crank length 180 or 175
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never raced but i will build a bike to race i am building a 55 cm classic road frame i am 5 ft 8 and have long legs i dont have many other ideas yet so i joined
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Get a 53-39 double and 172.5s or at most 175s. The only person I know who uses 180s is 6'4". I'm 5'7" and use 170s.
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thank you Duke , how is the Queen , i will forget 180 i am not a gorilla. not rocking the Carolina's yet but getting fit
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I rarely see anyone riding 180s on the road. I have 170s on my 55cm (I have short legs) and am just fine.
#7
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6'2" using 175, they work great for me.
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180s are for tall people with longer legs so they can move through the normal range of angles (at hip and knee) and ride most efficiently.
There is no advantage in an average size person using long cranks. Cranks dont generate power, they just transmit and you have gears to control the speed/force of pedalling.
The normal range of crank size for a 5'8" rider is about 170-172.5
There is no advantage in an average size person using long cranks. Cranks dont generate power, they just transmit and you have gears to control the speed/force of pedalling.
The normal range of crank size for a 5'8" rider is about 170-172.5
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I'm 6'2 with long legs, but run 172.5's (people have told me I should be on 175's). I like the shorter length so I can run a higher cadence. In all honesty, length doesn't matter that much, as there isn't even a half inch difference between 180mm and 170mm.
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6'1" with long legs. Went to 175's and thought I would try 172.5 to see if it would induce a better strok at higher RPM. Went back to 175 and haven't looked back. I wouldn't consider longer and I am all legs and I found a considerable different when going back to 175 which helps quite a bit climbing up hills.
Personally unless you are a giant or pure masher, I wouldn't go longer then 175.
Good Luck,
George
Personally unless you are a giant or pure masher, I wouldn't go longer then 175.
Good Luck,
George
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I am 5'-8'' with a 30in inseam. Just for kicks I swapped a 170mm triple crank for a 175mm triple crank on my Jamis Nova all around bike. To be perfectly honest, I cannot tell the difference. I can still fast cadence if I want or mash if I want. Maybe I am not getting something but it made no difference to me.
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triple or double
many people are trying to convince me that doubles are fast and triples are not .if it is only a few ounces what is this stigma all about moving on
#13
so much for physics
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Originally Posted by bikerboyd
I'm 6'2 with long legs, but run 172.5's (people have told me I should be on 175's). I like the shorter length so I can run a higher cadence. In all honesty, length doesn't matter that much, as there isn't even a half inch difference between 180mm and 170mm.
If you fit too long a crankset on too small a bike you increase your chance of pedal overlap with your fork.
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Originally Posted by simonpne
many people are trying to convince me that doubles are fast and triples are not .if it is only a few ounces what is this stigma all about moving on
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gruppos
i dont think i need 180 at the time i had no idea, now i know 180 is not for me , i am choosing gruppos and only ran into this thing 24hours ago thanks simon
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If you're a big strong guy and can power along in the 53x12 then you might get away with the 180s to put the hurt on. However, if the group attacks 'ya, it will take 'ya a while to wind it up to catch 'em.
175 would be my suggested max, 172.5 works well.
jw
175 would be my suggested max, 172.5 works well.
jw
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Originally Posted by bikerboyd
I'm 6'2 with long legs, but run 172.5's (people have told me I should be on 175's). I like the shorter length so I can run a higher cadence. In all honesty, length doesn't matter that much, as there isn't even a half inch difference between 180mm and 170mm.
#21
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-- Q-factor is the width between the pedals, which is slightly increased on a triple due to the extra gear. It's probably a more significant issue with shorter riders, due to the ratio of leg length to Q-factor.
-- Regarding the merits of a triple versus double, with a quick search you will find multiple debate threads on here discussing that issue; my take is that unless you live somewhere completely flat, there is very little downside to a triple for a beginner assuming you can get a good fit.
-- Probably the most important thing is to obtain the services of a competent fitter when you buy. If that person knows what they're doing, they will make sure you have crank lengths that put your knee center where it should be at the front of the stroke, as well as all the other adjustments necessary to get the most from your bike.
Cheers!
-- Regarding the merits of a triple versus double, with a quick search you will find multiple debate threads on here discussing that issue; my take is that unless you live somewhere completely flat, there is very little downside to a triple for a beginner assuming you can get a good fit.
-- Probably the most important thing is to obtain the services of a competent fitter when you buy. If that person knows what they're doing, they will make sure you have crank lengths that put your knee center where it should be at the front of the stroke, as well as all the other adjustments necessary to get the most from your bike.
Cheers!
#22
Aluminium Crusader :-)
what bemuses me is that most of us probably see 180 as a MASSIVE length which should only be used by very tall people (this may be fair enough); it's like, "woah, 180; are you 6ft5"? Yet there are plenty of short dudes gleefully fully using 175s!!! ?? Is there such a difference between a 6ft guy using 180s and a 5ft7 guy using 175s?? 175 is MASSIVE for shorter people.
Last edited by 531Aussie; 11-19-06 at 09:04 AM.
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Originally Posted by biker7
6'1" with long legs. Went to 175's and thought I would try 172.5 to see if it would induce a better strok at higher RPM. Went back to 175 and haven't looked back. I wouldn't consider longer and I am all legs and I found a considerable different when going back to 175 which helps quite a bit climbing up hills.
Personally unless you are a giant or pure masher, I wouldn't go longer then 175.
Good Luck,
George
Personally unless you are a giant or pure masher, I wouldn't go longer then 175.
Good Luck,
George
#24
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Peter White's comments on crank length:
Crank length determines the diameter of the circle that the pedals move in. The larger that circle is, the more flexion of your knee and thigh muscles will be needed to turn the cranks. Your thigh muscles cannot exert the same force throughout their range of motion. This is very easy to demonstrate. If you squat down so that your knees are fully bent and lift yourself up, say, five inches, it takes a good deal more effort than it would to squat down just five inches from standing straight and then lift yourself back up. At the full squat position, your muscles can't put out the same power as when your knees are just bent enough to drop you down five inches. So if you had to choose between a crank length that had your knees bending through their entire range of motion and a length that only required, say, 20 degrees of flexion at the knee, you would choose the shorter crank. That crank would have your muscles working through a more efficient range of motion. You would avoid having to flex your knees enough to bring you into an inefficient range of motion.
So how long should the cranks be? Well, that's a good question. I wish I had a good answer but I don't. It should be obvious that a 5' 2" rider would not want to use the same length crank arms as a 6' 7" rider unless they somehow managed to have the same leg length (highly unlikely). Some research has been done to determine the optimum percentage of leg length to crank length. I doubt that there is an optimum percentage that would apply to all people. One writer in a major magazine article quite a few years ago claimed that after considerable testing with many different riders, 18.5% of the distance from the top of the femur to the floor in bare feet should be the crank length. You can find the top of the femur pretty easily. It's 5" to 6" below your hip bone, and moves rearward when you raise your knee. After reading this I promptly changed from the industry standard 170mm cranks for road bikes to 175mm cranks. There was an immediate improvement in power and endurance. I began using this formula when recommending cranks to my customers. So far, I haven't gotten any complaints. But of course that doesn't mean my customers wouldn't be as happy or happier with some other length. And I must admit that I have never tried still longer cranks than 175mm for enough time to tell if I would be even happier with them.
The top of the femur measurement ignores differences in legs themselves. Differences in the proportion of calf length to thigh length should affect the optimum crank length. A rider with longer thighs and shorter calves would use a longer crank to get the same flexion at the knee as a rider with short thigh and long calf. Of two riders with the same body proportions, one might prefer to pedal at a faster cadence. That might favor a shorter crank length. And perhaps even two riders with identical skeletal proportions would find after testing that they required different crank lengths to achieve maximum performance due simply to differences in their muscles.
Trying different cranks to find the optimum length would be time consuming and expensive, but I believe it is the only way to determine the correct length for any individual, assuming there is a correct length. It would be nice to have a crank with many pedal threads at various lengths to test. But I know of no such thing being made and I lack the ability to make one! Of course, some riders with multiple bikes report being just as happy on one crank length as another. Go figure! So, for lack of a better system, I'm staying with the 18.5% guide for my customers until something better comes along. It hasn't failed yet.
In the United States, it has been difficult and expensive to obtain cranks shorter than 165mm or longer than 175mm. But a French company, Specialites TA has been making high quality cranks in lengths of 150mm through 185mm for many years. In order to offer my customers better fitting bicycles, I've decided to sell these cranks. See my web page; https://www.PeterWhiteCycles.com/Zephyr.asp for details.
#25
34x25 FTW!
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FYI, I'm about 6' tall, inseam of 85.6cm IIRC. 175s on the road bike and 170s on the folder. A big "meh" to crank length from me as I'm not sure I can tell the difference having ridden each bike thousands of miles.