175 crank
 

i'm 5 10 and am thinking about getting a 175 crank, does anyone my height run this length? what are the pros and cons of it?

Yup, I run 175. Might sound crazy but it feels more comfortable than 172.5.

how tall are you?

I just started running 175,and i love it.I'm 5,9 gave my seat a small adjust up,and it works for me.

You might as well flip a coin.

Better questions are what are you riding now and what are you hoping to acheive?

I'm 5'10" as well and run only 172.5. I've had 175 and while it may just be in my head, I felt that I had a harder time spinning up hills. Seemed to be better on flats though.

You might want to look at this link: http://www.nettally.com/palmk/crankset.html. This is one of the areas of great debate. There is another thread right now with a guy wanting to go shorter with crank length. I tend to think as long as you can keep your cadence up with the longer crank go for it as the leverage will help on the steep grades. Remember that I also think you need to have your cadence high as well, and the the long length can hurt you here.

6 ft love the 175 and the big ring

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I have 175's on my Madone and 172.5's on my Ti... I think you'd really need to go two steps in either direction to notice a difference.

+1, I would think the seat wasn't high enough to begin with then.

That is counterintutive. Being that your seat height is set at the bottom of the stroke, lowering the pedal by increasing arm length should result in lowering the saddle height.

I am 5'10" with a 30" inseam and ride 175 on my road bike and 172.5 on the cross bike. What I just stated is irrelevant to you though as so much goes into finding the right crank arm length for you. Most of it personal preference.

I'm 5'9" and 175 drives me nuts. I like 170.

+1 personal preference.

Spinning, low gears, I'd go shorter cranks. This for trackies, flat landers, riders who wonder why anyone ever made a 13T, forget about a 12 or an 11.

Power, higher gears, short power hills (90% of hills under a mile) I'd try longer ones.

When making a change (or trying a change) I'd go with a 5 mm change. 2.5 mm is not a big change, and if you want to really gain the benefits of a different crank length, really go for it. No half-hearted changes.

For me I dropped my saddle 5 mm when I went 170 -> 175. I initially tried a 2.5 mm drop and experienced knee pain within minutes (I have fragile knees). The full 5 mm and no problems at all. I had to be careful not to push too big a gear - with long cranks you feel like superman. I'd big ring a lot of hills that I'd normally small ring. It's the power hills, normally taken at 18-22 mph, which really get affected by the long cranks. I find I can roll a significantly larger gear on those little rises.

Finally I'd give it 20-30 rides before making a judgment if you go long. Fine, I judged my long crank preference in one ride (non-sprint speed on mountain bike with 2" knobbies, suspension fork, etc with 175s was higher than sprint speed on road bike with 170s), confirming it when I put 175s on the road bike (sprint speed went +10 mph on same stretch of road, about a month between rides, this when I was extremely heavy and extremely unfit).

I find longer cranks get some getting used to because you pedal so much slower. Your feet travel at about the same speed, but you're moving them in bigger circles. Math people, pipe up. Since I move to longer cranks after the season ends, or I keep them on most of the time during the season, I am more at home with long cranks. I haven't really figured out a time-pressed minimum adaptation time for longer cranks.

I think this adaptation time is critical. I put off trying longer cranks for two years because I had a very narrow window in which to switch cranks (Oct-Nov, to test and adapt before March, or, if it failed, to return to the shorter cranks in Jan or so). However I'm really glad I made the move to longer cranks.

Going to shorter cranks is much easier, but you lose the fluidity of weeks/months/years of riding the shorter crank. I find it takes 1-2 weeks to get 99% of my short crank game back. I've never gotten back to my 115-120 rpm averages though, it was always more like 90-95. I found myself speed limited on the track when I moved to the 170s on the track bike on Wednesdays. On Sun/Mon/Tue I did hard rides on the 175mm equipped road bike (race, hard group ride, race), and on Wed, on 170s, I couldn't spin well. I finally decided to go to 170s on the road in order to make my track pedaling more fluid. I won a few fast races (Keirin) right away.

Then I crashed and couldn't ride for a while, but that has nothing to do with crank lengths :)

cdr

A point of consideration is that if you increase crank length, and drop your saddle to keep your knee angle at extension the same, you will end up with a smaller knee angle at the top. This adds shearing forces to the knee, and can add to the dead spot at the top of the stroke.

Personally, I am 6'1" and anything over 172.5 just kinda bugs me. But then, I am a higher-cadence guy.

This one is actually fairly simple to do, at least from a perspective of distance traveled per revolution, as it's simply two times the radius (the crank length) times pi.



Below is a Python script to calculate the total distance and percent difference from a standard 170mm crank:

No my adjustments were fine for the 170 crank,but if you add length to the crank arm,it only makes sense to adjust the seat. I put these on to have more torque in climbing,but i've notice a gain in the flat speed also.

I also changed the bottom bracket from a 113,to 107 square taper english.

"A point of consideration is that if you increase crank length, and drop your saddle to keep your knee angle at extension the same, you will end up with a smaller knee angle at the top. This adds shearing forces to the knee, and can add to the dead spot at the top of the stroke."





And this is why i raised my seat after adding a longer crank arm.5mm to the arm ,1/8 inch to the seat

i'm 5 10 and i'm thnking 170 feels a bit long. maybe i should just work on my high cadence spinning more. i bounce about when i try to spin really fast.

Keep in mind we are talking about a very small difference. For CDR's distance traveled it's 1.5% change. So your foot speed is equal at 95 rpm on a 175 and 96 rpm on a 172.5. I've run everything from 165 on the Track to 175, and while you can feel the difference it's very subtle. I really think within the "normal" range for road cranks it's nothing more than personal preference, with a dash of placebo effect and a pinch of what you are used to.

I get the logic on the smaller knee angle at the top but I still think lowering the saddle would be the logical way to go if you lengthenthe crank.

I guess it's working for you so what's logic got to do with it.

is this true? wow, thats a small difference imo...

That's bad saddle height or too low a gear.

At r=172.5, the circumference of the circle your pedal makes is 1084mm (2*pi*r), for a 175 it's 1099. So in 96 revolutions of the 172.5 your pedal has covered 104,064mm (341.4 ft), 94.7 revolutions of the 175 is about the same distance.

Remember we are only talking about a 0.1" difference in crank length. If you did the same rpm comparison for 175 to 165 its a bit less trivial at 94.7 rpm = 100.5 rpm.

It's a static change independent of distance equal to (Old Crank Length/New Crank Length)^-1

I'm 5' 10" and went from 175 to 170. The 170's are right for me.

But if you can maintain that "pedaling in circles" and don't create dead spots (lose power and efficiency) in the stroke with 175's, go for it.

What I noticed when I went from 175's to 170's is that my knee and quad soreness went way down. And that 170's allowed me to finally learn how to pedal in circles rather than mashing it out using primarily my quads. Now my hamstrings and glutes are more engaged. It's a better pedaling technique now because the "circle" is slightly smaller.

Consider the changes that will take place in your leg angles at the top and bottom of the stroke if you use 175's. To get the same efficiency of 170's, it seems (at least, to my thinking) that the seat must then be set higher. Which might cause your hips to bounce. Hence, more possibility of chafing. And maybe more soreness in muscles and joints.

But you can always try it and change it if you don't like it.

One of the things I like about the 175s is that I seem to recruit more muscles. I get sore going to the 175s, not so much to the 170s. Specifically my glutes get more sore on 175s. This is when I make the change from one crank to another, not in general.

Since I drop my saddle when I go to the longer cranks (I tried keeping it the same, dropping 1/2 the difference, but my knees couldn't take either of those approaches), I keep the same extension. Therefore I bring my knee up further, stretching out the glutes more. Quads too but I have pretty flexible quads so it doesn't bother me at all.

Although the distance covered by longer cranks is marginally longer, I think coordination, fitness, and gear selection play a role in cadence too. On 170s I'd hold 90 rpm all day, and my efforts (TT, climbs, etc) were at 110 rpm. When I first went to 175s, I felt like my legs were flying at 80 rpm. After 3-4 months I could turn 175s over at 85-90 rpm comfortably (my average cadence five years later is 87-89 almost all the time). My max cadence on 175s is about 240; on 170s it was closer to 280+.

With 170s I can't turn the same big gears I can turn on 175s. I can't prove this scientifically, at least not now. I want to go over my power data from 2008/170s and 2009/175s which were on the same bike, just different actual arms (I swapped out the arms on the Cannondale SI cranks). I figure there'll be a relationship between length/cadence and cadence/HR

cdr

cdr, would be interesting to see some power data on this. From purely an engineering perspective this differences 5mm gives in leverage, and in angles/range of motion (any measureable) are very small. I would venture to guess they are within the range of what you could easily reach with a small variation in bike fit.