I've got a Propella 7S E-Bike (now defunct, local-to-me brand) with a Shimano Altus 7 speed derailleur in the back and a 1x ring + Lasco crank in the front (aka nothing fancy). I've had persistent issues with the chain jumping off the front ring (away from the bike toward the crank arm). It's not really happening when hitting massive bumps or shifting, but I am often in a higher gear when it does happen. I've tried replacing the chain and the front ring. I've verified the chain length. Everything looks mostly aligned to my untrained eye. I'm wondering if anyone has ideas what I should look at next.
by bdferris
9 Comments
pretty normal with 1x that does not have a clutch derailleur, or a chain guide. look into chainring guards, front chain guides, maybe even just throw an old front derailleur on to act as a guide or upgrade the derailleur to have a clutch.
You need a Narrow Wide chainring.
Check if this a narrow-wide chain ring.
Are you 100% that the chain ring is indeed narrow wide? I’ve been running a 1×9 with a clutch less derailleur for 5 years never had an issue with the set up.
Chain or chain snap-on incompatibility. Looks to be a single speed chain so make sure that isn’t the case.
If you’re sure the chain length is right, then I would have a look at the rear derailleur. Have the pulley tension springs relaxed? Have you lubricated all the joints in the rear derailleur recently?
This is a shifting chainring. Shifting chainrings are quite literally *designed* to easily drop the chain, because that’s how they downshift. You can’t expect the chain to stay on reliably at all without also having a front derailleur cage guiding the chain.
Get a narrow-wide chainring.
Combination of bad chainline, not a narrow wide chainring, and not a clutch derailleur.
Is this crank two sided? Like does it have room on the other side for you to mount the chainring there? I solved this by just moving the chainring to the back of the crank. It looks worse but i find I don’t really notice it.