Phil_gretz

I have a friend's Trek 520 with an indexed Deore 7-speed rear. The derailleur pulleys were so worn, that I searched for replacements, finding the TY05/15/20/22/30 CT92/MJ05 pulley set. It arrived today, and the pulleys are identical, both being the non-self-centering tension type. So, what do I do to modify one of the pulleys to "thin" the distance between the circular plates, thereby giving it room to slide on its mounting bolt.

Am I thinking about this wrong? Is there a replacement for the guide pulley that I'm missing? Should I just take a sanding wheel to the plastic pulley to take off a few mills?

What say you?

fietsbob

A wider bushing sleeve around the bolt, than the bushing in the pulley.

But Why not just get a Proper 'Center On' Guide Pulley ?







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Andrew R Stewart 

One could machine out a new bushing (yah, right) or thin down the pulley's surfaces that the end caps almost sit on. But really just get the correct pulley. If the pulley is a narrower one thin washers on on or both sides will respace it. Andy

Crankycrank

Some aftermarket pulleys are designed to have no float and work just as well as the Shimano OEM's. Possibly Shimano decided to follow suit with some of their pulleys since yours sound the same as what's described on the "TY05/15/20/22/30 CT92/MJ05" package. Install and enjoy.

Kimmo

Aftermarket guide pulleys with no float usually have thinner teeth.

But it's a pretty subtle feature; I think the point of it isn't to make up for bad adjustment so much, as to allow a shift to delay slightly so the chain hooks up on the right spot in the cassette for a smoother shift. You may not notice a difference without float or thinner teeth.

dabac

+1
Not that I've done a huge amount of experimentation, but IMO the overall condition of the drivetrain, derailer and shifter is more important than if the guide pulley has float or not.

Phil_gretz

Thank you for the feedback. The weakest part of this setup is the 7 speed indexed downtube shifter. Once the inner parts of the shifter become worn, there's a bit of sloppiness in the pull for each "click".

The shifting is okay on the 520, as I had previously updated it from uniglide to hyperglide.

I wound up shaving just a bit off of each side of the pulley. It has some float now, but that's not really needed unless at the extremes of chain deflection, where a bit of self adjustment makes the drivetrain quieter somewhat. Anyway, I appreciate the comments. Phil

Dan Burkhart 

Shimano has abandoned the Centeron pulley at least on it's higher end road groups. Check a newer Ultegra or Dura Ace derailleur, and you will find there is no float on the guide pulley.That may have filtered down to the lower tier groups by now as well.

Retro Grouch 

A bike old enough to have worn out the derailleur pulleys. I wouldn't feel right spending very much money on parts.

My typical solution would be to pick a derailleur off of a donor bike.

fietsbob

OK, makes some sense, gaps, by 10 & 11 get so narrow,
no tolerance for any float, +/- but, has to be spot on under that cog..


I've been friction shifting for decades (touring,JRA ) and personally got off the industry bandwagon
at 7 speeds ..

JRA, ..

OP want old parts , ask @ bike shops , not online discounters.
wholesale distributors to shops stocked up to keep bikes running..

"//,,






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Andrew R Stewart 

One more reason why shifting issues are so common with this current stuff. No ability to accept the designs that widen the tolerance window. Andy

Phil_gretz

This is my fifth year doing annual maintenance and repair on my friend's 1989 520. I keep it running, but he puts a lot of miles on it. I have a good handle on where the needed maintenance items are, and try to keep him just slightly ahead of things. He won't bring it to anyone else, because I'll take the time to fix what's wrong and not try to sell him something new.

migrantwing

I run Shimano 5700 and swapped my jockey wheels out for some aftermarket Tacx wheels, as they were a good price and also have stainless steel bearings. There is no float in these wheels, and my indexing is slighty off, always. Also, I have found that Tacx wheels make a lot more noise than the OEM Shimano ones. Now, that may be down to wear and the teeth of the jockey wheels and the chain meshing nicely. It may just be a little bad luck on my behalf, but I'll be buying Shimano jockey wheels next time. That float definitely makes a difference, albeit very minor.

blamester

+1 and friction shifting 7is surprisingly easy if the index shifter is worn. Try it.

Andrew R Stewart 

This! If metal pulley wheels made more sense to all (including the bike buyer) then we would no longer have plastic ones. When I first got into this game some the cheap ders still have metal ones (that, BTW, had serviceable and adjustable bearings). We found the same, that these pulleys were noisy and rough feeling. But they were on the cheap bikes so no surprise.

Fast forward a decade and that lesson was lost and metal pulleys (while with balled bearings not adjustable) became the "new kid" and were thought to be the cool upgrade (that they came in colors other then silver or black was their marketing coup). But once again we found them to be rough and noisy when in actual use. Fast forward another couple of decades and guess what? Funny how this business is so cyclic Andy

fietsbob

Decades ago I got some Carmichael Pulleys , (Metal; Ti)
they included flanged machined aluminum bushings ,

for float the 2 bushings butted together and combined,
were wider than the bearing between them..

My Tacx pulleys are nylon, (stock, In R'off chain tensioner )
and I substituted the stock plastic Brompton (3 speed) ones ,

with Tacx, nylon, and they're quieter than the harder plastic..









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WizardOfBoz

Aren't the plastic wheels supposed to float on the bushing, and not the whole assembly on the bolt? The thing I'm having a problem with is that if the bushing slides from side to side on the bolt, it can also rotate on the bolt, and bolts are not good axles.

It would seem to me that you could sand a little material off the sides of the wheel and it would move from side to side. Or, find a little bit longer bushing that allows the wheel to move from side to side.

Or am I completely misunderstanding this?