So, all of a sudden I have drivetrain issues that are driving me mad and can’t suss out what the issue is, up until last week all was well… 1×9 setup, narrow wide chainring, never a problem…

Last week I took the front wheel off to get the bike in the car for a ride around the Peak, took everything out of the car and started the ride but as soon as the trail took a turn upwards and I changed down the gears and up the block, the chain was dropped from the chainring!!!!

I managed to faff around with tension enough to give me 3rd as my lowest gear (managed to grind out the ride) but couldn’t risk going any lower for fear off dropping the chain. Today I’ve had everything apart from cleaning and bit of general tlc, including re indexing (roughly) the gears, but the chain is still jumping off the chainring when in the largest sprocket!

Anyone any ideas? Worn gear cable maybe? Bent mech hanger from being in the car (looks okay from above to be honest, don’t think it’s that, just seems wierd that the car journey seems to have brought it on)? Anything else I should be looking at?

Just to add, it always drops inboard towards the BB!

Worn chainring.NW’s seem to start dropping the chain well before you’d consider them being ‘worn’ in the traditional sense.
I’ve added a guide as direct mount rings are bloody expensive!

It doesn’t look too worn, I reckon I’ve only put maximum 300 miles on it, doesn’t seem like two minutes since I swapped everything out!

Stiff jockey wheels? If they don’t spin easily then the mech can struggle to take up slack, which then bounces off. I’ve done about 1500 miles on one NW ring and no drops yet, so I doubt it’s wear unless that was 300 miles in wet sand.

Had the jockey wheels off today, cleaned them up and regressed so doubt it’s them either… :-/