Almost all of my clients end up with 155mm cranks.

I went from 172.5 to 165 and feel great!! I'm 5' 7 btw. I have your problem from time to time and try to burp as much as you can. I've found that helps. I believe it's also related to swim as well because you stay horizontal for a while.

Is it regardless of their heights / leg length?
You'd recommend me to make the jump to 155mm directly? I have no idea how big of a gap 165, 160 or 155 cranks would be compared to 172.5 mm.

Great to hear that! And thank you for the tip, I'll try to keep that in mind.
The issue is that the second race was a duathlon as the swim was cancelled at the last moment, so that can't be a swimming related issue (at least on that race).

"Is it regardless of their heights / leg length?
You'd recommend me to make the jump to 155mm directly?"


Yes and Yes.

while not impossible that the fit play a part... it s 99% a issue with nutrition/intensity of the race. if you didnt have any issue in training and it show in races...it s the classic exemple of nutrition issue at race intensity. That would be the element i would investigate first.

how well did you run off the bike that day? how % of ftp on the bike.... do you have a history of good races with solid run off the bike?

i do have a few athletes that have there legs touching there abdomen....so not uncommune.

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
Instargram

One Hour Record broken by Bigham (6' tall) and Ganna (6'4" tall) on 170mm cranks. Not concerned about anything (comfort, acid reflux, having to run after getting off the bike) except going as fast as possible for 60 minutes.

I'm the exact same height as you, with a slightly shorter inseam. I went from 172.5mm to 165mm cranks a year and a half ago and have been very happy. They allowed me to get in a much more aero position and are much more comfortable, especially with the decreased hip angle. At the same time I also went to 165's on my road bike and it felt too small. I imagine this is how anything below 165 might feel on my tri bike. I now ride 170mm cranks on my road/gravel bikes. I went with a full Rotor setup so any future changes to crank arms or chainrings are extremely easy.

I have done several race pace (or slightly less efforts) for up to 1 hour intervals while using my race nutrition strategy and I've not had issue as far as I can remember.
But writing that down, I realize that if it was a fit issue, it should also happen while training...

For the 70.3 except for the first part where my gut was acting, I had an average to good run compared to what I'm used to: 1:17:13 for 21.4 km and around 100m of positive elevation. Around 86% of my FTP.

For the OD I was at 92% of my FTP, also an OK run.



Thanks for your input! Yeah I'm also looking at a Rotor setup, it seems to be the more adaptive one if one wants to make changes down the line.


Right now I'm really hesitating between 165mm or going lower, but I'm a bit apprenhensive with making a bigger jump.

My younger son is 5' 11.5" tall and went straight to 155mm cranks on his TT bike.

He has 172.5mm cranks on his road bikes.

yep..... if you are going at 86% of ftp for a half...you are flirting with that line where calories are much more difficulte to go in. it takes the right mix of sugar and to not over do it. you really cant process a lot at that effort level.

in training....longer effort at race pace or even at above race pace will give you the answers. 1h...perhps you could get away with it without running into your issue.

next time...if you can afford 5-10min of backing off a little the pace and get on water only for that duration...you might be suprise how quickly you can get rid of the acid reflux and resume full trottle after.

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Jonathan Caron / Professional Coach / ironman champions / age group world champions
Jonnyo Coaching
Instargram

6'1" 34" inseam and after a fitting by Dave Luscan, I moved to 155 and it's the best thing I have ever done to my bike. I am so much more comfortable, feel great off the bike, and am cycling faster times than before. When I was fit we tested 170, 165, 160, 155 and the testing showed 155 was my best for comfort and power output.

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Cheers, Ray

Regarding your recommendation of drinking only water if the issue arise: that's exactly what I did during the first part of the run when I realized I could barely eat a gel without throwing up. Apparently that worked!


Thank you everyone for all your feedback on switching to shorter cranks! Even though it probably won't help with my initial issue, I'm seriously considering switching one (not sure about the length I'll choose tho).

No one wants to address this? Bigham - a good rider + a Techno Geek, who I'm sure turned over rocks looking for every ounce of speed - was on 170mm cranks.

Why??

Are the Laws of Physics different for the One Hour Record?

No one wants to address this? Bigham - a good rider + a Techno Geek, who I'm sure turned over rocks looking for every ounce of speed - was on 170mm cranks.

Why??

Are the Laws of Physics different for the One Hour Record?[/quote]



I think it's an interesting question. Some will argue that short cranks will allow for more seat to handlebar drop and consequently a more aerodynamic position(which may or may not be true depending on the athlete). However, if you go from 170mm to 155mm cranks and have to raise your seat 15mm the higher seat height can be significantly less aerodynamic. So for someone looking to maximize their speed as much as possible it might make some sense to look for the longest cranks where power output can still be sustained in the aeroposition for the duration that they're racing.

Some need a more open hip and knee angle at the top of the stroke and others can be ok with a bit less. I don't want to speak for someone like Bigham but I highly doubt he sits on a fitbike and chooses the crank length that feels best to him. He probably figures out which position is fastest and does what is necessary to make it work/adapt to it. Of course triathlon and cycling is different so that might not necessarily be the best way to go about things for everyone.

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BA coaching http://www.bjornandersson.se

Thank you!


...and are most of your clients triathletes - do the run when they get off the bike?

Yes.

There is a range of crank lengths at which we can create a nexus of power, aerodynamics, and sustainability. For high level athletes doing shorter events with no secondary concerns, that range is bigger.

For triathletes, these are the ranges I have personally watched riders self select on a fit bike during a dynamic fit session. 90% of my triathlon fits are falling into these ranges, with a 98% stickines rate.
Saddele height :: Crank length
<60cm :: 145mm or less.
60-65cm :: 140-145mm
65-70cm :: 145-150mm
70-75cm :: 150-155mm
75-80cm :: 155-160mm
80-85cm :: 160-165mm
>85cm :: 165-170mm, maybe 172.5 (Keep in mind that of the tallest, strongest professional athletes I have fit literally ZERO of them have preferred anything over 165mm. These are 6’3” and taller athletes pushing wattage over 375 at threshold and close to 300 for IM races)