My guess is because they don't reduce friction and aren't more efficient.

At most you're going to get a 1.5 watt reduction...at most. More likely 1w.

I have this weird dollars to watts sliding scale in my head on how much I'll spend to save how many watts. The OSPW does not makethe list of upgrades.

For less $ you could get some Hawk racing pulleys & BB, get more savings in drag and have enough money left over for few bottles of the whiskey of your choice

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Brian Stover USAT LII
Accelerate3 Coaching
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Latex tubes offer a similar watt savings—noted at a different location in the bike/rider system—at a tiny fraction of the cost of pulleys, eh?

Bonus: latex offers a comfy ride, too.

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I've wondered this as well, and I hope the question isn't lost in the answers.

It isn't whether or not it's a real-world improvement.

It isn't whether or not it's worth it in terms of dollars to watts.

But just this: Why isn't Shimano doing it? If there's an after market demand for it (and clearly there is, whether it's worth it or not) then why isn't Shimano trying to capitalize on it?

I hadn't thought of it until I saw your post, but you're right: they do it on lower end derailleurs but not high-end ones. Why is that?

Your stance is completely normal/acceptable, the cost of these things is absurd. But I do look at it in a different way, which is that I ride my bike, I dunno, 400hrs/yr? And tend to get 0-2% gain in my FTP out of that effort. So if I can buy a widget that gets me some gain that otherwise would have taken a 100+ hours of training, I'm probably going to do it.

As to the direct question as to why Shimano doesn't do it . . . probably they prioritize shift quality and system durability, and need to keep their stuff at a price point for OEM spec, mass use, etc. Also, so few people care about that 1-2W that they can concede the market on it, no problem.

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Dimond Bikes Superfan

Latex is a lot more, watts saved, I thought! Isn’t latex like 2W or higher per tire, whereas a OSPW would be 1-2W?

As to why the drivetrain manufacturers haven’t thought of this, I’d suspect part of it is tradition, and part of it is that the testing showing that bit pulleys are slightly better is fairly new and probably has yet to be accepted as conventional wisdom. And another part of it is probably that the derailer is a complex system, and the big 3 are looking to optimize its shifting performance, and maybe they think that putting big pulleys on will probably degrade the shifting or make it more sensitive to setup.

As to the direct question as to why Shimano doesn't do it . . . probably they prioritize shift quality and system durability, and need to keep their stuff at a price point for OEM spec, mass use, etc. Also, so few people care about that 1-2W that they can concede the market on it, no problem.[/quote]
the real question is that making a cage and a wheel that is a larger diameter is not rocket science, the reason given is not just that the bearings are better but when the chain articulates over a smaller angle there is less resistance/ friction/ power loss. If people are paying incredible amounts for the use of an after market jockey wheels and cage, i understand that the name brands will not jump on but in most cases they come along later once it is "a real thing". So it is just a strange observation. Also as noted that the low end Shimano derailleurs do have these large jockey wheels??? why is it good at the cheap end is it shifting is less critical?

I am curious if anyone knows the reason from the Campy or Shimano point of view. maybe it is they don't care and their sponsored teams just swap them out as they wish? I can't imagine that the OSPW is a poor shifting solution but maybe.

if I'm not mistaken, the new GRX has 13 tooth jockey wheels, yet road groupos still have 11 tooth?

Ultegra 8000 and Dura Ace 9100 have 12/14T jockey wheels.

LOuis :-)

not sure what the basis is for the sizing but OSPW for newer Shimano is 13-tooth upper pulley wheel and a 19-tooth lower pulley wheel and 17/17 for older?

Depends who you are and what you do, as Well. Training and Racing hard, trying to win, you’d want any advantage you Can get. Training for Health, just enjoy riding with no care for the speed, you could always argue that anything But entry level would be a waste on money. Most people riding, are probably somewhere in the middle, wanting to see results to keep the motivation. It isn’t really those 1-2w makes any difference for anyone on its own, But save a few watts on a helmet, aero suit, shave legs, improve position and you’ll see that you speed goes up for the same wattage or wattage come Down for the same speed. As for FTP, with the same training, you’ll probably hit the same on a 20kg old banged up stel commuter. Those watts Will just result in much slower speeds on that bike

Arent aftermarket oversize pulleys just too flashy for the product line?

People usually buy them as way to customize a bike that is maxed out...hot rod color anodized wheels in carbon cage with NASA designed bearings.... not sure if they would fly off the shelves in 105 or ultegra grey and hanging on the wall next to deore chains and brakepads

You ride your bike a ton and that's great! I get the wanting to optimize. And no matter if you're racing for the podium or to just beat your buddies a watt saved is a watt that can go to the road to propel you forward.

If you have the $ and want to do the OSWP system, do it! There are other ways to spend less money and get the same drag reductions with your rear derailleur though. Plus you can still buy other drag reductions with the difference.

I do bike & equipment upgrade consults all the time. When you lay it out for people OSWP doesn't make sense when there are other options that are less $ and offer the same or greater ROI, leaving more budget for other upgrades/projects.

Here is one I wrote about: https://accelerate3.com/return-on-investment/

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Brian Stover USAT LII
Accelerate3 Coaching
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But my thought process, is it is mostly the pulley size for chain articulation. If that alone is worth a few watts and the real cost to make a larger cage and larger wheels is minimal then why not? I am not saying that Shimano or Campy need to go all crazy 3D printing etc or ceramic bearings, but why not just increase the wheel size and change the cage to accommodate it? I assume with their manufacturing abilities it is a small cost if any. But just looking at my 105 long cage derailleur it looks like there is room for a larger jockey wheel. I have not looked at the math to figure out the change in sprocket teeth but one could increase it for sure. Friction facts have a dog in the race so maybe they are not the best source but they do say that as noted here there is an advantage but they do not say if it is because of the size or if it is low friction bearings.

Any testing that shows pulley size alone is worth a couple watts? Per my limited research total system is worth less than two watts and most comes from much lower chain tension (how will that effect reliability?). Pulley size is about a quarter watt benefit from what I found.

Here's what I found: Old thread here and article. Perhaps there is more recent independent testing.

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Oversized pulleys always seems like a gimmick if not an outright scam. Think about it why is a larger pilot with paying (what were they when they first

My guess would be shimano doesn’t want to be associated with something like that

I agree with the first bit, I absolutely don't see why the drivetrain manufacturers shouldn't go to bigger pulleys. I agree there's space in the cage to go bigger as well; Kogel makes 12/14 pulleys for Shimano derailleurs, and this doesn't require changing the cage. NB: Campy went to 12/14t pulleys with its new Ekar group.

As to the second bit, I think there have been tests of both pulley size (and tooth count) and bearings independently. Friction Facts was independent when this testing went down, however. Ceramicspeed bought FF wholesale later on. Anything Ceramicspeed says now, no dispute that they have a commercial interest. If you read this article of theirs, which combines information that Friction Facts published independently and their own commercial testing, they do argue that it's both the pulley size and the bearing type and quality. (Edit: I see I was beaten to this; the thread that H- posted probably references that test when published on Cyclingnews in 2013.)

Go to section 4, which they say is the un-edited FF report published in 2013. They tested ceramic bearings (not sure whose) on several combos of plastic pulley wheels ranging (10, 11, 13, and 15t). Going from 11/11 to 15/15 was worth about a quarter of a watt. (That's in part 1 of the test, graph 2.) I'm not sure which version of Dura Ace this is (DA 9000 was released in 2012/13), but they tested that the stock DA 11t pulleys were a bit over .5W behind 11/11t Ceramicspeed pulleys. (Part 2 of test, graph 3.) Those parts were pulleys alone, separate from the cage, I think. I think part 3 is testing the Berner pulley system, which had a lower cage tension than the stock Shimano. I think Shimano may have argued that the stock tension is necessary to guarantee good shifting. I think CS's own cage has options to reduce the cage tension, and they showed that lower tension equals lower friction. I think CS has shown elsewhere on their site that stock Ultegra pulleys (one ceramic bushing, one bearing) lose about half a watt to stock DA pulleys (bearings in both).

Anyway, based on that, I am thinking that pulleys like Kogels are probably a bit over half a watt savings over DA. But you could probably get half a watt savings going from Ultegra to stock DA pulleys at $35. CS has argued that their pulleys are more resistant to contamination than DA. I'm not sure if that's the quality of the bearing seals. I got my used Kogel pulleys with road seals, and I bought a cross seal kit for the set that's on my gravel bike when I next service it.

So from the great replies so far it appears that most seem to see evidence of improvement for larger jockey wheels. If that is true, simply increasing the size should be a trivial thing to do for the majour players. Yes I agree that the after market brands charging incredible amounts of money seems over the top but that is not where I am coming from. What I think seems to be the feeling I get from the responses is that it seems like something most think would improve drive train efficiency at a very small or no cost. Hopefully someone from Shimano reads this and they work towards that if not already doing so.

Especially with the move to wider range cassettes and mid-cage derailleurs, it makes sense to enlarge the jockey wheels. Save the ceramic bearings for the aftermarket folks, just increase the pulley diameters.

Note: This has already been done once; jockey wheels in the 80/90s were 1-2 teeth smaller than today IIRC.

If the OEMs don't do this I'd at least like to see low-cost aftermarket options using std sealed steel bearings.

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I think that probably explains why manufacturers haven't bothered

I don’t necessarily agree. You want your racers to go faster. DA pulleys may be worth half a watt over Ultegra. The DA chain may be worth something like half a watt as well; I am recalling this statistic from Josh’s marginal gains YT vid. If increasing the pulley wheel size doesn’t affect the shifting, then manufacturers should be going down this route.

Wondering about the aero cost of those 0.25W saved on drivetrain efficiency.

I have tried one of the 13tooth oversized jockey wheels from Shimano's entry level deraileur in a R7000 deraileur, unfortunately the chain would slip of the jockey wheel and run between the jockey wheel and the cage.
On a similar vein why doesn't any mayor chain/groupset company sell their chains pre waxed? I can see little downside to this.

wouldn't it be nice if instead of that anti rust goop they put on chains they waxed them at the factory? I suspect that it might be an added cost though, need heated bath to hold the wax etc, whereas spraying some anti corrosion goop is dead simple. I have to say I really dislike the anti corrosion stuff on the chains though and it is really hard to get it all off to start a nice new waxed chain. So I agree (via rant) with that idea for sure but doubt it will happen. larger jockey wheels seems like a no brainer? There are probably other benefits to less articulation such as reduced wear. The more a chain moves the more the dirt and grit can wear the plates and the pivots. So less articulation should also extend chain life while reducing friction over all.