I am pretty much decided on getting some rf turbine cinch cranks. They are available in 175 and 170mm. Being 5’8, some would say I’d benefit from the 170mm cranks (current cranks 175m). So who’s changed crank lengths and did you notice a difference? I do have occasional knee niggles but this is more related to an inwardly collapsing foot caused by forefoot angle

Running 1by with 34t front at the moment, was going to go up to 36t, but I’m not sure if the lesser leverage of a shorter crank should make me reconsider this?

My ‘cross bike is 175mm, and when it gets really dark and wet I’ll be using it on turbo trainer a lot through the week, will my training with 175mm cranks mean my legs are less suited to racing xc on 170mm cranks?

170 here, and I’m 6’2″. Didn’t notice any difference in pedalling when I swapped from 175s but best difference was less pedal strikes when climbing rocky stuff.

I have to have 170mm because of pain in my knee when I use 175mm.

170mm allows for my reverb to be set at a good height as well.

5’7″ and using 170s and 165s. FWIW, I find climbing easier with a shorter crank. Saddle height goes up a bit and fewer pedal strikes too.

165 here, on the mtb (for pedal strikes mainly)

I’m 6ft 1

I used to have 180s on my road bike – can’t say the difference is significant to me in use, though you can tell that big a gap when you first jump on

Going from 175 to 165’s cured the hotspot on my knee and I haven’t noticed any drop in efficiency ..

5’10.5″

172.5 on my do-it-all-bike
165 on my fixie.

I’m not very sensitive to component changes and how it is affecting my riding but every time going to 165 or back to 175 is a MASSIVE difference.

In my opinion (and feel) short arms cranks fore more cadence based peddling, longer promote more physical action.

Cheers!
I.

170 on my bandit. Definitely works out with less pedal strikes. Have put 175’s on everything else though.
I’m 6 ft and they work fine. In fact other than the pedal strikes i can’t notice any difference

i’m 5’10” and short 31″ legs. i have 175 on the fs, but had some second hand 170s on my hardtail and i think they were better tbh, certainly felt easier to spin and less pedal strikes too – surely shorter legs need shorter cranks. i’m seriously considering getting some shorter cranks for the fs.

Cheers all, porter Jamie, do you notice a difference switching between bikes?

I had 165’s on my Meta55 to sort out the pedal strikes from the low bb on those. It worked and I didn’t really notice the difference from the 175’s

May ’14 I changed bikes and just swapped everything over. Recently I put some 175’s on the current bike (higher bb) and I think, I think it’s easier to pedal. Maybe.

5’6″ and 29″ inside leg.

170 here 5’6 , not much pedal strikes as before as I like to run more sag than norm..should have gone 165 really..

Ran with 175 for absolutely years. Switched to 170 a few years ago, definitely notice the difference. I’m almost 6.2″ but moved to lessen pedal strike etc. fine tuning and worth it.

Mmmm, think I’ll maybe try it, do get a few pedal strikes, including one that sent me flying head first into a rock.

Any race-heads or people who understand physiology fancy commentating on whether training on two bikes with different crank lengths would make a difference to performance? I guess the muscles are still being worked the same.

165 and 6’3 here. Could feel it a touch at first, but then settled in great and personally prefer them now.

5’8″ here and have been using 170mm for years. I used to get knee pain with 175mm

I’m sure I read on here that 170mm cranks the hole has been moved 5mm , arms are still same length??

I’m on 185 here. Not looking forward to the day that they break, no idea how I’d replace them.

I have some 175 turbine cinch cranks which will be up for sale soon.

I’m 5’9″ but more relevant to this discussion I have short legs with a 30″ inside leg. I have 175mm on my MTB, 172.5 on my good road bike and 170mm on my knock-about/pub/’gnarmac’ road bike. I really cannot tell the difference going from one bike to the other. I do get pedal strikes on my MTB but I put that down to lack of skill rather than crank length – reading the trail and timing your pedals – I often put in a quick half rev, or delay the start of a downstroke to time my pedal revs if I see something coming up and want to avoid a pedal strike, but I don’t spot every instance. And in the pedal strikes I do get they are more of than 5mm worth of strike (i.e. quite firm strikes), so i’d get them no matter what crank length I ride.

175mm cranks seem to be cheaper than the others so that’s why I’ve got 175mm on my MTB. I replaced the cranks the bike came with when I went 1×10. The origianal X5 cranks were 170mm and I wanted some X9’s so I could get a spiders chainring and on eBay the 175mm cranks were alot cheaper than the other lengths. Again, I noticed no difference going from one to the other, apart from the cost of the crank.

I really struggle with the arguments for any crank length. Unless you have any medical/physiological issues then it really doesn’t matter, and surely you’re better off running as long cranks as you can, because for any given RPM you’re generating more torque and therefore power. This is cycling and when you need power you can’t get away from having to push down hard on the pedals (and pull back at the bottom, pull up on the upstroke and kick forward at the top) so if you’re putting in the effort you may as well try to get as much mechanical advantage out as you can.

170mm on the MTB…..172.5mm on the road bike.

If I was building a true AM, DH type bike from scratch I’d go 165mm to avoid pedal strikes over rough ground.

5′ 9″ by the way with 31-32 inch inside leg.

165’s on my full susser to sort pedal strikes. Noticed how much I could keep pedalling through the rough stuff and started spinning more. I do notice jumping back on a bike with longer cranks 175 etc but after a few minutes you settle back into it. My new bike has 170’s and I doubt I’ll ever buy longer again. FWIW I’m 5’10 and would say height is only of minor relevance in the case of road bikes.

I’m 5’11” and tried 170mm for a couple of months but got a lot of knee pain. Tried adjusting them but just couldn’t get on with them. Switched back to 175 and now have zero issues.

167.5 on the summer road bike and the improvement in knee pain was noticable. Everything else has 170, but will go to the small size when I can afford to replace them all.

I’m 5’8″

170mm, 165mm and 175mm on my MTBs, 172.5mm on my roadies.

Cranks get shorter as bikes get more gravity focused to prevent pedal strikes.

Leverage not a massive issue IME, unless you have weak sparrow legs?

more about leg length than height. With 175s I always felt like I was bobbing on the saddle at high cadence, with 170 that goes away. If you can borrow any 170 cranks off a mate for a few weeks it’s worth seeing if you can tell a difference.

175 on all my bikes apart from the singlespeed which has 180mm.

Dropped to 170mm on my CX from 175. Felt a ton better, just easier to spin. Short legs, though.

Also built my HT With 170s and that has always fel right. No idea what’s on my FS as its in the LBS.

1 70’s on the full sus
175’s on the fat bike.

No noticeable pedaling difference but I get more pedal strikes on the 175’s…..

There’s been a fair bit of academic study on this. Basically there’s no difference in power output between about 140mm and 200m cranks. On longer ones torque goes up but cadence goes down.

I’m 5’10.5″ tall, measured my inside leg accurately recently and its actually 34.5″ (book to floor method) though I wear 33″ leg trousers. 175mm on the hardtail, changed to 170mm on the full-sus and I think that’s better in every way.

I’m sure I read on here that 170mm cranks the hole has been moved 5mm , arms are still same length??

Only on cheaper ones I think.

I use 175s on my SS, 170 for road bikes and when I get round to getting a new crank for my geared MTB it’ll probably be 170mm. 6′ / 34″ IL. I think anyone under 5’10 is probably better off on 170s on any bike but when I specced 170 on a M size 29er a couple of years ago it got marked down for it in MBR.. ‘ a lack of power’ or something like that. And we still get people asking if we use 170s on the MTBs occasionaly, seeing it as a negative (gone back to 175s). I think it’ll all change before too long though.

One daft crank length thing I found recently is that the shortest Shimano STEPS E-bike cranks go is 170mm and there you hardly need any leverage.

I’m 5’11”, Run 175’s on my hardtail and 170’s on the full suss (to reduce pedal strikes). Can’t say I can feel any difference.

175 on the HT. 165 on the FS mainly for pedal strikes but it gets up to speed quicker too.

davewalsh – Member
I’m 5’11”, Run 175’s on my hardtail and 170’s on the full suss (to reduce pedal strikes). Can’t say I can feel any difference.

There isn’t much difference to feel (between 175 and 170), it’s about 3%.

C’mon shimano, you go to the trouble of making cranks in different lengths, but only over a really small range. It’s just daft.

182cm 172.5 on one bike, 175 on the other, cant tell the difference.

I’m 5’6 and went from 175mm to 165mm cranks and I can absolutely tell the difference.

I have ridden occasionally for years, but became more active a year ago and got a new hardtail on the bike-to-work scheme. Gradually I realised that I got knee pain after riding for longer distances (>20km) and especially if pushing hard up hills. I thought this was due to lack of fitness / condition, and stuck with it for ~9 months. Then I decided it was just a case of rule 5, and started trying to ‘ride through it’. I ended up with a *really* sore knee.

On my way back from this, I eased myself back into it on my old bike OK, but whenever I rode my new bike, I could feel the knee pain coming back, even with moderate exertion. Even on the old bike, if I pushed hard, I could feel the same thing,

About this time, my mate got a new bike and we swapped over during a ride. The first thing I noticed was that the cranks felt better (despite going from 100mm XC hardtail to 160mm Enduro FS).

I hadn’t looked at crank length until this point:

My old bike, and my mate’s new bike had 170mm cranks.
My new bike had 175mm cranks.

Now the difference in my knee could be put down to differences in saddle height, gearing or setup between bikes, etc. but try as I might with adjusting these, I couldn’t eliminate the tell-tale signs of knee pain on my new bike.

I rode similar routes on both bikes and found that even though my speed was similar, I ended up with knee pain on my new bike, but not on my old one.

Having tried all the adjustments I could think of, I was convinced that crank length was a likely factor. Having then read this , which suggests that going shorter is unlikely to be a problem, I decided to bite the bullet and blow £100 on some 165mm cranks.

They felt like a kiddy’s bike to pedal for the first 30 seconds, then were no different to anything else. On the first outing with them I broke my PR on a local climb without really feeling like I was ‘going for it’, and have set new PRs on other climbs since. I find it easier to keep up a decent cadence, and *much* easier to pedal out of the saddle with the shorter cranks.

I’m definitely not slower with the shorter cranks. I also used to get lower back pain on long, draggy climbs, but this has gone too, since changing cranks.

I suspect that people above about 5’9 can’t tell any difference, but that it becomes much more significant as height (and proportionate leg length) gets shorter than this. In hindsight, the feeling of pedaling the 175mm cranks was akin to walking up stairs two at a time – doable, but energy sapping and not particularly comfortable.

I’m not trying to present this as conclusive evidence, but I do think it is significant data point for the short-arses amongst us.

I’m sold. Going to give 170mm a crack. I’ll heli-tape them up and the worst comes to the worst I’ll sell them on in a few months.

Thanks for the comments.

5’7″ on 165 XT, son uses 150mm cranks and he is 4’7″

5’9 with a 32″ inside leg. I was using 165mm for a few years there and decided to try 170mm to get a bit more leverage. Can’t say I noticed much difference in pedaling (though out of the saddle sprinting seems better than seated spinning) but far more pedal strikes. Bottom of the cranks are getting seriously chewed up after maybe 3 weeks use.

I can only comment regards their road use. I’m 5’8″ and can tell the difference between 170 and 175.
Mainly racing, just chipping along and on seated climbs. They seem a little less reactive. And less fatiguing.
The only time the longer crank feels useful is on standing climbs and when under way like time trialing.

The MTB has whatever the factory fits.