I'm 6'1" and moved from 175mm to 170s and then 165s over the past year. I make just as much power with the 165s and am easily more aero as well. I've seen no down side and to be honest don't really notice the cranks being shorter.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

There have been other postings on this topic. I don't recall all the arguments, but you will find people arguing heavily for both sides. I left feeling it is very individual (science doesn't favor short or long cranks) and there is no real downside to trying them. If you produce same watts and RPE goes down on the run then go for it.

not selling - read for the information/article http://www.cobbcycling.com/catalog/crankset

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yeah I've tried to read some of the other forum threads on it, but they seem to be over run by opinions of peoples feeling and not much based on research. Hoping maybe we can avoid that for a chance and focus on the research!!!

Cobby Cycling's article is interesting, I'd really like to know more about natural running stride length and cadence, and how that translates into cycling? Interesting stuff ... anymore information on this?

Lots of false logic in there
1. More efficiency breathing b/c oxygen consumption decrease? Not exactly.
2. Higher saddle height? So what?

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I am 5'4" and have always just used the default cranks that come on my bikes. However, I have been doing a lot of reading and watching videos, and I decided to get 165 mm on the bike that I just ordered. It should allow me to raise the seat a bit and get more aero. Also, I am hoping that it allows me to have a slightly higher cadence.

It easy and common to think that crank length has some big effect on power. I saw a presentation recently that referenced a study that said that's not the case. When we discuss crank length as it relates to triathlon (or TT) it's more about the riders position and how we can set up a bit lower in handle bar elevation (and, therefore the presumption is that the rider can reduce some front area). When the cranks are shorter the handle bars can be lower and the hip won't get all bound up at the top of the pedal stroke. Athletes commonly feel the legs flow better, cadence goes up, riders often find they can drop to a smaller cog than normal.

Ian

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might be less aero for the legs to go to shorter cranks, but overall.?.....test test test :)

I say that as you will be creating larger frontal area of saddle to spindle height is kept same, area same at bottom of stroke for one leg, but higher than previous for other leg as it is slightly less horizontal at top of stroke. how marginal? I don't know

http://myworldfromabicycle.blogspot.com/...s-fine-you-just.html

I am 5'8" and have used everything from 172.5 to 160 mm

I feel 172.5 is too long for me to keep smooth and it just feels a bit too long. When I was younger I could use 172.5, but now in my 40's no.

170mm seems to be a nice length for me and I now run that on all my bikes (except my fixed gear). On fixed I use 165mm and like it.

On season I used a bmx style crank to get a 160mm length. I really tried to like it. But when I went back to 170, it felt so right that I stopped the short cranks.

IMHO, for you a 165 to 170 is right for you. But ultimately it is what feels good to your body.

I LOVE my 200mm cranks. Tried shorter and it was a disaster.

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Good point............Yes, the retracted leg is 2cm more extended with the 165s so there is a bit more area exposed there but by dropping my whole upper body 1 cm there appears to be a significantly larger frontal area decrease than that caused by the increase due to exposed leg. ........I'm faster on the same wattage with the 165s.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Is there any easy ways of trying out different lengths without buying one of each!? I'll have a chat with the tri / bike shops here and see if i can test a few out... Not sure any of my friends will use a 165mm or smaller as I'm pretty much the shortest in the group :(

 

Did you reduce the chainring size also when changing to shorter cranks?

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Once, I was fast. But I got over it.

You can do that or increase the size of cassette to get the same "gain", which should basically be {gear inches in any gear} x {old long crank length}/{new short crank length}

As Dev eluded to, it's about gain ratios. Changing from 175 to 165s is a bit less than a 6% difference or put another way about the same as shifting from a 16 to a 17 cog on the cassette to compensate. You won't even need to think about it.

YMMV,

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

There is no real easy way to try different length cranks. From what I know, if you want to try below 165mm, you are going to have to either go BMX square taper bottom bracket and cranks or stupid expensive stuff. The good news is this stuff is all relatively inexpensive and 110mm BCD so compact rings work also.

So square taper BB gets you short cranks (down to crazy short 125 mm to 170 +mm), very inexpensive $50 per/crankset (or less), and the rings are cheap too. This gets you the ability to try different length and chainrings on the cheap.

I have found that the Origin8 and Sinz brands are good for the money. Chainrings can be had with pin & ramps and in 50t and smaller.

Note:

I also tend to use old octolink cranks, so I have picked several sets of 170 and 172.5mm over the years. However, now I use 170's and the 172.5s are paperweights now.

I'm 5'8" and just got a set of 165mm cranks. Love them, and have already adapted.


They are 7.5mm shorter than your cranks now. That's a very small measurement.

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The Shimano fit bike has adjustable crank length, and I've seen several other types of fit bikes fit with adjustable cranks. Maybe not the same as on-the-road testing. But a good start.

Only because you don't understand gearing :-/

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http://bikeblather.blogspot.com/

If you're lucky, you can find a friend or shop that has some adjustable length SRM cranks, like I was able to use here:
http://bikeblather.blogspot.com/...erwithin-reason.html

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http://bikeblather.blogspot.com/

Another option is if you can borrow a pair of powercranks from someone local and use them 145 up to 185mm in lockout mode as conventional cranks.

• I am 5'11" and have experimented 175 down to 155mm.

I am currently running octalink wired arm in 155. You can either buy them custom or do what I did. I sent them to Mike Burrows to be re drilled and shortened. I recently set a new. Ftp on on the turbo so they don't affect my power and I can sit in my lower position for longer. I have no idea if its more aero or affects my running.

Good point............Yes, the retracted leg is 1cm more extended with the 165s so there is a bit ore area exposed there but by dropping my whole upper body 1 cm there appears to be a significantly larger frontal area decrease than that caused by the increase due to exposed leg. ........I'm faster on the same wattage with the 165s.

That is true if you are comparing it to 170s. It's double the length difference, anyway. And you aren't dropping your "whole upper body" just the front. Relatively. The rear goes up.

The legs are a big part of drag (more than the torso, I'd wager), and it isn't just area, it's shape. Cylindrical shapes can reduce their drag a good amount if they are at an angle to the airflow.

The bottom line is that short cranks should allow you to get your upper body more horizontal at an equivalent power. You may also find it easier to run. I wouldn't bank on them being faster in a TT though. My n=1 with 22mm shorter cranks didn't yield any speed gains.