I’ve recently turned my commuter into a 1×9, but the chain falls off now and then. I have a one of the seat stay chain guide things for the inside, but need a 48t bashguard to prevent it fallng off the other way. It has to be a 104bcd 4 bolt.

Anyone know of anything?

I thought BBG might be the ones for you, but they only go up t0 44T in 104bcd. Can’t think of anywhere else that does anything that big.

Superstar do the XCR single ring chain keeper which says only up to 42T, but I assume you can mount it anywhere on the seat tube, and as it’s not a full cage it doesn’t matter how big the ring, or what the chain line is doing underneath. Might be worth a try.

you can use a bodged front mech to do that, or maybe an extra-dinner-plate (52??) sized front ring mounted as a bashguard? I’m not aware of any dcd that big aside from old-school stuff from the late 90s

Yes, thats a great find. £20 isn’t bad, plus I think it would solve it. Do non ramped chainrings make a difference?

Deore “trekking” chainsets come with a 48t ring and a plastic bash but not sure if you can get it separately

If you’re running a ramped chainring, that’ll be why you’re losing the chain now and then. I went from a ramped to unramped (both with a Superstar XCR) and haven’t lost the chain once since doing it – previous to that I was losing it a few times a ride.