Does crank length matter?

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simonali

Guru
I have a little toe overlap on my CX bike and am considering slightly shorter cranks as a solution, as I'm not sure I want to fiddle with my cleat position. Gives me an excuse to buy something shiny and lightweight, too, innit!
 

Ajax Bay

Guru
Location
East Devon
The challenge is procuring shorter cranksets at a reasonable price to try them out. My daughter had a H2 BB and 105 cranks and one can get 165s for H2 but that's about it. Spa Cycles do a range of shorter cranksets (and chainsets) but they require a square taper BB. When doing the maths, I calculated that replacing the H2 BB'ed 105s with a UN55 and a Spa Cycles 160mm crank double would mean a 140g weight penalty. In the event she found a new (as in 'last year's but unused') TT bike with a small frame and a 165 crankset fitted. @dave r @simonali @DCLane had a surplus 165mm Ultegra chainset his son had grown out of.
 
D

Deleted member 1258

Guest
The challenge is procuring shorter cranksets at a reasonable price to try them out. My daughter had a H2 BB and 105 cranks and one can get 165s for H2 but that's about it. Spa Cycles do a range of shorter cranksets (and chainsets) but they require a square taper BB. When doing the maths, I calculated that replacing the H2 BB'ed 105s with a UN55 and a Spa Cycles 160mm crank double would mean a 140g weight penalty. In the event she found a new (as in 'last year's but unused') TT bike with a small frame and a 165 crankset fitted. @dave r @simonali @DCLane had a surplus 165mm Ultegra chainset his son had grown out of.

My Eastway has a Hollowtech bottom bracket on it, and on a search I did it looked like a square taper conversion would be needed to put a shorter crank on it. Weight wise extra weight isn't a problem, I'm only a leisure rider these days, but I did have concerns about whether I could convert the bottom bracket.
 

jowwy

Can't spell, Can't Punctuate....Sue Me
I used sram red 165s on my Ti.........now i got sram rival 165s as i switched to single chainring upfront and wasnt happy paying £200+ for the force crankset
 
Typically, with a shorter crank you can get a better lean angle without risking grounding the pedal as well, which is useful for tight, Crit circuits, and can’t hurt with being able to corner faster and being able to pedal through the corners in road rides either.

If you look at the BB height across the range of frame sizes, for almost every make and model the height is constant. This puts smaller riders much higher up off the ground than necessary when using short cranks and makes mounts and dismounts harder.
 

Sharky

Guru
Location
Kent
My Eastway has a Hollowtech bottom bracket on it, and on a search I did it looked like a square taper conversion would be needed to put a shorter crank on it. Weight wise extra weight isn't a problem, I'm only a leisure rider these days, but I did have concerns about whether I could convert the bottom bracket.
I went that route. Went back to square taper and bought a set of SINZ expert cranks. Actually got my LBS to fit the new square taper BB as I didn't have the tools to remove the hollowtech and I wasn't sure of the BB axle length needed. They did a great job.

In total, I have now 4 bikes running with short cranks (145mm & 150mm). Two with Sinz cranks and two re-drilled by Highpath engineering.
 
D

Deleted member 1258

Guest
I went that route. Went back to square taper and bought a set of SINZ expert cranks. Actually got my LBS to fit the new square taper BB as I didn't have the tools to remove the hollowtech and I wasn't sure of the BB axle length needed. They did a great job.

In total, I have now 4 bikes running with short cranks (145mm & 150mm). Two with Sinz cranks and two re-drilled by Highpath engineering.

Was the bottom bracket a straight swap?
 

simonali

Guru
I used sram red 165s on my Ti.........now i got sram rival 165s as i switched to single chainring upfront and wasnt happy paying £200+ for the force crankset

I am happy for buying Force crankset! :hungry:

My bike is already 1x11 with Rival cranks, so another set wouldn't be an upgrade, would it? ^_^
 

Sharky

Guru
Location
Kent
Was the bottom bracket a straight swap?
Yes standard English thread size
 

Ajax Bay

Guru
Location
East Devon
If you look at the BB height across the range of frame sizes, for almost every make and model the height is constant. This puts smaller riders much higher up off the ground than necessary when using short cranks and makes mounts and dismounts harder.
Good point but it's millimetres in'it, so not "much" higher. The shorter rider will already likely be on 170s so going to 160s (say) means a saddle height rise of 10mm: less than 1.5% of saddle to road distance.
 
I had a quick search for 165mm Force cranks and they appear to be rarer than unicorn droppings.
They’re popular, so harder to get hold of. 165mm is a bit too short for my liking anyway. Riding up to 20000 miles a year gives one an idea of what suits, 170mm is as short as I’d ever go personally.
 

Crankarm

Guru
Location
Nr Cambridge
It's not about power output though, it's about stress on the knees and comfort.......having used 175 down to 165 I always feel better on 165s and my knees do feel the difference

I would have thought crank length would be largely irrelevant riding an E-bike as you have the motor assisting you?
 

jowwy

Can't spell, Can't Punctuate....Sue Me
I would have thought crank length would be largely irrelevant riding an E-bike as you have the motor assisting you?
I also ride a custom Ti with sram etap
And a custom TT with di2.......

On both crank length matters
 
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