So jumping on the band wagon and trying to fix a back issue by spending money on bits rather than waiting for the exercises to sort it out… I have swapped from 170mm cranks to 165mm on both my gravel and XC (epic evo 2023) bikes.
I’m 182cm / 6ft tall so I don’t really need shorter cranks but because of hip / lower back issue I thought i’d give it ago.
I’ve liked the shorter cranks (although sprinting feels harder to get up to speed ) - but found I span slightly faster - which was expected.
I raced for the first time on the xc bike this weekend and found I got hung up going up rocks / large routes where I would have been able to PUSH over them with the extra leverage.
I’ve just swapped back to the 170mm on my xc bike as experiement but i’m curious for anyone elses feedback on if they also tried shorter cranks and if they have stuck with them or gone back.
I think that’s the one scenario where longer cranks have, at least, a perceived benefit – low cadence, muscling up super steep climbs or over technical terrain.
It’s about balancing what you need, when, and what works best overall.
If you’re rarely running out of gearing or climbing technical areas, then a shorter crank might work well for you.
If, however, you’re doing those things often, “longer” might be better.
My trail bike came with 165’s (Specialized Enduro) and I broke the original crank in a wreck. My friend at the LBS accidentally ordered 175’s to replace them and we didn’t notice the mistake. The first couple of rides I had more pedal strikes, and thought my riding was just off, but the bike as a whole felt better. After adjusting my riding, I stopped getting pedal strikes. Months later, I noticed they were 175mm.
But I have also found I like oval chainrings for tech climbing. No difference anywhere else in my riding (put some on my old roadie, no changes), only tech features.
Should add: I’m 5’7" and do very big days on this bike. I did 15 hours of riding on a 3 day weekend riding technical SW Utah riding just a couple weeks ago (you can look up Gooseberry Mesa if you want an idea).
I swapped from 170mm to 165mm on my MTB and found the switch to be anywhere from neutral to positive, but I’m considerably shorter than you at 5’6"/167cm, so it’s not an apples to apples comparison. I made the switch based on a recommendation from my fitter, and I generally feel more comfortable on the bike for long durations with the shorter cranks, so with no noticeable downside for me, I’m sticking with it.
I love tinkering and trying different things.
I’m not getting any younger or flexible and thought why not give it ago.
My enduro bike has 170mm and I grew up with 175mm cranks (as that’s all there was really) and only swapped to 170mm 5 years ago due to a toe overlap issue on my gravel bike.
More testing is required which luckily requires more riding
5-8 and I went down from 175 to 170, and my speeds have gone up.
I have always made power by spinning faster and the shorter cranks help.
Liked it enough to change them 170 on the gravel bike as well.
Hijacking this thread slightly
I’m 6’3" and currently have 175 cranks on my gravel bike. I’m definitely not a great technical rider (coming from a road background) and the one thing that’s put me off going for shorter cranks is that I’d have to put my saddle up to compensate (?) and absolutely don’t want to be sitting even higher up than I already do on steep downhills (granted I could probably run a dropper)
Is this a valid concern or am I overthinking it?
I generally ride more upright on the MTB, so 165-175mm doesn’t really make a huge difference in my hips and knees. The big advantage for me is with 165’s you get an extra CM of ground clearance and it leads to a lot less pedal strikes and more pedaling through corners. In general I find the shorter cranks a positive in most situations. The torque loss is around 6%, which generally less than the difference between one cog and the next on the cassette.
5’7" and have been running 165 cranks for 2 yrs now. Big fan. Less quad recruitment. They do take a different riding style and instead of “powering” over punchy climbs, spinning a steady even cadence is better
That’s me and I prefer it that way. I’m a little taller and dropped down to 170’s on the MTB a few years ago, it works for me. I’ve had guys ask me about it after races because they noticed me spinning away uphill. I haven’t been racing much lately but I might even try 165’s. When I built my most recent road bike I started with 165’s just to see and while they’re no revelation so far I haven’t seen any drawbacks for me either.
Fewer pedal strikes is nice. But the slow technical trails where you’re not spinning are what I felt were harder.
Although I was quite broken after several laps of racing that everything was hard.
More race testing is required… I’ve a 200km gravel event next week to try out the 165mm cranks but that’s on fire roads so should be fine
For me this is the other way around. I came from 175 to 165 and my hometrail is a twisty, rooty, sometimes technical trail where flow is important between a couple pedalstrokes you can get in before you have to turn again.
I am much quicker to accelerate with the 165 compared to the longer cranks and yes, fewer pedal strikes is quite nice as well. It’s weird to get on the XC-bike for the first couple minutes because all my other bikes have longer cranks but once I’m on the XC-loop I hardly think about my crank length anymore. So far I can’t see any downsides in shorter cranks - only upsides.
That’s valid. Especially on road bikes. I suspect that we’ll start to see bigger BB drop figures (or at least more size-specific) in road bikes in the future to compensate for this.
The same rules apply for MTBs, and I, like you, generally like a low bike, but the nature of most MTBs is a higher BB height than road bikes, so I get your concerns about feeling like you’re riding a horse.
I personally wouldn’t let saddle height determine my crank length, but if you feel like you really don’t want to go any higher and you aren’t having any issues with the 175s, then I’d stay where you are!
I’m 5’8 and have been riding 170’s on my XC bike for a long time, just because that’s what came with the bike and I didn’t really think about changing when I bought a Quarq crankset for it. Recently bought a trail bike with 165’s and rode it quite a bit before putting my 170 Quarq on it. Suddently started getting alot more pedal strikes. If I hadn’t known the trail bike had shorter cranks, I probably wouldn’t have even noticed when I started riding it, but now after comparing, I’m thinking about throwing 165’s on the XC bike as well.
I’m really surprised nobody has mentioned changing gearing (chainring size) to account for shorter cranks. If you’re naturally spinning faster at all power outputs then you should also be able to turn a faster max cadence before spinning out your 10t cog at the top end, right? So shouldn’t that mean you can drop 2t from your chainring and get a bigger bottom gear to compensate for the reduced leverage in those really slow technical bits?
Or is there something else going on here that I’m not fully understanding?
(I’m mostly a gravel rider but dabble in MTB and the Quarq PM on my Epic Evo is the most expensive reason why I haven’t tried changing any of my bikes from 170mm to 165mm yet - I’m sure once I do it to one bike I’ll like it enough that I’ll avoid riding any of the other 4 bikes that still have 170s until I can afford to change them too.)
The trail sections I was affected by I was mainly in the middle of the cassette.
I think it’s more that I need to practice the type of trail I encountered a bit more.
I generally spin more on my gravel bike than my MTB.. but that’s purely down to the terrain. You can’t spin an easy gear if you have to be in and out of the saddle a lot to move the bike around and over obstacles without constantly changing gear.
It’s been awhile but I think that’s what I did, drop 2t. I was adding a Quarq to a new bike at the time and thought I’d go to shorter arms as long as I was doing it.
On the technical stuff, TBH I’ve never thought about it in regards to the shorter cranks. Rock strikes yeah I’ve considered it but not for anything else. I’d estimate I’m neither a great technical rider nor the worst.
