make any difference, other than ground clearence?

Can’t tell any difference between 170 and 175 myself. 165, a little bit but still not much.

Yes. It’s leverage, innit?

As a rule, small cranks spin faster, longer canks exert more leverage (assuming we’re comparing like gear ratios).

There’s also the consideration of what the optimum crank length is as a ratio of your leg length.

I can certainly notice 10mm difference on each side. That is on a unicycle mind you.

I dropped to 165 from 170 after a knee injury and it has solved all the old issues of a wierd feeling inside the knee that I used to get, as has been said, something about ratio of crank to leg length….

You’d notice a seat 5mm too high/low, so you’d notice the cranks – whether though you could tell the difference between them ‘blind’ I’ve no idea.

If I ride my bike with 170 cranks for an extended period then ride my bike with 165 cranks then for the first few minutes I can feel a difference. It doesn’t seem to happen the other way round. 175’s on a previous bike were ok off road by my knees did not like them if I was riding a road section where I wouldn’t be moving around on the bike.
I’d have 165’s on everything by choice.

used to have 180 cranks on my SS, but TBH I struggled to notice any real difference

I remember a time when we all went to Sheldon’s site automatically for questions like these:

Crank length

Still gets me that he’s gone 🙁

Yeah, I can’t stand 170, 175 is ok, but I really like 180… But I am a big guy.

I run 175’s on my Roadie and 170’s on my 29erSS.

I’ve been measured a few times over the years, each time it’s been 175’s on the Roadie. Never been measured for my 29er though. I’ve run 175’s on there and now 170’s. but it’s different riding styles init.. For different environments.

b r – Member

You’d notice a seat 5mm too high/low, so you’d notice the cranks

Eh. What’s the connection? I notice a seat 5mm out but I don’t notice the difference between my 175 and 170 cranks.

I guess some people are more sensitive to it. I notice crank length and cleat placement a lot.

Cleat placement I do notice to be fair. But then bad foot position’s very noticable.

OK, I have the identical cranks- I pepsi taste challenge y’all 😉 There’s a shiny penny for anyone that gets it right 3 times out of 3.

My knees do notice the difference a bit. Smaller circles cause me less pain, I’m 5’10” and reckon 170mm suit me better I’d say 175 are more appropriate for a 6’+ rider IMO of course…

5mm, not really. 10mm yes. There is about a 5mm difference between my winter boots and my normal road shoes. I try and convince myself it’s important, but don’t really notice. Now saddle fore and aft and cleat angles, those I really notice.

My work bike has 170mm and all others 175mm – I notice that.

Mrs has a couple of mtbs she uses at the moment – came in from a ride and asked directly if bike X had shorter cranks than bike y (it had – 170 vs 175). She once tried 162.5 mm (what the TA catalogue said she should be riding) and it felt crazy – like someone had stolen the power stroke when standing. I guess they were OK if you sat and span everything at a specific cadence but very weird in the constantly changing pace of off-road.

Eh. What’s the connection? I notice a seat 5mm out but I don’t notice the difference between my 175 and 170 cranks.

If you set up your seat hight according to your leg length for the pedal at the bottom of its revolution, then when at the top of the stroke it would be 10mm difference for a 5mm longer crank.

I find it noticeable, but I do tend to be quite finicky about stuff like that.

i didnt think i would notice but i do.

yes, no, maybe; how much do you ride. road, off road, etc.

The more you ride the more your joints learn, so changes are more noticeable ime. Road v Off-Road, your in and out of the saddle much more on the mtb so crank length is hidden a bit more than on the road with a much more constant fluid spin.

Would running shorter cranks make much difference to pedal strike? Obviously the BB height would be the same but if you raised seat height to compensate surely it would put pedals a little further away from the ground or is the difference to small to make a real world change?

why not try 165 on the left & 175 on the right & then see if you can spot the difference.

I’ve always run 175mm on mtbs comfortably. It totok me a while to figure whay my (second hand) road bike didn’t feel “right” especially when out-of-the-saddle cranking, and I think its down to the 170mm cranks.
But at times, the shorter cranks do feel better. But I like riding out the saddle and stretching my legs a bit, so I’m just in the process of compromising with a 172.5 set. Haven’t tried them yet…

When I borrowed the Kingdom Bike Project prototype Brigante for a ride in the Lakes last year, I discovered to my horror it had 165mm cranks, to reduce pedal clash due to the very low BB. First bit of the ride was up Honister Pass, running a single 32ish chainring. By God that hurt!

But at times, the shorter cranks do feel better. But I like riding out the saddle and stretching my legs a bit, so I’m just in the process of compromising with a 172.5 set

That way lies madness. I speak as somebody with 172.5 cranks on my road bikes, and certainly if you have multiple bikes it’s a good way to make life more awkward for yourself (I have 4 with that crank length) without actually making any noticeable difference – at one point I thought it did, hence the madness. I suppose it does mean I don’t notice the difference in length of the 175s on my MTB, CX and the tandem, but the same effect could probably have been achieved with 175 cranks on the road bikes! Oh and I also have a fixie with 170s.

Not to mention the unis on which I have 150, 140 and 125 – I can definitely spin faster with 125 than 150!

it’s a good way to make life more awkward for yourself

Hardly.
I want longer cranks, but like some of the benefits of shorter cranks, so I’m going to compromise. Sounds very similar to the argument about 262, 650b and 29″ wheels, but lets not go there. 🙂

Besides, I got a good price on some 172.5 Ultegra cranks so I figured I’d try something a teensy bit longer. If they still feel uncomfortable, I’ll go up to 175s. Hell, I might go even longer just to check that 175s are right for me.

I’m sure there must be a fairly simple equation relating thigh/shin/total leg length with optimal crank length? If not, there’s a Phd in the making…

I use 170mm as I find I clip 175mm pedals a lot. I tend to buy bikes with low BB’s though.

Used to ride DH a lot and remember Iron Horse Sunday owners nearly all ran 165mm cranks for this clearance reason due to the seriously low BB on those frames.