Shorter cranks for my Stumpy EVO?

Hey Lee,

Happy new year! Quick question: Am I crazy for wanting to put 165mm cranks on my new Specialized Stumpjumper EVO? My inseam is 32 inches, and I ride aggressive trail, with some XC racing. I hope to squeeze in more pedal strokes in these tight Squamish trails, have more ground clearance and hopefully increase my average wattage by spinning a smaller, faster circle. What are your thoughts?



Thanks for the great question.

I want to geek out on this more deeply, but for now:


• Changing from a 175mm to a 165mm crank reduces torque (and increases required force at the pedals) by 6%.

To maintain the same feel at the pedals, reduce your gearing by 6%. Changing from a 30-tooth chainring to a 28 will more than do the job.

• Shorter cranks yield a smaller pedaling circle, which theoretically means you can spin faster, which can lead to higher overall wattage.

A study by Dr. Jim Martin titled “Determinants of maximal cycling power: crank length, pedaling rate and pedal speed” (Eur J Appl Physiol (2001) 84: 413-418) compared maximal sprint power among 16 trained cyclists with 120, 145, 170, 195 and 220 mm cranks. Are you ready? There was no statistical difference between the 145, 170 and 195 mm cranks. More info at

So … If you practice spinning the slightly smaller circle, you’ll likely get good at it. Track racers, time trialists and downhillers all tend to ride shorter cranks, and they’re pedaling just fine.

Ground clearance

A Stumpy EVO is low-slung shred rocket. As such, it likes to stab pedals on technical climbs and when you sprint in the rocks.

Shorting your cranks from 175 to 165mm will give you 10mm more ground clearance when your pedal is at the down position. If you miss a rock by 1 millimeter, you missed it, right?

When I was 16, I drove a forklift in a warehouse that was laid out with one inch of clearance for the forklift and a palette. My boss used to say, “an inch is as good as a mile.”

Let’s use the 2015 Stumpy EVO 27.5 as our example:

Bottom bracket height: 327 mm
BB height at 20% of travel: 308 mm
BB height at 50% of travel: 260 mm
Pedal thickness: 18mm (Shimano Saint flat pedal)

Clearance at 20% of travel – standard sag
175mm cranks: 120 mm
165mm cranks: 130 mm (+8%)

Clearance at 50% of travel – railing a turn, crushing a G-out, etc.
175mm cranks: 72mm
165mm cranks: 82mm (+12%)

Keep in mind: A millimeter is as good as a mile!


On a motorcycle, the footpegs place your feet next to each other. This puts you in the standard human ready position with your hips facing the challenge. This is ideal for lifting heavy objects, riding bulls and, in my opinion, shredding.

On a bicycle, the crank arms put you in a staggered stance, which tends to make you crooked. This can be overcome with some attention (Skills clinics!), but it gets harder with longer cranks. Shorter cranks make it easier for you to ride with your hips square to the challenge. One more reason short cranks feel good on DH bikes.

To sum it up

• Shorter cranks give you measurably more pedal clearance and might help you maintain a better attack position.

• You can probably pedal them just fine. Reduce your gearing and spin to win.

Tell us how it goes!


Know more. Have more fun!

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17 replies
  1. Wacek says:

    BBBut… when you drop the pedal your COM gets lower on longer cranks, therefore you can generate more momentary pressure? Longer crank allows you to ride harder gear, therefore peel is less often in low position, thus less chance of hitting the object?

    Just a thought like acceleration vs momentum vs both debate 😀 Concept of Jungian duality destroyed my mind!

  2. ben says:

    Great timing with this post Lee! I’m about to start a new build and am contemplating cranks right now. Hard to make the leap to shorter with the cost of cranks so high on the bling end of things.

  3. charlie says:

    I found shorter cranks were easier on my knees. For each revolution I lift my legs 10mm less. smaller circle all the way around.

  4. Bas Rotgans says:

    This obviously isn’t ‘scientific’ by any standard, but: during a 9 month rehab from knee surgery I tended to do a fixed twelve minute warm-up on a stationary bike 5-6 times per week. It had adjustable crank length and after establishing sort of a base routine (and how many kilometers I could cycle during my 12 minute warm-up), I started messing around with crank length.

    After a few months I got pretty convinced that the furthest I could go in those twelve minutes was with the crank set at 165mm. I’m 184cm (6′-6’1″?) and should ‘normally’ fit on ‘normal-sized’ cranks. There was something about spinning that slightly smaller circle that gave me more speed/distance (which is just speed x time). I have never taken it too a trailbike, but reading this has sparked my interest in it again… Mmmmh.

  5. Max says:

    So whats the drawback of shorter cranks for general riding and ripping? Given the fact you adjust the gearing, what would I lose if I went from a 175mm crank to a 165mm crank if I’m 6’2″?
    Running a 1x setup.

  6. leelikesbikes says:

    Max, that’s a great question.

    On Facebook, one of my clients, Dan Godard (a pro DHer and all around trail badass) says he runs 165mm cranks at 6’3″. He is not sucking by any means.

    Off the top of my head:

    At full height, your seat would be 10mm higher. But that won’t make any difference when you’re shredding with the seat down.

    I suppose you lose some pop for technical climbing. With reduced leverage at the cranks and smaller gears to make up for that, you won’t get the same distance when you power-pedal up a ledge. I think.

    I’ll give this some thought and research. Any other thoughts out there?


  7. Amit Efraim says:

    Interesting post!

    Just out of my head, trying to think of benefits that might come out of shorter cranks.

    Mathematically speaking, longer crank give you larger momentum. But on the real world you drive this momentum with your legs which have their own mechanical properties. My instinct tells me that shorter crank can put your knee in a position that allows you to get more power out of your quads.

  8. leelikesbikes says:

    I’ve been reading online and paying attention to my body on the trainer. It’s Week 9 of Pump Up the Base, so I’m getting at least 5,000 pedal strokes per session. Got nothing better to do, so might as well learn.

    A theory:

    * A shorter crank has less leverage. We know that.

    * With a shorter crank, your knees are less bent, which give you more leverage.

    * So those factors might cancel each other out.

    If you believe that, plus you can learn to spin them well, you get all the power you need with that extra shred you want.


  9. Nick says:

    Lovin’ the posts Lee, healthy chat like this keeps people thinking about what really works, not just reading the overwhelming amount of marketing hype by the brands.
    I’ve looked at this topic for a few years now, read quite a bit of research and more importantly tried a few options on various bikes and I’m a convert to short cranks (currently 165mm). There are studies that have shown that power output is actually best at around 120mm, which I find hard to believe and that spec just isn’t’ available but challenging the ‘norm’ will continue to drive the standards and performance higher in the sport, keep it up!

  10. leelikesbikes says:


    My bikes all have 175 mm cranks — for no other reason than that’s what I’ve been riding.

    I’m curious about shorter cranks, but then I also think consistency is important, and I’m afraid to open that can of worms.

  11. Alex says:

    Hi Lee, just to further open the can of worms that is crank length I found this quote from Adam Hansen, one of the most analytical pro riders in the peloton, on crank length. He runs 180’s on his road bike and while I appreciate mountain biking is a totally different sport with different requirements, do you have any thoughts? When the leverage is longer, it’s easier. This is endurance sport so obviously you want to push with the lowest amount of effort and power is torque-by-RPM, right? Okay, people say that with longer cranks your pedalling action is longer. That’s true. But, the time is the same. What I mean by that is, if you ride for five minutes, you ride for five minutes, it doesn’t matter if you’re doing a cadence of 90 or 110rpm. You’re still doing five minutes of effort but the one with the shorter crank is doing it at a higher power.”

  12. Alex H says:

    I recently purchased a 1980’s road bike. I am 6ft2 and the bike came with the original 160mm cranks. I was talking about the ‘short’ cranks wth a wise cyclist from my club. He suggested that shorter cranks are good for long distance because the smaller circle means less distance to lift your legs and so you get less fatigued. Just another thought for the discussion.

  13. MW says:

    How about Q? You mentioned lifting heavy objects. I ride with the widest pedals I can find and still get a worn grove in my 5.Tens that are 3/4 of an inch in. We all know that in Snowboarding and “lifting heavy objects” that the width (or Q) helps a ton. I wonder if there is a way to figure what is optimal? Bars got wider, rims got wider……..what next? I know the fat bike dudes run 100mm bb width? Do they feel it in their hips?

  14. leelikesbikes says:

    More worms … all over the place!

    I suppose one could do a bunch of deadlifts in a bike stance (feet about 350mm apart) and see how wide the feet like to be. that’s analogous to the old MX pushup test: do a bunch of pushups, see where your hands end up and make that your handlebar width.



    PS: When i ride a full-on fatbike, the Q factor kills me. That’s why i’m so curious about the new options with narrower Qs.


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