Crank Length ?

[Betsy]

I'm not personally a fan of the tiny crank brigade - I'd suggest 175 for a person who wears 34" trousers...

Is this based on the classic range of tailoring from Marks & Sparks which you see on the Antiques Roadshow?

The trousering of most folks under 40 hasn’t reached their shoes for at least a decade.

 

[bikeworkshop]

Misjudged the target audience

 

[Betsy]

I'm not personally a fan of the tiny crank brigade - I'd suggest 175 for a person who wears 34" trousers...

I’m 5’ 11” with a 32” inside leg so based on this^ .. 165 suggested by the appleman calculations might not be too far off.

 

[bikeworkshop]

170s should be ok, better for out-the- saddle, but 165s will suit spinning mpre, less stress on the knees

 

[SFP]

Ahhh the internet....

I actually just started looking into this, this past week as I will be building up my first road bike since 1994.

On my MTBs I have always rode with 175mm and been happy.
My race BMX has 180mm, my cruising-around/pump-track/skatepark BMX (20" wheels) I run 175mm.

For reference I am 5' 9", my inseam measures 28.75 inches.

Back in the day I ran 172.5mm cranks on the road bike.

As I look into building up the new to me frameset, I thought, hrms... what size cranks do I need.

Searching online it suggests a 170mm length, with 172.5mm being the max, and 165mm would work as well.

Needless to say this has given my head a lot to think about. As mentioned previously finding high quality used shorter cranks is not the easiest thing.

I have only clipped the cranks on a road bike in a corner maybe twice, three times in my life time. On pavement I prefer to spin cadence rather than pound. I like hills (to a degree eh).

Yes crank length makes a difference. But I will be the admit I am just kinda eye-balling it as it were at this point. Going by the "what feels right" to me.

Advise is totally welcome. And I shall be following this thread.

 

[bikeworkshop]

Ahhh the internet....

I actually just started looking into this, this past week as I will be building up my first road bike since 1994.

On my MTBs I have always rode with 175mm and been happy.
My race BMX has 180mm, my cruising-around/pump-track/skatepark BMX (20" wheels) I run 175mm.

For reference I am 5' 9", my inseam measures 28.75 inches.

Back in the day I ran 172.5mm cranks on the road bike.

As I look into building up the new to me frameset, I thought, hrms... what size cranks do I need.

Searching online it suggests a 170mm length, with 172.5mm being the max, and 165mm would work as well.

Needless to say this has given my head a lot to think about. As mentioned previously finding high quality used shorter cranks is not the easiest thing.

I have only clipped the cranks on a road bike in a corner maybe twice, three times in my life time. On pavement I prefer to spin cadence rather than pound. I like hills (to a degree eh).

Yes crank length makes a difference. But I will be the admit I am just kinda eye-balling it as it were at this point. Going by the "what feels right" to me.

Advise is totally welcome. And I shall be following this thread.

The truth is:
For many people it just doesn't matter.

Most midrange bikes come in sizes xs (say 14" mtb) to xl (say 22" mtb) - to fit riders from 5'0 to 6'4 - yet the cranks are nearly always 170s or 175s and plenty of models have the same length on all sizes

If you're not needing to squeeze every drop of efficiency out of your bike and body, and your joints don't hurt, ride away!

If you're a triathlete, racer, enduro weirdo, get back on the net!

Otherwise, 170s would be the one to go for to get choice and value.

(Comfort and efficiency aren't in the bmx design requirements - and the pedals are doing quite a different job)

You could possibly get shorter cranks, but most likely at a price, and you would probably never notice the benefit.

 

[Betsy]

Even for me.. with a little knee pain, I mean, c’mon, I’m from the north of England, I’d have to be unable to flippin walk before i consider spending money replacing something I already own..

Especially when it’s 5mm shorter, I wouldn’t even be getting better value for money!

 

[bikeworkshop]

Raising your cadence 5% probably has a greater effect than shortening your cranks 5mm.
... and it costs Nothing!

 

[Woz]

I'm just glad when you were talking about 175mm and 32" trousers you weren't referring to waist size.

 

[Betsy]

^^ the next time I’m in the market for new cranks, I’ll probably give 165 a spin.. I just wouldn’t pay to swap.