Kogel Kolossos Ceramic Oversized Derailleur Cage Review



Review by Ryan Cleek

When it comes to mountain bike upgrades, there aren’t many bits that you can’t find a way to spend money on. Sometimes these upgrades claim performance benefits beyond just the bling factor. Kogel is a specialist in ceramic bearings, designed to improve the performance of all things that spin on a bicycle. This write up is specific to Kogel’s Kolossos Oversized derailleur dage and ceramic-bearing equipped oversized pulleys, which they say improves shifting accuracy, can reduce friction and improves chain retention. I’ve been testing these for quite a few months now, and it’s time to share how I got on.


A little, short and quick basic bearing intel is a good contextual starting point for a rider considering spending the cash on a ceramic bearing-equipped derailleur cage and pulley system. Such as, where ceramic bearings typically make sense when installed on a bicycle, the physical and material differences between steel and ceramic bearings, and also the claimed performance advantages of ceramic over steel. In the same way spendy wireless drivetrains aren’t for every rider, Kogel would likely agree neither are ceramic bearings. So, if you’re still awake at this point, you may be a candidate for considering such an upgrade.

For at least a couple of decades, ceramic bearings have been in the performance cycling conversation and today are commonplace in road racing genres. There’s been no shortage of debate whether ceramic bearings deliver a discernable performance advantage over traditional steel ball bearings. I’ll forgo the risk of such narcolepsy inducing details and do my best to just hit the key claimed performance advantages as they pertain to mountain biking.

Kogel Kolossos Ceramic Oversized Derailleur Cage Review

Generally speaking, ceramic and steel bearings are designed to do the same function: allow the parts of a bike that move to do so more freely and with less resistance. Texas-based Kogel Bearings offers ceramic bearings inside the oversized pulleys of their aftermarket derailleur cages, in their aftermarket bottom brackets, and also as aftermarket wheel bearings. According to them, the key difference between traditional steel ball bearings and ceramic ball bearings is that obviously, one is made from steel and the other of silicon nitride, one of the toughest ceramic materials. The benefit of a ball bearing made from silicon nitride is that it does not deform under a heavy load. Steel is a more malleable material and it could compress under a large load, such as an out of the saddle sprint or perhaps a harsh impact from a massive, on-trail drop. Silicon nitride balls can also be made with more accuracy than steel, which means the balls are rounder, smoother and ultimately will be easier to roll. Why the price difference between commonplace steel balls and ceramic ones? To create ceramic bearings, Kogel’s silicon nitride balls sit in a tumbler for weeks until they’re near-perfectly round and polished. Whereas, although steel balls share a similar, but shorter, polishing process, due to the material properties of steel they cannot achieve the same smoothness or roundness. Kogel says the pitfall is that making something that accurate is a time consuming and therefore an expensive process. They also say that if you find cheap ceramic bearings, they are probably cheap because the manufacturer cut a few corners. And, cheaply made ceramic bearings are more prone to crack.

Side by side with a “standard” derailleur cage, the Kolossos cage screams, “look at me, I’m bigger and shinier!” The aluminum cage is claimed to be several times stiffer than a stock derailleur cage, which therefore can deliver better shifting accuracy. The oversized, 7075 aluminum 14-tooth top and 18-tooth narrow-wide bottom pulley are said to reduce chain deflection which reduces drivetrain friction; are stiffer for more precise shifting; will rotate slower, which means slower rotating bearings and more reduced friction; and they also outlive stock plastic pulleys.

Kogel Kolossos Ceramic Oversized Derailleur Cage Review

On the mountain bike side of things, Kogel’s aluminum Kolossos derailleur cage is available for Shimano’s XT / XTR derailleurs and SRAM’s 12-speed Eagle derailleurs (tested here), which is compatible with all mechanical and AXS versions of XX1 Eagle, X01 Eagle, and GX Eagle derailleurs. The Kolossos cage and pulleys tips the scales at 99 grams, which is a 26g weight increase compared with the stock SRAM items. There’s no impact to ground clearance, with only a 2mm increase in length but the same hang height. As standard the Kogel cages ship with “Road seals”, which offer the least resistance but don’t prevent the ingress of dirt and water as effectively. Customers can choose to opt for the “Cross seals” to improve this resistance to adverse weather conditions, at the expense of a little efficiency out of the box.

The Kolossos cage is available in a variety of colors, and is offered in a pretty cool custom build option which can be done directly on their website. I took advantage of the custom cage option and had silver pulleys mounted to a black cage and all held together with Oil Slick finished hardware, all intended to match my Specialized Stumpjumper’s black and silver aesthetic. The stock Kogel Kolossos cage with pulleys sells for $474.99. Custom builds go for $524.99. All come with a two-year warranty.

Kogel Kolossos Ceramic Oversized Derailleur Cage Review


Other than changing the stock 30-tooth chainring to a 32-tooth option, my S-Works Stumpjumper Evo is the only bike I’ve ever had where I didn’t feel obligated to switch out all kinds of vital components to create a bike with my desired performance characteristics (which, for a bike with a price tag over $11k would hopefully be the case). Weather permitting, I ride that bike four to six times a week, and also use it for enduro races.

Equipped with SRAM’s top-shelf XX1 Eagle AXS wireless drivetrain, admittedly I wasn’t too excited about disassembling the derailleur to put on an aftermarket cage with claimed performance benefits when I had no discernable performance issues with the stock derailleur. Obviously, I don’t manufacture drivetrains in my spare time (rather, I tend to destroy them). I’ve built dozens of race bikes from scratch, but one thing I haven’t ever done was take apart a rear derailleur and monkey with the inner workings.

So, once I emotionally came to terms with the fact I did indeed need to disassemble a perfectly fine working derailleur to install the Kolossos, I literally rehearsed the very simple process over and over. I’ve replaced broken plastic pulleys and straightened bent hangers, which are relatively mindless procedures, but foolishly I was concerned that if I made a mistake winding the derailleur spring back in place with the Kogel cage installed I’d end up with a handful of XX1 Eagle AXS bits and Kogel-equipped non-functioning derailleur. I sort of felt like I was disassembling the internals of a Rolex, just to put on an aftermarket watch band that claimed to help me tell the time a bit better. Regardless, the installation process was extremely simple, and I quickly felt foolish for being so concerned about terminally messing up one of the most expensive derailleurs in the mountain bike game.

Any rider worth their weight in chamois butter knows it’s recommended to change all drivetrain bits at once, rather than only putting on a new chain, etc. The reason being, the longer the chain, cassette, and chainring are all working together, they more they tend to wear into each other and eventually will only play nice with those exact components they’ve grown to know so well.

Kogel Kolossos Ceramic Oversized Derailleur Cage Review

Since I’d changed the pulleys (with significantly more pronounced teeth than on the stock plastic XX1 pulleys) on the derailleur I felt it was best to then install a new chain, cassette, and chainring as well. Due to the supply chain issues, I waited several months for an XX1 chain and cassette, and a new 32-tooth oval chainring to become available. Eventually, I just gave up and decided to give the worn drivetrain a go with the new Kolossos cage. The only modification I did make was to add three links to the chain, because the Kolossos uses 14 and 18-tooth pulleys, which are larger than the stock 12 and 14-tooth ones I removed. I already run a chain that’s likely a smidge on the short side, because when descending in the smallest cog on a 1x 12-speed drivetrain there’s a lot of chain leftover that can flap and slap around when charging down rough terrain. On one piece of instructional material from Kogel it suggested installing a new chain with the Kolossos cage. Whereas on another I read a new chain was not necessary, however adding a few links may be. Regardless, I had no choice other than to add a few links to my old chain, and thankfully after months of riding that setup I’ve had zero issues of any kind.

Not only does the Kogel Kolossos system look killer when installed on the bike, but I instantly noticed a reduction in drivetrain noise over the stock plastic pulleys. Instead of the chain rattling back and forth on the stock pulleys, the chain sits deeper in the longer pulley teeth and therefore makes for a more quiet ride, presumably improving chain retention as well. When it comes to shifting, the SRAM’s AXS wireless setups are already pretty darn precise. Yet, shifting with Kolossos cage felt more crisp in crucial gear-change moments, like downshifting for a sudden steep uphill section of trail, or upshifting and popping through the gears under full-power sprint.

When it comes to the claim of increased wattage, it would be disingenuous if I said I noticed anything significant in that area. In fact, simply meticulously cleaning one’s current drivetrain, and servicing their bottom bracket and wheel bearings, would almost certainly reduce the energy loss over a given distance. Road racers in a peloton or time trialists who hold one particular body position over a significant distance would be much more likely to notice increased drivetrain drag than on an often grime-filled mountain bike drivetrain. However, in the world of elite mountain bike racing, fractions of a second accumulate and ultimately matter. Whether in a 3-minute downhill race, over multiple stages of an enduro event, or during a fast-paced World Cup XCO cross-country event, performance advantages add up and ceramic bearings make perfect sense in those applications. For me, the benefits to looks and shifting crispness are good enough reasons to have the Kogel system, and it’s nice to know that I’m having to work that little bit less hard to summit those climbs.

It is worth mentioning that installing an aftermarket third-party product, like Kogel’s cage and pulleys, will likely void the derailleur manufacturer’s warranty. I asked SRAM if installing the Kolossos cage would void the warranty on the roughly $750 (original MSRP) XX1 Eagle AXS derailleur, and it appears so. Here is their response: “We do not test the use of third-party parts as spare parts nor do we support the use of these parts. Because we do not test third-party compatibility, installing one of these parts may cause unforeseen damage to the component. The official language in our warranty policy is that the warranty does not apply when the product has been modified.” So, proceed with fitting the Kolossos system at your own risk if you can foresee any need to pull the warranty card on your derailleur.

The Wolf’s Last Word

Like most bike nerds, I am proudly in tune with my bike setups. Each ride, I set the exact same tire pressure with a digital gauge. And I regularly service my fork and shock and refer to the notes I make so I can return to the exact performance characteristics after the service. Despite not really wanting to disassemble my derailleur, I’m probably the type of mountain biker Kogel’s Kolossos cage was designed for. You certainly don’t have to be a World Cup competitor to appreciate the reliability, subtle performance benefits, and increased bling factor Kogel’s Kolossos cage provides, although adding a $475 derailleur cage and pulleys won’t be for everyone.

Price: $474.99 (stock color) / $524.99 (custom)
Website: Kogel.cc

We Dig

Killer looks
Notable shift crispness benefits
Supposed drag reduction

We Don’t

Gotta pay to play
May have to replace other drivetrain bits to fit


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