Crank length confusion.

Osprey

Veteran
Location
Swansea
I,m looking at a new Campy Veloce chain set for a new build project which comes in options of 170, 172.5 and 175mm. When I,ve bought complete bikes in the past, crank length has never been an option. I'm 6'2 and ride 58cm frames so is it logical I choose the larger 175mm option. I can't believe you would appreciate a difference of 2.5mm radius difference. Any of you guys offer some advise would be appreciated.
 

Pale Rider

Legendary Member
Not advice as such, but I discovered the other day some Whyte mountain bikes - aimed at female riders - are labelled 'compact' and have shorter cranks.

Their compact bikes also have a shorter reach.

Presumably, the thinking is a person with relatively short legs will get an overall better fit.
 
Yeah, I've never been too sure about it myself. I used to have an old crankset with 165mm and that was definitely too short. 170, 172.5 and 175 are fine and I can't really tell the difference if I'm honest. It's said that longer helps with climbing and short helps with sprinting.
 

Sharky

Guru
Location
Kent
Must reply to this one.

There have been lots of theories over the years about cranks, even L shaped ones.
But there is a lot of riders switching to shorter cranks and lots of articles on the web
http://www.powercranks.com/cld.html
I am 5' 9" and for the last couple of years have been riding 150mm on three of my bikes and have 145mm on my tt bike.
Comfort, cadence and aero are all improved and even climbing. I can pedal faster and stay in the saddle for longer. And less strain on the knees.

You need to find your own perfect length, but don't fall into the trap of thinking that longer means more leverage.
Read also Sheldon Brown on gain ratios.

Keith
 

Soltydog

Legendary Member
Location
near Hornsea
If you have a bike at present check their length. I ride 175mm cranks (6'5" tall) & once had a belt driven hybrid with 165mm cranks, I didn't think it would make that much difference, but boy it did. So much so I didnt enjoy riding the bike & ended up selling it :sad:
 

shadow master

Well-Known Member
Cranks lengths should be closest to 9% of your height........allegedly
 

Smokin Joe

Legendary Member
Must reply to this one.

There have been lots of theories over the years about cranks, even L shaped ones.
But there is a lot of riders switching to shorter cranks and lots of articles on the web
http://www.powercranks.com/cld.html
I am 5' 9" and for the last couple of years have been riding 150mm on three of my bikes and have 145mm on my tt bike.
Comfort, cadence and aero are all improved and even climbing. I can pedal faster and stay in the saddle for longer. And less strain on the knees.

You need to find your own perfect length, but don't fall into the trap of thinking that longer means more leverage.
Read also Sheldon Brown on gain ratios.

Keith
That's a very interesting article which I will study more later. I've never thought much about crank length and was going to dismiss that piece till I got to "If you throw your knee out at the top of the stroke". I've been doing that for fifty years so maybe it's time to experiment a little.
 
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