Jockey wheels

[johnk1]

A bike repair shop told me my jockey wheels need replacing but they look fine to me. What's the best way to check them and what do I look for?

[Brucey]

depends what RD you have

cheers

[pwa]

Take the chain off.

Do the jockey wheels turn freely?

Do the teeth look very worn?

If they are worn or don't turn freely, order replacements and changing them will take you ten minutes.

[thelawnet]

Take the chain off.

Do the jockey wheels turn freely?

Do the teeth look very worn?

If they are worn or don't turn freely, order replacements and changing them will take you ten minutes.

If the jockey wheels don't turn freely, the bushings or bearings can be cleaned and lubricated.

If you are going to replace them, then I wouldn't necessarily order the same ones - the deore xt or ultegra jockeys are better than others. They are more expensive obviously so if your existing rear derailleur is very cheap it might not be worth replacing the jockeys at all.

[AndyK]

Take the chain off.

Do the jockey wheels turn freely?

Do the teeth look very worn?

If they are worn or don't turn freely, order replacements and changing them will take you ten minutes.

Or 40 minutes if you include the time spent searching the floor for the bits of jockey wheel you've just dropped.

By the way, "worn teeth" in this case usually means that the teeth will look pointy. I say that because some people, if they haven't got a new set to compare the old ones with, assume that the teeth are supposed to look pointy. Jockey wheel teeth start off with flattish tops and reduce to sharp points with wear. Helpful photos here: https://bicycles.stackexchange.com/ques ... eplacement

[peetee]

The top jockey wheel can also loose the the teeth entirely if the mech sits too close to the cassette.

[cycleruk]

Before and After.

The top jockey may have a small amount of sideplay but not wobble and that is designed in on Shimano units.
The lower jockey should have virtually no play but not be tight. Both should spin easy.
Easy enough to strip and clean but do not mix top and bottom parts as they are different.
Some lower jockeys are directional and have an arrow to show rotation direction. ( I don't know why they are directional but they seem to be noisier if fitted the wrong way. )
The top pulley is the "G" pulley (guide pulley).
The lower pulley is the "T" pulley (tension pulley)

If the gears change with no problem then I don't usually change them until there is obvious wear or malfunction.
Just a clean and lube' now and again.
P.S. If you do clean or replace the jockeys, make sure the holding screws are done up tight as it known for them to come out if not.

[Marcus Aurelius]

Sometimes the jockey wheels look knackered, but they are actually just shrouded in road muck. A quick clean will bring them back to normal looking. As long as they spin freely, and there’s no flattening of the ‘spokes’ they are fine usually. You have to bear in mind that most jockey wheel sets are designed with a guide and tension pulley. The guide pulley ( at the top nearest the cassette ) is designed with some more play than the tension wheel ( the bottom one ) so that it can track across the cassette. Don’t confuse this built in ‘play’ with wear.

[Brucey]

there has never been as much variety in derailleur pulleys than at present; there are different sizes, different tooth shapes, directional pulleys, different bearings. Hence advice which is spot on for one model of RD is at least misleading and at worst potentially wrong in relation to another model of RD.

Some lower pulleys are directional and it is asked 'why' above; you can see in this photo of 10s XT pulleys (9s XT, and 9s + 10s ultegra are similar)



have a directional lower pulley with a cartridge bearing in it and a (often ceramic bushed) top pulley that has a small amount of float built in. The directional pulley is so that the teeth (which are slightly chamfered on one edge) engage cleanly/quietly with the chain even when running cross-chained.

The latest shimano designs eg XT RD-M8000 use an upper pulley with very tall teeth to give extra traction on the chain during shifting. Obviously these tall teeth can bear directly against the sprocket teeth and wear out/make a terrible noise if the RD adjustment is wrong



other models of shimano, Sram and Campag RDs each have their own quirks

cheers

[thelawnet]

<SNIP>
The latest design is rd-m9100/m9120



Both teeth are rather tall.

[Brucey]

Both teeth are rather tall.

in for a penny.....

cheers

[johnk1]

Thanks everyone, I'll have a look at them today when the garage is not so cold!

[MikeF]

As well as other variations jockey wheels come in different widths. On my T661 derailleur I found a Shimano ultegra ceramic bushed lower pulley would fit, but the top ultegra one was too narrow so I used the specified replacement there.

[thelawnet]

There's a bit here on the various changes in the latest M9100/M9120 jockey wheels

[youtube]0xgUeaZUZIw[/youtube]