Oversized pulley cages have become common in road cycling on pro and amateur bikes alike in the last five years. They are offered for curly-barred bikes by everyone from Ceramic Speed
to Muc Off
but haven't become a popular choice for mountain bikers just yet. Hoping to change all that is Kogel, who are bringing their Kolossos cage to SRAM's Eagle ecosystem.
So, why go supersize? Well, the theory is that larger pulley wheels mean the chain has to articulate less therefore reducing unwanted drag. Larger jockey wheels also have a lower rotational speed at the same chain speed, which in turn means less drag in the bearings. These small amounts of drag in the drivetrain probably aren't a huge worry for most mountain bikers but for XC racers and long-distance riders, those little bits of resistance are worth reducing wherever possible.
The current SRAM Eagle derailleurs use 12T top and 14T bottom jockey wheels but the Kolossos increases that to 14T top and 19T bottom. This, combined with ABEC 5 Kogel bearings with silicon nitride ceramic balls, is claimed to translate to a 2.5 normalised watt saving over a standard Eagle set up.
The cages are made from 7075 aluminium in El Paso Texas and Kogel claims their assembly "provides maximum strength and stiffness, improved shifting efficiency, precise shifting and improved chain retention". The cage length is the same as an Eagle set up so ground clearance remains unchanged and there is no need to resize your chain. The Kolossos plus the anchor bolt weighs 87 grams, a 9-gram penalty over SRAM's own system.
The Kogel Kolossos cage is compatible with the mechanical and electronic versions of SRAM Eagle, specifically with the following models: SRAM XX1 Eagle AXS, SRAM XX1 Eagle, SRAM X01 Eagle AXS, SRAM X01 Eagle and GX Eagle. The cage comes in gold, black and red while the pulleys and bolts are available in black, red, gold, silver and blue. The Kolossos is available now for $399. More info, here