Negative effects of shorter cranks

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Martin.F
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by Martin.F

@Warthog How many wins do you need to see before you see the trend and benefits?

Your arguments are similar to saying a few years ago that box section alloy wheels and 25mm tubs are better at roubiax since there are so few wins on deep section wheels and 30mm+ tires.

I'm also a converter to short cranks. It's easier for me at my 170cm to keep higher cadence, keep a more open hip angle at the same torso-to-ground-angle (or get my torso more horizontal and get more aero with the same hip-angle), top of pedal stroke feels smoother and hip rocking is substantially less.

That doesn't mean that it's better for everybody, but the crankarm to leg-length ratio has been way off for shorter riders for many years now and I'm glad to see the change.

HBike
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by HBike

TobinHatesYou wrote:
Thu May 09, 2024 12:26 pm
This is pointless histrionics.

The miniscule possible Pmax disadvantage in very short cranks is 1) irrelevant to GC riders and 2) irrelevant to mostly everyone because nobody is recommending 145mm cranks. Short cranks DO have significant advantages in improving aero, preventing injuries and reducing the risk of pedal strikes. And hey since this is weight weenies, shorter cranks are lighter weight.

It mostly comes down to personal preference. I have considered putting 172.5s on my Emonda for climbing heavy races while having 165s or even 155s on my Domane and Madone for flat/rolling races. I have no issues switching between crank lengths.
Agree. And there are enough scientific publications on the effect of crank length on different metrics.

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pdlpsher1
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by pdlpsher1

Tall people don't need to come here to defend their positions. The cranks they are riding now are already sized appropriately for them. What got us into this mess is that manufacturers (crank producers and bike manufacturers) got it wrong when they fitted all bikes with 170-175mm cranks. That's simply too small of a range for crank lengths. Think about it- just a 5mm difference between a XXS and a XXL frame. My partner is 5'4" (162.5cm) tall and is riding 145mm cranks. It's the short to average height riders who have been suffering the most because they had no other choices. Bikes should be configured and sold with a wider range of crank lengths, from 145s on XXS to 175s on XXL bikes. That's still only a 3cm spread when bike sizes range from a 46cm to a 62cm, a 16cm spread.

CR987
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by CR987

Your foot/pedal spindle has to travel is 3cm further per revolution using 170 Vs 165 cranks. Let's say the power phase is a third of that, it means your foot travels 1cm shorter distance with slightly less leverage.
This part of the equation has not been understood or taken into consideration. I found the power phase of the pedal stroke is over too quickly, especially if you like to climb out of the saddle. AgaIn, marginal differences in all aspects of this conundrum
Last edited by CR987 on Sat May 11, 2024 3:07 pm, edited 1 time in total.

toxin
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by toxin

Sounds like confirmation bias

maxim809
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by maxim809

Controversial claim: I think some pros know lots about how to go deep during training, and race prep, strat, and tactics. But they don’t know as much about bike tech, bike fit, biomechanics, or even how to wrap bar tape or press a BB.

I think there are pros like Bigham, Dowsett, Taco, Camp, Caleb, Obree who push innovation in some or all of the latter categories. With the first two being exceptional at even explaining their thought process.

But then there are other pros, even if they are winners, who are sometimes poor examples of people to listen to and copy. It’s sometimes not even their fault, but what their RD/DS, mechanic, nutritionist or sponsors ask of them.

toxin
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by toxin

That shouldn't be controversial, it is absolutely true. Van der Poel has never worked on any of his bikes and he admits he has no idea about any of it.

maxim809
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by maxim809

Dang. Well, I will continue doubling down with more controversy:

Road is slow to adopt and is sometimes its own worst enemy. Track has been exploring the tradeoffs of short cranks, forward position, narrow bars far longer than Road. Triathlon community already knew the importance of aero and knew laces were faster 10 years ago. CX/Gravel is deep in the nuances with tires and the art of having fun. And MTB the tradeoffs with bike geometry & setup and its impact to handling.

Key call out is the word 'tradeoffs', and not just benefits or negative effects.

If Road Community could leverage the learnings from all other disciplines and build upon it with an open mind instead of just looking at its own closed history, the Road Hivemind would be unstoppable.

TobinHatesYou
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by TobinHatesYou

maxim809 wrote:
Sat May 11, 2024 5:16 pm
Controversial claim: I think some pros know lots about how to go deep during training, and race prep, strat, and tactics. But they don’t know as much about bike tech, bike fit, biomechanics, or even how to wrap bar tape or press a BB.

I think there are pros like Bigham, Dowsett, Taco, Camp, Caleb, Obree who push innovation in some or all of the latter categories. With the first two being exceptional at even explaining their thought process.

But then there are other pros, even if they are winners, who are sometimes poor examples of people to listen to and copy. It’s sometimes not even their fault, but what their RD/DS, mechanic, nutritionist or sponsors ask of them.

Nobody was more right about every eventual fit trend than Adam Hansen. He is even kind of right about long cranks when used with his fit, which is essentially the "progressive fit" riders are adopting today. With the saddle slammed forward and raised, there is no chance of tummy/thigh interference with long cranks. You get the leverage benefit of the longer cranks, you get the leverage benefit from your hips being closer to directly on top of the BB. As long as you have a naturally long stride/gait, longer cranks are going to work very well (outside of the aero benefits of lowering the saddle with short cranks because there's even less chance of tummy/thigh interference.)

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wheelbuilder
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by wheelbuilder

toxin wrote:That shouldn't be controversial, it is absolutely true. Van der Poel has never worked on any of his bikes and he admits he has no idea about any of it.
This cannot be overstated. Yes they were women, but I worked at a service course for a pro tour UCI team and was around a fair bit of male pros at TOC etc.... the riders that had any interest or knowledge of how their equipment worked could be counted on two hands. We at this forum are a miniscule subset of the cycling community.
Never cheer before you know who is winning

Lina
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by Lina

wheelbuilder wrote:
Sun May 12, 2024 1:29 am
toxin wrote:That shouldn't be controversial, it is absolutely true. Van der Poel has never worked on any of his bikes and he admits he has no idea about any of it.
This cannot be overstated. Yes they were women, but I worked at a service course for a pro tour UCI team and was around a fair bit of male pros at TOC etc.... the riders that had any interest or knowledge of how their equipment worked could be counted on two hands. We at this forum are a miniscule subset of the cycling community.
And is it really even a surprise if you spend a couple minutes thinking it through. Most pros have been riding competitively since they've been very young. They've had their parents taking care of their bikes at the start and since they've been fast most of them have had a team mechanic taking care of their bikes as older juniors. And then they've made the jump to the pro peloton and again have mechanics taking care of anything. Unless you're a bike nerd there's never even been a chance for them to learn about bikes.

TheBelgian
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by TheBelgian

toxin wrote:
Mon May 06, 2024 2:33 am
TheBelgian wrote:
Sun May 05, 2024 5:57 pm
That's also why aerobars don't always make you faster and actually make you slower at lower speeds.
Do go on
What do you want to know? If you have a road bike fitted with aerobars, using them closes your hips as compared to riding on the hoods. When you close your hip you reduce the max power output of your legs (and even lower power numbers become harder to sustain). At certain speeds the air resistance isn't a huge contributing factor in slowing you down, let's say 20km/h. In that case you will be slower when on the aero bars because your legs have a lot more trouble generating power with that closed hip angle compared to when you're riding on the hoods with more open hips.
Now when you're going 40km/h the gains in air resistance are a lot bigger than the power losses of those closed hips.

Of course, everything is a compromise. You could pull the saddle so far forward and tilt it that it opens the hip a lot more on the aero bars, but then you'll be in trouble if you need to ride a lot on the hoods since it will increase the pressure on your hands a lot in order to not slide off the saddle. For a TT it doesn't matter because it's 40 minutes of suffering, and as the saying goes "if you're comfortable on a TT bike your fit is wrong", but if you do multi hour rides you have to choose what position you prioritise when fitting the bike, if you use it for general road riding.

toxin
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by toxin

Ah, they're tri bars in my vocabulary

TheBelgian
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by TheBelgian

toxin wrote:
Mon May 13, 2024 4:06 pm
Ah, they're tri bars in my vocabulary
Not all aerobars are tri bars, but the word is confusing, as you will also find aero optimized handlebars under the "aerobar" umbrella.

PeanutButterCups
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by PeanutButterCups

So Adam Hansen was an early adopter of the forward seat postion and narrow handlebars but from memory he 'was' using 180mm crankarms. I'm not sure what he is using length wise now but would be interested as it was the one area going against the trendy short cranks?

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