Big pulley wheels were not the final step to free speed. Kolossos now comes in Aero, shielding your wheels and chain from the wind for those riders looking for maximum output. Aero Kolossos is built with Kogel ceramic bearings and road seals. 

Fully built in CNC machined aluminum with an internal spine for maximum stiffness, Aero Kolossos will help you cut through the wind as well as help you maintain shifting accuracy. When it comes to marginal gains, there is just no point in gaining a few watts, only to give away your benefits every time you change gears or hit rough tarmac.

While the obvious use is for triathlons and time trials, we did not want to restrict the range of use for these cages. The Aero Kolossos is equally at home in road and crit racing, where the terrain can be bumpy and shifting happens often and aggressively. 


Aero Kolossos for Shimano has a 12-tooth upper and 19-tooth lower wheel. It fits 11 and 12 speed Ultegra and Dura Ace derailleurs.

  • R8000 11-speed Ultegra series, both Di2 and Mechanical
  • R9100 11-speed Dura Ace series, both Di2 and Mechanical
  • R8100 11-speed Ultegra Di2 Series
  • R9200 11-speed Dura Ace Di2 Series

We do not stock the cages for Shimano 105 11 speed (R7000 series) and 12 speed (R7100 series) derailleurs, but we can build it for you. Please reach out via the chat window on your screen or

As fast as it looks.
Customer reviews
"I've been using the Aero Kolossos for a few months now, and the difference in my ride is night and day. The reduced drag and smoother shifting have genuinely improved my time trial results. Highly recommended for anyone looking to upgrade their performance without a complete bike overhaul."
— SpeedSeeker99
"Fantastic upgrade! The Aero Kolossos was easy to install, and I noticed the benefits immediately during my rides. It's not just about the lower friction; the bike feels more responsive overall. Perfect for road racers like myself who are serious about every detail."
— Tim S
"Upgraded to the Aero Kolossos before my last triathlon and was blown away by the performance. The shifting is incredibly smooth, and it really cuts through the wind. This derailleur cage is a game-changer for triathletes. Worth every penny!"
— TriathlonTara
"I swapped to the Aero Kolossos for my crit races and the improvement in shifting accuracy and bike handling is noticeable. It handles aggressive shifts flawlessly, and the aero benefit is a nice bonus. Definitely sticking with Kogel for my setup!"
— Brian
"Though it's designed for road and triathlon, I took a chance with the Aero Kolossos on my gravel bike. The result is fantastic. It holds up well even on rough terrains and the efficiency in power transfer is something you feel on long rides. Excellent product from Kogel!"
— Mike


The Aero Kolossos Oversized Derailleur Cage isn't just an upgrade; it's a transformation in cycling performance. Designed with precision and aerodynamic efficiency in mind, it's your secret weapon for cutting through wind resistance. Its optimized shape minimizes drag, allowing you to maintain higher speeds with less effort.

Slice Through Air, Shift Into Speed



Installation is easy, but does require disassembly of the stock cage.

The process takes roughly 20 minutes, including minor adjustments to the B-screw and limit screws to fine tune placement on the bike.

Frequently asked questions

How hard is it to install a Oversized Derailleur cage?

Installing an oversized derailleur cage is best left to expert level mechanics. Derailleur manufacturers do not support disassembly of the derailleur. For this reason online instructions will be limited.

The installation procedure is also different for each model. Some types are straight forward, with some types you need to disassemble the entire cage and use proprietary tools for the installation. With others you run the risk of having to rebuild the clutch if the parts pop out while you’re happily tooling away. Derailleur failures are typically expensive: the chances of breaking a wheel or a seat stay are probably not worth the risk.

Kogel recommends leaving the installation to a professional.

How hard is it to install a derailleur cage

This depends on the derailleur model. Some require special tools, others can be done with regular allen and torx keys. Please have a look at the installation video for your model for the specifics.

Will my existing chain work?

Probably not. Installing an oversized system demands a longer chain than the one used on a stock derailleur. The longer cage and larger wheels create a need for additional chain links.

Will I notice a difference in performance?

Yes and No. Kolossos has been designed to shift just as accurate as your stock derailleur cage. You will notice reduced drive train friction. Upgrading to an oversized derailleur cage is one step in the eternal search to go faster with less effort.

Are Oversized Derailleur cages noise?

The only sound you will hear is from using aluminum wheels instead of plastic. Aluminum wheels are stiffer and more durable than their plastic counterparts at the expense of a faint rattle when the chain runs across the cogs. We like to call it the sound of speed.

What are the downsides to an oversized derailleur cage?
  • Every installation requires a new chain
  • A slight reduction of ground clearance due to the longer cage
  • Your friends will envy you