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  1. #1
    Senior Member biker7's Avatar
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    Gang,
    My first foray onto the 50 and older board and a heart felt hello to my cycling friends over here. I am 51 years young and feel great in no small part due to cycling which I try to do every day.
    My question may be age specific as I grew up riding on 165mm cranks when shorter cranks were more the norm. My newest bike has 175mm cranks and after 1500 miles, I am still considering changing back to a more happy medium length of 170mm. Many said I would get used to the longer cranks but even though I can ride and climb fine...they never felt completely comfortable. My bike fit feels spot on, I just don't like the big pedal circle of the 175mm cranks (with Campy Veloce Triple) which belies my rather long cycling inseam of 35.25 inches. So much of fit is personal preference...like handlebar relative to seat height for example and wondered if others that are long legged still prefer a more ordinary or standard crank length of 170mm? I don't have any particular knee pain...some days maybe just a touch if pushing too much gear or climbing too intensely...just can't spin as comfortably as I can on shorter crank bikes.
    Similar experiences and/or all advice is welcome.
    George
    Last edited by biker7; 08-16-05 at 08:07 AM.

  2. #2
    Let's do a Century jppe's Avatar
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    Welcome aboard!

    In your case it really sounds like you have a personal preference that until you try a change you're not going to know for sure if that's the route you want to go. Sounds like you out to try it just to see for sure. Since you rode so much on 165's the 170's might just be a happy compromise.

    My recent experience was just the opposite. I learned on 175's but had to use 165's on a bike that I had to borrow for a couple months. I could not wait to get back to the 175's. It seemed I had more power with the 175's (more leverage maybe?) and my overall performance was better. I also picked up some knee pain but that was probably due to the seat not being properly aligned. Some of it might just be what we're used to.

    Just a thought, but if you go to 165's, since you're not having any knee pain you'll need to raise your seat by the difference in crank length so your leg length will remain the same. You might also check to see if this is still comfortable that high above the handlegars. You will also want to adjust the seat back a little to keep the knee properly over the pedal as well which will increase your reach to the handlebars.

    Good luck with your quest!!

  3. #3
    Senior Member biker7's Avatar
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    Quote Originally Posted by jppe
    Welcome aboard!

    In your case it really sounds like you have a personal preference that until you try a change you're not going to know for sure if that's the route you want to go. Sounds like you out to try it just to see for sure. Since you rode so much on 165's the 170's might just be a happy compromise.

    My recent experience was just the opposite. I learned on 175's but had to use 165's on a bike that I had to borrow for a couple months. I could not wait to get back to the 175's. It seemed I had more power with the 175's (more leverage maybe?) and my overall performance was better. I also picked up some knee pain but that was probably due to the seat not being properly aligned. Some of it might just be what we're used to.

    Just a thought, but if you go to 165's, since you're not having any knee pain you'll need to raise your seat by the difference in crank length so your leg length will remain the same. You might also check to see if this is still comfortable that high above the handlegars. You will also want to adjust the seat back a little to keep the knee properly over the pedal as well which will increase your reach to the handlebars.

    Good luck with your quest!!
    Thanks for your thoughtful response. I am a long time cyclist so well familar with all the tradeoffs you correctly mentioned regarding saddle positioning. Think the operative point is what you learn on which establishes your sense of normalcy over and above say proportional crank theory or 20% of inseam. 10mm in crank length difference is a big jump as most know...a full 20mm increase in pedal circle diameter is going to feel profoundly different. 170mm may be a decent balance for me. No question in the hills the longer cranks do feel strong but I spend most of my time spinning on the flats.
    Thanks again,
    George

  4. #4
    Roadie
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    when I was 16 and racing i rode on 170 mm. In my mid 20's, most of my riding was recreational and I changed to 175 mm. I came back to the sport at 52 and started using my old 175 mm. Due to an accident I had to get another bike, couldn't find replacement parts for my old bike so I got a bike with 172.5 mm.
    (my inseam is about 36 inches, 6 ft 1 inch height).

    A few observations:
    Although the absolute differences are small, 2.5 and 5 mm, they seem to be significant.
    I felt that my climbing was better with 175 mm.
    Spinning was better with 170 mm
    Although I sometimes think about getting 175 mm (hill climbing is my preferred activity), the 172.5 is a good compromise for me, allowing comfortable riding on the flats and sufficient leverage in the hills.

    Recommendation:
    Your riding style, (slow vs fast cadence; ankle angle and movement, etc,), abilities (hill climber or sprinter), and femur length (http://www.nettally.com/palmk/crderiva.html) will dictate your optimal crank length.

  5. #5
    Senior Member biker7's Avatar
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    Quote Originally Posted by berts
    when I was 16 and racing i rode on 170 mm. In my mid 20's, most of my riding was recreational and I changed to 175 mm. I came back to the sport at 52 and started using my old 175 mm. Due to an accident I had to get another bike, couldn't find replacement parts for my old bike so I got a bike with 172.5 mm.
    (my inseam is about 36 inches, 6 ft 1 inch height).

    A few observations:
    Although the absolute differences are small, 2.5 and 5 mm, they seem to be significant.
    I felt that my climbing was better with 175 mm.
    Spinning was better with 170 mm
    Although I sometimes think about getting 175 mm (hill climbing is my preferred activity), the 172.5 is a good compromise for me, allowing comfortable riding on the flats and sufficient leverage in the hills.

    Recommendation:
    Your riding style, (slow vs fast cadence; ankle angle and movement, etc,), abilities (hill climber or sprinter), and femur length (http://www.nettally.com/palmk/crderiva.html) will dictate your optimal crank length.
    Excellent advice...and we are close to the same size...man you have long legs for your height...we are the same height and I have long legs

    I agree with all you wrote. It is not only personal preference...but related to a preferred cadence...spinner versus masher and how much time you spend in the hills versus flats....why the norm is different for mountain versus road bikers for example. I believe it comes down to trial and error...that means...you have to experiment. The question for me if making a change...what should the change be...172.5 or 170? Some have suggested that a 2.5mm delta in crank arm length is noise and not substantive...others have reflected like yourself and say that a 2.5mm change is definitive and hence justified by the 2.5mm crank length increments offered by manufacturers.
    I may very well go with the 172.5mm length and give that a try. My ratio of flats to climbing is 85/15 or so.
    If the ratio were reversed, I may likely stay on the 175's which do work great for hills.
    George
    Last edited by biker7; 08-16-05 at 08:06 AM.

  6. #6
    Time for a change. stapfam's Avatar
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    The recognised way of working out which crank length to use is longer legs = longer cranks. I have a 30" inside leg and I use 175 cranks. In theory these should be too long for me, and I did once drop down to 170's. Whether it was several years of using the longer cranks, I don't know, but within a couple of years I was back onto 175's. It is personal preference, but According to your inside leg, you should be using 175's. Acording to mine, I should be using 170's. Just proves that you ride what you want, but don't junk the 175's for a couple of years.

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