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Crank length preference?

Old 05-12-20, 05:10 PM
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Crank length preference?

Iíve always used 170 and 172.5, I just bought a Shimano triple crankset with 175ís. Iím waiting on the
derailleurs so I havenít rode with them yet. Anybody switch to a longer crankset and have issues
with them? I have 170 arms on standby just in case.
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Old 05-12-20, 05:38 PM
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I somehow settled on 172.5 for my road bikes long ago, but do have 170s on two bikes for various reasons. I think since I never really learned to spin well the slightly longer crank makes pushing a bigger gear easier.

The only bikes I ever had 175s on were MTBs and they came with them like most MTBs did (still do?). The idea being if your seriously mountain biking the longer cranks gives more torque, at least as explained to me many many moons ago.
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Old 05-12-20, 05:44 PM
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This is an interesting video. It's long, but worth the watch in my opinion. I'm definitely going to experiment with some shorter cranks if I find any for cheeeeeep.

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Old 05-12-20, 05:46 PM
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It's never made much difference to me. I have all three lengths scattered amongst my bikes. I was thinking about that while riding today. Does 2.5 mm make much of a difference if my butt slides 1 cm along the saddle during the ride? If I measure my femur length 10 times, how often will I get the same measurement within 2.5 mm?

To each his own though; I get it if someone wants it just so.
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Old 05-12-20, 07:00 PM
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Originally Posted by Spaghetti Legs View Post
It's never made much difference to me. I have all three lengths scattered amongst my bikes. I was thinking about that while riding today. Does 2.5 mm make much of a difference if my butt slides 1 cm along the saddle during the ride? If I measure my femur length 10 times, how often will I get the same measurement within 2.5 mm?

To each his own though; I get it if someone wants it just so.
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Old 05-12-20, 07:07 PM
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Oh, you really don't want to get me started on this... I am a crank on the subject,

But shorter is better. There just isn't any advantage to longer cranks. People talk about leverage; yes, you have more leverage with longer cranks. That's great, but you don't need leverage. You need to spin. And you will spin better with shorter cranks.

Since the shortest C&V cranks you can find are 165 mm, I recommend 165's. If you can find shorter ones, go for it. You won't regret it for more than a half hour or so.
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Old 05-12-20, 07:17 PM
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I tried a pair of 165s once - felt like I'd lowered my saddle 6" or more. Very, very noticeable and weird. I took them off after one ride and put my normal 170s back and they've been there ever since.

What works for some...

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Old 05-12-20, 07:21 PM
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I have found the slightly longer 175 cranks can help a bit when running a larger range triple but don't seem to make much difference on a basic double or single where I would actually say go shorter to a. 165 for clearance you should be fine on most 80' though 90's road and mtbs. But with 70's stuff especially French and Italian you will have pedal strike clearance issues. Show us a pic of the bike you want to put the 175 and the crank and someone here will tell if it will work help.

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Old 05-12-20, 07:31 PM
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I'm vertically challenged at 5'4. I played around with 165's and 170's on road bikes until I found folding bikes, and decided to experiment with much shorter cranks. My purpose was twofold: shorter cranks for easier packing of the disassembled bike in a suitcase, and let's see what they do to the power curve.

I had Mark Stonich of www.bikesmithdesign.com shorten a couple cranks, which I still have. An Ultegra triple and a 105 double, which started life at 170mm, now both at 148mm.

Power curve results were not encouraging. Easier spinning, which was nice, but greatly reduced leverage. Hills and wind became more pronounced, or maybe just my ability to deal with them. Felt like a spinning hamster wheel going nowhere fast.

In the end, I removed them and went back to my 165 and 170. Might dig them out again for a project or if I need a short crank for a particular frame setup.

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Old 05-12-20, 07:35 PM
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Iím changing the derailleurs to LX and I just picked up a set of Deore 175ís. I have a set of 170 arms with the same bcd, I might switch them.
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Old 05-12-20, 07:36 PM
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I’m not worried about them fitting on the bike, I’m just not sure if they would be comfortable to use.
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Old 05-12-20, 07:38 PM
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Also a point to consider almost all component groups with stock gearing low to high old or new are optimized for a 170mm standard crank.
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Old 05-12-20, 07:39 PM
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My experience is 175s is only on ATBs- but 170s on all my "road" bikes.

I also have stubby legs.
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Old 05-12-20, 07:40 PM
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I moved down for a 160 mm 105 R7000 on mine. It was 165 mm before and my commuter has a 165 mm.
So far is great and I see my cadence is coming up to 80-90 rpm.
Since my commute was majority or rides before the stay home stay healthy, my cadence was on 70s.

When spinning hard on 165 mm last year I got some discomfort on my right knee that went away after couple days.
Also experimented a 145 mm last year and tried it but was too weird.... If some want to try, is a triple JIS one .
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Old 05-12-20, 07:42 PM
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[QUOTE=sloar;21471633]I’m changing the derailleurs to LX and I just picked up a set of Deore 175’s. I have a set of 170 arms with the same bcd, I might switch them.
[/QU

On this bike no stay with the 170's and keep it simple. Trek matched there cranks to the frame set using 160, 165.170 and 175 Why rethink something that was already done.

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Old 05-12-20, 07:55 PM
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I’ve long subscribed to the belief longer is more leverage for climbing and accelerating and have ridden 175 for the last 30 years. The video makes interesting points about fatigue and hip injury from longer crank arms. Not getting any younger so I might build something with 170 to see how it feels. I’d finally be able to use the take-offs I’ve accumulated over the years.
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Old 05-12-20, 08:05 PM
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I stick with 170’s and my knees seem to like it. I would go 165 but they seem hard to find. Right now I have to use a 172.5 on a project and am hesitant. Too close to 175 which I know causes me knee pain. I switched the rings on the 172.5 with bio-pace to maybe lesson the harshness as I go around and push down.
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Old 05-12-20, 08:17 PM
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I prefer 175, mostly because they are the most comfortable for me, and I feel like they fit me best. 172.5 or even 170 are OK too. I can feel the difference between all of these, but I'm not sure it makes a huge difference, or any difference in power. Shorter cranks are easier to spin up. Longer ones feel better for stomping big gears up climbs. I should note that my pbh is 36+ inches.

I remember Jobst B giving some long winded explanation of why it doesn't really matter on a ride a long time ago. Can't remember the reasoning though.
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Old 05-13-20, 02:23 AM
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Most of my bikes have had a crank length of 170mm but I have had the occasional 172.5mm and 175mm cranks and I don't take much notice of the crank length when riding. I also have one bike with 165mm cranks and they do feel slightly small but not to put me off the bike.
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Old 05-13-20, 07:17 AM
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[QUOTE=sloar;21471633]Iím changing the derailleurs to LX and I just picked up a set of Deore 175ís. I have a set of 170 arms with the same bcd, I might switch them.
quOTE]

If I had both sizes on hand I would try them both and go with what I liked best.
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Old 05-13-20, 07:54 AM
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Originally Posted by Spaghetti Legs View Post
It's never made much difference to me. I have all three lengths scattered amongst my bikes. I was thinking about that while riding today. Does 2.5 mm make much of a difference if my butt slides 1 cm along the saddle during the ride? If I measure my femur length 10 times, how often will I get the same measurement within 2.5 mm?

To each his own though; I get it if someone wants it just so.
2.5mm is really 5mm, in a circle
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Old 05-13-20, 08:09 AM
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I've been riding mainly 170, but have recently picked up 172.5 for a couple of rides. 165 is hamster cage for me at 6'2".

This thread reminds me that I have Campy SR in 180. I haven't used that bike in years.
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Old 05-13-20, 09:58 AM
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all the fit guides and thigh measurements told me I should use 170s which worked out
well as that was stock on all bikes BITD. after 6+ yrs. of hard riding and many miles
my beloved Campys started to crack. I was able to make a trade with a guy for 165s
I liked how I could spin faster but they seemed a bit much which is how I learned that
the size for me is 167.5 hard to find now. glad I have a NOS backup set!
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Old 05-13-20, 10:29 AM
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Each extra mm of crank arm length longer than what nomadmax told me is my fit is then magnified 10x in my head.

Otherwise, the math leaves me dumbfounded.
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Old 05-13-20, 10:44 AM
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165mm

I had a bike with 172.5mm cranks and never though about it, until I got a bike (same model) with 165mm cranks realized how much faster and more comfortable I was. My foldy still has 170mm cranks on it, and I often KT tape my knee when I'm on it all day, but other than that its 165mm all day for me. I'm 5ft 10 with a standover height of 31.5 inches and ride 21 inch 53-54cm frames. I ride mostly flat ground city riding.

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