Hello there, I’m using 170 crank and considering to switch to 165 too hoping it can alleviate my low back pain but I can’t raise my saddle because my frame has integrated seatmass. What do you guys think?
You might be able to get away with it, but theres a chance you won’t.
I swapped my gravel bike from 172,5 to 165 and I 100% needed to raise the saddle.
But if your saddle is slightly too high, the 5mm difference might be beneficial. There might be ways to compensate the 5mm but im not sure what theyd be without affecting fit somehow.
If it’s possible to test it first, id do that.
what’s the worst that will happen? I think my saddle is a little too high so I rock my pelvis that’s why I have constant back pain whenever I ride more than 2 hours outside. But on trainer I don’t have any back pain issue though.
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Give it a shot. I messed my knee up for a few weeks with a saddle that was too low but that was like 30mm too low lol (saddle slipped very slowly).
Currently my 165mm cranks are feeling amazing i must say.
Usually there is a little wiggle room with integrated seat masts depending on where it was cut. You may be able to raise it slightly.
Lower back pain can be a sign of a saddle that’s too high. But it can also be something completely different. Before you spend any money, I’d get a bike fit to dial in your position.
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When you go to shorter cranks, you generally want to move your saddle back and up to take up the difference. Just moving your saddle back a bit (not the full 5mm, more like 2) could get you there. In my experience, having a saddle slightly low is better than slightly high anyway.
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That is one option, but not agreed upon by all fitters for all situations. This idea hinges on the foot & leg place over the lead foot, which definitely has some merit.
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But the other take is that considering position more related to pure bottom bracket location, and as such doesn’t necessarily lead to changing saddle fore-aft in response to a crank length change.
As ever, fitting is not a simple A+B=C situation, so even good “rules of thumb” need evaluation on a case by case basis.
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I switched from 172.5 > 165 cranks in June and it made a world of a difference. I’m 5’9 with a 33”(ish) inseam. I had hip surgery last year to fix an impingement and labral tear, so anything to keep my hip a bit more open makes a big difference. I have a custom titanium bike on order and during my fit, the fitter was very impressed with how aggressive of a position I could be in while still maintaining a relative open hip angle (and also being comfortable in that position). The 165mm cranks were a big contributor to that.
It has also significantly reduced most any rocking in the saddle during high rpm efforts. Obviously everyone has very different body geometry, but I do feel that most bike manufacturers put longer cranks than they should on most off-the-shelf bikes.
Leg extension does not have to be along the direction of the seat tube so it’s quite likely that the saddle can be moved back instead.
I would argue that using the bottom bracket as a reference is convenient but actually wrong - we should be concerned more with the interaction with the lead pedal in the important parts of the power stroke.
You can see this among the Youtube Fitters who are starting to buy in to short cranks but then warn that it can make you feel like you’re coming over the pedals, but somehow don’t make the connection that you can move the seat back so that your KOPS (whatever it may be) stays the same.
Yes I think so. Actually I had my bike fit last year with quite trusted bike fitter but it doesn’t solve my back pain issue. I think the best way is to borrow my friend’s 165 crank arm and test it 
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I put 145mm cranks on for a laugh whilst I waited for a set of 165s to arrive. The effect was comical. The maths said raise the seat 20mm & pedal at 115rpm. It seemed to check out, though I had to un-slam the stem in order to make the drops accessible. Cornering clearance was a dream. No fears of pedal strikes. [Edit: another benefit when standing at lights was no toe overlap.]
Yes, when climbing I needed lower gears. And on most downhills I still couldn’t spin out the top gear (55:11 at the time).
Out of the saddle work felt harder than with longer cranks.
Though I didn’t notice it at the time, I quite like the idea of feeling like I’m more over the pedals on the downstroke. This might provide relief for those who are hard up against the 50mm saddle setback rule.
Pic for laffs.
When I changed to shorter cranks (172.5 to 165), I went up a full centimeter and moved the seat forward, so much so that I went to a 0 offset seatpost from the stock 20mm offset. I also went from a compact gear set to a semi-compact. I stayed with an 11-34 rear cassette. I can definitely put more power through the cranks, and I’m certainly moving quicker up the hills. I can still pedal at high cadences, and the gearing feels much more natural.
It sounds like you haven’t done many rides with the new cranks yet. Your feet are pedalling smaller circles. It can take a while for the legs to get used to the change and return that smooth souplesse style of pedalling. Give it a bit more time before you change anything.
Was this a reply to me? If so, made the switch on my road bike about 4 months ago, and had made the switch on my trainer about 3 months before that. Pedalling is really smooth.
No was meant to be to the OP
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