My derailler pulleys spin very freely (unless they are dirty).

My cogs (cassette) don't spin on the free hub cause it transmits the force.

?????

 

I'm not good at this kind of stuff, but I'll give it a shot.

Drawbacks
-More weight
-The balls would have to be really small if conventional derailleur design is used
-I don't think ball bearings can really handle lateral force, like that seen on derailleurs. Maybe they can?

That's all I got for now...
Tim

----------------------------
"I'm hopeful. I know there is a lot of ambition in Washington, obviously. But I hope the ambitious realize that they are more likely to succeed with success as opposed to failure."-That's as close as Dubya'll get to admitting he's wrong, and it was an accident...

 

My derailler pulleys spin very freely (unless they are dirty).

My cogs (cassette) don't spin on the free hub cause it transmits the force.

?????

hmm.. they definitely dont spin free. you take the pulley in your hand (so that the two plates are together and your pinching them) spin the thing and it will stop in less then one turn.

yah they move, but they dont spin free like a ball bearing would.

 

I got it! Cartridge bearings:thumbsup: Oh wait those are already on the XTR and XO deraileurs. All the bearings in the world won't do any good if the drivetrain is all yucky!

 

I'm not good at this kind of stuff, but I'll give it a shot.

Drawbacks
-More weight
-The balls would have to be really small if conventional derailleur design is used
-I don't think ball bearings can really handle lateral force, like that seen on derailleurs. Maybe they can?

That's all I got for now...
Tim

yah the weight --- im not 100% sure what the weight diff would be but with titanium bearings, or aluminum core that weight could be cut down. the thing is there is already a dry bearing in each of the two cogs on the derailieur.

as for handling force, or how small that wouldn't be a problem, in fact they would probably be better at both. - ie roller bearing.

just taking example from turbos: all turbo`s were at one point dry bearing style, then ball bearings hit them and the % efficiency went from 60 to 80% or more. thats quite a bit in my mind.

 

They'd probably cost more, no?

 

Been done

Ok so i had to replace the inner cog on my de-railer, and although ive taken apart many before, the idea just came to my mind... why aren't they made "free spinning"? I've got a shimano LX rear...

So why not have ball bearings in each cog - benefit would be obvious - less friction, the drawback? none that i can tell... the parts it takes to make the inner part of the standard cogs would weigh the same, it wouldn't require more engineering or anything...

Does something like that exist? it should if it doesnt.

what do you guys think?

Carmichael makes CNC alu with cartridge bearings, Performacne bike sells thier house brand ones (which I suspect are Carmichaels), KCNC makes some.

I have two sets, adn the primary drawback is that the ball bearings get crudded up fairly easily, which makes them run crunchy. I have to take mine out twice a year, pull the seals off, clean and regrease them.

That said, I love them.

On the plus side, my drivetrain is stupid smooth and free running when they are clean, and the shifting is super crispy because they don't slide side-to-side like the stock ones. The downside is that it is super touchy on the adjustment.

Shimano and SRAM probably use the ceramic bushing type because they allow for some side to side slop (less finicky about deralleur cable adjustment) and they don;t get crudded up so easily... so less service needed. I've seen people go years without ever touching them.

Weight? Yeah, the probably weigh more. It's hard to beat plastic and ceramic in the weight department. In reality we're only talking what... 20 grams tops? Not enough to make a difference.

 

hmm.. they definitely dont spin free. you take the pulley in your hand (so that the two plates are together and your pinching them) spin the thing and it will stop in less then one turn.

yah they move, but they dont spin free like a ball bearing would.

The LX use bushings. The pulleys spin on the bushings (the hollow cyclinder that sits outide of the bolt), not the two metal discs. The discs are meant to keep the dirt out not to be pinched by your fingers or anything else. The pulleys spin freely, but there's simply not enough mass to keep them spinning more than a turn.

I'm not sure about XT and XTR, but Shimano's higher level (Ultegra and Dura Ace) deraileurs do use bearings in their pulleys. A few companies make aftermarket pulleys with bearings. But I think the difference is neglibible. Again, these won't spin more than a revolution in your hands.

 

The LX use bushings. The pulleys spin on the bushings (the hollow cyclinder that sits outide of the bolt), not the two metal discs. The discs are meant to keep the dirt out not to be pinched by your fingers or anything else. The pulleys spin freely, but there's simply not enough mass to keep them spinning more than a turn.

I'm not sure about XT and XTR, but Shimano's higher level (Ultegra and Dura Ace) deraileurs do use bearings in their pulleys. A few companies make aftermarket pulleys with bearings. But I think the difference is neglibible. Again, these won't spin more than a revolution in your hands.

actually the plates serve two functions, one keeps the cylinder in place and keeps from the two sides of the derailieur from clamping down on the cog thus making it not move and keeping it from dirt.

i realize the diff isnt that big your right but still they should use the best parts available!

 

Carmichael makes CNC alu with cartridge bearings, Performacne bike sells thier house brand ones (which I suspect are Carmichaels), KCNC makes some.

I have two sets, adn the primary drawback is that the ball bearings get crudded up fairly easily, which makes them run crunchy. I have to take mine out twice a year, pull the seals off, clean and regrease them.

That said, I love them.

On the plus side, my drivetrain is stupid smooth and free running when they are clean, and the shifting is super crispy because they don't slide side-to-side like the stock ones. The downside is that it is super touchy on the adjustment.

Shimano and SRAM probably use the ceramic bushing type because they allow for some side to side slop (less finicky about deralleur cable adjustment) and they don;t get crudded up so easily... so less service needed. I've seen people go years without ever touching them.

Weight? Yeah, the probably weigh more. It's hard to beat plastic and ceramic in the weight department. In reality we're only talking what... 20 grams tops? Not enough to make a difference.

very interesting! im suprised more companies dont do it!

 

Carmichael makes CNC alu with cartridge bearings, Performacne bike sells thier house brand ones (which I suspect are Carmichaels), KCNC makes some.

I have two sets, adn the primary drawback is that the ball bearings get crudded up fairly easily, which makes them run crunchy. I have to take mine out twice a year, pull the seals off, clean and regrease them.

That said, I love them.

On the plus side, my drivetrain is stupid smooth and free running when they are clean, and the shifting is super crispy because they don't slide side-to-side like the stock ones. The downside is that it is super touchy on the adjustment.

Shimano and SRAM probably use the ceramic bushing type because they allow for some side to side slop (less finicky about deralleur cable adjustment) and they don;t get crudded up so easily... so less service needed. I've seen people go years without ever touching them.

I just installed the Performance alloy pulleys four rides ago on my roadie's dura ace (only $10/pair on sale). This set does have a lot of side to side play built in, and shifting's been better so far...very crisp. Because they're alloy and not plastic, it's very slightly noisier (chain on pulley). Looking at the design, I'm guessing they would get gunked up easier. These have sealed bearings.

 

The LX use bushings. The pulleys spin on the bushings (the hollow cyclinder that sits outide of the bolt), not the two metal discs. The discs are meant to keep the dirt out not to be pinched by your fingers or anything else. The pulleys spin freely, but there's simply not enough mass to keep them spinning more than a turn.

I'm not sure about XT and XTR, but Shimano's higher level (Ultegra and Dura Ace) deraileurs do use bearings in their pulleys. A few companies make aftermarket pulleys with bearings. But I think the difference is neglibible. Again, these won't spin more than a revolution in your hands.

True they are not meant to be pinched. However, I do know from that XT is bushing only, and Ultergra is a mix; one pulley is bearing, one is bushing. IMO, bearing especially on a MTB setup is only asking for more maintenance and trashed parts from all the crud. Bushings are easy to rebuilt and clean, and are cheap. I would think any extra friction is a minor factor; just ride more and build more muscle to compensate.

 

More companies don't do it because....

it's more expensive and it's not necessary. The ceramic bushings (even brass ones) are more durable and take less maintenance than bearings. As for pinching the plates. If you are pinching the bushing cover plates together enough to cause resistance or binding when you re-install the jockey wheels you have a problem! The bolts that secure the cage halves and act as an axel for the wheels is shouldered and does not push the cage together beyond a given dimension. This leaves the jockey wheels free to spin. If they are binding then either the cover plates are not fully seated in the recesses in the jockey wheel, or you have damaged the shoulders on the bolts through over torque and reduced the dimension between the cage halves. The covers aren't there to prevent binding at all, they are there to keep crud out of the bushing.

The advantage that the Carmichale has over the standard composite wheel is the durability of the cog and the precission of shifting that come with the bearing. The alu cog is tougher and more resistant to grit and such, and the bearing makes for less lateral movement of the cog during shifting.

The down side to them is as pimpbot noted. More maintenance, and more finicky derailleur adjustment.

The reason you don't see the Carmichael style jockeys as standard are simple. Cost vs. Benefit. The Carmichael style jockey doesn't increase the longevity of the derailleur nor increase performance enough to make it worth the additional cost until you get above the LX level of components. Current Shimano MTB offerings that come with bearings are XTR, tension and guide pulley use bearings, and XT, tension pulley uses a bearing, guide pulley uses a bushing. LX and below use ceramic bushings.

As for SRAM, I know the X.0 uses sealed bearings for the jockey wheels, and I believe the 07 X.9 got the bearing treatment as well, not sure though. Anything below that is pretty much bushings as well.

So technically they do use the best materials available. YOU just have to be willing to pay for the best to get the best materials. If your LX derailleur had all the features of the XTR then it wouldn't be an LX would it. It's the old adage all over again, "you get what you pay for".

Good Dirt

 

very interesting! im suprised more companies dont do it!

They've been available since the 1970's, I think Bullseye was the first to bring them to market.

http://www.bikepro.com/products/rear_derailleurs/rrder_pulley.shtml

They tend to make index shifting worse, add noise to the drivetrain and weigh a little more than plastic. During the annodized craze of the mid '90s, they were very popular, but the negatives outweighed the positives and they've found their place in the cycling history books and not on current bikes.

 

Look at the reverse: Suppose all derailleur pulleys were currently Al with bearings. What we currently have now would become the "new need to have item". "YOU CAN SAVE 20 GRAMS! BUY ME! YOU NEED ME!" and of course everyone would rush to get them. Then we'd be looking at threads here that start with "Difference between Al pulleys and plastic? Need Advice". Half the answers would extole the virtues, lighter weight and no maintenance. The other half would claim less durability, not as smooth. Of course each would be backed up with "solid" logic. No bearings for dirt to screw up. The forces and action are such that the plastic wouldn't wear out quickly. For the other side: "What? It's clear Al lasts longer than plastic and the lack of smoothness MUST make shifts worse."

The point: What we have now is flat out good enough to the point that there is no major difference that could ever make the performance marginally enough better to warrant a change. Yes, they are currently that good.