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Hi,
I recently built up a new frame, transfers over some old components and fitted a new 105 crankset. I just got the same length as I've used before - 172.5mm - as I have no experience with any other length.
However I have now worked out that the BB is lower on this bike, by only 5mm, compared to previous and I am experiencing pedal strikes like never before.
Is it worth swapping the crankset for one with shorted crank arms? Or just keep riding and adjust to it?
If you're getting pedal strikes either ride differently or get shorter cranks.
Note if getting shorter cranks you may need to lower the gearing slightly, if you 'depend' on the lowest gear.
What sort of bike? 105 cranks suggest gravel. You could go to 170mm cranks but woulkd 2.5mm really make that much difference? I think the next step down is 165mm, I don't recall ever seeing 167.5mm.
I don't notice the difference between 170/172.5/175 that I have on different bikes so it wouldn't bother me to change, but as i said, for 2.5mm i'd adapt the way I ride.
I am actually wondering if the pedals are making a difference. They are slightly thicker than the pedals I was using by a couple of mm but they are also about 20% longer, front to back than my old pedals. So any tilt of my foot will result in the toe of the pedal being quite a bit lower. I've awapped to my old pedals and will take it for a spin.
Been loads of threads on this recently. My view is that shorter cranks (165mm) are essential if you enjoy pedalling and gave a modern geo bike.
( off road)
IIRC Steve Peat ran 165mm cranks. And he's not a small man!
Pedal strikes when - cornering?
105 is actually available in 165mm and 160mm (but good luck finding them!), you might have better luck with GRX but that's also rarer than hen's teeth right now and brings it's own issues (chainring spacing is different and so needs it's own front mech, assuming you aren't 1x).
Have to say I didn't even realise that pedal strikes were a thing on a gravel bike.. must be some chonky gravel.!
Pedal strikes when on uneven ground where there's maybe small rocks lying on the surface (dodge it with the tyres, clip it with a pedal) or yes when "cornering" through a mild bend in the trail. Obstacles that hadn't previously considered to be very obstacley and required any thought.
I’m 6ft1 and swapped from 175mm to 165mm cranks recently. It felt weird for about half an hour but I haven’t thought about it since and I haven’t clipped a pedal either.
Swapped pedals to my older smaller ones, problem solved 👍
165mm 105 are available, never tried less than 170mm on any adult bike, even though theoretically shorter cranks would suit my ~82cm cycling inseam bowed legs (and reduce the stress on my knees a bit at the same time).
But you often pay a bit of a premium for non-standard sizes.
No idea if cheapest, but know they usually have a few lengths in stock. https://www.probikekit.co.uk/bicycle-cranksets-and-chainrings/shimano-105-r7000-chainset/11746895.html
Switched all of mine to 165, there's very little drawback imo since we have gears, and the benefit of ground clearance is really worthwhile. I mean, you notice a couple of mm difference in pedal thickness.
I had 160s in an old dh bike years back, because it was stupidly short and I used to pedal it up quite a bit and I kept kneeing the boxxers 🙂 That did feel weird, not when pedalling but when in attack position the stance just felt short.
Over the last couple of weeks I’ve ridden 175z, 170 and 165mm cranks, all with roughly similar gears, all the same wheel size.
Can’t say I’ve noticed any difference that could be ascribed to the crank length, save for number of pedal strikes