Skipping caused by jockey wheel?

mask of sanity

Over the last few weeks my bikes developed a tendency to skip every so often, normally after a junction after having back pedalled to get my leading foot in the right place. I've re indexed my gears a number of times and the chain and cassette are fine so am pretty sure it's not that but in checking my bike I noticed that the top jockey wheel is quite loose (has a few mm of play). Could this be what's causing the skipping? If not what could be the cause of it?

Many thanks.

alfablue

The top jockey wheel (called the guide pulley) is designed to have lateral play, this allows good meshing with the sprockets even if indexing is slightly out. A jumping chain is more likely due to a stiff link, a breaking link (check thoroughly) or the indexing being out so the chain is trying to grab the next sprocket. Best observed by getting the bike on a stand and get eye-level with the back of the cassette/mech whilst turning the crank.

mask of sanity

I don't think it's any of those because the jumping happens at a random position with regard to the chain. There's also no lateral chain movement when it happens so don't think it could be indexing.

How about an issue with the hub? It almost feels like the cassette isn't gripping properly with it. That might explain why it's worsened after back pedalling?

thel33ter

Have you checked if the cassette is a bit loose? the lockring on my Spesh was loose and a similar thing was happening to me.

Burton

Spooky - had a similar problem on my TT bike on Monday.....

Raced it on Wednesday, rode home, cleaned it off put it away (this is still about the bike by the way!)

Loaded it in the car on Monday anticipated a hot day so left windows open...Got to the TT and the chain was skipping.
So I spent the entire warm up time trying to see what was what.

We eventually traced it to one tooth on the upper jockey wheel, it wasn't quite engaging the chain properly.

With no time to do further investigation I bought new jockey wheels yesterday and fitted them last night and the problem has gone.
When I looked at the old J/wheel I couldn't see anything that would cause this (I marked the offending tooth before strip down)

The only thing I can think is the bar end shifters moved in the car putting pressure on the jockey wheel, add in 8 hours of very hot sunshine whilst it was in the car and I reckon the j/wheel has warped slightly.

I will get it on the flat table in our inspection dept at some point to further test this theory.

So be warned, Bikes (and Dogs) die in hot cars.

ynyswen24

stiff link in the chain...