Short-ish cranks for a tall-ish rider (XC)

Equipment
1

At 6’2” I’ve pretty much always run 175mm cranks on the mountain bike but now I’m looking to go shorter (pedal strikes, hip angle).

Curious what the other XC folks are running. I was thinking 170 but maybe 165?

2

I’m 6"1, have been on 175mm cranks for years. Just switched to a bike with a lower BB and was getting way more pedal strikes. I was pretty apprehensive to reduce crank length after so many years on 175mm, but pulled the trigger with 170mm a few months ago.

I hardly notice the difference in crank length. Maybe riding with a bit higher cadence than normal on the trainer. But definitely have way less pedal strikes. No difference in power output. Overall definitely recommend the switch to shorter cranks, 165mm does seem pretty short at your height though.

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3

Second that opinion. I’m shorter at 5’9" and have been running 170s forever. Started on Mtb (Thanks Tinker Juarez) and just felt right to have 170’s everywhere.

4

6’0 165mm cranks here on my road bike (aftermarket), 170mm on XC bike (stock).

5

6’ and run 170’s on all my bikes (including XC).

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6

193cm and changed both MTB to 170mm cranks.

Only positive sensations.

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7

6’ and use 170 for the XC, 165 on the trail bike

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8

I changed from 175 (MTB) to 170 with my first road-bike, the difference in pedal stroke felt immediately restrictive, as though I could “just not get the power down” - especially on climbs.

My Quads were over worked, and had to take a week off to reset.
(Probably the change in geometry more than anything)

I gradually adjusted, and now actually prefer the shorter length, it feels more efficient and now ride with a slightly higher cadence.

You will probably need to raise your saddle at least 5mm and move forward a fraction to compensate for the shorter crank. - for me this was a pain as the previous owner had slammed the stem and cut the forks… I eventually got used to it but most likely need to raise my bars somehow

9

6ft and immediately went 170 after trying stock 175. Shorter cranks for off-road is a no brainer if just to keep your feet away from stuff.

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10

5’ 10" on and 165mm on all my bikes to help open up hip angle. Never looked back. My feeling is its a lot easier to spin at higher cadences. Would still go to 165mm if I was 6’
I got them after being recommended to do so by a bike fitter 5 years or so ago. I had another fit 12 months ago and the guy completely agreed with the choice before he even saw me on the bike.

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11

I just shortened mine 172.5 → 165 today (5’8"; very short legs) and this “restricted” feeling captures it perfectly. I don’t feel like I’m opening up and don’t feel like I can properly engage my glutes. Not thrilled.

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12

5’ 11” & 165mm cranks on my road bike, 175mm on the mtb. Being more upright on the mtb I don’t find as need a super short crank to open my hip angle, but I can see how 165 maybe have some clearance advantage.

On my road bike I generate more power in a full aero position with the 165 due to a more open hip angle and less stress on my lower back and hips. When i’m riding more upright just cruising in zone 2, 165-170-172.5 doesn’t seem to make much difference. Most people probably don’t need shorter cranks IMO.

13

Have you raised the saddle to compensate for the shorter cranks? The saddle to pedal at lowest position distance should be the same whatever crank length you have.

14

Yes. Moved it up the difference between the arm lengths.

I will mess with it more. I definitely want the clearance and I can get a lot lower before kneeing myself in the chest now. But disappointing that RPE went up.

15

5’8" and I have major discomfort at below 170. 170 is tolerable, but I prefer 175. I haven’t tried going longer.

I did a blind test (my LBS accidentally installed a 175 instead of a factory 165) on my long travel bike, and that did wonders for my riding, and I didn’t even know why for a couple weeks.

16

I am 178 cm, but I have long limbs. I opted for 165 mm cranks to combat hip impingement, riding aero with 172.5 mm cranks was really uncomfortable, I’d literally massage my breakfast.

I have 175 mm cranks on my mountain bike coz that’s what it came with. And I don’t have it in my heart to throw away or auction off for cheap a mechanically perfect XTR crank. Pedaling felt super weird, so I put an oval chain (Rotor) ring on it and that helped some. My next mountain bike will have 165 mm cranks simply because that’s what my legs are used to now.

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17

I’m 6’3” 220lbs riding an XL Rocky Mountain Instinct with 170mm cranks, and am XL Chromag Rootdown hardtail with 175mm cranks. Both bikes running 30t front ring. With current low bottom bracket designs, I think 170mm cranks are necessary, especially for heavier riders.

If you’re pedal striking P, then yes change to shorter cranks and then maybe change your chainring and adapt your cadence.

Observations:

  1. Both bikes feel good to ride. I ride the Instinct 80% of my rides and I can immediately tell the cranks on the Chromag are longer when I get on it.

  2. The Chromag accelerates faster. Sure, it’s a hardtail, but even locked out the Instinct takes more rpm to get up to the same fast speed. Smaller cranks require faster rpm to match initial leverage and power in some situations.

  3. In slow, technical riding (like trials) the longer cranks provide greater leverage and I find it easier to pull off some pedalling power moves. Also, the application of power is smoother when you pedal. (Longer circumference)

  4. On a full squish bike, using “trail mode” on the shock keeps the BB higher for less pedal strikes overall. You can also add volume spacers to keep the bb riding higher in the “open mode” depending on your riding style.

References:

http://www.flammerouge.je/factsheets/torque.htm

http://www.flammerouge.je/factsheets/cadence.htm