Crank Length?

[ricnott]

I am looking to upgrade my groupset in the next month or so. My current set up has 172.5mm cranks and the new group only comes in 170 and 175mm. The bike is used 90% for commuting year round and 10%leisure rides aroung Nottingham. I have another bike for long rides and sportives so this bike will not be fulfulling these duties.

Does anyone have any advice/guidance on appropriate crank length that I should be looking at?

 

[ianrauk]

Look at 2&half mm's on a ruler. Tiny ain't it?
It will make very little (if any) noticeable difference to a commuting/leisure rider.
You just have to adjust the saddle to compensate.

 

[ricnott]

Thanks Ian. I was of the same mind.

 

[Nigeyy]

What Ian said.....

I've cycled with cranks of various lengths 170,172.5,175, and probably more, and tbh, haven't noticed any difference. The only time I notice a difference is when I ride my Grandad 3-speed Rudge special which must have something like 150mm crankarm lengths (or at least feels like it). But we're talking about a total 5mm difference in diameter to your pedalling circle here, which is pretty small. Maybe a pro rider can tell the difference, but I think mere mortals usually can't.

If you go up hills a lot, maybe go with the 175mm as theoretically it will provide you with a bit more leverage. Having said that, I'd probably just get whichever is the cheapest. Once you start riding it, my guess is you'll never notice.

 

[Nigeyy]

Oooh, forgot to say, I remember cycling on the ring road in Nottingham back in the 1980's past the Raleigh factory.... those were the days!

 

[Dusty Bin]

I know of someone who cycled for several months (without realising) with a 170 on one side and a 172.5 on the other. Having said that, it is practically impossible for anyone to recommend a specific crank length for you when you have provided zero information on your size, leg length and other potential influencing factors.

 

[ricnott]

I know of someone who cycled for several months (without realising) with a 170 on one side and a 172.5 on the other. Having said that, it is practically impossible for anyone to recommend a specific crank length for you when you have provided zero information on your size, leg length and other potential influencing factors.

Thanks Dusty. I know that for a full fit I would need all that info. Just wondered if anyone had any general advice on the matter.

 

[ricnott]

Oooh, forgot to say, I remember cycling on the ring road in Nottingham back in the 1980's past the Raleigh factory.... those were the days!

I know . Now it is the new University campus.

 

[lukesdad]

Thanks Dusty. I know that for a full fit I would need all that info. Just wondered if anyone had any general advice on the matter.

If you are short go 170 if you are tall go 175 if you are medium erm.... Well basically you're fecked! Hope this is general enough?

 

[zacklaws]

I'm just over 6' and always used 175mm, till I had a bike fit and 172.5mm was my recomended size, and since fitting them it was a big improvement.

As a rule though, its normally acceptable that short cranks promote high cadence and longer ones for hill climbing due to the extra leverage

 

[Dusty Bin]

As a rule though, its normally acceptable that short cranks promote high cadence and longer ones for hill climbing due to the extra leverage

the 'extra leverage' that 5mm gives you - really ??

 

[musa]

No improvement And no extra advantage of leverage just your angles are out by 2.5/5mm

 

[Soltydog]

Depends on your size I'd guess. I have 175mm normally, however on my belt drive hybrid, there was no option for longer cranks, so I have 170mm & I find the difference noticable.

 

[Richard A Thackeray]

All of my bikes (barring the now sold Trek MTB) have 172.5 cranks

I must be sensitive to variations in length, well - more position, as a change of inner soles in my Sidis made me readjust saddle height very slightly
I'll admit I never really noticed with the MTB, as I ran the saddle half-inch lower

 

[themosquitoking]

Look at 2&half mm's on a ruler. Tiny ain't it?
It will make very little (if any) noticeable difference to a commuting/leisure rider.
You just have to adjust the saddle to compensate.

It's 25mm isn't it? Still not massive i know but........