Originally Posted by
Don in Austin
It is normal for a chain to jump from one ring to another pedaling backwards depending on the following:
Excessively cross-chained gearing selected.
Bike with short distance between BB and rear hub.
Seven speed is not as bad as 9 or more speeds.
Don in Austin
It happens sometimes. The chain tensioner can not keep up if you pedal backwards quickly. And of course the derailleur does not guide the chain onto the cogs. Don't make any adjustments based on what the chain does in reverse. Try not to pedal backwards. The only reason it's possible is that the bike needs to be able to coast when traveling. So there needs to be a freewheeling effect.
The only thing that matters is if the chain works correctly when pedaling forward. I've seen 10 speeds (ten rear cogs), that have insane chain angles, they jump right off if you pedal backwards. They have to, the chain is way off.