I’ve always ridden 175mm cranks. I probably saw something years ago that said that 175mm was right for my height & stuck to it.

My ancient 9 speed Octalink chainset will one day give up the ghost and I’ve picked up a set of (not much younger) 9 speed HTII cranks from Ebay to eventually play around with; these are actually 170mm.

I tend to get a bit of leg pain if my saddle isn’t ‘just right’, so that might need a tad of adjustment but other than that, is 5mm noticeable?

A quick browse on the ‘net comes up with the usual lack of consensus with some sites rigidly sticking to the 5’ 11″ = 175mm cranks and others stating that shorter is better.

I’m not a performance athlete, just a keen pootler – just try & see & adjust if necessary?

I spent a year on 170 on the left, 175 on the right, never noticed.

I’m 6ft1 and have used 175 and 170mm cranks.

Both are fine.

I used to think it did and religiously ran 175mm cranks. My three bikes now have 170,172.5 and 175mm cranks and I can’t tell the difference between them after a few hundred yards.

If you’re really sensitive you’ll probably notice for about 5 mins, and then you’ll doubtless adapt and forget all about it

At least, that’s what happened to me

You might notice something strange in the first 2 minutes but then you’ll get used to it and never think of it again. I’ve currently got 165mm, which replaced 175mm crank on the MTB and 172.5 on the road bike and commuters no issues chopping and changing between those bikes and no issues riding at my preferred cadence.

My dad runs odd length cranks after a total knee replacement. If I ride his bike, it feels weird for a few mins, then you get used to it.

I genuinely have no idea how long my cranks are on any of my bikes (I’m pretty sure they all match though).

170mm on MTB and 172.5 on g-bike – honestly can’t tell the difference but they have flat and SPD pedals respectively and are pedalled in different environments so there’s a lot of factors at play.
The shorter cranks are probably a benefit on the MTB because it has a low BB other than that I doubt you’ll notice anything

I use different longths on various bikes and I think 1 has each crank different by 2.5mm

Never noticed a difference.

Have met folk who say 5mm gave them loads more power etc.

I can tell going from my bike with 170 cranks to 165 but not the other way around. I’ve had 175 in the past which were fine off road but I didn’t get on with them if I took that bike on road and was seated for a long period. And your height isn’t really relevant it’s your leg length to be considering. I think the conesus is that cranks that are too long for you may give you problems but there isn’t really a crank that is to short in terms of causing discomfort or injury.

Much weirdness for me! I’m 6’1″ and all my bikes (6) have 175mm cranks except one (the cranks that came with the bikes), the one that hasn’t has 172.5 and feels much nicer to pedal!

I’m quite happy on the longer cranks and have no issues with riding those bikes all day, but the shorter ones just feel sweeter. I’ve messed about with all the bikes seating positions and such like to try and make them all feel that sweet but to no avail. Everything else is the same on the bikes, all SRAM, all GPX BB’s (except one, not the sweet one though). I wouldn’t have thought that 2.5mm would’ve made that much difference, but it does!

I can tell. I’m on 165s on the FS and 170s on the 29er. 175s feel too long these days, for me.

I switch between 165 and 175 and don’t notice it. Probably because they are bigger things to notice when swapping between a slack hard tail and a fixed gear track bike.

Too long is meant to make a difference.
Too short isn’t.

I think that was from Sheldon.

https://singletrackworld.com/forum/topic/crank-length-10/

Reading from various fitting books and articles it seems that crank length is mostly about fit.
I think same goes with Q factor, one width is no better than other performance wise but comfort on bike may depend on it.

The much quoted “longer cranks = more leverage” probably works for singlespeeds but if it’s not possible to push one gear, I’ll swap to an easier one.

Too long is a greater problem for me. I tried 180mm which meant lowering the seatpost to fit at the bottom of the stroke. This meant that the top of the stroke overbent my knees and caused issues that way. Sit 5cm lower with a 5cm longer crank is 10cm on the top of the stroke.

So, yeah, what Sheldon said.

I had a (Road) bike fit and the difference between 172.5mm as fitted and 165mm that I ended up with was huge. On the fit rig when the cranks were dropped I could considerably increase the resistance whilst maintaining the same cadence.

All my drop handle-barred bikes now have 165mm cranks, although I’ve not caught up on my MTBs yet that have 170 and 175mm cranks; I will change them in time though.

When I went to a single chainring setup, I used Sheldon’s online gear ratio calculator to work out what size chainring and cassette to use for the best range of gears. Crank length is a factor. I’d been riding 180mm cranks for years (I’m 6’8″), but when I entered 175mm into the gear ratio calculator, it actually gave me a better higher gear and overall gear range. So I changed to 175mm, and certainly couldn’t notice any difference in how they felt whilst pedalling.

I can tell. On road I prefer 170 because it’s more comfortable to.spin at a higher cadence seated. Off road I prefer 175 because it feels better if I’m standing, although I’m not quite sure why.

I can’t tell the difference if I’m honest, so long as the pedal spindle to top of saddle is set right.

I’ve got 162.5 on my track bike, 172.5 on my road bike & cross bike and 175 on my MTB’s

Cheers all. It sounds like it’s a regular topic of conversation & debate and almost certainly not something I’m going to notice (bar perhaps a saddle height adjustment).

I prefer 165mm if I can get them, otherwise 170mm. I had been using 175s and 172.5s but then I borrowed someones bike with shorter cranks and found climbing much easier. I’m 172cm with average leg length for my height.

Surely its all relative to your height/leg length.
I’m 170cm and prefer 165 to 170. Actually find my bike handling is better on 165.

175 are very tiring on climbs- spinning those huge circles.

Surely longer cranks have the effect of lowering the gear ratios .

175 are very tiring on climbs- spinning those huge circles

Yeah actual spinning is much easier on 170s for me – hence their use on road. On MTB I find myself ‘pushing’ the pedals more than spinning them, and for that the biomechanics seem better for me at 180cm.

Surely longer cranks have the effect of lowering the gear ratios .

Yeah they do but also increasing the range of motion of your muscles, which changes (slightly) how they are recruited. You have to move your legs less on shorter cranks which is why I think they work better at higher cadence. Moving your legs up and down takes energy all on its own.

Also… if you are shorter of leg, on a large wheeled bike and want to go bikepacking, shorter cranks give you a bit more space for a decent-sized seatpack.

165 on track bike and FS bike. Up to 175 on other things.

You can feel 10mm difference but it doesn’t matter. If anything I find shorter cranks better for my knees (with saddle slightly higher) as I’m bending them less. I do wonder about the difference it makes to my ideal cadence and gearing though – I maybe should fit a bigger block to compensate.

I have 170s now on both bikes (FS trail bike and gravel bike) for the first time, I’ve always had the default 175s.

I’ve found no drawbacks – but two very noticeable benefits.

A) – Increased ground clearance with low BB trail bike – prone to rock strikes as it is, the shorter cranks have lessened this.

B) When I changed to flat pedals I needed to drop my saddle height a few MM to make up the difference – this was impossible as the Reverb post is slammed in the frame. Changing to the shorter cranks gave me the shorter saddle – pedal distance I needed.

Means I can ride the large size (I.E. longest) frame, with the 5″ travel dropper, but still fit my comparatively long torso/short legs.

I am definitely interested in trying 165s next!

Pedal stack height could also impact as much as different length cranks. Worth considering.

rickmeister

The much quoted “longer cranks = more leverage” probably works for singlespeeds…

I have often wondered if that is actually true in practice rather than in theory, and if I ever find a set of short cranks, ie ≤ 160mm I’ll do a back to back test on a climb.

The long crank gives you more leverage, but countering that is where your peak muscular force is applied, eg if you are doing squats with heavy weights, the portion of the lift where your knees are less bent is relatively easy.

So maybe a short crank which doesn’t bend your knee so much will enable more force to be delivered from your leg, and if it is greater than the amount of leverage lost by the shorter crank, then it’s a win.

The mechanical leverage of the crank is offset by the gear ratio you choose. The amount your legs bend is not.

Pedal stack height could also impact as much as different length cranks. Worth considering.

DIfferent factor though, you just move everything up or down a bit for different pedal stack heights.

(FWIW I’m 6′ and like the 165mm cranks – switched to minimise pedal strikes as I’m more used to old-skool geometry)

I’ve yet to find a downside to shorter cranks! I used to use 175s, then tried 170 and then 165 for a bike with a very low BB. I’m 179cm (5’10.5″) tall with long (about 33.5″ / 85cm) legs.

I suspect most shorter people, especially those with short legs, are being done a huge disservice by the current range of crank legs on offer, which is very limited compared to frame sizes / seat tube length / reach.

At the moment the biggest range we have is 165mm to 180mm. I think I’m happiest on 170mm cranks but I’d rather ride 165 than 175. My legs are slightly longer than the average 6′ man. So what about the majority of the population that has shorter legs than me?!!

https://specialites-ta.com/pedaliers-complets/298-1124-pedalier-specialites-ta-horizon-super-compact-noir-phantom.html#/90,longeur-de-manivelles,165mm/120,couleur-de-la-manivelle,noir/122,denture,46-30