Anyone here roll 172.5mm cranks?

I’m considering changing over my 165mm cranks on my fixie to 172.5mm to better match the fit with my other bikes.

172.5mm on a road bike conversion fixed-gear- am I asking for pedal strike trouble?

dunno - guessing it’s going to depend on a few factors - height of Bottom Bracket, size of pedals and how far you tend to lean into turns.
(I run 170 something, but I’ve got a high bottom bracket)
I’d get a tape measure out and guess. (or just put them on anyway and see if you stack or not - maybe get some of those sweet kirin shoulder pads to soften the blows)

I’ve got either 171.5mm or 172.5mm Sugino cranks (can’t remember). I have them on a track frame, so no real pedal strike issues, but I do get pretty harsh toe overlap.

Yes, well being a road frame I imagine the BB is going to be lower than a track frame. :expressionless:

Shimano SPD’s- as small as you’re going to get

I run 170mm cranks on my roadbike fixed conversion (and my track fixie for that matter) and have not encountered any probs (I raced the roadbike in the St Kilda fixed crit race and we were taking right angled corners at reasonable speed and still didn’t strike).

Doubt the extra mms will make much difference.

SW

I’ve had 175s on a track frame for 2 years. Never touched.

Simple test: put cranks and pedal on and lean bike over till it touches. Do you lean over that far when turning? Not usually, not even unusually.

thread hijack!
best quote ever

I’m not sure it’s that simple.
I have had pedal strike on a fixie before- not very often, but it happens.

The test is that simple: of course riding the street throws up some variables, but it still gives you a good guide.

Perhaps the correct question to ask is about clearance, because it is more about clearance than crank length.

^ what’s recommended clearance?
I realise it differs from frame to frame.

Ditto, I run 175s on my fixed commuter pig, never had pedal strike but the BB is a high one. Try S.E.'s simple test.

Well a recommended crank clearance won’t change from frame to frame, that’s why I think it is a better question. I think the easiest measurement is just to measure from the ground to the centre of your pedal axle (centre of the pedal hole) when the crank is at 6 o’clock.

Of course pedal choice will also effect your propensity to suffer pedal strike, but that changes for each user.

So I’ll start off the with some measurements from my bikes:
Street track track: 110mm (with 175mm cranks)
Road bike: 100mm (with 175mm cranks)
Velodrome track bike: 115mm (with 170mm cranks)

So I’d say aim for clearance of at least 110mm.

This ignores the different q-factor of the cranks, but should be a good guideline. Running a narrow bottom bracket (decreasing q-factor) will help your clearance. Try for BB axle length of 108 or less.

thing is is that often when you’re powering fast through a corner, and you’re out of the saddle, you tend to angle the bike in the direction which will give you the most power (vs balance) which means that the angle the bike is at is not the same as how much you are leaning
In my experience this is when pedal strike happens (only happened once to me, I did the same test as you did, and taking a corner at speed, on a hill caused pedal strike - I was using 175s though)

Track or road frame… how much clearance (valuable info for the ‘survey’)?

The point of the test though is to provide a guideline so you know how far you can lean… it doesn’t stop you from leaning further!

i get pedal strike on roundabouts with my 172.5 cranks and road conversion. only roundabouts though… that said they are pretty wide so ymmv

I use my staps as a guide to wether i am gonna strike the ground.

kind of like cats whiskers i guess. You can feel the vibration when the strap hits the ground when cornering

was a SE lager, SS/FG. I’d measure the distance but it (and myself) went under a car about 8 weeks ago, and any measurement wouldnt be valid anymore.

The point of the test though is to provide a guideline so you know how far you can lean… it doesn’t stop you from leaning further!

I think you kind of missed my point… I’m saying you lean the bike further when you power around corners when you’re out of a saddle so you may only be at say… 20º but when you push your leg around, you instinctively tilt the bike to say… 23-26º and 25º is where you get pedalstrike, but the pedal needs to be perpendicular to the ground when that happens, but the bike is only at that º for a fraction of a second. ie: you start pushing the bike from 23º at with the 1/2 revolution of your ‘down’ pedal and that follows a curve through to 26º and back again (so would rock say… 26º to maybe… 15º through the entire revolution - you move the bike the other direction to get more power with your opposite foot)

frustrating… this could be explained irl so much more easily :stuck_out_tongue:

i used to rock 172.5s

i palp 170s and have had pedal strike twice.

I ride a conversion with 165mm cranks and I pedal strike all the time.
Might come down to the fact that I’m a crap rider though.