I’ve always been 175 on the mountain bike and 180 on the bmx.

have a set of 170 for the mountain bike at the moment and they feel really short. Is there any benefit to me using the 170’s or better to just go back to what I’ve always known…

165 on one bike and 170 on the other. Not a lot of difference but would opt for 165 out of choice though it limits the cranks available.
I’ve had 175’s which were fine off road where you’re moving around a lot but my knees didn’t like them for road sections.

I have 170, 172.5 and 175 and really can’t tell the difference

175 on th emtb and 172.5 on the road, there are probably other variable affectingit like seat height, but they do feel smaller. 170mm on the roadie SS (was supposed to be fixie but CBA building a new wheel), and they feel really short.

Once had 165/175 on L/R as a bodge, that felt really wierd!

Once had 165/175 on L/R as a bodge, that felt really wierd!

haha!

Can people REALLY tell the difference of a couple of mm in crank length?

Geared roadie and MTB both have 175mm cranks,my SS roadie has 170mm and I can jump from one to the next and cannot tell any difference what so ever.

The mtb and SS both have Crank Brothers pedals so no difference in stack height either.

unovolo – Member

Can people REALLY tell the difference of a couple of mm in crank length?

God yes.

170mm on the road bike and the mtb, 175 on the tourer – will be 170mm on everything soon though.
I’m short with dodgy knees – does make a difference to me.

Deffo less rock strikes with 170mm off-road. All I use now.

Geared roadie and MTB both have 175mm cranks,my SS roadie has 170mm and I can jump from one to the next and cannot tell any difference what so ever.

Put 175mm cranks on the SS. The difference is pretty obvious. Whether it actually makes any difference is anyones guess.

165mm on my mountain bike, 175mm on my road bike. Prefer the improved ground clearance of the 165mm on my MTB.

170 on the MTB. But then, I am a shortarse.

MTB 175. Road/cross 172.5. No real reason other than that that’s what I started out with. I’d probably benefit from 180s given my stupidly long legs, but I can’t be arsed to pay extra to find out.

175mm mtb and 170mm Road

my retul fit a couple of weeks ago on the road bike suggested i should go even shorter as it would help me be less ‘upper thigh feeling like its hitting you stomach’ when im in the drops

He was pretty surpised is ran 175 on the mtb at 5’8 he might be right tbh but im not gonna bother changing!

Not that bothered tbh, I think I have half 175 and half 170 on the mtbs now but I couldn’t tell you which. Oh and the DH bike needed 160s as it’s really short and I kept kneeing the fork crowns when climbing.

I have 170s on my Reign to improve ground clearance, 175 on all others. Don’t notice the difference for pedalling

unovolo – Member
Can people REALLY tell the difference of a couple of mm in crank length?

If I’m riding for 3 hours, that’s 15,000 repetitions of the leg movement used in cycling. Having a crank length preference is legitimate!

Oh yeah, 170 for me.

Never rode anything other than 175mm

175mm. Speaking of which any interest in a SRAM red 53/39 double with 175mm cranks? (Unused…)

No idea. In some cases just whatever came with the bike. Mind you, I’m not a princess when it comes to bike-fit. I reckon that if can pedal all day without discomfort then it fits just fine and if I can’t then a couple of wee tweaks will fix it. I guess it’s probably more important for all you professional racers and your incremental gains.

So having read all that its no clearer, other than ground clearance, what the supposed advantages of shorter/longer cranks are? Leverage?

175mm here though.

175 on the road bike and MTB

i noticed the change from 172.5 on the road bike. I think it does matter how much you ride though.

once a month i doubt you’ll notice. 6hours a day and you will notice any change.

I have no idea what mine are on either bike. I think they are both 170 but really not sure.

I’ve got 175 on my MTB and “city” bike and 170 on my Specialized Sirrus. Only thing I’ve concluded is 52T is too big for my twiglet legs.

170 on both bikes. I am stumpy of leg though.

165 to 180, various bikes – didn’t ever feel “wow, that’s a change”

I did take off the 180s a while ago (road bike) but I’m going to put ’em back on for the spring and see what I can “feel”

I think the ones on my road bike are 175’s and the ones on my MTB are 165’s. I had some 175’s on it, apart from not clipping pedals as much I can’t tell any difference when pedaling.

170 on cx,mtb and road.

Settled on 175 for both. IME of 170, 172.5 and 175 they all feel fine but I prefer the wider stance and leverage of the longer cranks. I did notice whacking my pedals more when enlarging on the MTB, but soon adapted my technique to be more conscious.

I’ve read that the clearance and high cadence of shorter cranks is favoured by the 700c crowd. Apparently the dead centre is reduced as well as a more open angle at the hip (think thighs banging in you chest). Also there’s less chance of pedal strike if you keep spinning through a corner. However, longer cranks have been more associated with MTB, climbing and added leverage therefore torque but power was measured as the same. As well as the clearance issue already mentioned the platform you have to stand on is affected, I feel more stable with a wider base. Height and crank length are often associated, but obviously preference affects this too. OP how tall are you?

You also need to adjust your seatpost if you want to be precise about leg extension when tinkering with crank length as 6 o’clock will be lower/higher depending.

I’m 6ft tall Herman.

I use the 180’s on the bmx as it was always thought you got more power from the longer lever, which sort of makes sense. But then theoretically you are using the same power, but the extra leverage should make it easier to get going (think bmx race here).

However, I recently jumped on my sons race bmx to have a go and it has 170 cranks. It’s very noticable but it felt good!

Interesting, I think I prefer the shorter crank… time to experiment…

Got 165 on my commuter and really notice it. In a bad way. Shame, as they’re nice middleburns…so if anyone wants to do a swap for some 175 let me know

170, all (both!) bikes.

I can see a short crank benefiting a BMX racer as there are short sprints between rollers, doubles and other things. A tighter circle to spin takes less time so more can be squeezed in between obstacles/features. I guess pedal technique is a big part of it. It’s a big jump at 180-170, on an mtb I would have assumed 170 to be on the smaller side for you unless you have a low BB or slick pedal stroke, although pedals and the geometry of your set-up are bound to contribute too. So many variables!