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I'm curious what crank setup is on your Kickr Bike? My wife and I share a Kickr Bike and if that crank is suitable for normal training rides, and not just fitting, I think it might be worth buying at the right price. We use different crank lengths so it'd be much easier to change between our settings. Thanks!

Can you recommend any other brands with more tumblehome? I originally had a Bontrager Montrose and that was great but cannot find a similar replacement. Ergon is much more gradual.

from the photos it seems 30 have more wave than the 30c is it true? got the 30c but it looks just flat, where the 30 it seems a little bit waved that i would prefer, but then i prefer shorter nosed saddles also

I liked and subscribed from the UK. Thank you. That was so informative.

I'm sure you know, but SRAM flat top chains do not run well on chainrings and cassettes for Shimano and other old school 10, 11 and 12 speed chains.

I have no back, knee, leg or hip issues whilst doing 200km+ rides. My bike fit physio recommends going from 172.5 to 165mm cranks. I'm 183cm & don't want go raise the seat higher. I like pedalling whilst standing for long periods of time whilst climbing. Thinking of going 167.5mm on my new bike but a bit unsure.

Great breakdown and explanation of an otherwise confusing lineup of saddles (many to choose from). Thank you!

Really love Your calm and logical approach to this popular question of crankarms length. Thanks, Tim! May I know how tall Bob is?

Does Zwift have Track riding?

@greshfit I'm 5'11, 32.5 inseam with all other parts not outside of the ordinary and currently riding 172.5 on a 56 frame. I can hold an aero hoods position for 30+ minutes but I do notice breathing gets hard. Been thinking about going 165mm but thought it might be to drastic of a change for someone at height and inseam. Would you ever recommend 167.5?

I had the 172.5 and now I am using 165s! I can say for sure that smaller cranks feels better specially on the mountains!

13:01 So funny I say that same exact quote to my clients also “if you’re happy, I’m happy”

Man, this was so cool because the first time I saw anyone talk about these was Neal from the “Road Cycling Academy”. Thank you so much for creating this video and spending the time to share your knowledge!

Yep. Integrated cockpits are the work of the devil 😒

@greshfit Hi Tim. I've recently started a bike fitting business in Australia and I'm an SQlab dealer. They also have the 512 look Keo compatible road pedals available in "standard", +8mm and +15mm as well as a -4mm The other option worth mentioning are the cleat extender plates from the UK company FORM. They have 3 and 4 hole compatible plates with variants that can be installed normally or reversed to create +/- 3mm or +/- 10mm width in addition to whatever additional rearward cleat placement that variant allows. Extender plates are less ideal than longer axles as they shift the centre of pressure under the shoe laterally, but if you have to, you have to.

Fascinating. I would have thought longer was better from the point of view of reducing strain on the knees. ie: greater length travelled on the pedal to achieve the same linear length covered. Interesting how “Bob felt” compared to what “the numbers” were. Boggles the mind.

It's possible he didn't like the middle length cranks because the gearing was not adjusted to compensate and he ended up between gears on the cassette and therefore in a slightly suboptimal cadence. I'm sure the muscle recruitment throughout the range of motion introduces many more complexities but I can't really comment since it's beyond my expertise, besides citing the research published by Too et al in the Human Power Technical Journal

Very cool experiment. Can't wait to see you Friday

thanks a lot from Barcelona. Nice and usefull video

All these lengths are fine unless you have major physical impediment/ condition where your body can’t adapt.

I went from 170 to 155mm and I love it. Simply everything is better.

How about some actual data? How much power was he able to generate and for how long using various lengths?

I think this would have been better with motion capture.....hard to substantiate feel to actual mechanical improvement. I'm 6'2" and the motion capture actually showed the longer cranks put hip angle in a more favorable position for me which also felt the best.

One notable study, by J C Martin and W W Spirduso, suggests the optimum crank length for maximal cycling power production (sprinting) is “20 per cent of leg length or 41 per cent of tibia length”.

great video and kudos to Bob on his progress and determination. what a great rider!

This is great! As soon as he sees the results, he knows his judgment is wack as he should have liked options 1 and 2 more than he did. From there, you made the right choice, just drop down incrementally. Maybe in a year, he'll want to try 160 mm.

This was a lot of fun to watch! I was also very surprised of the 155 feedback. But clearly that was a winner reaction wise in my eye. The moment you revealed the 155 label all kinds of considerations come through in one's mind clouding/influencing that initial reaction. I would've actually tried again the 160 when you suggested it. But hey you have a happy customer in the end. Great job Tim! I went from 170 to 165 and liked it a lot. Now I am curious of 160! :-)

I’m 64 and on my mountain bike I went down to 155 cranks on both my ebike and regular mountain bike and absolutely love them world of difference on my hips an knees just got into road biking 2 years ago and went from 172.5 to 165 and is much better but regret not going down to the 155. I ride mostly by myself so I’m not looking what is the fastest I’m looking for comfort and what’s going to be best for my joints. I think mentally going from 172.5 to 155 I was afraid 155 would be too short for road biking I might have to rethink going to the 155. Great video 👍

So the two sizes he liked most were 155 and 170. Then he said tHat he would go down to 165 coz it makes most sense. Goes to show how much its all about media influence upon the mind and not real feel. Numbers. Just ride what you have and enjoy it without thinking too much.

The main difference is the additional legroom you get when you ride in the drops. Which he didn’t try.

I think what's missing is time for the body to adapt to the new lengths. I agree completely with @tanhalt about having to adjust much more than saddle height when changing crank length.

I liked this video as it was a real blind test I have tried 175 , 172.5 and 170 cranks and small changes make big a difference my favourite is 172.5 but 175 is to long but 170 is very comfortable, haven’t tried 165 yet.

Very interesting video!

Great video Tim! It's really interesting how the 155's felt so good. You could hear it in his voice how nice they felt. The 170's felt good too because they were familiar feeling. Once you unveiled the actual length then the brain took over and tried to make things more logical. Super cool! Thanks for being open to this Bob!

some say crank= 41% of tibia lenght

To do a better comparison, one should not only change the saddle height to make the leg extension consistent, but the saddle fore/aft should be adjusted so that in the power stroke (i.e. crank "3 o'clock" position) the relationship of the knee to the foot is kept consistent...e.g. 5mm shorter crank, move saddle rearward 5mm in addition.) Of course, that would also mean moving the bars up/down and fore/aft to match as well. Not doing that is changing the fit coordinates. IMO, although the center of the BB is an easy reference, that's only true if crank length isn't changing...the true foot reference is the path of the pedal through the downstroke, where the vast majority of power is produced.

longer leverage comes from the hip/pelvis!1 so shorter is most ly thighs!!!

Would be nice to know the length of the cyclist or even better his inseam length and bike size

What he likes or what he is used to?

For the last month or two, I've been temporarily trying 155s (down from 170s) on my indoor trainer bike. The change felt surprisingly non-weird. I think I'll eventually go shorter on all of my bikes, but probably 160s just because they're a lot more available than 155s. (But I just had hip surgery yesterday, so no riding at all for a while. Part of my motivation, though, was that maybe the shorter cranks would make things a little easier post-surgery.)

Great video. Does the front chainring need to be changed to make up for the reduced torque at the crank axle, or do people find that in practice that it's not necessary? Thx.

Perfect is the enemy of good. This test clearly proves that his judgement is totally irrational because fallacy is an absolutely natural property of a human being and the truth is that trying to change the cranks length within 5-10mm is nothing but nonsense.

I think you should have tried to use Zwift to see how much power you can generate in a 4 minute block on flat or hill to really see the difference

I’m 6’2” 34” inseam and ride 175. I have 325 FTP and sit on the rivet for 30 min when racing on Zwift average power of 315 avg cadence 85.

I went from 170 to 165, i love it

Went down from 172.5 to 160. Pressure on my hips/SI is much less.

Is it fair to say that any of these standard lengths are a compromise in one area for gains in others?

Great teamwork. Glad you got there in the end.

I have the kitchen sink bars but I’m tempted to try these. Can’t bend my neck like I used to, lots of pain after a long day of riding.

You assume seat height should be based on “reach” at bottom of pedal stroke. Is there consensus on this assumption?