Anyone around 172cm (5’7.5”ft) tall using 165mm cranks?

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dedaciai
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by dedaciai

I just listened to the most recent Fast Talk podcast on fit and saw on Pinkbike ( https://www.pinkbike.com/news/why-short ... ience.html ) that most people are running cranks that are way too long. I am 1.72m, around 5’7.5" and currently running 170mm cranks on my road, gravel and MTB bikes. Reading these articles makes me want to try 165mm cranks and see how it feels.

Anyone here around my height running 165mm cranks, or maybe someone taller running 170mms? If so, how is it?

Thanks in advance!

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spdntrxi
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by spdntrxi

I use a mix of 165 and 170

Gravel. AeroRoad. 170mm
TT and other Road bike 165mm

I dont really notice a difference.. but I'd probably just ride 165mm but some of the cranksets I have are not available in 165.
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pdlpsher1
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by pdlpsher1

I'm 170cm tall and using a 170mm crank just like you. I've read that when it comes to crank length most people can't even tell a big difference with a 5mm change. So it's best to do a bigger change like a 160mm if you want to go through the expense of buying a new crank. But then a 160mm crank would have poor resale value should you move on to a new bike/crank. Additionally the 'gain' from a shorter crank is mostly on the aero aspect and not so much on your power performance. A shorter crank opens up the pedaling hip angle, allowing your torso to drop and achieve a more aero time-trialing position. A shorter crank also changes your saddle height from the BB to the saddle. A 1cm shorter crank requires you to raise your saddle and bar by 1cm in order to maintain the same reach/stack/bar drop. So unless you're a time trialist I see the change as being not worthwhile (too marginal of a gain for a great expense). I would be happy to be proven wrong on this. Just my $0.02.

ps I'm posting this prior to having listened to your linked podcast. I will listen to it and if I have an altered opinion later I will repost it here.

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by kode54

I'm exactly the same height as you @dedaciai...and ride the 'wrong' sized cranks. 172.5
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AJS914
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by AJS914

dedaciai wrote:
Wed Nov 17, 2021 6:08 pm
Anyone here around my height running 165mm cranks, or maybe someone taller running 170mms? If so, how is it?
I'm 6 feet tall and went from 175s to 170s so I can tell you how it felt to go down 5mm. It felt great. I raised my saddle and left my bars where there were. This had the effect of making me more aero and giving more clearance between my knees and torso.

The only downside is that I felt like I needed one extra easier gear in the back so I could spin more up climbs since I no longer had the leverage of the longer crankarms.

In any case, one quickly adjusts. Researchers have studied crankarm length and for the most part people can pedal a very wide range of lengths and still make the same power. Shorter is probably a little bit better ergonomically for most people.

ghostinthemachine
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by ghostinthemachine

I'm noticeably taller than you and riding 165s on a couple of my bikes after a recommendation from someone else who is slightly taller than you and riding 165s.
I usually run (ran?) 172.5 or 175 and 165 feels much better.
Friend who recommended them was on 170s and has switched wholesale to 165. Cost him a fortune already.

dialtone
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by dialtone

Same height as you, used to run 172.5 until my bike got destroyed and now I've only done one ride indoor woth 165mm and it felt really good, as others said, more clearance in the chest and less extreme angles and force on the knees.


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TobinHatesYou
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by TobinHatesYou

I'm 178cm/5'10" and using 165mm cranks and I've considered trying even shorter cranks. It's nice being able to pedal out of corners earlier in surgy crits. I think the only time I miss the extra leverage is on very steep climbs at max aerobic capacity.

ThunderJack07
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by ThunderJack07

I'm 170cm and switched from 170 to 165 cranks on 2 road bikes after having read similar articles. My first tests with the shorter cranks kind of went in the same direction as the theory: FTP improved over 20min test and Anaerobic/Neuromuscular power slightly decreased over 1min and 5s tests. It is clear that many other factors played a role (I was out of a training block focused on FTP, different levels of fatigue for the 2 tests, temperature difference (this was a test on HT i.e. overheating easily)) but still. But for me the biggest improvement I found was on overall fit: the bigger opening of my hip angle allowed me to drop the front end a fair bit with no loss of comfort whatsoever. I did my longest rides and multi-day events with this position and it's the most comfortable and efficient I have ever felt. I think you do loose a bit in very short,explosive efforts, but unless you're a sprinter, not sure it really matters. You have to keep in mind it impacts cadence and perceived gearing as well: at identical foot speed, your cadence will be higher with shorter cranks hence having the impression to push a lighter gear for the same force applied on the pedals. Opposite is true if you keep cadence identical, you have to provide more force so you feel like you are pushing a bigger gear.
Last edited by ThunderJack07 on Thu Nov 18, 2021 11:55 pm, edited 1 time in total.
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Andrew69
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by Andrew69

Same height (172cm) and always rode 170 or 172.5mm cranks
Recently started riding more and started to get terrible knee pain
Swapped to 165mm cranks and all pain is gone. Power still the same, just at a slightly higer cadence
Will now swap out all cranks to 165mm. Im sold on the concept for sure

ghostinthemachine
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by ghostinthemachine

pdlpsher1 wrote:
Wed Nov 17, 2021 6:31 pm
I've read that when it comes to crank length most people can't even tell a big difference with a 5mm change.
I guess this depends how much "too long" the cranks were before. For me going to 165 was a noticeable and pleasant change, though i can still hop on my other bikes comfortably. My mate who suggestted the change found it to be night and day. Can't ride bikes with longer cranks (even 5mm) without discomfort.

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Lewn777
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by Lewn777

I think some of this is fashion. Younger folks can spin at high cadence for long periods, so I really believe short cranks as with 165-170 will work well.
Older folks esp over 40-50 can't spin at high cadence for extended periods, maybe 10 minutes max so need longer cranks as they grind more at lower cadence.

Think younger have higher horse power older people produce more torque. However most of the data crunching seems to suggest crank length makes little difference within the extremes, so really go with what feels most comfortable. I'm 6ft (183cm) and would always choose 172.5, ridden all three on many bikes, probably nearly a decade on each.

At 6ft and with borderline shorter than average leg length:
175cm - Good power and mostly fine but cadence too 'grindy' and prone to knee pain, seem to fatigue quite easily.
172.5cm - Goldilocks - perfect
170cm - Alright, but feel a bit too 'spinny'. Power numbers are fine and fatigue is reduced but seem to run out of oxygen at constant high cadence.

My conclusion: If in doubt go shorter, but don't go crazy.

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by TobinHatesYou

The most commonly cited study saw a power output difference of just 4% between 120mm cranks / 220mm cranks and the riders’ optimal crank lengths. Between 145mm and 170mm the difference was just 1.6% and that was prior to longer term adaptation.

So it’s not really fashion at all. There are obvious benefits of going shorter. You see less knee flexion at TDC, you can get your back more horizontal, you are less likely to pedal strike. Even the MTB guys are going shorter.

dialtone
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by dialtone

If shorter than 165mm was available out there I would have bought lower than 165mm for sure.

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ghostinthemachine
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by ghostinthemachine

TobinHatesYou wrote:
Sat Nov 20, 2021 12:27 am
The most commonly cited study saw a power output difference of just 4% between 120mm cranks / 220mm cranks and the riders’ optimal crank lengths. Between 145mm and 170mm the difference was just 1.6% and that was prior to longer term adaptation.

So it’s not really fashion at all. There are obvious benefits of going shorter. You see less knee flexion at TDC, you can get your back more horizontal, you are less likely to pedal strike. Even the MTB guys are going shorter.
TBH, the older you are the more benefits there are to gong shorter, what with all the knackered knees from running too long cranks for 30 years.

(And i can still spin 130+ for 20-30 minutes, given a good reason to do so. Like being silly with the kids. Or training with slower riders. And i'm a long way past 50 :lol: )

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