Crank Arm Length

[Tractor]

I'm busy planning another mtb build using a 26er On-One frame I recently bought and was doing a bit of web crawling / searching to see what the ideal crank arm length would be for my height - I've by default always just used 175mm cranks since that was what was fitted to the bikes. I came across this - seems to be a pretty useful table which gives some guidelines:

 

Crank Length = 160mm

If you're 1.5m tall or shorter

 

Crank Length = 165mm

If you're between 1.5m and 1.65m tall

Inseam less than 73.6cm

 

Crank Length = 170mm

If you're between 1.65m and 1.78m tall

Inseam between 73.6cm and 81.3cm

 

Crank Length = 172.5mm

If you're between 1.78m and 1.83m tall

Inseam between 81.3cm and 86.4cm

 

Crank Length = 175mm

If you're between 1.83m and 1.88m tall

Inseam longer than 86.4cm

 

Crank Length = 180mm

If you're taller than 1.88m

[fanievb]

I'm busy planning another mtb build using a 26er On-One frame I recently bought and was doing a bit of web crawling / searching to see what the ideal crank arm length would be for my height - I've by default always just used 175mm cranks since that was what was fitted to the bikes. I came across this - seems to be a pretty useful table which gives some guidelines:

 

Crank Length = 160mm

If you're 1.5m tall or shorter

 

Crank Length = 165mm

If you're between 1.5m and 1.65m tall

Inseam less than 73.6cm

 

Crank Length = 170mm

If you're between 1.65m and 1.78m tall

Inseam between 73.6cm and 81.3cm

 

Crank Length = 172.5mm

If you're between 1.78m and 1.83m tall

Inseam between 81.3cm and 86.4cm

 

Crank Length = 175mm

If you're between 1.83m and 1.88m tall

Inseam longer than 86.4cm

 

Crank Length = 180mm

If you're taller than 1.88m

 

so my crank arms are too long on both my bikes.

 

i think i need a refund on the bike fitment i had done.

[igknot]

so my crank arms are too long on both my bikes.

 

i think i need a refund on the bike fitment i had done.

So are you selling ?

 

How much ? for how long ?

[Tractor]

so my crank arms are too long on both my bikes.

 

i think i need a refund on the bike fitment i had done.

 

According to that table all the bikes I've ever owned have been fitted with the wrong length arms BUT that's what you get when you purchase an off the shelf bike as opposed to a custom built bike where you can actually specify the length.

 

Is it perhaps a case of making do with what you have when it comes to fitment services?

['Dale]

I roll with 175

Should be 172.5

 

My bike fitment corresponds with this table.

 

A new crankset (Hollowgram) will be more than 10 big ones

:-O

[Brighter-Lights]

I'm 1.72 tall and have always used 175mm cranks. I can't say that I was unhappy with them but I DID on numerous occasions wonder how shorter arms would be since most bikers taller than me also use 175mm.

 

I then by accident bought an XTR crank with 172.5mm arms and I much prefer the 172.5mm - the most noticeable difference for me is when standing up attacking a hill... much more efficient pedal motion.

 

I also tested a 170mm crank and it felt much shorter than the 175mm - personally I like the 172.5mm better than the 175mm, but the 170mm felt too short. - on a mountain bike.

[fanievb]

According to that table all the bikes I've ever owned have been fitted with the wrong length arms BUT that's what you get when you purchase an off the shelf bike as opposed to a custom built bike where you can actually specify the length.

 

Is it perhaps a case of making do with what you have when it comes to fitment services?

 

I guess, but my roadbike comes with different crank arm lengths depending on the bike size e.g my 54cm has 172.5mm crank arms. I presume this is to cater for shorter rider. (my length is 172 inseam of 79)

 

http://2013.feltracing.com/International/2013/Road/F-Series/F95.aspx

 

But then again, as you said, bike fitment is then done to fit the rider "around" the bike

[davetapson]

I've read somewhere that single speed cranks should be on the short side - can't remember the reason, but probably to allow you to spin.

 

I've also read that crank arm length doesn't make a whole bunch of difference - one of those marginal gains thing. Ergofit says I should be using 180mm (I'm 183cm tall) and I'm running 175mm. Would be interested to see if there was any diffs with 180mm... maybe when I buy another bike / crankset.

[ScottCM]

I'm 1.72 tall and have always used 175mm cranks.

 

I', 1.89m tall and my bike came with 172.5mm cranks, going to cyclefit end of the month for my first fitment and hopefully they will be able to tell me how to proceed.

[Tractor]

I', 1.89m tall and my bike came with 172.5mm cranks, going to cyclefit end of the month for my first fitment and hopefully they will be able to tell me how to proceed.

 

Please update as to what they have to say

[quintonb]

Interesting topic.

I am 1.87m tall with an inseam of 91cm, I have been riding 175 cranks on my road bikes for a good 20 years.

I rebuilt my 1989 Hansom with its original components, the cranks are 172.5 and I love riding them.

I am not a power rider, I prefer riding at slightly higher cadence and the 172.5 length is far more comfortable to turn.

Been thinking of changing my current road bike set up.

['Dale]

Shorter crank length assists with high speed accelerations - one main benefit.

It'll be critical for MTB specifically, especially if it's too long for the rider.

 

 

[madbradd]

Also longer cranks on an mtb reduce pedal clearance.

 

I'm 193cm tall and have only ridden 175mm cranks. They're what come standard on most xl frames, so it's what I ride.

[JA-Q001]

Don't fall for the length crank according to your length mambo, it has very little to do with it. Some track cyclists, that are 1,9m tall use a short crack (160mm - 165mm), its because the want to be able to get a higher speed, shorter crank = smaller circumference = legs move slower at the same rpm. Someone like Pantani (think he was around 1,7m) used 180mm cranks to get leverage on climbs, he also never used a cassette with a gear larger than a 23.

 

If you like spinning and sprinting go shorter, if you like grinding go longer.

['Dale]

 

If you like spinning and sprinting go shorter, if you like grinding go longer.

 

Sums it up nicely

[Tamlyn]

Came across your discussion while researching 160mm cranks. Does anyone know where to buy or order a 160 or 165mm MTB crank in Johannesburg? I'm 1m59 so research shows it should fit...