Cook Brothers Cranks


These cranks are machined from solid pieces of 7075 T6 aluminum stock. Each of the arms is turned on a lathe to produce the tapered shape, with a 37.72mm diameter ball at the B/B and a 29.14mm diameter ball at the pedal end. The ball shapes are then milled flat with the specific angles required for the spider and pedal and B/B spindle installation. The pedal end ball is drilled through and tapped with 9/16" by 20 threads per inch threads for the pedal spindle. The crank arm dust cap hole is bored and tapped with 22mm by 1mm threads, (no caps are provided with this crank arm set). The square B/B spindle hole is milled with 2 degree tapered sides when the rear of the arm is machined. The back side of the arm is drilled and tapped for a Torx bolt that holds the spider to the rear of the arm. The rear of the large ball has three steel pins driven into it. These pins are used to fix the precise position of the spider on the arm before the Torx bolt holds them together.

The crank arms are high polished, and then anodized. After anodizing, the Cook Bros. logo is finely engraved on the face of each arm. The spider is machined from a single piece of 6.63mm thick aluminum plate stock. It is cut to shape, then drilled and tapped for the chainring bolts where needed. The arms have a 6 degree offset for chainstay and ankle clearance, and come with a triple chainring spider (adapter) with threaded inner ring bolt holes. The chainring bolt pattern is the standard 110mm outer, 74mm inner. The crank arm set will work with any standard 2 degree tapered bottom bracket, and naturally Cooks recommends their own sealed bearing bottom bracket. The crank arms come anodized in Black, Purple, or Silver with the spider anodized in Black. We stock them in 171mm, 176mm, or 181mm lengths. We found the CBR Mountain cranks to have a Bike-Pro Q measurement of 168mm. Cooks CBR cranks come as right arm with spider, left arm, and a set of five steel inner chainring bolts with aluminum spacers. Chainrings, the double chainring bolt set, crank bolts, and crank arm caps will be needed separately. The 176mm arm set with spider in Black weighs 507.5 grams. The inner bolt set provided weighs an additional 35 grams. Be sure to specify color and length.
Size-71-76-81 / Color-BK-L-S  $ Price in Catalog 

Cook Bros Racing RSR Series Crank Arms
Copyrighted material - All rights reserved

This site sponsored by