Narrow Cranks for the Stumpjumper

This is a quick one while I’m busy modeling the new bike and about to head up to Oregon to do some press at the MADE show.

Back when we were assembling Windy’s Stumpjumper one year ago, there was one detail that I didn’t address. It was the Q172 Shimano FC-7100 SLX 170mm cranks.

While the fit and finish of these cranks is nice enough, the width is just absurd for most uses. Even I haven’t run cranks this wide in well over a decade and I’m considerably taller than Windy. Getting that width to something narrower would be nice, especially as how tuned this bike is.

I had a few SRAM cranks on hand that might work. 00.6118.303.008 FC RIVAL 11SPD 24MM 73 170 5034 GXP. I did some measuring and found a chainring and bottom bracket to make for a fit test. The ends of the new cranks were so mangy and I could open up some space if I chamfered them, so I did.

These old Rival cranks measure at Q155. I could bring that down with some Q150 (wide) SRAM Force cranks but this will be fine for now, and I got out cheap.

This was a 17mm decrease. That’s pretty huge in the tuning world. I know of few that invest this deeply in performance setup.

It was some basic rotary table work on the mill. Along with a chamfer mill.

Luckily, this bike is set up with a 32t chainring and there was just enough clearance for that. It may not work with a larger ring.

A few test rides in and there’s been no issue. I’m happy that I finally got to this.