Shimano 12s GRX RX820/RX822/RX610, cable pull actuation ratio 11s/12s compatibility

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pdlpsher1
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Location: CO

by pdlpsher1

warthog101 wrote:
Wed Mar 22, 2023 11:23 pm
https://road.cc/content/feature/pogacar ... olo-285041

All of his bikes use a 172.5mm crank length.

https://dmcx.com/2022/06/14/jonas-vinge ... ng%20shoes.

Jonas Vingegaard rides with 172.5mm crank length

https://dmcx.com/2022/03/13/primoz-rogl ... D%20pedals.

Primož uses 172.5mm crank length

https://dmcx.com/2020/03/24/egan-bernal ... bike-size/

He uses a 170mm Crank arms length

https://dmcx.com/2022/07/12/geraint-tho ... L%20pedals.

Thomas uses a 175mm crankset arm’s length

https://www.firstcomponents.com/bike-cr ... 20involved.

Chris Froome at 1.86m in height uses 175mm cranks

https://dmcx.com/2022/05/02/vincenzo-ni ... s%20length.

Vincenzo Nibali rides with 172.5mm crank arm’s length


Meh, I expect Shimano is selling what works.
All of these people are much taller than me. The problem of the industry in regards to crank arm length is that the spectrum of available crank lengths don't match the wide spectrum of riders' height/inseam length. If Chris Froome is 16cm taller than me, why should I be riding a crank that is only 5mm shorter than him? If you're 186cm tall, stick with 175mm cranks. But for someone short like myself and my wife, 165mm cranks just don't cut it. My wife needed 145mm cranks. I even think she might be even more comfortable on 135mm cranks.

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pdlpsher1
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by pdlpsher1

I just looked up Jasper Stuyven. He's 186cm or 6'1" just like Froome. He's one of the early adopters of short cranks, and rides a 170mm crank. Again, the issue isn't that Pogacar is riding too long of a crank. The issue is that Shimano needs to make shorter cranks than 160mm, and bike manufacturers need to put a 155mm instead of a 165mm or 170mm on a size 50 or 52 bike.

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warthog101
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by warthog101

pdlpsher1 wrote:
Wed Mar 22, 2023 11:35 pm
warthog101 wrote:
Wed Mar 22, 2023 11:23 pm
https://road.cc/content/feature/pogacar ... olo-285041

All of his bikes use a 172.5mm crank length.

https://dmcx.com/2022/06/14/jonas-vinge ... ng%20shoes.

Jonas Vingegaard rides with 172.5mm crank length

https://dmcx.com/2022/03/13/primoz-rogl ... D%20pedals.

Primož uses 172.5mm crank length

https://dmcx.com/2020/03/24/egan-bernal ... bike-size/

He uses a 170mm Crank arms length

https://dmcx.com/2022/07/12/geraint-tho ... L%20pedals.

Thomas uses a 175mm crankset arm’s length

https://www.firstcomponents.com/bike-cr ... 20involved.

Chris Froome at 1.86m in height uses 175mm cranks

https://dmcx.com/2022/05/02/vincenzo-ni ... s%20length.

Vincenzo Nibali rides with 172.5mm crank arm’s length


Meh, I expect Shimano is selling what works.
All of these people are much taller than me. The problem of the industry in regards to crank arm length is that the spectrum of available crank lengths don't match the wide spectrum of riders' height/inseam length. If Chris Froome is 16cm taller than me, why should I be riding a crank that is only 5mm shorter than him? If you're 186cm tall, stick with 175mm cranks. But for someone short like myself and my wife, 165mm cranks just don't cut it. My wife needed 145mm cranks. I even think she might be even more comfortable on 135mm cranks.
Several of the riders listed there are 1.75m tall or 5cm taller than you as I read it. They are on 172.5mm cranks.
Egan Bernal is 1.75m and on 170mm cranks.

From Shimano's point of view they are making crank lengths that would suit the majority of riders.

warthog101
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by warthog101

pdlpsher1 wrote:
Wed Mar 22, 2023 11:43 pm
I just looked up Jasper Stuyven. He's 186cm or 6'1" just like Froome. He's one of the early adopters of short cranks, and rides a 170mm crank. Again, the issue isn't that Pogacar is riding too long of a crank. The issue is that Shimano needs to make shorter cranks than 160mm, and bike manufacturers need to put a 155mm instead of a 165mm or 170mm on a size 50 or 52 bike.
Yes you can find outliers.
I chose to post TDF winners.
Clearly they are able to ride fast on the crank lengths they are using.
It would seem counterintuitive that were shorter cranks faster for them they'd not be using them. Given the millions of dollars invested in protour teams, a change in crank length to go faster is a relatively small investment. Certainly there is enough riding on the results to make that change were it faster.

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pdlpsher1
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by pdlpsher1

warthog101 wrote:
Thu Mar 23, 2023 1:02 am
pdlpsher1 wrote:
Wed Mar 22, 2023 11:43 pm
I just looked up Jasper Stuyven. He's 186cm or 6'1" just like Froome. He's one of the early adopters of short cranks, and rides a 170mm crank. Again, the issue isn't that Pogacar is riding too long of a crank. The issue is that Shimano needs to make shorter cranks than 160mm, and bike manufacturers need to put a 155mm instead of a 165mm or 170mm on a size 50 or 52 bike.
Yes you can find outliers.
I chose to post TDF winners.
Clearly they are able to ride fast on the crank lengths they are using.
It would seem counterintuitive that were shorter cranks faster for them they'd not be using them. Given the millions of dollars invested in protour teams, a change in crank length to go faster is a relatively small investment. Certainly there is enough riding on the results to make that change were it faster.
You're still completely missing my point. TDF winners are riding the right crank lengths. The problems is that shorter people need proportionaly shorter cranks, and those shorter cranks are not available. If you're the same height as TDF winners, stick to what they are riding. I would too if I were your height. But if you're the same height as my wife at 5'4", 170mm is a bear. And nobody makes a 145mm crank except for Appleman. There are plenty of women with a height of 5'4", so why can't Shimano make a 145mm crank?

warthog101
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by warthog101

pdlpsher1 wrote:
Thu Mar 23, 2023 3:24 am


You're still completely missing my point. TDF winners are riding the right crank lengths. The problems is that shorter people need proportionaly shorter cranks, and those shorter cranks are not available. If you're the same height as TDF winners, stick to what they are riding. I would too if I were your height. But if you're the same height as my wife at 5'4", 170mm is a bear. And nobody makes a 145mm crank except for Appleman. There are plenty of women with a height of 5'4", so why can't Shimano make a 145mm crank?
Disagree I am missing your point.
People at 162.5 cm in height would be a very small proportion of people buying a groupset.
Each generation is getting taller not shorter.

Furthermore at 162.5 cm in height, specifying a crank length as per the same ratio vs height as 175 cm rider using 172.5 mm, would result in a 160 mm crank not 145mm

thirdsun
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by thirdsun

pdlpsher1 wrote:
Wed Mar 22, 2023 11:43 pm
The issue is that Shimano needs to make shorter cranks than 160mm, and bike manufacturers need to put a 155mm instead of a 165mm or 170mm on a size 50 or 52 bike.
Absolutely agree. I see most bike manufacturers putting 170 mm cranks on their smallest frames which is completely absurd. Canyon at least uses 165 mm cranks on smaller frames but it's the exception among manufacturers. Others often don't even mention crank lengths in their geo table. This stuff is important. Am I supposed to guess how ill-fitting your bike will be?
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ultimobici
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by ultimobici

All this talk about crank length being a funtion of leg length is misleading. Yes, inseam has a part to play. However, the other factor is the relationship between femur & tibia lengths is important. People have been searching for a magic formula to calculate crank length for decades. No one has yet found it because it is not a simple calculation. According to most of the "formulae", my height & inseam suggest I should use 167.5mm cranks. I actually use 167.5mm cranks on one bike, my fixed. On every other bike I have I use 172.5mm arms. Why? Because I have tried shorter cranks several times and could never get used to them. It was only when I delved into my Hinault/Genzling book I found that my femur to tibia ratio is higher than average. Despite having a 825mm inseam I need longer cranks to accommodate my longer femurs.

The idea that a mass producer of parts must offer every option is unrealistic. Shimano are a very conservative company, so aren't going to offer 160mm options on everything unless there is a good business reason to do it. They are easing into it in a way that makes sure they are not left with tooling they cannot use. The driver behind more accessibility is not Shimano, it's Specialized, Trek, Canyon, Fuji etc. Shimano's offerings are driven by what OEM managers ask for.

satanas
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by satanas

Somebody claimed that 170, 172.5 and 175mm cranks were effectively the same - yeah, right.

I'll say it again: Some people don't notice or care about small (or large) differences in crank length, others do. This has nothing to do with height or inseam. In Phil Burt's book "Bike Fit" he says there are two sorts of people, 1) macro absorbers (i.e., Geraint Thomas), and 2) micro adjusters (i.e., Chris Froome, and most likely Eddy Merckx). Obviously both types can be successful...

In my case I've tried 170, 180, 175, 172.5, 178 and 165mm cranks on various bikes, in that order; some came on bikes I owned, some were on test bikes or borrowed. Like the previous poster, I have relatively long femurs, and FWIW I'm a spinner. I now use 170mm on fixed and 172.5mm almost everywhere else, apart from a MTB that won't fit anything I can find in that length. That has 175mm, tolerable only offroad for me.

Those who want really short cranks should check out Dixna La...

https://alexscycle.com/products/dixna-l ... m-to-170mm

which come in 130, 135, 140, 145, 150, 152.5, 155, 157.5, 160, 162.5, 165, 167.5 and 170mm, but sadly not 172.5. :-(

RDY
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by RDY

pdlpsher1 wrote:
Thu Mar 23, 2023 3:24 am
warthog101 wrote:
Thu Mar 23, 2023 1:02 am
pdlpsher1 wrote:
Wed Mar 22, 2023 11:43 pm
I just looked up Jasper Stuyven. He's 186cm or 6'1" just like Froome. He's one of the early adopters of short cranks, and rides a 170mm crank. Again, the issue isn't that Pogacar is riding too long of a crank. The issue is that Shimano needs to make shorter cranks than 160mm, and bike manufacturers need to put a 155mm instead of a 165mm or 170mm on a size 50 or 52 bike.
Yes you can find outliers.
I chose to post TDF winners.
Clearly they are able to ride fast on the crank lengths they are using.
It would seem counterintuitive that were shorter cranks faster for them they'd not be using them. Given the millions of dollars invested in protour teams, a change in crank length to go faster is a relatively small investment. Certainly there is enough riding on the results to make that change were it faster.
You're still completely missing my point. TDF winners are riding the right crank lengths. The problems is that shorter people need proportionaly shorter cranks, and those shorter cranks are not available. If you're the same height as TDF winners, stick to what they are riding. I would too if I were your height. But if you're the same height as my wife at 5'4", 170mm is a bear. And nobody makes a 145mm crank except for Appleman. There are plenty of women with a height of 5'4", so why can't Shimano make a 145mm crank?
Because a 145mm crank would not suit the majority of people of that height. You likely need pretty severe hip impingement and disproportionately short legs at that height to need such a short crank.

A crank in the range of 160-165 is usually good enough for people of that height.

OnTheRivet
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Joined: Sat Jul 24, 2010 9:41 pm

by OnTheRivet

warthog101 wrote:
Wed Mar 22, 2023 11:23 pm
https://road.cc/content/feature/pogacar ... olo-285041

All of his bikes use a 172.5mm crank length.

https://dmcx.com/2022/06/14/jonas-vinge ... ng%20shoes.

Jonas Vingegaard rides with 172.5mm crank length

https://dmcx.com/2022/03/13/primoz-rogl ... D%20pedals.

Primož uses 172.5mm crank length

https://dmcx.com/2020/03/24/egan-bernal ... bike-size/

He uses a 170mm Crank arms length

https://dmcx.com/2022/07/12/geraint-tho ... L%20pedals.

Thomas uses a 175mm crankset arm’s length

https://www.firstcomponents.com/bike-cr ... 20involved.

Chris Froome at 1.86m in height uses 175mm cranks

https://dmcx.com/2022/05/02/vincenzo-ni ... s%20length.

Vincenzo Nibali rides with 172.5mm crank arm’s length


Meh, I expect Shimano is selling what works.
Short cranks are the new fad. Makes sense on a mtb where pedal strikes are a thing, on road/gravel its just another thing to talk about on forums.

markdjr
Posts: 250
Joined: Sun Sep 17, 2017 10:21 pm

by markdjr

OnTheRivet wrote:
Fri Mar 24, 2023 9:38 pm
warthog101 wrote:
Wed Mar 22, 2023 11:23 pm
https://road.cc/content/feature/pogacar ... olo-285041

All of his bikes use a 172.5mm crank length.

https://dmcx.com/2022/06/14/jonas-vinge ... ng%20shoes.

Jonas Vingegaard rides with 172.5mm crank length

https://dmcx.com/2022/03/13/primoz-rogl ... D%20pedals.

Primož uses 172.5mm crank length

https://dmcx.com/2020/03/24/egan-bernal ... bike-size/

He uses a 170mm Crank arms length

https://dmcx.com/2022/07/12/geraint-tho ... L%20pedals.

Thomas uses a 175mm crankset arm’s length

https://www.firstcomponents.com/bike-cr ... 20involved.

Chris Froome at 1.86m in height uses 175mm cranks

https://dmcx.com/2022/05/02/vincenzo-ni ... s%20length.

Vincenzo Nibali rides with 172.5mm crank arm’s length


Meh, I expect Shimano is selling what works.
Short cranks are the new fad. Makes sense on a mtb where pedal strikes are a thing, on road/gravel its just another thing to talk about on forums.

The list of riders you provided are all people who ride bikes for a living. They have adapted to their positions over many years and are paid to maintain that position. There is likely a physiological benefit to be had by running a shorter crank that a lot of people would benefit from. Not everyone, but there should definitely be a lot more people on 160-165 vs 170-175.

warthog101
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Joined: Wed Sep 25, 2013 10:05 am

by warthog101

markdjr wrote:
Sun Mar 26, 2023 3:21 am



The list of riders you provided are all people who ride bikes for a living. They have adapted to their positions over many years and are paid to maintain that position. There is likely a physiological benefit to be had by running a shorter crank that a lot of people would benefit from. Not everyone, but there should definitely be a lot more people on 160-165 vs 170-175.

Yep they are paid big money to ride professionally.
They are paid to achieve results.
There is significant pressure and motivation to achieve those results.
You would therefore assume they choose what helps them go as fast as they can to achieve those results.
They aint choosing short cranks.

I have nowhere near that ability but I still do greater than 10k km per year and have done for years.
I fail to see why some unfounded theory that there is a "physiological benefit to be had by running shorter cranks" should make me choose them.
Clearly where results count shorter cranks are not being used. It would therefore appear there is a physiological benefit to running longer cranks.
I am going with that sorry. :wink:

Volsung
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by Volsung

Just get some Appleman cranks and don't worry about them splitting in half. Plus you're supporting the little guy (and a local to me business).

Also power meter pedals, before you complain about that.

https://www.applemanbicycles.com/shop/2xr-crankset/

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ultimobici
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by ultimobici

Volsung wrote:
Sun Mar 26, 2023 1:57 pm
Just get some Appleman cranks and don't worry about them splitting in half.
Pretty sure GRX have no history of failures.

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