Sampson Cranks

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. The spindle is held in place, once properly seated, by a stainless steel bolt with a 4mm hex fitting. The spider is machined from 8mm thick aluminum plate and has just four arms. The fifth arm occurs on the back side of the crank arm itself as a "hidden fifth 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 


 

A variation in the machining of the Sampson Road cranks produces Sampson Mountain cranks. The Mountain cranks are again CNC machined of 7075-T6 billet aluminum in the same shape as the Road type. The variation occurs in the spider and the hidden fifth arm. The spider has two holes drilled through each of its four arms, the outermost is tapped with threads for an inner fixing bolt set. On the inner arm, 90mm from the B/B spindle center is a slight notch cut to allow clearance for the front derailleur when the chain is shifted to the outer chainring. The "hidden fifth arm" section of this arm is the immediate 1 1/2" adjoining the spider. There are two holes bored and tapped with threads for the inner chainring fixing bolts, both aluminum bolts are provided. One is 12.6mm long to hold in place the outer and middle. The other is longer at 20mm to hold inner chainring. Several aluminum spacers are included with the crankset which accommodate the thicknesses common to most chainring combinations.

This crankset is drilled for the middle and outer chainrings to have a 110mm bolt center diameter. The inner is drilled for a 74mm BCD. Three SR Roundtech chainrings are included all anodized Black. The included sizes are 24T, 36T and 46 teeth. Like the Road version the Sampson Mountain cranks are available only in a high polished finish, leaving a mirror-like un- anodized Silver. As with the Road cranks, the Mountain set doesn't come with crank bolts or dust caps, and care should be made to clean out any residual polish from the dust cap threads. The Mountain cranks are available in either 175mm or 180mm length. The weight of a complete 175mm Mountain crankset is 583 grams. All the bolts and spacers weigh 21.5 grams, the 24T chainring weighs 17.5 grams, the 36T weighs 34.5 grams, the 46T weighs 71 grams, and the arms weigh 439 grams.

Length-75-80   $ Price in Catalog 

Sampson as we understand it, is likely to make HyperDrive-C compatible crankset. What the decision comes down to in the making of a compact crankset is which standard, Suntour Micro Drive using 94mm mid-outer and 56mm inner BCD, or the Shimano HyperDrive using 94mm mid-outer and 58mm inner. It seems that even though Sampson uses SR/Suntour chainrings they are leaning toward the more widely marketed Shimano standard. When asked where they would get the chainrings for the sets, they weren't clear in the answer. The next question was, is it possible that SR/Suntour would begin making Shimano inner replacements having a 58mm BCD. The answer was that couldn't comment on that, but we got the impression that if it weren't true we would heard so, they just didn't want to be the source. When Sampson finishes and releases their HyperDrive compatible cranks we are certain to stock them. If they are of interest to you call occasionally to seem if we have them in stock yet.

Length-75-80  $ Price in Catalog