Crank Length?

[Kins]

After reading this article I am wondering whether to shorten my crank lengths to 165mm because my knees are a bit dodgy.

http://www.powercranks.com/cld.html

Anyone use 165mm and around 6ft or use shorter cranks?

 

[Mr Haematocrit]

Crank length calcuator

http://www.machinehead-software.co.uk/bike/cranks/cyclist_crank_length_calculator.html

 

[Mr Haematocrit]

I use short lightening cranks but I'm nowhere near 6ft

 

[Kins]

Yeah I used that already, 166mm it recommends, I wondered after reading that article whether to go even smaller.

 

[Brandane]

Presumably, shorter cranks means having to have the saddle set higher?

 

[Kins]

Aye, but your only talking 10mm from 175mm to 165mm but it would probably change all aspects of your setup including bar height and rotation.

 

[Deleted member 1258]

I've got 165's on my fixed, but I'm only 5'6", My geared bike has 172.5's on it but I cant tell the difference between the 2 crank lengths.

 

[gaz]

My inside leg is only 33inches and I used to use (bike got stollen) 175mm cranks. Size 12 feet makes a difference

 

[Theseus]

Many moons ago before I know how to do my own maintenance, an (or is that a) LBS stripped the pedal thread from the LHS crank. They did not have any in stock the same size as the RHS one. I was given the option to wait for them to get new stock or they could fit one a bit longer and when thenew one came in they would give me a call to replace. After a few rides I got quite used to riding with different lengths, so it all felt a bit odd when it went back to being as it should.

None of which has anything to do with the OP.

 

[GrasB]

Crank length, there's loads of pseudo-science & such like flying around. Best bet is to go with what feels right to you. If you want to go shorter go for it. Note if you reduce your crank length you may find you need to make your bottom gear lower.

 

[Bob Orbell]

Aye, but your only talking 10mm from 175mm to 165mm but it would probably change all aspects of your setup including bar height and rotation.

No, it's 20mm from 165 to 175, 10mm at top and 10mm at bottom, I too use 165mm on my MTB and 170mm on my road. BOB

 

[Ningishzidda]

No, it's 20mm from 165 to 175, 10mm at top and 10mm at bottom, I too use 165mm on my MTB and 170mm on my road. BOB

Kins is correct. Move the saddle by the difference in the crank throw radius.
Your sitting position will move according to the trigonometry of the seattube angle. For a 10mm movement in height, it could be 2.5mm fore/aft. Then its nit-picking.

 

[Kins]

Its interesting that quite a few tour riders use different crank lengths for flat or hilly stages. I've just stuck 165mm on my older road bike as I had a pair off an old bitza and see if it makes any difference to my knees or anything else.

 

[Bob Orbell]

After reading this article I am wondering whether to shorten my crank lengths to 165mm because my knees are a bit dodgy.

http://www.powercranks.com/cld.html

Anyone use 165mm and around 6ft or use shorter cranks?

A very good bit of data, thanks. In September of last year I had a total knee replacementwishing to get back in the saddle as soon as pos. I grafted some 150mm cranks to my MTB and found that I could ride, I have since changed to 165mm cranks and find this size much nicer than 175mm that the bike came with. Also one should be able to pedal faster with shorter crank's, think slow reving long stroke british motorcycles v's short stroke modern motorcycles.

 

[SatNavSaysStraightOn]

Its interesting that quite a few tour riders use different crank lengths for flat or hilly stages. I've just stuck 165mm on my older road bike as I had a pair off an old bitza and see if it makes any difference to my knees or anything else.

I understadn it is related to spin rate. IIRC you can spin a shorter length crank faster so going up hill should be easier, if you can spin it all the way that is. - though it could be the opposite way around, can't really remember!