of pressure on the pedals (could be one minute or 20 minutes). Maybe I should buy a replacement spring for the derailleur if that doesn't work. I will report back next week (this week-end is devoted to my newly built Rambouillet
)