Sampson Sports of Denver, Colorado sells two versions of cranks CNC machined from 7075-T6 billet aluminum alloy. This, their road crank, is a double crank for 130mm bolt center diameter chainrings. In cross section the arms have a diamond shape. At the front and rear edge of the arm it is 2.5mm thick expanding to 13,9 thickness at the center of the arm. The width of the arm increases from the pedal spindle area to the bottom bracket spindle, from 23mm to 35.5mm width. Each arm is 13mm thick at the pedal and 24mm thick at the B/B spindle. The crank arm builds from the pedal area in all directions starting toward the B/B.
The pedal threads into an area that has a flat face and allows the pedal spindle to seat fully. This design affords full contact and greater holding strength of the spindle. Once the arm piece is machine milled to shape, the dust cap and pedal spindle hole are drilled then tapped. The dust cap hole has 22mm x 1mm threads, the pedal spindle is 9/16" x 20 threads per inch. The 2 degree tapered hole for the B/B milled away, rather than drilled and broached as many arms are commonly finish. The spider is a separate piece, which threads onto the rear of the right arm.
An area of the arm is purposely left 17.81mm thick. This 20mm by 11mm flat area is drilled an tapped for the fifth inner crank bolt and it spacer which holds the chainring. To reduce weight, the arms of the 7075-T6 spider are milled tear drop shaped slots. Included with each set of road arms is the needed fifth arm bolt and spacer, made of aluminum and four other fixing bolts and nuts made of aluminum for the other four spider arms. To make the crankset complete, Sampson also includes a Black anodized 53 tooth and a 39 tooth SR Roundtech chainrings. The Sampson Road comes in a high, high polished Silver, which is the aluminum highly buffed and left un-anodized. The arm lengths available are 170mm 172.5mm or 175mm. Occasionally some of the polishing compound from the arm finish lodges in the threads for the dust caps, these should be checked and cleaned out before the dust cap is force threaded into the arms. The Sampson cranks don't come with crank bolts or washers or the necessary dust caps, (Grafton or Cooks later in this section are recommended).
The total weight of the 172.5mm Sampson Road double set is 528 grams. The arms and bolts weigh 399 grams, the 39T chainring weighs 35.5 grams, and the 53 T weighs 92.5 grams.
Length-70-72-75 $ Price in Catalog
Sampson Mountain Cranks
