Oversized Pulley Wheel Systems Upgrades

Apr 06, 2023

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They look extremely cool, but the watt savings are tiny and they can degrade derailleur performance.

Peter asks:

Last season I swapped out my jockey wheels on my SRAM eTap derailleur with new Kogel wheels, did the same with my wife's Di2. I looked long and hard at the Ceramic Speed but couldn't bring myself to spend so much more. What is the right answer on that, they look so cool but are they worth the extra cash?

Thanks for writing, Peter.

I have a fair amount to say on this subject, but I’ll start by answering your question, then go into my screed.

My opinion—partially based on first-hand experience with aftermarket pulleys and oversized pulley cage systems—is that you are burning money. From a performance perspective, you will spend a lot of money for a tiny reduction in friction. But more likely (though not always), you will get more noise and degraded shifting performance.

I think a better use of money is investing in a good drivetrain cleaning setup. Get an ultrasonic cleaner for your chain and a small crock pot. Then, pamper your chain with an awesome lube like Silca's Secret Chain Blend. Not only will this save you a fair number of watts, but it also extends the life of your drivetrain and save you big money.

Of course, a hot waxed chain doesn't look as cool as 3D-printed titanium pulleys or a brightly colored machined aluminum pulley cage. And, hey, I love an awesome-looking and super-customized bike. So, you’ll never catch me discouraging anyone from dressing up their bike with aftermarket accessories if it makes them feel good. Hell, even I bought a pair of expensive custom Italian-made titanium axles for my mountain bike just because I thought they looked cooler than the (lighter) stock aluminum axles.

But let's talk about performance. I’ll start with the oversized pulley wheel systems (OSPWs) first and then cover replacement pulleys.

Almost every OSPW system promises reduced friction, so your drivetrain consumes fewer watts, making your bicycle more efficient. And they are not wrong. It's well known that wrapping a chain around a larger-dimeter ring, cog, or pulley reduces friction, and less friction is less watts consumed by the drivetrain.

Here's the problem though: OSPWs don't make a big difference. At best ("best" meaning the largest pulleys), these systems save three (3!) or so watts, and often less. And the price of these systems can be astronomical. The Muc-Off LOPS sold for around $1,000, CeramicSpeed's OPSWs sell for $599 to $2,000, Kogel's Kolossos is $475, the Absolute Black HollowCage is $499, and SLF Motion's Speed System sells for $545 to $1,195.

That's just an awful return on your investment. Switching to a good chain lube can save one to three watts (or more), as can an aero road helmet, better tires, wearing different clothing, optimizing your tire pressure, or just dialing in your bike fit.

There are some cheaper options though: KCNC's is just $80, and there are a host of less-expensive options on Amazon like this $35 Lingmai.

No matter how much you spend on an aftermarket cage, you’re replacing the stock cage with something not designed by the derailleur manufacturer. That means you’ve potentially voided the derailleur's warranty. But I’ve also experienced degraded shifting performance after "upgrading" to an OSPW. And metal pulleys tend to be louder than stock polymer pulleys. (Though I have not sampled the Absolute Black system, which notably claims significant drivetrain noise reduction.)

Since OPSW cages tend to be larger than stock—mountain bikers take note: this means less ground clearance. They also can flex more (resulting in poor shifting) unless the maker bulks up the cage to offset the lost stiffness, which makes it heavier than stock. And the larger pulleys and longer cage often require a longer chain, adding a few more grams.

So, adding it all up: At best a tiny number of watts saved, voided derailleur warranty, usually louder, often degraded shifting, added weight. You can probably see why I don't rush to recommend these to all riders.

If you’ve done everything else you can to improve your performance—training, diet, weight, aerodynamics, fit, etc.—saving those last three watts might be worth the investment. But I also know that I, and many other amateur riders, have more gains to realize from tuning our bodies and other parts of our bike—particularly aerodynamics and rolling resistance. These are things to consider before throwing $500 or more at a pulley cage to save at best, three watts.

I don't have a great opinion about most aftermarket replacement pulleys either, especially aluminum pulleys which are often loud and wear quickly. And if they don't have the right tolerances, or if they have too much (upper pulley) or too little (lower pulley) side-to-side movement, shifting performance degrades. Since they’re about the same diameter as stock, they are unlikely to reduce drivetrain friction by a measurable amount.

That's why I usually recommend sticking with stock replacement pulleys. They were specifically designed for the shifting system. Plus, they’re inexpensive and, in my experience, most of them last a long time.

If you really, really want to "upgrade" your pulleys, I recommend Enduro's machined Delrin pulleys with XD15 ceramic bearings. These are quiet because they’re Delrin, not metal, and feature Enduro's proven and long-lasting ceramic hybrid bearings.

Quick bearing explainer: Ceramic-hybrid means steel races with ceramic balls. Almost all of the "ceramic" bearings used on bicycles are hybrid-ceramic. Full-ceramic bearings—ceramic balls and races—do exist, but are generally avoided because the ceramic races are fragile. This makes it tough to press them in without damage and raises questions about their ability to survive hard impacts.

I wouldn't count on any watt savings from Enduro's pulleys, but a good hybrid ceramic bearing like the XD15 can outlast a steel bearing. Here's why: Assuming high-quality ceramic is employed, ceramic balls are more durable, have better heat resistance, are seven times harder, and are more uniformly round than steel. Plus, they don't rust. Because the balls are so hard, they crush grit that makes its way into the bearing. And they polish the races as they move.

Because the balls are so tough and give the bearing a measure of self-cleaning, hybrid-ceramic bearings can use lighter greases and seals, which reduces friction. Ceramic balls are also 60 percent lighter than steel balls, though we’re talking about a small amount of material. So replacing all your bike's bearings with ceramic hybrids will only make it infinitesimally lighter.

But reduced friction and less weight are not the real benefits of running ceramic-hybrid bearings in derailleur pulleys. Their real benefit is durability and longevity, which Enduro emphasizes with a lifetime warranty on their XD15 bearings.

Note that I took care to call out that the XD15 is a good hybrid ceramic bearing. The word "ceramic" is not a guarantee of quality: There are bad and low-quality ceramic bearings. A good steel bearing is always better than a bad ceramic bearing.

Another thing to note: SRAM's Red and XX1 and Campagnolo's top-end groups have ceramic-hybrid bearings in the rear derailleur pulleys from the factory. So, there is little benefit to a more expensive aftermarket option for these.

As I wrap this up, I want to throw this thought exercise out there: If these low-friction pulleys and oversize cages offered such game-changing performance, why haven't SRAM, Shimano, and Campagnolo incorporated them into their top-end groups? So, I asked some of the drivetrain manufacturers this question. The answer I got was, "We’ve researched them and we haven't found any worthwhile benefits."

Oversized pulleys, aluminum jockey wheels, and ceramic bearings have been around for over a decade (two or more drivetrain redesign cycles from major brands). Other than SRAM and Campagnolo using hybrid-ceramic bearings in the pulleys of their top-end groups, the drivetrain makers have not jumped on these trends.

Maybe that will change with the next Dura-Ace, Red, XX, or Super Record. Designing rear derailleurs with oversize pulleys and/or metal pulleys (machined or 3D-printed) would be easy steps for those brands to take. And yet, Campy, SRAM, and Shimano continue using smaller-diameter pulleys made of polymer. For this reason, I remain skeptical of the performance benefits of this whole drivetrain "upgrade" category.

A gear editor for his entire career, Matt's journey to becoming a leading cycling tech journalist started in 1995, and he's been at it ever since; likely riding more cycling equipment than anyone on the planet along the way. Previous to his time with Bicycling, Matt worked in bike shops as a service manager, mechanic, and sales person. Based in Durango, Colorado, he enjoys riding and testing any and all kinds of bikes, so you’re just as likely to see him on a road bike dressed in Lycra at a Tuesday night worlds ride as you are to find him dressed in a full face helmet and pads riding a bike park on an enduro bike. He doesn't race often, but he's game for anything; having entered road races, criteriums, trials competitions, dual slalom, downhill races, enduros, stage races, short track, time trials, and gran fondos. Next up on his to-do list: a multi day bikepacking trip, and an e-bike race.

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