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-   -   There's a mouse in my derailleur (http://www.bikeforums.net/bicycle-mechanics/937427-theres-mouse-my-derailleur.html)

dweenk 03-09-14 11:26 AM

There's a mouse in my derailleur
 
I went for a 15 mile ride this morning. On the way home the RD began making a high pitched squeaking noise. I think it is coming from either the jockey or guide wheel. The noise is not constant, and it is most prevalent when I'm on the small chain ring and the next-to-largest rear cog. I'm running a six-speed cluster with Shimano derailer from the late 1980's.

Naturally, the noise goes away if I'm not pedaling. Anyone have a tip on isolating the noise?

Sorry about the spelling in the title.

Retro Grouch 03-09-14 11:34 AM

If it was my bike I'd spray a little silicone lubricant on the derailleur pulleys and see of that fixes it.

lopek77 03-09-14 11:41 AM

Or try WD40 first to clean it. I wasn't a big fan of WD40, but I found it very useful all around cleaner with "greasing" capabilities.

Kimmo 03-10-14 06:00 AM

Tsk.

The design of RD pulleys is calculated to minimise the lube being washed out of them, so just spraying them with some crap is more likely to just make a mess, I reckon.

Overhauling them is pretty simple. Derail the chain off the chainring, and just undo the bolts retaining the pulleys.

Unless you have fancy BB ones (which you obviously don't), there are four parts - a dustcap/thrust bearing each side of a metal bush through the plastic pulley. On Shimano derailers (and some others) the upper pulley has a metal sleeve in it and the pulley is slighty narrower than the bush to allow some slight lateral movement.

Clean, grease or oil, and reassemble.

Phil_gretz 03-10-14 07:10 AM

^^agree. Remove rear wheel. Break chain. Unbolt derailleur cable anchor. Remove rear derailleur. Disassemble pulley cage assembly. Clean entire derailleur. Grease pulley sleeves. Reassemble derailleur. Lube all pivot points on derailleur, all threaded parts. Exercise. Wipe off excess.

Degrease and lubricate chain while it's off the bike.

Reassemble bike.

This is good to do every year of riding, or so, anyway.

cny-bikeman 03-10-14 07:19 AM

If the rhythm is uneven, and especially if the rhythm per crank rev is different on different chainrings then it's the chain. If it's a more even rhythm or constant it's the pulleys. Some lubes are not good at keeping out water, and the chain can squeak even if it appears to be lubricated. I don't know about the current formulation, but many years ago Triflow was well-known for that behavior. If you determine the noise is in the chain and lubrication does not resolve it you need to either remove and totally clean it in solvent, or if unable to do so spray it with WD-40 and then re-lube.

Kimmo 03-11-14 02:31 AM

Quote:

Originally Posted by Phil_gretz (Post 16564455)
^^agree. Remove rear wheel. Break chain. Unbolt derailleur cable anchor. Remove rear derailleur. Disassemble pulley cage assembly. Clean entire derailleur. Grease pulley sleeves. Reassemble derailleur. Lube all pivot points on derailleur, all threaded parts. Exercise. Wipe off excess.

No need to break the chain; it's free as soon as you remove a pulley and loosen the bolt on the other one.

No need pull the wheel and RD off either, unless you get into a cleaning frenzy. The chain only cares about the rings, cogs, pulleys and inside of FD and RD cage plates.

You might prefer to remove the wheel rather than derail the chain off the ring to give some chain slack though, or you could just master the technique of replacing the pulleys with the chain in place; not real tricky.

Screw the upper pulley on, leaving the bolt loose enough for the inner cage plate to swing. Rotate it so the tab allows the chain through, then place the lower pulley against the chain and push it into position, while sandwiching it between the cage plates and holding the outer plate forwards with your other hand. It should be pretty easy to line up the holes so the bolt can go in; you can let go when you get it started in the thread.

All this in small/small, of course.

Phil_gretz 03-11-14 04:37 AM

Kimmo,
Of course, your right. This approach would be fine for you or me, where we'd want to go to the cause, get it corrected, and get that bike done to move to the next one. But for the OP, I thought that it would be instructive for him to view the parts as independent parts of the whole. He likely hasn't done a careful inspection and cleaning of the chain, and disassembling / repairing a derailleur in situ can be difficult while fighting against chain tension and the pulley cage. My advice was to break things down to their constituent parts, to inspect, to learn, and to re-integrate, thereby helping the OP to diagnose and correct his issue(s).

I'll now dismount my soapbox, and break it up for firewood. It's cold and lonely here in thoroughville.

Phil

DMF 03-11-14 01:06 PM

I've heard this type of noise when the CHAIN needs lubing. Done it recently?


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