Back in the day we used to have quite a few options in crank arm length and for us tall-ish guys and truly tall guys, a step up from a 'normal' 175mm crank arm to a 180mm crank arm was a fairly common deal. It makes sense to me...longer legs can use longer cranks. Shorter legs can use shorter cranks like 170mm ones. They make more than one stem length or frame size, right?
Now it was always assumed that a longer crank meant more power applied to the pedal stroke. Scientific tests seem to point to this being un-true, but that is not really the point of using them. Sometimes they just feel better or work better for the rider spinning them. When I moved up to 180s about umpteen years ago, it took a while to get used to the increased pedal circle, but after that, and some sore legs, I liked how the longer crank allowed me to stay in a higher gear and turn a slower RPM. I am a diesel by nature, not a gerbil, so I found that the slower cadence fit well with the demands of high torque-in search of traction-long climbs on bad roads mountain bike riding.
Then this testing gig comes along and NO ONE specs 180mm cranks on bikes off the showroom floor, not in any mainline brand anyway. So I get used to spinning 175s on all the test bikes and only keep the 180s on the SS scoots. Fine enough. I adapt. Just shift down a 1/2 gear or so and off you go.
And even I have some mixed feelings about longer cranks on an SS. When the RPMs are high, the 175 is easier to spin and they are also easier to get around the TDC position and onto the next downstroke. But here in the digital land of So Cal and its mountains, we spend so much time far underwater on a typical climb that the 180 crank comes into its own, giving me more leverage on that slow and torturous downstroke at 10 RPM. Still, given the option, I would run long arms on the SS for sure.
But now, just try and find a big box brand crank for an SS in 180s. Man that is getting hard. Is there even still an XT version or just XTR? And SRAM does not even offer a single MTB crank in 180s except the Stylo OCT SS crank and that, from what I have been told, is fading into obscurity too. Forget about FSA or Raceface or such like.
So that leaves us with older stuff we scavenge from EBAY...sweet XTR or something...or the little guys like White Bros or Surly, E Thirteeen, etc. And often that means running a square taper BB or putting up with someone's idea of the new mousetrap (like the Surly or E Thirteen) and discovering that it is not all that well thought out.
So why in the world can I not buy an SLX or X9 level or XT or XO level 180mm crank? And beside that, why so few dedicated SS cranks? Well, if you are a manufacturer or a product manager for a bike company, slapping a one size fits all crank on a bike, especially when no one is really likely to care anyway, is a slam dunk decision. It is likely what I would do too, if that was my job.
Then you add in the fact that the big guys seem to have no idea what to do with singlespeeders and any thoughts they might have for longer crank arm options, and you have a tiny, carbon wrapped over aluminum perfect storm of events that is stealing our easy options for a longer lever.
Now I like options and at least here, we have less than we used to. At least, that is the way I see it.