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Do you match crank lengths on road bike and tri bike?
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I recently got done building up and being fit on my new tri bike. I went with 165 cranks and am very happy with the resulting hip angles and overall fit of the bike, and the shorter cranks felt very natural after just a few minutes on the road.

I’m also shopping around for a new road bike at the moment. From a fit standpoint I don’t “need” short cranks on the road bike to achieve good hip angles but I’m wondering if there is any benefit to riding the same length cranks on both bikes vs riding my ‘regular’ 172.5’s on the road bike?

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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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172.5 on my road bike and 170 on my tri bike.

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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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170 on my tri, road and mountain bikes.

I don't think it's necessary though.
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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jkatsoudas wrote:
I recently got done building up and being fit on my new tri bike. I went with 165 cranks and am very happy with the resulting hip angles and overall fit of the bike, and the shorter cranks felt very natural after just a few minutes on the road.

I’m also shopping around for a new road bike at the moment. From a fit standpoint I don’t “need” short cranks on the road bike to achieve good hip angles but I’m wondering if there is any benefit to riding the same length cranks on both bikes vs riding my ‘regular’ 172.5’s on the road bike?

Nope. Not necessary.

I've got 165 on the TT bike and 170s on all the road bikes (3). The MTBs have 175s, but mostly because they're both "old school" :-)



http://bikeblather.blogspot.com/
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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jkatsoudas wrote:
I recently got done building up and being fit on my new tri bike. I went with 165 cranks and am very happy with the resulting hip angles and overall fit of the bike, and the shorter cranks felt very natural after just a few minutes on the road.

I’m also shopping around for a new road bike at the moment. From a fit standpoint I don’t “need” short cranks on the road bike to achieve good hip angles but I’m wondering if there is any benefit to riding the same length cranks on both bikes vs riding my ‘regular’ 172.5’s on the road bike?

You should PM H2Ofun.

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"Good genes are not a requirement, just the obsession to beat ones brains out daily"...the Griz
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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6 foot 3. i have 165 on the tri bike and 175 on the road bike and mtb. never noticed anything.
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Re: Do you match crank lengths on road bike and tri bike? [stringcheese] [ In reply to ]
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Thanks everyone. I figured it wasn't necessary but I thought I'd ask nonetheless.


stringcheese wrote:
You should PM H2Ofun.

I'd rather stab myself in the eyeball with a crank arm.

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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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I've been riding on 175's for >20yrs. Early this year I put 170's on the tribike and, to my surprise, found that I kinda liked them better. Now the 175's on the road bike feel "too big". Am thinking about putting 170's on the tribike.

"If only he had used his genius for niceness, instead of Evil." M. Smart
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Re: Do you match crank lengths on road bike and tri bike? [Cookiebuilder] [ In reply to ]
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Cookiebuilder wrote:
6 foot 3. i have 165 on the tri bike and 175 on the road bike and mtb. never noticed anything.

But h2ofun says that nobody understands people taller than 6', and that long cranks are the way to go for taller folk.

(Sorry. That thread is making me ornery)

Citizen of the world, former drunkard. Resident Traumatic Brain Injury advocate.
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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I think the question should be whether there is an advantage to having longer cranks on the road bike? Conventional wisdom is that there is no inherent disadvantage to shorter cranks, so why do people, including myself, default to the typical 172.5 on the road bike?
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Re: Do you match crank lengths on road bike and tri bike? [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:
I think the question should be whether there is an advantage to having longer cranks on the road bike? Conventional wisdom is that there is no inherent disadvantage to shorter cranks, so why do people, including myself, default to the typical 172.5 on the road bike?

Research has shown that there is no innate optimal cadence from a cardiovascular efficiency standpoint and when it comes right down to it, the only time you really notice the limits of the crank system is when you're either in the lowest or highest gear combination. If you are expecting to encounter a real grinder of a hill where you will spend extended time in the granny ring and big cog, then it may be worthwhile to have a bit of extra crank length to maximize your leverage. 165 to 172.5 is about five percent, which is going to be similar to increasing the big cog on the cassette from 32 to 34 (6%) or dropping the small chainring by a couple of teeth (40 to 38 would be five percent).

At the other end of the speed range, a shorter crank will give you a bit more ability to attain high cadence because the foot speed will be reduced compared to what you'd have with the longer cranks.

Longer cranks are a disadvantage in cornering because for any given bottom bracket height they will reduce the maximum lean angle you can attain while still pedaling (cough Dan Martin cough).

A nice thing about 172.5's is that they are very commonly available.
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Re: Do you match crank lengths on road bike and tri bike? [Big Endian] [ In reply to ]
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Big Endian wrote:
grumpier.mike wrote:
I think the question should be whether there is an advantage to having longer cranks on the road bike? Conventional wisdom is that there is no inherent disadvantage to shorter cranks, so why do people, including myself, default to the typical 172.5 on the road bike?


Research has shown that there is no innate optimal cadence from a cardiovascular efficiency standpoint and when it comes right down to it, the only time you really notice the limits of the crank system is when you're either in the lowest or highest gear combination. If you are expecting to encounter a real grinder of a hill where you will spend extended time in the granny ring and big cog, then it may be worthwhile to have a bit of extra crank length to maximize your leverage. 165 to 172.5 is about five percent, which is going to be similar to increasing the big cog on the cassette from 32 to 34 (6%) or dropping the small chainring by a couple of teeth (40 to 38 would be five percent).

At the other end of the speed range, a shorter crank will give you a bit more ability to attain high cadence because the foot speed will be reduced compared to what you'd have with the longer cranks.

Longer cranks are a disadvantage in cornering because for any given bottom bracket height they will reduce the maximum lean angle you can attain while still pedaling (cough Dan Martin cough).

A nice thing about 172.5's is that they are very commonly available.

Do you think there's an optimal hip angle at the top of the pedal stroke? A lot is made of the beneficial effects of shorter cranks on opening up the hip angle at the top of the pedal stroke in a tri/tt position, but is it possible to have too open of a hip angle at the top of the pedal stroke with short cranks on a road bike?

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Re: Do you match crank lengths on road bike and tri bike? [Big Endian] [ In reply to ]
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Big Endian wrote:
grumpier.mike wrote:
I think the question should be whether there is an advantage to having longer cranks on the road bike? Conventional wisdom is that there is no inherent disadvantage to shorter cranks, so why do people, including myself, default to the typical 172.5 on the road bike?


Research has shown that there is no innate optimal cadence from a cardiovascular efficiency standpoint and when it comes right down to it, the only time you really notice the limits of the crank system is when you're either in the lowest or highest gear combination. If you are expecting to encounter a real grinder of a hill where you will spend extended time in the granny ring and big cog, then it may be worthwhile to have a bit of extra crank length to maximize your leverage. 165 to 172.5 is about five percent, which is going to be similar to increasing the big cog on the cassette from 32 to 34 (6%) or dropping the small chainring by a couple of teeth (40 to 38 would be five percent).

At the other end of the speed range, a shorter crank will give you a bit more ability to attain high cadence because the foot speed will be reduced compared to what you'd have with the longer cranks.

Longer cranks are a disadvantage in cornering because for any given bottom bracket height they will reduce the maximum lean angle you can attain while still pedaling (cough Dan Martin cough).

A nice thing about 172.5's is that they are very commonly available.

Nice theory, but only that.
I have a quite noticeably higher cadence on 180mm road cranks over 175mm.
The spin is just more natural and fluid.
I used to run 175mm on tri bike for hip angles and also ride far forward, my preffered cadence is 83 rpm vs up around 100 for the longer arms on the road bike.
So I am completely opposite of your theory.
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Re: Do you match crank lengths on road bike and tri bike? [lyrrad] [ In reply to ]
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lyrrad wrote:
Nice theory, but only that.
I have a quite noticeably higher cadence on 180mm road cranks over 175mm.
The spin is just more natural and fluid.
I used to run 175mm on tri bike for hip angles and also ride far forward, my preffered cadence is 83 rpm vs up around 100 for the longer arms on the road bike.
So I am completely opposite of your theory.
I'm not going to debate your personal preferences - do what seems best for you. But, if you're comparing 175's on your tri setup to 180's on a road setup, then there are a lot of other factors that come into play (such as your torso position) and they might affect your self-selected cadence much more than a 3 percent change in crank length.

The stuff I was talking about is where you change the crank length on a given bike and at most tweak the seat position so you end up with the same effective leg extension.
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Re: Do you match crank lengths on road bike and tri bike? [Big Endian] [ In reply to ]
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Can we look to TdF riders? I.e. Froome rolls 175s if not mistaken. Or no?
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Re: Do you match crank lengths on road bike and tri bike? [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:
I think the question should be whether there is an advantage to having longer cranks on the road bike? Conventional wisdom is that there is no inherent disadvantage to shorter cranks, so why do people, including myself, default to the typical 172.5 on the road bike?

If nothing else, the vast majority of bikes are designed with a BB drop for 170-175mm cranks, and the majority of cranks are only available from 165-175 (with many not going smaller than 170)...

"I'm thinking of a number between 1 and 10, and I don't know why!"
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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jkatsoudas wrote:
I recently got done building up and being fit on my new tri bike. I went with 165 cranks and am very happy with the resulting hip angles and overall fit of the bike, and the shorter cranks felt very natural after just a few minutes on the road.

I’m also shopping around for a new road bike at the moment. From a fit standpoint I don’t “need” short cranks on the road bike to achieve good hip angles but I’m wondering if there is any benefit to riding the same length cranks on both bikes vs riding my ‘regular’ 172.5’s on the road bike?

I used to have 170 on my road bike and 165 on my tri bike, but I've switched to 165 for the road bike as well. The only reason for doing so was that using the same length cranks allows me to switch my P2M crank back and forth between the 2 bikes without having to do any adjustments...

"I'm thinking of a number between 1 and 10, and I don't know why!"
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Re: Do you match crank lengths on road bike and tri bike? [Big Endian] [ In reply to ]
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Big Endian wrote:
lyrrad wrote:
Nice theory, but only that.
I have a quite noticeably higher cadence on 180mm road cranks over 175mm.
The spin is just more natural and fluid.
I used to run 175mm on tri bike for hip angles and also ride far forward, my preffered cadence is 83 rpm vs up around 100 for the longer arms on the road bike.
So I am completely opposite of your theory.

I'm not going to debate your personal preferences - do what seems best for you. But, if you're comparing 175's on your tri setup to 180's on a road setup, then there are a lot of other factors that come into play (such as your torso position) and they might affect your self-selected cadence much more than a 3 percent change in crank length.

The stuff I was talking about is where you change the crank length on a given bike and at most tweak the seat position so you end up with the same effective leg extension.[/quote

Right now I have no tt bike but two road bikes. One is 180mm the other is 175.
I spin faster on the longer crank one than the shorter one.
The longer crank just spins more fluidly, It also climbs the 20+% grades much better.

Shorter crank length is not a driver for higher cadence. I am taller and the longer cranks spin easier for me.
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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I have 172.5 cranks on both my road and tri bike. I've never thought about it and assume it's just a function of the frame sizes of each bike and what size crank came with them. Both of the frames are 58cm.

"The first virtue in a soldier is endurance of fatigue; courage is only the second virtue."
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Last edited by: Don_W: Oct 11, 17 18:58
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Re: Do you match crank lengths on road bike and tri bike? [jkatsoudas] [ In reply to ]
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155 on TT
165 on trainer
172.5 on roadie

It all works out for me at the end of the day.
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Re: Do you match crank lengths on road bike and tri bike? [ErickBar] [ In reply to ]
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ErickBar wrote:
Can we look to TdF riders? I.e. Froome rolls 175s if not mistaken. Or no?

Froome *typically* rides 175mm with 52/38t elliptical rings.
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