Let's talk about jockey wheels

[Slioch]

I've got a confession to make. In 40+ years of cycling, I've never replaced a jockey wheel. Never had to.

No, I'm not still riding the same bike I was riding 40 years ago as replacement/upgrade bikes have come and gone during that time, which may be part of the reason, but still it makes me wonder why these things never seem to wear out.

For example, in my current stable of bikes I've got a 15 year old Dawes Galaxy, I don't keep a record of my annual mileage, but guess I must have done at least 20K plus miles on it. During that time I have replaced the cassette several times, and the chainset at least twice, but never the jockey wheels. Performance in the JW department seems to be as good now as it was on day 1.

My maintenance regime for the jockey wheels is fairly basic. When I clean the bike I clean the crud off the JW's with a toothbrush, then spray some GT85 into the gap where it rotates. And that's it.

So the question is, how do you know when your JW's need replacing? What are the signs that they are gubbed? How often do you replace them? Am I worrying unnecessarily?

 

[fossyant]

Usually if they become star shaped or if a cartridge bearing get's rough (many Shimano are bushings). I've only ever replaced a pair of Tacx jockeys on a MTB after a few years as they are quite 'soft', but hadn't become star shaped, just tatty.

SRAM are cartridge bearings, and need to be regreased every 3-6 months on an MTB as they don't come with much grease. The Tacx I never touched.

Road bikes, never replaced any. MTB, then they wear. I usually pop some grease in the Sealed Shimano jockeys (Ultegra / DA level) and re-greased every 6 months. Cheap ones, not worth bothering about.

 

[Yellow Saddle]

I went through plenty of jockey wheels in my life. Plenty.

They don't like mountain biking but live forever on clean roads and clean conditions.

New, they have blunt teeth, but used, the teeth become sharp. Once the teeth are sharp, they become unreliable and tend to derail the chain when cross chaining, which happens often when racing MTBs.

They have to keep the chain on rail no matter what the chain angle, so they tend to become thinner and sharper, i.e. wear in two directions.

 

[Yellow Saddle]

Replacement ones should always have an uneven number of teeth and, have bushings in the top wheel, not cartridge bearings.

 

[raleighnut]

Never worn one out either but I do regrease the bushes every time I 'service'* a particular bike (used to do one or two of the 10 every year) I did once put the wheels on 'upside down' on an early 105 (indexed) mech but a guy in the 2nd bike shop I went in told me of the difference (the bloke in the 1st shop just told me to buy a new mech.)


* A 'service' generally entails a full strip down and replacement of at least Chain, Inner Cables and Brake Blocks and maybe a set or 2 of bearings.

 

[Slioch]

Never had a JW go "star shaped" on me yet, neither had one go "sharp" and cause derailling. Less then 5% of my riding is on MTB in mucky conditions - the rest is on-road so things are fairly clean.

Sounds like I need to stop worrying. I take it the signs that the JW's need replacing are quite obvious?

 

[fossyant]

Very. You'll have a Chinese Throwing Star. You may get chain drag if it has bearings, i.e. back pedal, and the chain drops, but that can also be knackered freehub.

Easy to check by hand if bearings rough.

 

[Yellow Saddle]

 

[ColinJ]

View attachment 485631

I've had quite a few that looked like the second wheel before I changed them, and I have bought/been given old bikes with jockey wheels that looked like the third!

 

[Slioch]

View attachment 485631

Thanks for the pic - that's a real help. My most worn JW is half-way between the one on the left and the middle one.

 

[DaveReading]

Replacement ones should always have an uneven number of teeth

Yet your subsequent photos show a 10-tooth jockey wheel - is that why it has worn so badly ?

 

[Tigerbiten]

I've worn a few jockey wheels to look a little further on than the third one in the picture.
They're from my Rohloff chain tensioners lower jockey wheel on my recumbent trike.
The two halves of the chain run side by side under the seat with the upper power side on the ideal line and the lower run offset.
Chain tensioner and hanger are probably bent/twisted a little.
Because it's a chain tensioner, it doesn't move laterally so a very constant wear pattern.
On a 20" wheel so closer to the ground.
And most important, I tend not to clean the chain, just keep it well oiled.
Combine the above together I wear jockey wheels out to the point the chain falls off the lower one and start to rub on the cage.
At which point I replace both of them.

Luck ...........

 

[Jenkins]

Old and new side by side for comparison - SRAM Apex , somewhere around 10k miles on an all weather commuter bike with Tacx replacements

 

[Pale Rider]

Size matters - or does it?

I've seen oversize jockey/pulley wheels on pro team bikes.

No idea if they make any difference.

The likes of Ceramic Speed will tell you big wheels is the way to go.

But as a manufacturer, they would say that wouldn't they?

https://www.sigmasports.com/item/Ce...heel-System-for-Shimano-Ultegra-Dura-Ace/DTH8

 

[Yellow Saddle]

Yet your subsequent photos show a 10-tooth jockey wheel - is that why it has worn so badly ?

That's not an endorsement, it's what I could find.

The reason they should have an uneven number of teeth (11 is optimal) is so that it doesn't wear into the chain pattern of fat gap/thin gap. If it is worn like that and you happen to refit the chain so that it is now mismatched with the chain, you get plenty of problems of the chain derailing in the cage, jamming the cage and ripping the jockey out of the frame.

They wear thin sideways when you ride cross-chained in big/big. This also causes derailment in the long run.