I have a new bike with a 2010 Shimano Ultegra rear derailleur. When I spin the pedals backward as hard as I can, it will barely spin one revolution, so I took the chain off to find the problem. One of the derailleur pulleys has a lot of friction. I made sure it wasn’t overtightened, and had grease in the bushing, but still it doesn’t spin well.
Can someone recommend a good set of aftermarket pulleys that have high quality bearings? Does anybody use Omni Racers?
I will be the first to admit this being a do it yourself kind of guy, but having a ‘new’ bike as you do can I assume it’s from an LBS? If so this is where buying new can pay off. You should be able to walk in and get that resolved gratis if it’s indeed new.
The top wheel on a Shimano derailleur, the “Guide Pulley” is a specific Centeron Guid Pulley to maintain alignment with your cogs and reduce side load and chain wear. If you opt to replace your original Centeron Guide Pulley with an aftermarket pully, such as ceramic bearing equipped ones, you may actually degrade your chain alignment and increase effective friction as a result.
One thins to remember about both the Guide Pulley and the Lower Jockey Wheel are that they rotate very slowly and under tension from the chain. Consequently, the characteristics you feel rotating them with your hands may be entirely different with chain force on them and, additonally, may not exert much effective resistance.
It is probably better to have the more precise shift perfromance rather than the lower bearing (bushing) resistance.
I guess I’ll just take it in and see what the shop thinks. So, I assume most people keep these stock? Also, are the Dura Ace pulleys superior to the Ultegra’s? Maybe I’ll just stick with Shimano.
One thins to remember about both the Guide Pulley and the Lower Jockey Wheel are that they rotate very slowly and under tension from the chain. Consequently, the characteristics you feel rotating them with your hands may be entirely different with chain force on them and, additonally, may not exert much effective resistance.
What? If I’m doing 90 rpm in my 53 tooth chainring, my 11 tooth d. pulleys are doing (53/11)*90=430+ RPM. That’s the fastest spinning item in the drivetrain!
The only time my wheel bearings are turning the same speed is when I’m I’ve spun out the 11 tooth in the rear cassette.
“That’s the fastest spinning item in the drivetrain!”
You’re right, but it still isn’t rotating very fast in terms of a bearing’s capacity. Specifically, while bearing resistance is obviously a factor (and no, I don’t have a study, data, a Ph.d, charts, a powerpoint or any other “proof”) I’ll suggest these things rotate so slowly in the grand scheme of things that the range of bearing quality from polymer bushings (which Shimano uses in some derailleurs guide wheel) to ceramic bearings isn’t enormous.
There does seem to be a claimed difference in the very large guide pulley and jockey wheel combinations made popular by Hellriegel, Al Sultan and Normann Stadler at Kona.
While I don’t have a PhD. either, your reasoning seems backwards to me.
It seems that the lowest quality bearings in the drivetrain are in the pulleys, and they’re spinning the fastest. Granted they aren’t under much load, but those bearings seem to be spinning closest to their maximum, not farthest.
Bearing loadings are calculated using speed AND force (known as PV for pressure*velocity). They are interdependent and loading cannot be considered without both. While the pulleys are moving fast, their load is relatively light. Plain bearings have tremendous load bearing capabilities, especially when greased and using a hardened surface like Shimano does. Deraileur pulleys rarely fail due to bearing load, but mainly to wear from dirt, or from damage by impact. By comparison, bottom brackets spin slower, but have the forces equal or greater to body weight. They are highly loaded, and it’s not unusual for a bottom bracket to fail, which is one of the main reasons they’re now made to be replaced so easily. As an aside, the derailleur pulleys use “bushings” which are a subset of “bearings”
With regards to the original poster, there is a certain period of break-in associated with bearings. Assuming your LBS agrees the bearings are installed correctly, you may just need to ride a 100 miles or so to really smooth out the hardened surfaces. Bearings generally should not “free spin” with no load(Note: these are not crankshaft tolerances of .0005!). This is because there should be enough grease to slow them quickly. This same grease will ensure proper lubrication when cranking hard on the shift lever, and isolate grit from the working surfaces.
Not sure what you mean. The question was “small stuff” to begin with, so what’s your point? Train harder? HTFU? If we answered every question with HTFU, this would be a useless forum.
I am in a bad mood. Just fixed a frozen waste pipe . Toilet to septic. Clogged toilet lots of nasty shit inside the frozen pipe. In a crawl space . I was to fat at 5’ 10" 160 lbs to get under the 2 beams . Skipped lunch ! Just wasn’t hungry . Still think spending money on Fancy pulleys is a waste. The spin test is not very scientific .
Not trying to offend .
Thom
Not sure what you mean. The question was “small stuff” to begin with, so what’s your point? Train harder? HTFU? If we answered every question with HTFU, this would be a useless forum.