Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
Technical discussion, description and outright lies
18 posts • Page 1 of 1
I'm 173cm with a 79cm inside leg.
Apparently, my ideal/optimal crank length is 163mm.
This poll is for those guys/gals who are less than 180cm tall...
What crank sizes are you using ?
I'm 178cm. I don't know what my in-seam measurement is, but I ride with a crank centre to seat top effective measurement of 79 cm. I use 172.5mm cranks on the road and 175mm off-road, although I'm experimenting with a 170mm crankset from time to time.
Edited - oops, I just noticed that I'd put 'cm' in my crank sizes
Last edited by LuckyPierre on Tue Jun 17, 2008 3:02 pm, edited 1 time in total.
Litespeed Classic - 3Al/2.5V titanium tube set, Record 9-speed groupset, Open Corsa Evo CX
Alchemy Diablo - Columbus Zonal tubing, Ultegra 9-speed groupset, UltraGatorskins
Gitane Rocks T1 - U6 tubing, Deore/XT groupset, CrossMarks
Not exactly short (178 or so), but short in the leg (generally wear 30" inseam pants, which calcs out to 76cm).
Several of my bikes have 175s, because that's what bikes tend to come with. I've had a few shorter cranksets, and I like 'em. I would struggle to pick the difference between 170s and 175s without checking the stamping/castings on them, but a few times I've had a bike feeling just right, and noticed later that the cranks are 170. Or even 165 (I think that crankset is on Mrs Barefoot's bike now - I should claim them back).
'Crank Length for the shorter chaps out there...'
What? I am 173cm tall, with a 79cm inside leg, too. I frequently stand significantly taller than other commuters when standing on packed Sydney trains. You are by no meets 'shorter', unless of course cycling tends to attract taller guys, who have a better natural mechanical advantage to inspire them to stay with the pursuit.
Give up cycling and move to Sydney to utilise the public transport so as to overcome your inferiority complex!
Seriously - why is the calculator telling me I should be using a shorter crank? I have only ever used 175mm cranks - becuase that is what the MTB's I have bought from bicycle shops are sold with. Would my irregular cycling and commute of 34km improve if I went for a shorter crank?
Live every day as though it is your last - one day you will be right...
What I have and what I'm going to put on my bike are two different things.
I've got 175s on my MTB, and they're fine for the riding I do on it.
I've also got 175s on the recumbent, but I'll be putting 150mm cranks on it as soon as I can source some. Spin is king on the 'bent, so shorter cranks are where I'm headed.
Horses for courses, right tool for the job, etc.
Knew I would get a few bites there
I'm no expert, but do like to approach these things from a technical or scientific angle, as well as the 'feels right' angle.
If the crank is too long for your leg then:
1. Your knee angles will be too high, potentially leading to excessive stress/wear on your joints.
2. The longer the crank the more the mechanical advantage - so if your gearing is too steep you can 'survive' this better with cranks that are too long. Ideal cranks may force you to ensure the ideal gear ratio's for the terrain you are in most of the time.
3. Crank length, knee angle, and frame size are all somewhat inter-related - so you can change a few variables to find your fit. Assessing or thinking about crank angle seems a natural part of that process I guess.
I am no expert - I've just paraphrasing a few hours reading and mulling over the potential impacts.
I'm seriously thinking about 165mm cranks IF I do change my front chainring setup.
This point is very important. I can easily swap to a 150mm crank without effecting the fit of my bike because it doesn't have a top tube, seat tube, fore and aft seat positions, bar height, etc. for me to worry about. On the 'bent, I simply move the seat back about 25mm and pull the bars back to suit.
On a conventional bike, shortening the crank by that much means raising the seat to allow correct leg extension. It also means move the saddle back a little (if KOPS is your thing), which then means getting a shorter, higher stem which in turn may lead to an unbalanced ride. In short, getting 150mm cranks on a conventional bike would necessitate a rethink on frame design if you're to do it properly.
Track Bike: 165mm
Road Fixie: 170mm
Road Bikes: 172.5mm
Mountain Bike: 175mm
Single Speed 26" MTB: 177.5mm
Single Speed 29" MTB: 180mm
I guess I've got nearly every length covered, though I have sometimes run 167.5mm and 170mm on the track for various events.
whats next on the shopping list then? .
Why do you run such long cranks on the Single Speed MTB's ?
Fixie riders never freewheel
18 posts • Page 1 of 1
Who is online
Users browsing this forum: No registered users