downwheeler
New Member
can anyone advise me if it makes sense to change my crank length to 175mm from 170mm i am 6,3,, tall?
crank length
- Thread starter downwheeler
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Ben M
Senior Member
- Location
- Chester/Oxford
What's your inside leg?
Mine's 32" and I can ride either a 170 or a 175. Much longer inside leg than me and a 175 would probably be best.
Mine's 32" and I can ride either a 170 or a 175. Much longer inside leg than me and a 175 would probably be best.
downwheeler
New Member
mine's 33,,so do you think it would be more comfortable for me considering i do biggish mileage?
Ben M
Senior Member
- Location
- Chester/Oxford
I don't know a huge amount about it. My only experience of it is that I had 175mm cranks, then had a problem with one and needed a replacement, my bike shop could only offer me 170mm replacements, I asked them whether it would be okay and they said that at my high I am within the range for using either. I have had the 170mm ones on it ever since and not noticed the difference, I've certainly not though "you know what i could do with... longer cranks".
If there's anyway that you could try out longer cranks, for example a friend's bike or one at your bike shop, then do so as, ultimately, these things are down to the individual.
A quick google brings up this:
http://www.machinehead-software.co.uk/bike/cranks/cyclist_crank_length_calculator.html
Which suggests that your "optimum" is 170mm
And this:
http://www.cptips.com/crnklth.htm
Which might have some other useful information on it.
If there's anyway that you could try out longer cranks, for example a friend's bike or one at your bike shop, then do so as, ultimately, these things are down to the individual.
A quick google brings up this:
http://www.machinehead-software.co.uk/bike/cranks/cyclist_crank_length_calculator.html
Which suggests that your "optimum" is 170mm
And this:
http://www.cptips.com/crnklth.htm
Which might have some other useful information on it.
swee'pea99
Squire
I've never really understood different crank lengths. If you think about it, the difference between a 170mm and a 175mm is, what, 3%? Can that really make a significant difference? Put it another way, your legs are pretty long...5mm is tiny. Even a cm is really small, and 5mm is half of that. That's really small. I've ridden 175s, 170s, even different lengths on each side, and I've never noticed any difference. FWIW.
[quote name='swee'pea99' timestamp='1282518194' post='1371661']
I've never really understood different crank lengths. If you think about it, the difference between a 170mm and a 175mm is, what, 3%? Can that really make a significant difference? Put it another way, your legs are pretty long...5mm is tiny. Even a cm is really small, and 5mm is half of that. That's really small. I've ridden 175s, 170s, even different lengths on each side, and I've never noticed any difference. FWIW.
[/quote]
+1
If we were talking 5cm, not mm, then we'd have a real difference. 5mm is sod all on toast.
I've never really understood different crank lengths. If you think about it, the difference between a 170mm and a 175mm is, what, 3%? Can that really make a significant difference? Put it another way, your legs are pretty long...5mm is tiny. Even a cm is really small, and 5mm is half of that. That's really small. I've ridden 175s, 170s, even different lengths on each side, and I've never noticed any difference. FWIW.
[/quote]
+1
If we were talking 5cm, not mm, then we'd have a real difference. 5mm is sod all on toast.
Bill Gates
Guest
- Location
- West Sussex
I'm 6 ft 0 in and use 175mm cranks for training and normal riding, but I have long legs in proportion to my body My inseam crotch to floor no shoes on is 90cm whereupon the average for my height is 88cm.
There was a time when 170mm used to be considered on the long side when 165mm was the norm. I found that shorter cranks are more conducive to higher rpm. I had an "old iron" that I used to cycle to/from work and that had 170mm cranks. I raced and broke records on my TT bike and that had 177.5mm cranks because I felt that my pedalling speed dropped to around 90-95 rpm on the longer distances and the extra leverage was preferable. Might not have made much if any difference, however sometimes what feels right just gives you more confidence.
Jan Ulrich used 180mm and he too was 6ft 0ins tall.
So all in all, IMO for your height, 175mm should be more appropriate than 170mm.
There was a time when 170mm used to be considered on the long side when 165mm was the norm. I found that shorter cranks are more conducive to higher rpm. I had an "old iron" that I used to cycle to/from work and that had 170mm cranks. I raced and broke records on my TT bike and that had 177.5mm cranks because I felt that my pedalling speed dropped to around 90-95 rpm on the longer distances and the extra leverage was preferable. Might not have made much if any difference, however sometimes what feels right just gives you more confidence.
Jan Ulrich used 180mm and he too was 6ft 0ins tall.
So all in all, IMO for your height, 175mm should be more appropriate than 170mm.
MachineHead is not strictly correct here.
Crank length is determined by the dimensions of the leg's pivot points. The point where the foot applies pressure to the pedal, the ankle pivot, the knee pivot and the hip ball joint centre.
After much research, it has been found that the distance between the sole of the foot and the centre of the hip ball joint is the dimension to measure to determine crank length. All the other differences in upper leg an dlower leg don't make a lot of difference, although they are needed to calculate seattube angle.
Peter White has the answer, which is 18.5% of hip height ( floor to hip ball centre with bare feet ).
When it comes to the professional ranks, crank length is trimmed to suit their muscle fibre type. A guy who pedals at a natural low cadence will opt for a longer crank length to take advantage of the little bit of extra torque that he can generate.
Spinners can get away with shorter cranks. They have to due to foot speed around the circle. Shorter cranks are also a few g lighter.
Crank length is determined by the dimensions of the leg's pivot points. The point where the foot applies pressure to the pedal, the ankle pivot, the knee pivot and the hip ball joint centre.
After much research, it has been found that the distance between the sole of the foot and the centre of the hip ball joint is the dimension to measure to determine crank length. All the other differences in upper leg an dlower leg don't make a lot of difference, although they are needed to calculate seattube angle.
Peter White has the answer, which is 18.5% of hip height ( floor to hip ball centre with bare feet ).
When it comes to the professional ranks, crank length is trimmed to suit their muscle fibre type. A guy who pedals at a natural low cadence will opt for a longer crank length to take advantage of the little bit of extra torque that he can generate.
Spinners can get away with shorter cranks. They have to due to foot speed around the circle. Shorter cranks are also a few g lighter.
lukesdad
Guest
We ve discussed this before at great length in the fitness section,and Im not going to go into to greater detail.
170s are ideal for me as Jimbo explains. 175s Put my knee slightly further forward than the ideal with the pedals at 90 degrees, but as most of my riding is spent going uphill the extra crank length gives more leverage as Bill has said. As I climb out of the saddle most of the time the seated position is not too much of worry.
Bill Gates
Guest
- Location
- West Sussex
Are you ever going to come down?
He's so knackered when he's got to the top, he gets on the farmers trailer to get back down.
snailracer
Über Member
I guess you're doing the opposite of downhilling
Chris S
Legendary Member
- Location
- Birmingham
Does 5mm make much difference? It's less than the difference between my shoe and trainer soles.