Rotor???s 3D+ MAS road crank is light, practical, versatile. More importantly, it???s designed to improve your ability to fine-tune the OCP on your Rotor Q and QXL chainrings. MAS is short for Multiple Adjust Spider. If you???re starting from scratch with Rotor???s Q-Rings,? MAS offers you the most fit options. At the same time, if you???re simply looking for a light, strong crank with a solid spider for time trialing, it works fabulously well at that, too.
Let???s start with versatility. Rotor utilizes a 30mm-diameter thru-axle that is permanently affixed to the left crankarm. While the size might seem too big for threaded bottom brackets, Rotor has designed their own BB???s, which allow you to install this crank on English-threaded, Italian-threaded, BB30, PF30, BBright, BB386EVO, and BB86 bottom brackets. This is why they call this their UBB, Universal Bottom Bracket, System--if you get this one crank, you can move it from bike to bike without regard to the standard the frame employs. You just need to utilize the spacers that come with the cranks, and the proper Rotor bottom bracket.
But versatility isn???t enough. This crank is stiff and light. Rotor employs 7055 aluminum alloy, which they found to be best-suited to this application. They have forged the arms, which are then CNC-milled both on the exterior and interior. The interior possesses Rotor???s Trinity Drilling System, which means that each arm has three hollow channels running the length of the arm. The material and shape make the arms stiff, and the careful drilling makes them light. The cranks weight 497g with 175mm arms and 130mm spider.
Because they wanted the arms to work for all cyclists regardless of leg length, you can find these in a wider range of sizes than just about any other crank out there.
The spider is a five-arm design, available in either 110 or 130mm bolt circle diameter (aka compact and standard). The MAS drilling means that there are two sets of chainring bolts. They you're your OCP5 Rotor Q and QXL rings into OCP10, allowing you to double your Optimum Chainring Position options. Obviously, these spiders will fit Rotor Q, QXL, and NoQ chainrings. They should also fit appropriately-sized 9/10/11-speed rings from their competitors, especially those with non-round offerings.
The Rotor 3D+ MAS Road Crank comes with the fixing bolt and all the spacers necessary to get this crank onto any of the bottom bracket standards it is designed to work with.