Do jockey(pulley) wheels wear out

[tintin40]

At the same time? Or will one wear out quicker?

 

[REKIBorter]

The top one wears out much faster. They become star shaped with sharp points if left too long.

 

[Tad]

When I've bought used mechs I've noticed that the bottom jockey's tend to be more worn than the top.

EDIT: Or maybe I've remembered it arse backwards.

 

[tintin40]

I would have thought they would wear at the same time as the mech keeping tension? Or the top as close to the action?

 

[MikeD]

The top one bears most of the brunt of shifting.

 

[utahdog2003]

I dont think they wear at different rates, given all other things being equal. On used bikes though, many times it seems like the previous owner, especially a more sedate fitness recreation style rider, puts the derailleur in one gear and rides it to death. In that circumstance irregular wear would be evident.

 

[hamster]

Disagree there. The top pulley has to push the chain sideways to shift, and so there is wear on the sides of the teeth.

The bottom one just has to spin under chain tension, so wears less. Indeed, that's why Shimano puts a less durable bearing in the lower jockey than the top.

 

[chriscl]

For what it's worth, the top pulley does more work than the bottom one; I'm currently refurbishing a '98 XT Rear Mech to go on my East Peak, and I noticed the top pulley has a ceramic bearing, where as the bottom one does not - I guessed the top one is under more load, hence the use of a ceramic bearing.

 

[cornholio's RC200]

Shimano used to put a degree of float on the top pulley, mainly to improve shifting but I guess it would also reduce the chances of jockey wear.

Don't know if they still do it now but I seem to remember they had a patent on it at one point in time.

 

[BerthaPog]

Daft question time...

What difference do you get as the jockey wheel wears?
And would it make any difference if you started with guide wheel rather than a cog, some of the very early rear mechs had plain "jockey wheels" with out teeth?