Has anyone played with crank arm length on their Sled?

[starcitymtb]

I am 5'8" and running 175mm crank arms on my bike. I was at my old LBS at home and my guy says "So when are you going to try out 170mm crank arms?"

I guess I hadn't really thought about it but I understand the premise for someone my size. Has anyone ever tried changing and felt a significant enough difference to endorse the change?

I just switched to a Shimano LX crank with the external bearing (hollowtech) and don't want to have to dump more money in it if there isn't a significant enough difference to make the change. What are your thoughts?

Thanks in advance. :)

[brian_brox]

I'm 6'4" so I went the other way. I noticed a big difference. I'm not totally convinced that at 5'8" there is much reason to switch.

[vamodeo]

I'm 5'7" and totally happy with running 175's on my mtbs. I run 172.5's on my road bikes. I don't see any need for you to go down to 170's on an mtb if you are perfectly happy with 175's.

[DaveG]

I am 5'8" and running 175mm crank arms on my bike. I was at my old LBS at home and my guy says "So when are you going to try out 170mm crank arms?"

I guess I hadn't really thought about it but I understand the premise for someone my size. Has anyone ever tried changing and felt a significant enough difference to endorse the change?

I just switched to a Shimano LX crank with the external bearing (hollowtech) and don't want to have to dump more money in it if there isn't a significant enough difference to make the change. What are your thoughts?

Thanks in advance. :)

and I run 175's. I tried 170's for awhile and honestly I couldn't tell a difference. The only reason I might try shorter cranks is if I were having really bad pedal strike issues.

Dave

[rsosborn]

I am 5'8" and running 175mm crank arms on my bike. I was at my old LBS at home and my guy says "So when are you going to try out 170mm crank arms?"

I guess I hadn't really thought about it but I understand the premise for someone my size. Has anyone ever tried changing and felt a significant enough difference to endorse the change?

I just switched to a Shimano LX crank with the external bearing (hollowtech) and don't want to have to dump more money in it if there isn't a significant enough difference to make the change. What are your thoughts?

Thanks in advance. :)

i've always found this a pivotal role in my enjoying a bike. it's hard to say what the perfect length is for you and your bike. i think it's worth finding the sweet spot though. i owned a 2000 s-works hardtail. test riding it and a litespeed, i knew when i got on the specialized i was much much faster. part of it was the frame geometry. i know part of it was the crank arm length. when i stepped on it, it ran.

i think when you have the right length, it helps you accelerate faster. i think it helps you keep a pace as well. too long and you'll accelerate fast, but you'll tire from too much continued work. too short and you'll lose initial torque to keep cadence.

[TiRyder]

I am 5'8" and running 175mm crank arms on my bike. I was at my old LBS at home and my guy says "So when are you going to try out 170mm crank arms?"

I guess I hadn't really thought about it but I understand the premise for someone my size. Has anyone ever tried changing and felt a significant enough difference to endorse the change?

I just switched to a Shimano LX crank with the external bearing (hollowtech) and don't want to have to dump more money in it if there isn't a significant enough difference to make the change. What are your thoughts?

Thanks in advance. :)

I dont think it would be a big deal and if you are comfortable now, I wouldnt change anything.

I would also say that while your height is indicative, the more important factor is leg length. if you have abnormally short or long legs, it may become a factor.

Also, some people run shorter crank arms on bikes with lower BB height to avoid peddal strikes.

I am 5'9" with a pretty short inseam, like 29 inches, and run 175 on all my bikes except the SS I just built. I actually went up to a 180 and really like it as it gives me more torque for climbing. I do have to pay better attention to rocks, logs, etc to avoid pedal strikes, but it has really been a non issue.

[CRAIG2]

Yeah, hold off for now - hey, we're going to need something to do with those 'economic stimulus' checks coming our way later this year.... heheheheh :rolleyes:

[saxman]

I'm 5'6", but with a 32 inch inseam. I run 175s. My Trek Fuel originally came with 170s and it drove me absolutely bonkers. I swapped them out for 175s immediately and life was good again.

Sheldon Brown has a calculation for what size crank you should be using. I know mine ended awfully close to 175. I'm sure someone here has that calcuation

[Vecsus]

I've been eyeing a set of Middleburn R7 180mm cranks for my next build. Square taper with a Phil Wood BB. I'm gonna put them on my steel 29er and move my old-but-trusty XT 175mm cranks onto my RIP 9 build.

Not sure I will be able to easily tell the difference between the 175 and 180 but there is enough evidence out there indicating the advantages of a appropriately-size set of cranks. Even if the benefit is all in my mind then it's worth it....i hate riding with an empty mind.

[starcitymtb]

I dont think it would be a big deal and if you are comfortable now, I wouldnt change anything.

I would also say that while your height is indicative, the more important factor is leg length. if you have abnormally short or long legs, it may become a factor.

Also, some people run shorter crank arms on bikes with lower BB height to avoid peddal strikes.

I am 5'9" with a pretty short inseam, like 29 inches, and run 175 on all my bikes except the SS I just built. I actually went up to a 180 and really like it as it gives me more torque for climbing. I do have to pay better attention to rocks, logs, etc to avoid pedal strikes, but it has really been a non issue.

I think that solves it. From reading yours and everyone else's post thus far. I am 5'8 with a 30" inseam. I can eliminate that thought from my mind.

I really like my set up and for the first time, I feel like my bike is just fine. Thanks all!

[Dirt]

There's been a lot of good info in here. Sheldon Brown's calculator is a good starting point. Some folks have biomechanical issues or riding preferences that take you out of his norms.

If you're not experiencing problems with your 175s, there's no reason to change to shorter cranks.

I'm 6'4" with abou a 34" inseam. I ride 180s on most of my mountain bikes. I'm going to 175s on the RIP9 because I'm getting a lot of pedal strikes.

I ride 175mm cranks on my road bikes, but would change to 172.5s if I were to start racing again.

Hope that helps.

Pete

[drevil]

I'm 5'8" with a 32" inseam. For years I've used 175, but then I tried other lengths as my current crop crapped out. Plus, I found 170s on blowouts more often.

I like 170, especially when riding fixie off-road because it helps with rock clearance (if only in my head). However, like others have said, I wouldn't switch if you are fine with the current ones.

BTW, I don't like 165. Maybe my mind will change, but on MTB, they didn't work for me. They sit on the "bad" shelf.

[allencb]

I'm 5'10" or so with a 32" inseam. I run 180s on my SS (pedal strikes be darned). I simply like the longer pedal stroke. I develop more power and don't get as fatigued at any sane RPM. It is kind of annoying at faster RPMs, but I can tolerate it.

I run 172.5mm cranks on my road bike, but I'd prefer something longer. I'm letting fashion get in the way of functionality there (older DA cranks with mirror finish).

Chris

[starcitymtb]

There's been a lot of good info in here.

Yes there certainly is. I guess it is more common an issue than I originally thought.

My biggest thing is I have a good deal slower cadence (50-60 rpm) now on long sustained climbs (such as Flag Pole or Reddish Knob, etc.) When we were talking about climbing, he injected the comment about shorter crank length to increase that speed and efficiency. Makes sense but what does that do to my cadence on flat to 3% gradients.

Maybe I'm thinking about this too much... or I'm trying to spend my $500 gov't check before I get it. ;)

[BikerMiker]

For DH bikes (I thought that's what you meant by 'sled'), everyone is running 170mm and 165mm cranks for clearance. With the low bottom brackets on long travel bikes (when your shock is WAAAAY into it's travel), it helps to clear rocks and stuff. You aren't pedaling a whole lot on the DH race scene...

mike

[rsosborn]

There's been a lot of good info in here. Sheldon Brown's calculator is a good starting point. Some folks have biomechanical issues or riding preferences that take you out of his norms.

If you're not experiencing problems with your 175s, there's no reason to change to shorter cranks.

I'm 6'4" with abou a 34" inseam. I ride 180s on most of my mountain bikes. I'm going to 175s on the RIP9 because I'm getting a lot of pedal strikes.

I ride 175mm cranks on my road bikes, but would change to 172.5s if I were to start racing again.

Hope that helps.

Pete


if your having trouble keeping your feet inline all the way around the stroke and staying in the saddle at your ideal cadence, i would go smaller. i think roadies have a list of to-do's to fine tune your stroke. it involves pedaling with one foot, and a bunch of other stuff, if you want to look it up. i think that would help with finding your most powerful and efficient overall setup.

this will sound weird, but the golden ratio for me was getting a feeling like i'm almost
running on my mountain bike. it was nice because i got a large range of motion, without feeling like i'm getting thrown around in the stroke. i would shoot for that: as large a range of motion without feeling like you're getting thrown around at the top of the stroke. that's just me.

[allencb]

this will sound weird, but the golden ratio for me was getting a feeling like i'm almost
running on my mountain bike. it was nice because i got a large range of motion, without feeling like i'm getting thrown around in the stroke. i would shoot for that: as large a range of motion without feeling like you're getting thrown around at the top of the stroke. that's just me.


Dang. That's exactly how I feel with the 180s. That's the perfect description. When I'm climbing a steep hill at speed, I almost feel like I'm running up the hill rather than pedaling. It feels "right" to me.

The only time the 180s don't feel good is when I take my fixie mtb on a road ride with a bunch of road bike or geared mtb equipped riders and try to maintain 17mph or more with a 32x17 gear. :o

Chris

[pirate]

For DH bikes (I thought that's what you meant by 'sled'), everyone is running 170mm and 165mm cranks for clearance. With the low bottom brackets on long travel bikes (when your shock is WAAAAY into it's travel), it helps to clear rocks and stuff. You aren't pedaling a whole lot on the DH race scene...

mike

If I could find reasonably priced 160mm cranks, I would put them on my Sunday... The bottom bracket on that sucker is already low, and me being a total hack doesn't help either. I am constantly whacking rocks.

The only 160mm ones I could find were really pricey Profiles.
EDIT: I take it back... I think they were Middleburns, not Profiles.

[rsosborn]

Dang. That's exactly how I feel with the 180s. That's the perfect description. When I'm climbing a steep hill at speed, I almost feel like I'm running up the hill rather than pedaling. It feels "right" to me.

The only time the 180s don't feel good is when I take my fixie mtb on a road ride with a bunch of road bike or geared mtb equipped riders and try to maintain 17mph or more with a 32x17 gear. :o

Chris

yea, depending on your riding style, you can pace your pedaling over obstacles or simply rig smaller and let them pass beneath you. i think it depends on your style.

do you keep a pace? do you do more XC style? is strength of the equipment a factor?

i like that full range of motion and strength in pedaling strong. if it's up to me, i rig it as big as i can and still maintain maybe 70 revolutions/min.

[starcitymtb]

For DH bikes (I thought that's what you meant by 'sled'), everyone is running 170mm and 165mm cranks for clearance. With the low bottom brackets on long travel bikes (when your shock is WAAAAY into it's travel), it helps to clear rocks and stuff. You aren't pedaling a whole lot on the DH race scene...

mike

Sorry for the mis-direct. I mean sled as in my big mean trail bike.

[piperj]

Some folks have biomechanical issues

Then there is Pete with neurochemical issues... :p

Sorry Pete, couldn't resist...

[allencb]

Hey Starcitymtb...

I'm in yur cownties messin up yur starz. ;)

Chris 'live in the Star City...'

[jed]

I am 5'10" of average proportions and ran 180's on my SS for a few years. I swore by them, too. But after cracking 2 drive side crank arms within a year and a half I finally just switched to 175's because I had some around since that's what I run on the geared MTBs, and I really haven't looked back since. I noticed that the longer cranks gave me a little help on the tougher climbs and didn't feel like they hurt me in the flats, but I run kind of a big gear. I didn't notice that I hit a lot of rocks or anything with the 180's, at least not any more than usual. But I pay attention to what's under my pedals and if I notice I hit stuff I adapt pretty quick.

I run 172.5's on the road bike, and it's kind of the same thing: I somewhat wish I had 175's for the climbs but otherwise don't notice much difference. I don't wish I had 175's enough to spend money on new road cranks.

[Pinoy Rider]

I guess I hadn't really thought about it but I understand the premise for someone my size. Has anyone ever tried changing and felt a significant enough difference to endorse the change?

I didn't pay attention to crank arm length until I got my new bike a couple of years ago. Old bike 15.5 frame hardtail size with 170mm. New bike 17.5 with 175mm dualie. I still rode both bikes and I thought I felt more fatigued on my new bike. Thought it might have something to do with the suspension or just more weight of the dualie initially. Quads would be smoked after rides on the dualie compared to my hardtail. Looked into it a little further and noticed the difference in the crank arms. Looked up all the different equations to determine crank arm length and it turns out my 28-29 inch inseam at 5'6" frame warranted 170s. Made the change, can't be happier. Feels better when I sit and spin up hills. Plus for me, at the top of the pedal stroke, the further away from full flexion of my knee the better(prior knee surgery).

[bkjoe]

I've had the same experience as PR - very happy to be on 170's.
At 5'10" and 29" inseam (I prefer long-waisted, not short legs :)), I found riding the shorter cranks much more comfortable, a much better fit for my body. I have not noticed the difference in clearance. It just feels better as I'm pedalling along.

I'm waiting for my other cranks to wear out/fail so I can replace those, too.

bk

[starcitymtb]

Hey Starcitymtb...

I'm in yur cownties messin up yur starz. ;)

Chris 'live in the Star City...'

LOL. Hell fire! Did ya at least bring yur bike home?

[allencb]

I brought my road bike. I was only passing through yesterday, but I'll be back Thursday night through Saturday afternoon.

Chris