I switched after a bike fit, can’t say I noticed much difference, I adjusted the saddle height to compensate. I would need to go back to 170 to compare, which I am not planning on doing. Ordered a new bike this year and went with 165 to keep the same. Bike fit also suggested stem length increase by 10mm. This is on my new bike and does take some time to get used to.
I’m 6’ (183 cm) tall and I went from always riding 172.5 or 175 mm cranks straight to 165 mm on my road bike last year. It helped me get significantly lower on the bike and got rid of some low back pain. I won’t go back.
On the mountain bike I’ll be sticking with at least 170 mm because I like having more leverage from the longer cranks for steep climbs. Hip angle doesn’t really matter there but avoiding rock strikes does.
Gravel is more debatable and depending on how low you want to go with your position.
Went down to 165 back in 2016b and never looked back. Could ride longer without hamstring cramping, less pedal strikes on corners, the pedal strike was just more fluid and ran off the bike much better. Genuinely couldn’t find a reason to stay with longer cracks.
Same situation and I did the same, as well as moving to 170s from 175s.
Note that reducing crank length means that your foot is closer to you when your foot is at the bottom of the pedal stroke, which means that you would need to raise your saddle a similar amount as the amount you shortened the crank. This will also move you slightly backwards.
Of course, this assumes your original saddle height was correct and was measured from the center of the crank.
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But also consider that at the bottom of the pedal stroke you aren’t really doing anything useful. Where you apply power and therefore have the highest loads on your joints is around 3 o’clock. Here the shorter crank moves the pedal backward and while it will also close your knee angle slightly, more appropriate adjustments might be moving the saddle back or the cleats forwards.
Based on the anecdata of dozens of bike fitter YouTube channels, saddles seem to be mostly too high anyway. I suspect many of these are to clear impingement at the top of stroke, and shorter cranks reduce this problem allowing the seat to be lowered to a more stable location.
Unfortunately, the bike industry’s refusal to scale crank arms means we locked ~170mm cranks into ~73 seat angles that are instead steepened or slackened. A broad shift in crank lengths might really need a different approach to seat angles.
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I’m 170cm tall and 66 kg. Best thing I ever did. Never looking back.
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I had a bunch of different crank sizes on different bikes (145-172.5 or 175, not sure). I didn’t notice the difference in pedal feel between them.
What I did notice on the shorter ones was the higher center of gravity. And on the longer ones (my commuting bike) I noticed clipping my pedals occasionally [never hard enough to crash, thankfully]. I guess I had gotten used to the clearances on my other bikes which were all shorter (165 or less).
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I recently went to 165 on my epic evo and I’ve enjoyed having less pedal strikes but its raised my center of gravity up which has taken a bit to get used to. Im thinking of going back but Ill give it a few more months. Im honestly surprised more people arent complaining about their higher center of gravity and saying they feel less “in the bike.”
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I was also wondering what is more aero…Raising your entire body up a half inch when you put on shorter cranks or staying lower with the long cranks and with less saddle to bar drop.
I think generally you get more aero when moving to shorter cranks because while your butt does move up the front stays the same so usually you are just flattening out your back
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I’m massively more aero with 165 cranks vs the 172.5 that came on my Tarmac. The reason is that my hip flexibility was the limiting factor in getting my back flatter. Raising my seat slightly and getting my chin way closer to the bars is a huge difference. Combined with narrow bars, I can draft small riders now. Total game changer.
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My worry with 165 cranks (coming from the defacto 172.5) is steep climbs.
Where I live sustained 15-20% grades are not uncommon. I’m 6ft, 80kg with an FTP of 285.
In 34/34 I just barely survive the most sustained steepest stretches around here.
As far as I can make out this is the one time where the lack of leverage of short cranks will cause an issue, as there’s no easier gear to switch to to spin faster.
Anyone else in a similar boat but made the switch anyway?
I suppose it’ll just force me to get stronger…!
(I also have the mental health issue of weightweenieism, so I’m not about to stick a 105 11-36 out back 
)
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So you prefer to have inadequate gearing, because you want to avoid that your bike gets 46 g heavier? (Shimano lists its Ultegra 11–34 speed cassette as weighing 345 g and its Ultegra 11–36 cassette as being 391 g.)
The solution is simple: put the 11–36 cassette on. Done. Having adequate gearing is much, much more important.
It’s not an issue, you just need to compensate for it by changing your gearing. When I went to a 1x12-speed drivetrain, I was debating whether to go for a 44-tooth or 42-tooth chainring. I went for the latter as I knew I’d be spinning slightly faster. Worked out great, the gearing was spot-on.
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So you prefer to have inadequate gearing, because you want to avoid that your bike gets 46 g heavier? (Shimano lists its Ultegra 11–34 speed cassette as weighing 345 g and its Ultegra 11–36 cassette as being 391 g.)
I mean, I already acknowledged that it’s a MH issue, you don’t need to bully me about it… that’s not very 2025 of you 
(FWIW I currently run a 156g Ztto cassette, having had a D-A one before. Not sure why you think I’d be happy with an Ultegra one )
I am coming back from injury though, maybe in a month or two I’ll be able to turn the 34/34 over more easily on even the 24% gradient peaks I see around here. If not I could always try an 11-36 Ztto, depending on how this one pans out (only had a few rides on it so far).
It’s not an issue, you just need to compensate for it by changing your gearing.
That’s a strange response to “the lack of leverage of short cranks will cause an issue, as there’s no easier gear to switch to” I’m not saying that changing the available gearing on the bike isn’t a fix, but we’re only talking about a fix because there IS an issue to fix 
I feel that it’s actually easier to climb with the shorter cranks (180cm). Running 160mm now and the difference in hip angle when climbing is incredibly nice, as it doesnt require as much to get over the top of the pedal stroke you feel much calmer and stable when climbing.
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You lose leverage but gain cadence which to me makes climbing easier
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A company called Gearoop makes a 33t for 110mm BCD, both the standard 5-arm & the modern Shimano X pattern. I found them on ebay being sold by Ram Cycle Parts based in Adelaide. There may be other sellers worldwide. It should be marginally lighter than a 34T so stick that on with a 36t in the rear & you’ll notice a difference over your current 1:1. 
You should be able to continue to use your current big chainring. I have one & I’m using 33-52 combo on my other bike.
Or if you really want to go low (as well as your bank account) you could try a Dixna La. They do subcompacts from 32T down to 24T, with an appropriate big chainring. Chainline is supposed to be matched to 105/Ultegra/etc. Not sure what its weight is though, nor what it’s like with mounting the FD. Perhaps you can get a mount extender to drop it down. Or if you’re okay with an increased Q-factor, you could go full GRX up front.
If 1:1 is all you’ve ever had then you have no way to compare what difference higher cadence would make on those steep grades.
Do you also like to grind on the flats?
I wonder if pros who’ve switched to shorter cranks switch back to longer ones for mountain stages.
Or do they prefer to spin in a lower gear and stick with the change to shorter cranks?
I seriously doubt they’re changing crank length and the rest of their bike fit accordingly, on a stage by stage basis.
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