Jockey wheel fun and games

[ChrisEyles]

I've just finished doing up an old 90s mountain bike for off-road fun and games, and one of the many things which needed a fettle was the upper jockey wheel. It was very stiff, to the point where turning the cranks backwards caused the rear derailleur to pivot around rather than the chain moving through the jockey wheels as it should.

I tried to solve this by loosening the bolt fixing the jockey wheel to the derailleur cage, and initially this seemed to work fine.

However, on tonight's test ride, the bloomin' thing fell off! I managed to find all the parts except the bolt (wasn't easy!), which I've replaced with a suitable new one, filed down to the correct length so as not to snarl in the spokes (I hope it's suitable anyway... it's threaded all the way along, and I suspect the proper bolts are smooth in the middle and only threaded at the end?).

Now I'm left with the same problem - if I tighten up the bolt, the wheel stiffens up, and if I loosen it so that the wheel turns freely I'm worried about a repeat performance, only this time a lot further from home.

So, I've got a few questions

1) how tight should this bolt be done up?

2) is the solution to this simply a bit of threadlock to hold the bolt in place in it's slightly loose position?

3) is it possible my jockey wheel is missing a spacer/washer that would take the squeeze from the derailleur cage while still allowing the wheel to rotate freely around the sleeve bearing (that's how I'd design it if I was making one, anyway). If so, can this be bodged, do you think?

Thanks for reading!

 

[steve50]

To be honest I wouldn't waste my time faffing about with what is potentially a worn out derailleur, they are very cheap to replace and you will have the peace of mind that it will not fall apart or seize up on you.
the bolt should tighten right up as it is a measured length of thread that once tightened still allows the jockey wheel to turn, if it was tightening up there must have been some kind of obstruction stopping the wheel from rotating.
Or you could try a new bolt, http://www.ebay.co.uk/itm/SRP-Rear-Derailleur-Bolt-Mech-Bolts-/160662032758?var=&hash=item2568341176

 

[Hugh Manatee]

Should be a bit through the middle that the plates do up against leaving the middle bit to spin freely. Don't forget the top jockey should have a bit of float with Shimano. Don't buy modern ones, yours will have fewer teeth.

 

[steve50]

exploded view of rear derailleur showing metal tube for bolt

 

[raleighnut]

The top jockey wheel has a bonded in bush and a sleeve bush, sounds like they have corroded together (the sleeve bush is the one that allows sideways 'float' on the top jockey wheel) as for the bolt it must be tight.

 

[fossyant]

Just get a Tacx set from Decathlon. They work great on my old 90's MTB.

 

[ChrisEyles]

I've already given it a good clean and a spot of grease on the cylinder bearing. Everything looks OK and the wheel is freely floating and turning - until the bolt is tightened right up. It looks like the bit in the middle of the wheel that the plates do up against is simply too short, so that the cage is compressing the wheel itself.

I'll try and bodge a washer as a fix, otherwise one of those tacx wheels from Decathlon would be a great solution.

Great to know they should be tightened up nice and tight though, that will save me making the same mistake again!

 

[ChrisEyles]

Good question - I'll check this out too!

 

[ChrisEyles]

Sorted it

I stuck in a washer with the same inner and outer diameter as the cylindrical bearing inside the jockey wheel, effectively extending the length of the axle. Now the bolt tightens down on the axle as it should do rather than the jockey wheel itself, and I can screwit into the derailleur cage (which is straight as far as I can see) good and tight. The culprit seems to be one of the side plates that fit over the cylindrical axle - it is a bit deformed and must have been snagging on the jockey wheel.

Planning on taking the bike out to the woods at the weekend to put it through its paces, and feel a lot more confident in it now. Thanks a lot @steve50 and @raleighnut for confirming the bolt should be tight - you have saved me a long walk home I think!

 

[mrandmrspoves]

I lost the top jockey wheel on my new to me PDQ a couple of weeks ago. Fortunately I was hardly moving when it came apart (not that fortunate really as I spend most of my cycling time hardly moving!) A quick back track and a sharper pair of eyes than mine from one of my cycling companions resulted in locating all the parts and I could put it together again. The bottom jockey wheel bolt had a bolt head whereas the top wheel had a screw head - so I guess the previous owner had a similar problem. I have now added a top and bottom jockey wheel and bolt to the spares kit that I carry on rides.

 

[ChrisEyles]

Well, my jockey wheel survived a bumpy 15 miles or so out on Woodbury common today, so I'm going to call it good. Haha, I can see why you would pop a spare set in the tool bag once you've had one disappear on you - I very nearly didn't find mine again after it came out!

It's now very slightly off centre in the derailleur cage (I only added a washer on one side of the axle), but doesn't seem to be shifting any the worse for it.