Originally Posted by
Iride01
Might need to re-visit chain length if after correcting the DR height you still have the chain fall off occasionally.
I usually would expect too long a chain having slack in some gear combo's to be more prone to falling off the front.
Chain length will be low on my list of other things to check normally for dropped chains. I only bring it up because you said you lengthened it.
Shimano rear DR? They tell you how to size the chain in their DM's for that model DR.
https://si.shimano.com/
How would this happen? If you're pedaling the bike the 'tension' on the chain is what it is depending on how hard you're pedaling. The chain has no more or less 'slack' because the top run of chain will have tension on it. The bottom run has tension from the pulley cage of the derailleur. The only place you could have slack is on the bottom run in the smallest cog or 2 when in the small ring if it was actually too long. As long as there is tension on the bottom run of chain in small/small it'll be the same everywhere else.