I have installed 160mm R7000 cranks on my bike. I must say that the first ride felt amazing. I could feel torque at every point of the pedaling circle while in the drops, even though I kept the handlebar position after raising the saddle. I previously rode 170mm cranks being 173cm tall with 78cm inseam, fwiw. That is all.
145 on my TT bike and it’s awesome.
I’m same height and went to 165’s from 172.5’s, increase in cadence was awesome!
My mountain bike is sitting idle unrideable with 175mm cranks. 165s are arriving in mail soon ))
Any particular reason why you decided to change lengths? I have been reading recently that it can help with knee issues.
Very interesting post. I’m als considering shorter cranks. Why did you guys switch? And did you have to change your gearing to account for the higher cadence and shorter leverage?
Can’t speak for the OP but mine was because I was consistently struggling to meet a decent cadence, 80 used to be high for me, everything seemed to be pointing to higher cadences being more efficient so I wanted to get on that bandwagon, plus being short at 5’8" I think 165s were a better choice regardless.
I’m 5’ 11" and after a bike fit went from 172.5mm to 165mm. The primary reason, the fitter said, was to open up my hip angle. He also said I was the least flexible person he had ever fitted on a bike! I have to say since then all my lower back niggles have completely disappeared, I’m spinning a faster cadence and I love them and wouldn’t go back to longer cranks.
@Alen what inside leg and height are you Alen?
I moved to 165 and have an inside leg of 29.5 and am 5’8". It made a really nice difference. What make
did you use as a 145 crank?
Deleted my response as it was garbage.
I’m also 5’8”. I have no idea what my I seam is by it’s pretty much the same as you i think.
For those with questions about cadence.my road bike is 165mm and my TT bike is 145. I can’t tell the difference at all! Cadence and power is the same. If you’re worried about cadence, there is a gear ratio that will accommodate whatever your cadence preference is. Not like we ride fixies.
It made a huge difference in my fit though. I was able to move my saddle up and forward and open up my hip angle. Not only comfort, but my FTP on my TT bike now is the same as my road bike as a result. And a lower cdA!
I will add the caveat that as a triathlete I am not bound to UCI rules. So I don’t have to follow their stupid restrictions.
Some of us do.
165 on my SS commuter (track geometry); no problem with 110+ cadence, power, or sprinting.
172.5 on my roadie. Ditto above.
But perception tells me the 165 set up feels somehow more natural/smoother. It’s certainly more fun.
Would be interesting to know what has more influence on correct crank length — total leg, femur, or tibia length.
I’m 99% sure that’s not true. Same gear and same cadence is going to equal the same speed, regardless of crank length. Same speed (assuming everything else is the same) means same power.
Shorter cranks simply mean you have less leverage to push a gear, but are pedaling smaller circles.
Switched my road bike from 172.5 mm to 165 mm cranks based on bike fitter’s recommendation. I feel more comfortable as I’m not bouncing around on the saddle as much (due to my tight hamstrings). Had to go for an Ultegra crankset, couldn’t find 105 R7000 crankset in 165 mm anywhere.
I forgot to mention which cranks I use. Cobb makes different length cranks.
@Captain_Doughnutman, I’m not sure what the science is. But I started with 172.5 and then went to 165 and it was good. Then 155 and it was good. 145 was good. Really, the difference from 165 to 145 is 2cm. Not even an inch! If anyone knows someone making 135 cranks, I’m willing to try it.
Not sure about the 135s but I found a large supply of 0mm crank bikes:
And red makes it go even faster!
My cadence has increased this year, but am not sure it is down to cranks alone
- I have been cycling for years but only in the past 5 or 6 returned to cycling seriously and to Time trialling. (I cycled when young and in my 40s, as a triathlete doing Ironman twice)
- In the last 2 years I have competed in around 70 time trials from 10m to 12 hours.
Last year I started on 172.5 cranks (the bike came with it) and soon swapped to 170 cranks. I have 170 cranks on my road bike and 165s on my winter bike (to encourage spinning).
Last year I tended to push hard at a lower cadence (around 82 or so) and that seemed to work. This year, my position is much more comfortable with 165 cranks. Also I find I am also able to spin comfortably at an average of 92 for a race. In fact I will often reach 100rpm or more. Spinning seems a better way to race this year. I am rarely down at the low/mid 80s.
This ability to spin higher and faster might be influenced by going on the velodrome over last winter on a fixed bike, and getting track qualified. There I would often be spinning at 125-135 or higher. Also I would regularly practice spinning up in turbo training. Something i have always done, just for a bit of a challenge. I suspect I have trained myself to spin at a higher cadence and it has definitely helped. So I think shorter cranks have helped, but also I have trained differently to spin faster.
In erg mode, I do notice a rise in HR at a constant power if I spin up from 92 to 105 for a couple of minutes. Only a few beats but it is there.
You know I think you’re correct. I should know this and think I’ve been looking at this all wrong for years. Knowing torque= force(distance) and power= (force)(distance)(rpm)if two identical riders one on 172.5 cranks and on with 165’s both in the 53/11 spinning at 100 rpm the power would have to be the same. I think I’m misunderstanding torque. Since the distance is less on the 165’s more force is required to make the same torque. Then I lose it. Any help appreciated.
I recently had a bike fit with Phil Burt (head physio/Bike fitter at Team Sky and British Cycling) and he is a massive advocate of going smaller with your cranks. When I suggested going to 165s I laughed… then he pointed to his Bradley Wiggins yellow Jersey on his wall and said “he was on 165s for his hour record”… and then he pointed to Bradley Wiggins signed skin suit from the 2016 olympics and said “and the team pursuit team were all on them at Rio”. I stopped laughing and bought myself a pair.
You still got it👍, to compensate for the shorter cranks you have to either increase force on the pedals or chose an easier gear to increase rpm to keep the power constant.