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6

I can only speak somewhat objectively to the bearing size. I believe that 689 is the complete specification for the bearing size. This appears to be a 9mm inner race, 17mm outer race, 5mm deep size. (NB: Swifty measured his current bearings at 4mm deep with calipers, not 5mm). Adding a Z suffix appear to pull up a lot of bearings with non-contact shields (i....


0

I believe I mistook mixing English words PLASTIC SLEEVE, DUST CAP, SPACER and SEAL into one thing so make my words hard to be understood.  I have installed the Ultegra crank but I am not sure whether it is the best way. I am now trying to explain what I was facing and my solution as best as I can. (sigh, language is a big issue) The dimension of the Wilier ...


2

TLDR: if you are enough of a bike geek to read a post about jockey/pulley wheels, then you probably don't need a summary of five measly paragraphs. It really depends on the quality of bushing or bearing being used. In the past (i.e., 20 years ago) bushings were much more commonly found in Shimano derailleurs, especially the upper guide pulley. The Ultegra ...


1

TLDR: I do not believe the claim and I personally think it is the other way round. Sealed ball bearings are more resistant to contamination in my experience. I would not worry about the watt when they are clean and new. But in practice, I never noticed a problem with my Deore XT RD with sealed ball bearing pulley wheels. Even when I did not take care of the ...


2

I've replaced bushings with bearings in derailleurs I've had and noticed improvement. I've had bushings get gunked up and bind or freeze, and have had bearings do the same, but over all when my derailleur is clean, there is less friction and the benefit is noticeable. Derailleur pulleys, like all other parts of the drive train should be kept clean. I do ...


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