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  • Advice on choosing correct crank size length
  • I’ve just received my new crankset today I(Hope Evo 175mm ) to fit onto my orange five mk 2. I randomly stumbled across a video on YouTube regarding getting the correct crank lengths and now I’m debating if I should of got a smaller 170 or maybe even the smallest hope do the 165 I believe it is or something similar). I have always used 175mms as they are generally the standard bikes come with so I didn’t know any different untill watching the video.

    I’m 5 ft 9 with a inside leg of 29” , and this particular crank is for a five 2016 model. I’m not really I’n a position to buy random cranks with variable sizes to find the perfect one so this is basically why I’m asking on here. I’ve never used another crank size than 175 so I don’t know if smaller cranks will be any better. I do get the occitional pedal strike although how much that has to do with the cranks pacifically I don’t know.

    Reason I’m asking for advice is because the crankset as you can imagine I was quite expensive very infact for a crank and I wonder do you think it’s worth returning it for a smaller 165 or 170mm version. How important is it?

    Basically would you say it’s worth it to send mine back for a smaller one or is it really not that much big of a deal?


    Inside leg of 29″ might point to 170mm or even 165mm.

    I’ve a 30″ inside leg, 5’7″ and use 170mm.

    What size frame? I’m guessing at small or you won’t get much drop to a dropper.

    Middle ground would also be 170mm.

    I ride a medium it’s pretty perfect for me tbh.


    I’ve gone go 165mm due to pedal strikes, nothing negative so far, all positive, if anything a bit easier on the knees and hips.

    My legs are almost 5” longer than yours and I ride 165 and 170mm cranks. I think 170 suits me best but 165 is better than 175. You will definitely prefer shorter cranks!

    Premier Icon Poopscoop

    My view?

    If you hadn’t seen the video you would have been entirely happy with the 175’s.

    I’ve always had 175 since I was even aware of what length they were and that choices are

    Pedal what you’ve always pedaled I say unless you have a damned good reason not to.😃

    Premier Icon jairaj

    If I’m throwing my 2p in …

    I have similar views to Poopscoop, the disadvantages with a longer crank are either increased pedal strike and or uncomfortable knees or leg pain.

    If you’ve used 175 before and it works fine and you feel trying something else might be too risky then stick with the 175.

    Premier Icon Alex

    As bikes have got lower, I switched from 175 to 170. For latest build it’ll be 165. More clearance (esp with flats), same cost so works for me. Also if you’re short-legged (like me for height) then it helps with dropper posts as well.

    I’m sure there’s some leverage/power loss argument but I’m not sure 5mm is going to make much difference…

    Premier Icon Dickyboy

    You seem all at sea over your choice of crank length… if you can change them to shorter at no expense then do so, otherwise stick with what you’ve got.

    Premier Icon wobbliscott

    I went from 175mm to 165mm for pedal strikes when I got a new bike with a lower BB height. It felt a bit different (not better or worse) for about the first 5 mins of the first ride and not thought about it since. And I still get pedal strikes. Got 172.5 on my road bike and 170mm on my commute bike and have no issues going between them all. And I do a few spin classes a week and I have no idea what the crank length is on the spin bikes.

    I don’t think there is a ‘correct’ crank length…its all personal to the individual. You can use some guideline based upon your height or inside leg or something as a starter for 10, but with cranks its hard to try before you buy so you just have to decide somehow and cross your fingers. You can overthink some things and crank length is one of them. Unless for some reason you don’t get on with a particular crank length and you can’t dial it out by changing saddle position or cleat position then clearly it becomes an issue for you, but the chances are if you didn’t know what length your cranks were you probably wouldn’t care or even think about it. Sometimes ignorance is bliss.


    If you do go for shorter cranks then you’ll need to raise your saddle accordingly.
    When herself had her first bike built by Andy Thompson it was designed for 165 cranks with a lower bottom bracket which meant she sat further into the bike rather than on top of it.

    Premier Icon notmyrealname

    I’ve just bought a new groupser for my Solaris build. It was £180 cheaper with 175mm cranks rather than 170mm. That’s good enough reason to decide my crank length!


    I had a telephone conversation with Cy at Cotic in this …
    He feels it makes very little difference …

    Premier Icon oldnpastit

    Some of my bikes are on 170mm, some are on 175mm. I can’t remember which, and I don’t notice any difference when going from one to another.

    Premier Icon Greybeard

    Shorter cranks will stress your knees less, but the reduced leverage means you’re effectively in a higher gear and may need to tweak tooth numbers if you normally need the lowest gears on climbs.


    I’d never thought about it until I had to for kids bikes.
    I’d put the discomfort on riding one bike down to geometry or something … and I’d never thought about crank length. One bike just killed me and had me hobbling for a week and the other didn’t.

    I’d probably better add I was approaching my 50’s at this point and 29″ inside leg
    A lifetime of the wrong cranks has screwed my hips and knees… I never used to notice it but in retrospect I feel the damage was cumulative and accelerated as I got older.

    So…. I swapped the cranks on 2 bikes and the comfy one swapped over… this was just 175mm-170mm
    No disadvantages noticed…. such as reduced leverage. It also places my differently on the bike so when seated I’m further back and moving the saddle back also has advantages (previously as far forward as possible)

    From time to time I ride VERY short cranks (142mm on the kids bike) and even with that extreme the reduced leverage isn’t a huge difference.

    If I was buying new cranks I’d be getting 165mm

    165 here

    Less pedal strikes. Simple.

    Premier Icon chakaping

    28in inside leg here.

    Settled on 170mm but have been OK on 165mm too.

    No point in 175mm any more, for me.

    Premier Icon Alex

    I think Ben @ Bird first got me thinking about this. His view – if I remember correctly – was the 175mm was a hangover from Road bikes?

    I guess we didn’t care until bikes got lower to the ground. Then if you live somewhere rooty/rocky you care a lot. Pedal strikes rarely end well. My mate bought a Liteville XL and it came with 180mm cranks. He was bashing pedals everywhere. He’s happy on 165 and he’s blooming enormous!

    Premier Icon 13thfloormonk

    Not much to add, I bought a complete build singlespeed (Charge Plug) which bizarrely was slightly over-geared for its intended use, but came with 170mm cranks, when 175mm might be considered standard for a size Large.

    This became my most ridden bike so when given the choice I’ve swapped all my cranks to 170mm also for consistency.

    A Bikefitter commented on my road bike that (including cranks) I had pretty much the most knee friendly position going, which was enough for me, so all bikes going forward will be 170mm also!

    Haven’t noticed loss of leverage, but then am a spinner anyway.

    Haven’t noticed a difference on hire bikes, but they’re usually 172.5mm I think so doubt I’m sensitive enough given that I’ll only do a couple of rides on a hire bike.

    If you have the time and patience I would maybe return for a shorter length.

    Premier Icon snotrag

    I never thought about crank length much until a few years ago realsied that if I went to 170mm cranks, I could buy the large (read: long) frame size I wanted, and still fit a dropper post.

    This has now happened a couple of times and my last few bikes have been size large, with the dropper post slammed in. I am 5ft 10 but with short-ish legs and long torse.

    It has also had the effect of reducing pedal strikes a lot, particularly on modern full suspenion bikes. I have noticed zero drawbacks, to the point where all my bikes since have ben changed to 170mm.

    6ft here. 32.5 inch inseam. I’ve run 175s for 18 of 20 years mtbing and not thought about it.

    I’m now running 170mm for pedal strike considerations on lower bikes. I found 170mm tiny bit more spinny and nitro my knees and hips.

    I’m now contemplating 165mm, mostly to improve pedal strikes some more.

    6ft here. 32.5 inch inseam. I’ve run 175s for 18 of 20 years mtbing and not thought about it.

    I’m now running 170mm for pedal strike considerations on lower bikes. I found 170mm tiny bit more spinny and nitro my knees and hips.

    I’m now contemplating 165mm, mostly to improve pedal strikes some more.

    Pretty much me too, only 2″ taller, there’s no downside to shorter cranks that I can feel when riding.

    Premier Icon ads678

    If you’ve fitrd them leave em. If you can change them, I would.

    165 here with 31″ inside leg. I did have a bike with 170’s until recently and couldn’t tell the difference

    But shorter cranks means less pedal strikes, so keep your nice ano cranks looking sweet for longer.

    Premier Icon lunge

    6’4″ here and on 175’s, and to buck the trend, am debating longer.
    I’m a grinder and not a spinner so like the leverage. I’ve also got very long legs so the knee issue isn’t a factor for me.


    Good topic op, was funnily enough going to start one

    As considering an expensive crankset that needs a decision of length on arms firstly though

    Ah so I’ve read each reply and decided to go with a smaller crank based on the advice given. Now the question is 165 or middle for diddle 170. Thanks for all your replies very inedepth and informative!

    Premier Icon mcnultycop

    After a road bike fit I went to 165mm and it made so much difference, it was just more efficient (power data from the fit showed this). I’m similar dimensions to the OP.

    I’ve not swapped on my MTBs yet and get by on 175mm but as soon as I get a few quid I’ll drop to 165mm on them too.

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