hobkirk

My jockey pulley teeth are pointy (I let the chain stretch). Is there anything special about replacing the pulleys?

THANX

FBinNY 

Other than some RDs having floating jockeys and others not, nothing special to deal with.

Andrew R Stewart 

1st choice - replace with the same kind.
2nd choice- replace with the same gear count and "tooth diameter"

There's some wiggle room, sometimes, with pulleys but duplicating origonal spec is always the best choice. What kind of der do you have? Model # is the best way to be specific. Photos are next best. lAndy.

onespeedbiker

What make is the derailleur? Assuming it's Shimano, as said, it's best to match the OEM pulley. If you are going to replace one pulley, you might as well replace both as they usually come as a pair.

thedevilisbad

If it's a new fancy RD I would buy a proper pulley. A lot of us don't realize it all of the time, but it's the fastest rotation part on our whole drivetrain so it can make a difference in the feel. If it's an older RD made to work with 8speed or less I would just use whatever was around.

HillRider

Even 7 and 8-speed era index compatible Shimano rear derailleurs had floating "Centeron" jockey pulleys so that type should be matched.

zacster

And let's not forget that this is typically the dirtiest part of the drive train. You can put the crud in your pipe and smoke it.

hobkirk

OP Here -

Thanks all. And yes, there was LOTS of crud!

To answer the question -

• RD is a Shimano XT CS-M771 and, as a temporary measure, I pulled a pulley off a Shimano Ultegra 6600 RD.

The worn pulley caused the new chain (Dura-Ace) to skip when I was dialing in the cable for the RD (done upside down). I took a 90-minute ride and it seemed reasonable. I replaced the crankset (new Ultegra 6603) and wheels (DT Swiss 4.0, takeoffs from a Specialized Roubaix Expert) at the same time.

Sadly my legs seemed just as dead as they had before I changed the drivetrain!

onespeedbiker

The Ultrega 10 speed tension pulley is actually the same as a 9speed XT, but I'm not sure about the Jockey pulley. Regardless, this is what you want..https://www.artscyclery.com/Shimano_6...-SH772DPS.html

BTW, your XT rear derailleur is an RD-M771; the CS-M771 is the cassette..

Kimmo

I disagree; IMO plastic BB pulleys with no float are always best, but then I have no love for Centeron-G; I think it's stupid. Just learn to adjust the indexing.

Also, bigger ones are quieter and perhaps slightly more efficient; I'd use the biggest that fit in the cage. I've gone +1 on the pulley tooth count a couple of times with no problems. Might affect B-screw adjustment, requiring more screw.

Andrew R Stewart 

Kimmo- It is my understanding that the float in guide pulleys is to absorb the tolerances that develop in a gear system. Some, often the largest, is the cable tension. But since this variable is so easily "corrected" but other aspects are much more difficult to change, I have always thought that the float was for more then simple cable tension issues. I

IRC when SIS was first introduced many of the aspects that control shifting were still based on the pre-index designs. Cables (Dura Ace first used the same 1.6mm diameter inners as other high quality friction systems did), casing (flat wound/tight spirals but with plastic liners), "classic" cable stops on the frame and downtube levers to name some. (I remember reading in Bicycle Dealer Showcase that there were 17 different design requirements to a fully systemized index design). Then as the early years went along there were "improvements" like encapsulated cable stops (the split stops common now), SIS casing with a many strand "slow" helix winding, 1.2 and 1.MM inner cables, and down tube lever boss cable stops with "on the fly" cable tension adjustment.

All helped "tighten up" the tolerances of the shifting system between the lever and the der. But other manufacturer issues remain to this day. Like rear hanger bolts not perfectly machined (so as you thread them into the hanger the der wobbles/orbits some), Same with the cage pivot bolt as well as the cage it's self, cassette wobble and free hub slop. Then there's the cogs being not fully flat, in fact some are this way by design.

So the guide pulley's float, IMO, is there to help work through all these other aspects that are never perfect.

When Sun Tour and Campy (Sachs) came out with their early systems their upper pulleys were "fixed". The noise and touchiness of their adjustments is but one reason that they were viewed as inferior to Shimano. Many of us mounted float pulleys on these and saw improvements in smoother chain runs and less jumping.

As to larger pulleys- No argument here. Excepting the pulley knock and B screw issues that Shimano is plagued with. Andy.

Kimmo

I'd say that any inconsistency in derailer positioning should be solved first; the Centeron-G float seems like a total band-aid to me.

And the way I see it, it's just as likely to aggravate any issues as to solve them, if not more so... the float equals a built-in lack of responsiveness; if the derailer is hesitating to shift, one of the most common problems, Centeron-G can only make that worse.

Its only function as far as I can tell, is to half-arsedly compensate for poor engineering. Well, I say screw that - make the system work consistently in the first place.

And that means more cable pull. Here's a thought for anyone struggling with S10 and internal routing with full-length housing - Shimano->SRAM Shiftmate at the lever, SRAM->Shimano Shiftmate at the derailer.

That, and/or segmented housing.

Andrew R Stewart 

Kimmo- I wish that manufacturing was spot on, every time, at every cost level. But i work in the real world and it's not. Pulley float might effect shift response. But unless the guide pulley is well worn, I see far more cable friction reasons for shifting issues. The floating pulley helps make real systems more consistent, IME.

It seems like we share the dislike of internal cable routing or full length casing.

While I run a Shiftmate on many of my bikes, have done so for over 10,000 miles, I will say it does add a pause into the system. But it also does allow combining levers, ders and cassettes to the choices that work for you. Andy.

Kimmo

I'm surprised to see you say that; I've had no such issue with mine and can't imagine how it could do that unless the pulley's BB is seizing. In fact, it eliminates some friction from the derailer loop.

Are you sure it's the Shiftmate's fault? Now I think about it, if you're using thicker cable it might cause a bit of friction in the pulley grooves, or develop a springy curve where it wraps around the pulley...

Or are you using 9s Ergos by any chance? My shifting wasn't great until I locked out the float (the built-in overshift) in the right shifter, now it's perfect

onespeedbiker

I would say that the guide pulley lateral movement is simply a requirement of indexing derailleurs. In order for the indexing derailleur to work, the guide pulley has to be positioned directly over the cog, and without a floating guide pulley the shifting will be noisy and prone to non-centering issues. It is not just Shimano that uses a floating guide pulley, Campagnolo has had a floating guide pulley since their Ergo design (when they first released top and bottom specific pulleys) and SRAM has a system where the entire derailleur floats, so they pulley (or derailleur) float is the industry standard, and the result of decades research, fine tuning and premier engineering. It appears to me that the floating guide pulley is and was designed to counter the ever changing state of the drive system, that would require constant attention and parts replacement to maintain without it. I would also think that rather resulting in the derailleur hesitating to shift, it simply extends the amount of cable pull by an extremely small amount, as the pulley would have the same median rigidity as a non-floating pulley, it just moves from side to side.. Therefore in the course of a shift, once the pulley has reached the boundary of it lateral movement and is derailleuring the chain, it has no additional movement that differs from a non-floating pulley that would cause any shifting hesitation. Once the shift has been completed than the pulley will again have some lateral movement and center itself over the cog.

Kimmo

I don't run counter to an army of engineers lightly.

What you say about the float accounting for the inconsistency of the system is correct enough (as long as you meant to say the cable system rather than the drive system; the cogs don't move sideways) - as far as Shimano's 9s and 10s systems are concerned, because their cable pull is short enough to be corrupted far too easily, although I've run S9 quite reliably without a floating jockey wheel. With S9 I've found adjustment just requires a finer touch and can take a little longer to finish bedding in, but I can see it being a necessary evil with S10... I've only shifted 10 cogs with SRAM so far, though.

Let's break down the cable maladies and see how they relate, huh?

Housing mush/springiness: cheap or damaged housing will give the lever a rubbery feel, making shifting inaccurate, and sometimes requiring the cable to be pulled past the click to make it to a bigger cog despite the cable tension being correct. S9 and particularly S10's inadequate cable pull magnify the mushiness of even good quality housing too much IMO (I've seen a S10 RD not even move when the cable was pulled). So housing issues mean the cable doesn't get pulled far enough at the derailer, in general.

A floating jockey wheel makes this symptom worse, requiring more cable pull again to make it to a bigger cog.

Excess friction: too much between cable and housing makes shifts to smaller cogs hesitate or fail, and again, this is magnified by a system designed with insufficient cable pull. Friction dramas mean the cable doesn't get released enough at the derailer, and when it's pulled can make the lever feel stiff, and introduce more inaccuracy via housing mush.

And a floating jockey wheel makes this symptom worse, requiring more cable released to make it to a smaller cog.

All the floating pulley is good for, is to make up for slightly off cable tension adjustment. In fact, it even masks slight maladjustment, which without a floating pulley is more easily detectable via the sight and sound of the chain running on one cog, but with one you need to compare upshifts to downshifts.

Because the pitch of threads on barrel adjusters can only be so fine, dialling in a modern Shimano system is a fine line - IMO that's the only point of Centeron-G, which as far as I can figure and observe, only hurts shifting (I know, it's been around since 6s, but indexing was a new concept then so Shimano probably figured a fudge factor would help, and it was less of an issue with much greater cog spacing).

Even more useless on Campy with their decent cable pull; they were probably just copying features when it came to that one.

As for SRAM's entirely floating derailleur, I had a 10s one that was really shagged and every pivot was sloppy, so I'm not sure what the deal is there... is it a tad of side float on the upper pivot? If so, dumb feature; SRAM has miles of cable pull and their RDs are super easy to dial in.

You might as well sell a car with wobbly steering just cause most punters don't aim straight.

HillRider

I agree with Kimmo. I've run Shiftmates on three different drive trains, matching a mix of Shimano and Campy component, for a total of over 50,000 miles. I've never noticed any extra hesitation or delays in the shifting compared to a "straight" system.

onespeedbiker

Interestingly enough Shimano continues to use their Centeron pulley with their electronic shifitng..

Andrew R Stewart 

Perhaps i need to clarify my "pause" comment about ShiftMates. I run Ergo levers of the pointy hood vintage. When the ShiftMate is used the index gear (inside the lever) has been changed out from the 8 speed to the 9 speed version. The need to use a ShiftMate is driven by the desire to mix system brands. In my case Ergo levers and Campy rear ders with Shimano cassettes.

So the ability to directly compare the feel of the same set up BUT without the shiftmate (in real world riding) is pretty much not going to happen. As we all know after a couple/three shifts the index movement differences will build up and the shifting will suffer (with the mixed brands). My perception of a "pause" is, therefore, not directly comparable. I do feel a little bit more direct a call anresponsece with my Ergoed bikes that don't have a ShiftMate. BUT these bikes also run Sachs freewheels with no shift gates on the cogs. So their shifts are starting to happen sooner then when Shimano HG cogs are in play (with the ShiftMated bikes).

I have set up a ShiftMated bikes initially without the SM (didn't have one on hand yet and wanted to do all the adjustments and bar wrap I could while waiting for the SM to arrive) and I do feel that the first shift (or two) felt more direct then after installing the SM. I attribute this slight difference in call and response to the added cable length and it's wrapping around a small diameter pulley. There is a slight amount of cable settling into the pulley's grooves as one pulls on the cable. (Now this lessens with time as the cable gets broken in but a small amount still persists).

I never have found this small, added feel, to be a problem. My use of the word "pause' was to try to verbalize what my hands and brain feel. Perhaps I should have said "I feel a small amount of cable wind up during the shift movement".

By the same standards I can feel the difference in cable movement between a down tube lever and a bar end lever. The, maybe, 50% more cable length is noticed. Not a problem but noticed. I last used DT levers in 1973 on my own bikes, switching over to ST Barcons as soon as I saw them. But I do get to service bikes with DT mounted levers often enough to enjoy their very direct feel, even if i don't like their location. Andy.

thedevilisbad

This reminds me. Can you believe that there are pulleys that cost $250? eek! https://www.treefortbikes.com/product...erailleur.html

FBinNY 

That's not so bad. What's unbelievable is that people actually buy them.

gyozadude

As long as the amount of float in the top pulley is a small fraction of the width between cogs, IMO, Shimano's approach is superior because it allows the chain to stay centered better and more quietly on a gear relatively well until a deliberate shift initiations derailment of the chain to another cog. As long as the float is a small fraction (e.g. less than 1/4th the gap between cogs) then an indexed shift will happen and complete just as fast. Yes, psychologically, some of us want to hear the grinding of chain on gears sooner. But the evolution to Hyperglide and more speeds on the rear happened very fast and a lot of it was due to pulley float along with ramps/teeth cutouts. The actual shifting these days occurs when the chain, under a lateral load by the top pulley reaches a release tooth (lower than most) and has a ramp that guides the chain to the next cog. We've all had that experience where we just missed that half rotation, and the crank slips a 1/4 turn or so and then we engage the next gear on a shift because we had to wait for the rear cassette to rotate a half turn over. So unlike the old days of heavy wear and tear requiring that we lighten our pedal stroke during shifts, a lot of riders are grinding hard and shift anyway, under load. I don't because I've grown up on the old school under friction shifting. But today's shifting has changed the way many newer riders approach shifting.

And I believe this is why Di2 has floating pulleys. Because it's going to shift for you and it leverages release locations on the cassette in conjunction with floating top pulley to allow the shift to happen under relative load without the need to lighten up much, but the cost of course is a slight amount of latency to get the shift lined up with cog tooth, ramp, and pulley ready. For some of us, I'm sure, this is bad because it seems less responsive. But I think that there is little advantage, even with top riders, to them shifting under load manually without pulley float. It only risks higher wear and lateral forces on the pulley and creates greater opportunity for misadjustment which would suck in the middle of a ride.

And one more thing that floating pulleys fix. Big riders with power going up a hill. Not all frames flex and reduce cable tension. But many do. And that's enough to really grind the gears and make noise.

In the end, the real test is how long it takes from initiation of shift to completion and how precise the adjustment has to be. I think Shimano's engineers have tested this and that's why they continue to have floating RD top pulleys. We could argue how the float might make shift initiation that much slower or reduce later load to applied to initiate a shift, but I think the design center around shifting has changed for all makers and we no longer truly derail chains so much as synchronize the shift with a location and ramp on the rear cog and allow the chain, with minimal side load, to be released to catch an adjacent cog. In this different design center, we don't need much side load, and we don't need to force the chain off one cog by rapid, forceful action. We just let it happen when the cogs line up twice per revolution in the rear for that to happen.

It's sort of like PCs and DRAM. We used to have chipsets with memory management that would page fault on a physical address request when it wasn't found in cache, and we'd randomly fetch that page. Then we evolved to have memory pre-fetchers, and now we have a synchronous bus that fetches memory every multiple clock cycles and only fetch pages memory, like every 12 or 15 ticks of the CPU. If you miss, then you gotta wait another 15 ticks or so. But overall, the speed of computers continues to go up. I would make the floating pulley akin to level zero cache. It holds data and instructions for the CPU and feeds the CPUs allowing it to keep pipelines full, meanwhile, page fetching occurs on a regular cycle to fill the cache but the cache keeps up with the CPU and keeps feeding it regardless. Question we're sort of asking here is if the cache has to be perfectly aligned to the CPU. And I ask how many cores does the CPU have and do they share that cache? We discussed all the possible things why Shimano put float into their top RD pulleys. Well, if multiple cores require coherent cache to pull data and instructions from, then it would be good to implement float so we don't thrash memory and TLBs and stall processors. Float is sometimes good.

HillRider

I've had three different setups requiring a Shiftmate:

1. 10-speed Ergos, 9-speed Shimano cassette, Shimano rear derailleur.
2. !0-speed Ergos, 10-speed Shimano cassette, Shimano rear derailleur
3. !0-speed Shimano indexed shifters, 10-speed Campy Cassette, Campy rear derailleur.

In every case I've never noticed any hesitation in the shifting compared to using a "straight" single maker drive train. Maybe I'm just not all that perceptive.

joejeweler

For $250 do they include extra lube? You're going to need it!


BTW,.....i have a few older but mintish Dura Ace RD-7402 rear derailleurs. I mounted one on my Serotta "commuter".



This one came with a custom set of aluminum jocky wheels with ball bearings that the previous owner had installed but not used. The wheels have virtually NO lateral float. Wonderful feel to them, and the drilled holes give a classy look.



The Centeron-G float wheels seem unnecessary to me on this old 8 speed system, and that's what i run. (1x8)

I rarely use more than a few gears anyway, but used with one of the matched downtube shifters mounted to a Paul thumbie shifter it never misses a shift and is super smooth running and virtually silent!



Maybe it's the extra width of the cog spacing and chain thickness that gives more leeway,.....but it seems to me the older stuff was less fussy. I do maintain a clean drivetrain,.....so maybe that's a big help?