using different crank lengths

[bicycletricycle]

anyone use different crank lengths on their bikes? I have used 175 on everything for quite some time and i am thinking of trying some 170s on a new bike im building. I am sure lots of people may have something to say about ideal crank lengths for different height people but i am interested more in using different crank lengths on different bikes at the same time. I know lots of people run shorter cranks on their fixed bikes. Anyone doing lots of miles in different lengths? anyone try to do this and have their legs fall off or knees explode or something?

[sbparker31]

I run 175 on my mountain bike, 172.5 on my road bike, and 165 on my track bike. To be perfectly honest, I can't tell a whit of difference between the 175 and the 172.5. The 165s, on the other hand, feel pretty "spinny" -- but I guess that's the point. I have considered swapping them for 170s, but since I am on the track 1x per week at most, I haven't been able to justify the expense.

[AngryScientist]

i, like most of you all, have a few bikes i ride regularly. i have a mix of 170 and 165 cranks. no problems.

one thing to be cautious of, although it might be obvious, is adjust saddle height to compensate for different crank length. my first trip on a bike with 165's, my knees began to ache, and it turns out my saddle was too low, which had been set up for the 170's.

165 on the fixed too, spin more, corner harder.

[tuscanyswe]

Usually i run 175s but for my track bike i have 170s. I dont really have a problem with this at all. I suspect if i dident know it i might not feel it at all. I use to think i could tell between 5mms but im not so sure anymore.

[BillG]

I generally ride 175s on my road and 170 on my fixed. I just rode a serious dirt road climb/ride on 170s and I could definitely feel that I was lacking torque when the grade got serious. Seated climbing was smoother but standing was a beast. Back to 175s on the road bikes!

[buldogge]

My crap's all over the place, crankarm lengthwise...and...I ride a variety of saddles as well.

I guess, being slow, I'm not in-tune enough to notice...

YMMV of course.

As already mentioned, can't hurt to set the overall dims up the same though.

-Mark in St. Louis

[sg8357]

Another vote for the famous "All over the Place" fit system.

175 Kvale, roadie
172.5 Ebisu All Purpose
175 Crescent fixed
170 Bates B.A.R.
170 WmJ Hood, Palace Special

[wooly]

I've got 172.5's on my roadies and 175 on my 29er.

Not to highjack the thread but is there any logic to crank length? At 5'11" my first factory spec'd bike (Litespeed) came with 172.5's in 1998. Never thought to change. The 29er came with 175's. I can definitely feel the difference but don't have a preference.

[fiamme red]

I thought this was going to be a thread about using different crank lengths on the same bike, right vs. left.

[Ken Robb]

I have ridden 170, 172.5, 175 (most often), and 180. I can feel a 5mm difference but not 2.5. I thought I loved the 180 because I felt like I could muscle up hills in bigger gears with them so I did. Then my knees got a little sore so I got rid of the 180s. I don't know what would have happened had I kept them and resisted the temptation to mash bigger gears than normal but it seems to me that since I couldn't keep using the additional leverage it made sense to go to shorter cranks that are easier to spin.

[oliver1850]

I thought this was going to be a thread about using different crank lengths on the same bike, right vs. left.


If you would like to try this, I have a new Rival crank that's got one 175 arm, and the other is 172.5.

[schwa86]

I had been running 170 on the road bikes and 175 on my mtb commuter. My knees started to hurt. I switched pedals on commuter to speedplay, and cranks to 165 (under theory that my 6 miles each way of commuting was often "getting warmed up" and better to spin than mash). Knee achiness almost totally gone, definitely spinning more. Going from 175 to 165 very noticeable in terms of "feel."

[Hindmost]

A few people have touched what on what the effective differences are. When you first jump on the bike you may only be able to perceive the difference in a jump of 5 mm or more. The differences in perfomance and feel will be pronounced at the extriemes: achieving maximum speed on a fixed gear--maximum spin is easier with shorter cranks; lower cadence riding while climbing or time-trialing--it is easier to generate torque while turning over the longer cranks.

I have used 170 on the track and from 172.5 to 180 on the road. For me going back and forth was not a big deal. As has been said, saddle height should be adjusted accordingly.

[mtnbke]

anyone use different crank lengths on their bikes? I have used 175 on everything for quite some time and i am thinking of trying some 170s on a new bike im building. I am sure lots of people may have something to say about ideal crank lengths for different height people but i am interested more in using different crank lengths on different bikes at the same time. I know lots of people run shorter cranks on their fixed bikes. Anyone doing lots of miles in different lengths? anyone try to do this and have their legs fall off or knees explode or something?

I have a 100cm cycling inseam. I obviously can't effectively use clown cranks (175mm) on any of my bikes.

I've tried, and I hated it, more on the road bikes than the mountain bikes.

I currently use 205mm triple cranks on my touring bike, I have 200mm captain's cranks on my tandem, and 185mm cranks on my mountain bike (though I may go back to 180mm to avoid crank/rock issues or get a frame custom made with a raised bottom bracket).

A couple of interesting links regarding crank length:

http://www.customcranks.de/en/cranklength.html

The above includes a great graph of where historic pros fell, regarding crank length.

http://www.zinncycles.com/cranks.php

and just because people think Sheldon Brown knew so much about everything, when really he really only should have stuck with what he knew (fixing bikes, and bike repairs/tricks):

http://www.sheldonbrown.com/cranks.html

The reality is that someone of Sheldon's height couldn't possibly comprehend how completely out of proportion the 165mm-180mm range is for many people. I actually hate stairs because they are exactly the wrong "size" in terms of the height of each step, and because I can not safely walk down them with my size 15 feet. Sheldon knew a lot of stuff, but he didn't know half as much as he thought...

The reality is that bicycles are typically made in frame sizes from 49cm to 63cm. That's fifteen different sizes to accommodate a very small range of cyclists (I ride a 68.5cm frame c-c, and 70cm c-t). It is absurd to suggest that the standard offering of cranks (170mm, 172.5mm, 175mm, 177.5mm, 180mm) which represents only five different crank lengths will accommodate cyclists from 4'11 to 6'3".

The reality is that 172.5mm and 177.5mm are all but unheard of anymore, and 180mm is very scarce. I don't know any mass offerings still making 165mm cranks, and few cranks are available in 170mm.

The reality is that the component makers know that the typical cyclist will buy whatever they manufacture, even if it is one size fits all.

Trust me, the average roadie would much rather have a wrong size SRAM Red crank or Campy Carbon Record crank than a properly proportional Zinn, Customer Cranks, or High Sierra crankset. End of story. Cycling is much more about the pretense of the bike and the notion of the Fred factor than it is about riding what actually works for a non UCI Pro racer.

The fact that most roadies are on bikes perched on top of the hoods, and believe they have good bike fit, when they couldn't possibly spend even 1% of their mileage comfortably in the drops tells you everything you need to know.

I'm an outlier and the crank length conversation to me is a given. Its obvious to me in the first 100m how much a difference a proportionately sized crank makes to spinning, climbing, and just enjoying riding. If you a shorter man or a normal height woman, I seriously doubt you'll seriously notice switching crank lengths of 2.5mm or even 5mm at a time.

I don't really notice the difference between the 205mm and the 200mm cranks, and really don't notice the 185mm mountain bike cranks as being different as mountain biking is so different to begin with.

I did however ALWAYS notice the difference between 175mm cranks and 180mm cranks, that change was monumental, as 175mm cranks were just so absurdly short for me.

[SpeedyChix]

Road / CX all the same length (170), mtb using both 172.5 and 175. Don't really notice the difference. The mtb has been a bit of an experiment and the weather so far this year isn't offering up many good trail days. So far though I haven't noticed the difference on those (which is a good thing in the long run).

Have used 172.5 on road and went back to 170s, seem to be more aware of the difference on pavement.

[bicycletricycle]

mtnbke-

there are also a lot of people in the HPV world who are going with even shorter cranks now, 120-150mm with no recorded loss in power after a break in period. To my understanding there is not strong data to support an length as optimal for any body type. I do agree that the 165mm-180mm range for people between 5 feet and 6 foot 5 is a little ridiculous. If anything it proves that an "optimal" formula for crank length is not necessary for success as a rider based on the performances of riders like Thor Hushovd and Jose Rujano. I think that if anything it is probably just important to stay consistent. Most crank length formulators say i should be running 180+ which i have tried for some time and didnt feel an increase in anything of note.

[mtnbke]

BT: You didn't notice an increase in Max wattage with the longer crank? I definitely noticed. It was a bit frightening, as I can push such a tall gear with the longer cranks that it can almost get me in trouble. I'm serious. I can push such a tall gear that if I don't pay attention my cadence will drop to 20-40 mashing a monster gear. The funny thing is it takes no real effort. That's definitely something I can't do on 'clown cranks'. If I'm spinning my normal cadence, I still realize a noticeable difference in the perceived effort required to complete a climb/ride.

Case in point, one of the first rides I did with the new cranks involved a bike with a bent frame. I spent half the ride with the wheel against one of the brake pads and didn't notice the difference in effort, as compared to what I was exerting making little circles on 175mm. True story.

I stopped and wondered why I was so tired for only a couple of miles, but the perceived effort was actually less than what I was used to. Hard to explain, but funny.

Well not funny in that my aluminum big bike is bent, but the discovery and the wheel/brake bit.

[billythekid]

I'm always amazed when I hear people saying they can't tell the difference in crank length. I tried jumpin from 170 to 172.5 and it was completely different. I don't know if it was because I'm extremely dialed in to 170's or if I'm just too short to go any longer but it threw my whole cadence off. My knees were all over the place. Even tried it for 3 months before going back. definately won't try it again.

[Ken Robb]

I'm always amazed when I hear people saying they can't tell the difference in crank length. I tried jumpin from 170 to 172.5 and it was completely different. I don't know if it was because I'm extremely dialed in to 170's or if I'm just too short to go any longer but it threw my whole cadence off. My knees were all over the place. Even tried it for 3 months before going back. definately won't try it again.

It's probably that a person with short legs will find a given change in crank length a bigger percentage of his legs than a rider with long legs would experience with the same change.
As you say you may already be at the far end of usable crank length at 170mm and going over that is really out of your range.