The chain on my commuter bike was slipping when I applied power (i.e. accelerating hard from traffic lights) yesterday. So I thought it was time for a new chain and cassette as the teeth on the two sprockets I use the most on the cassette are distinctly warn when compared to the others.

I took the chain and cassette off to change them and whilst cleaning the chain rings, I noticed a tooth missing on the front. So to avoid any potential issues with the new chain/cassette, I put the old ones back on.

Today on my ride, the two warn gears are slipping all the time so I can’t use them and these are the gears I use the most for my commute (fastest without destroying my quads). The slipping is in any of the chain rings so isn’t related to the missing tooth.

Any ideas why this has suddenly got worse? Is it a case of putting up with it as my fiddling has just made it worse and will stay like this until the new chain ring arrives and all bits can be replaced?

Any ideas fellow STWs?

whilst cleaning the chain rings

It’s possible that all the gunk was the only thing stopping the constant slipping (I’ve had this before!)

ime slipping chain has always been because of mixing up a combo of new and old chain/cassette/chain rings. So yes iiwy if you’re replacing the casette and chain replace the chain rings as well, if the other two were new it can’t be anything else (before someone jumps down my throat, it could be a bent mech hanger but since you didn’t mention it wasn’t slipping before we could rule that out)

It might be something like this. When the cog and chain wear, the chain gets a little longer (slack in the pivots), and the teeth on the cogs wear thinner, the curves between become deeper, maybe.

So the chain wraps around the cog but only the bit right at the end, where it’s being pulled, makes proper contact. You could wiggle the rest up and down. It’s depending on friction on the edge of that tooth. You reduced that friction.

I wonder if re-doing the chain so it’s running in the opposite direction and inside out might show a temporary fix.

Thanks all, I think it’s the lack of gunk and the friction issue you’ve mentioned. I’ve just tried putting the chain on the other way in my lunch break but it’s no better

The chain and cassette are knackered so I guess it’s no surprise and I’ll have to wait for my CRC chain ring delivery.

Going to be a fun 9 mile each way commute on nobblies tomorrow!