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Pulley Bearings Replacement
Hi, everyone!
I was cleaning my bike, and notices that the rear derailleur top pulley is skipping the chain. Checked the chain, and it was good. So, I decided to take off the pulley. Opened the cover, and.... dropped on the floor. The balls are tiny as molecules, I was unable to find them. I am using Tiagra pulley on my Dura-Ace RD temporarily and chain skipping stopped. But I would like to replace RD pulley I have few questions to bike mechanics experts: Do I have to replace RD pulleys regularly and if so, how often? Do I have to replace the pulley, or just the bearings? Does it matter what pulley goes on top and what on the bottom? If so, are the cheap eBay parts will work ok? Like this one: http://www.ebay.com/itm/New-11T-CNC-...item4174f02c0f Thanks!!! |
some pulleys use bushings , and some use cartridge Sealed bearings
there is the self bushing using the plastic of the pulley as the bearing surface as it rotates around a steel sleeve, and there is an oil bronze bushing with a steel sleeve the plastic pulley is molded around. good luck with Ebay if they are bling colored , and that is what you feel you need, fine. as a spectator , rather than seeing the problem 1st hand , in the bike shop, I cannot say. Metal pulleys are noisier than plastic ones , so dont complain if that is heard. last dura ace top 'centron' pulley I saw was a bushing type the index stuff needs the pulley to slop sideways a bit. bushings make that practical .. |
I never bother servicing RD pulleys. They last a long time then wear out, either at the bearing, or the rim. Either way it's a long slow process, so springing for new ones every few years isn't a burden.
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Yes it matters which pulley is on top...specifically for shimano. The top pulley has some side-to-side play purposely engineered into it as has been mentioned. The bottom pulley does not typically have any side-to-side play. If you swap them around you will probably experience a decrease in shifting performance or become super frustrated with not being able to dial your rear derailleur in consistently.
After market sealed bearing pulleys (top and bottom) tend to not have any play in them. Some folks have had great success with them and others have sworn them off. I would recommend finding any pulley that is compatible with your derailleur model made/marketed by its manufacturer. If you have dura-ace there is no specific need to use the really expensive dura-ace pulleys with the bearings in them as you probably would not notice any decrease in performance from shimano's less expensive pulleys with bushings. The plus to the dura-ace pulleys is that they make your wallet lighter which can amount to significant gains when climbing those steep hills if you use your wallet to help create an aerodynamic hump in your jersey pocket. YMMV -j |
if the pulley has bearing they are 1/16 " and 12 of them per pulley .
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The top pulley has a ceramic bushing and should have a sliht amount of side to side play. The bottom pulley has small ball bearings and no play.
http://techdocs.shimano.com/media/te...9830667242.pdf |
Originally Posted by Greenfieldja
(Post 16106912)
Yes it matters which pulley is on top...specifically for shimano.
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Originally Posted by Kimmo
(Post 16109276)
The float is a lack of precision itself, so I wouldn't say you 'must' have a floating upper pulley. In fact, I've found it helpful to swap them when the pulley's become worn and even sloppier, or the derailer is worn and there are too many errors adding up.
I'd say no float usually means the indexing adjustment must be more precise, but also that the pulley's position will more accurately obey the shifter, which should be a good thing unless the shifter is worn or not exactly compatible. On that note, yesterday I worked on a bike rocking 8s Campy Ergos, a Sachs-Huret RD (600 FD with alternate quicker cable routing), and 8s Shimano cassette... it was an impressive mix and match. At work we stock replacement pulleys; we just have these cheap plastic BB jobs that come with a few sets of different plastic bits to go in the BBs to space them for various derailers. There's no float as such, but the upper pulley has thinner teeth. They work great. Oh yeah - don't get sucked in by blingy anodised ones - unless they're plastic they're noisy as hell. |
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