Crank length ! How important !

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Comments

  • dennisn
    dennisn Posts: 10,601
    mmacavity wrote:
    http://www.youtube.com/watch?v=HFxBg7BnFlQ

    Something that really bothered me in this video was the guy saying "assume shorter is better until proven otherwise". All those "facts and figures" and then he tells you to assume something? :roll:
  • cswitch
    cswitch Posts: 261
    Also the max power stuff was out the saddle type efforts at 1200w or so. I would have thought the leg impacting the upper body not relevant in that scenario.
  • StillGoing
    StillGoing Posts: 5,211
    John.T wrote:
    Talk of a shortened 'dead spot' is a red herring. Proportionally it does not change. What does change is the rotational foot speed relative to cadence. The only way to change the dead spot is by using non round rings.
    If you stay within the more usual 170/175 length you will probably not notice any difference other than in the first 5 minutes of changing. All the formulae for calculating crank length are basically rubbish as if they were not then they would all agree. Shorter legs (not necessarily shorter riders) need shorter cranks. That is all you need to know.

    You talk of the dead spot being a red herring, where is your evidence for that view? The counter view is if the leg is restricted in movement at the top of the stroke due to too long crank length, then the effort to clear the dead spot is far worse than if using shorter cranks giving more room at the top of the pedal stroke. Also, to suggest that all the formulae is rubbish otherwise they'd all agree on it is surely your opinion rather than fact? My fitter certainly didn't sell crank sets so wouldn't have been getting any benefit by recommending shorter cranks to me. He'd already made enough alterations to my position to justify his fee so didn't need to convince me he was some guru with a mystical insight into some new fangled theory. I fully agree with your simple notion that short legs need short cranks, but there is a clearly going to be a range of crank length appropriate to a range of height/leg lengths. If off the shelf bikes all come with 170mm or 172.5mm cranks, then some people are going to have crank lengths too long, or even too short for their leg length.

    There are always going to be doubters with any new innovation or idea with whatever, but it doesn't always mean the innovators are wrong. People were doubting the benefit of electronic shifting not long ago and many still do today. We have enough crap about nothing but Campagnolo is fit to be on a bike let alone theories into the benefits of crank length or Q rings etc.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • dennisn
    dennisn Posts: 10,601
    philthy3 wrote:
    There are always going to be doubters with any new innovation or idea with whatever, but it doesn't always mean the innovators are wrong.

    Couldn't agree more. Maybe this thing is aimed at triathletes. Just by hinting that something is better it seems that the tri boys suck it up. :wink:
  • John.T
    John.T Posts: 3,698
    Read my first paragraph properly. It is 100% accurate. The proportion of the revolution that could be considered the 'dead spot' is the same with any crank length. Only non round rings will change this. Forget the old Rotor cranks. I agree that cranks that are too long will cramp the leg over TDC but what is too long will vary depending on the individual. If unusually short cranks suit you fine but I am perfectly happy with my 175s with round rings on the road bikes and Osymetric on the TT one.
    Most off the peg bikes do not come with the same length crank. They usually start with 170 on the small size and work up to 175 on the larger ones.
    My Fleet.
  • StillGoing
    StillGoing Posts: 5,211
    John.T wrote:
    Read my first paragraph properly. It is 100% accurate. The proportion of the revolution that could be considered the 'dead spot' is the same with any crank length. Only non round rings will change this. Forget the old Rotor cranks. I agree that cranks that are too long will cramp the leg over TDC but what is too long will vary depending on the individual. If unusually short cranks suit you fine but I am perfectly happy with my 175s with round rings on the road bikes and Osymetric on the TT one.

    I think we kind of agree but express it in a different way? My experience is just as we've both posted; I'm a shortie whose bike had 170mm cranks. Switching to 165mm cranks has worked for me. If I was taller, then the 170mm may well have been better. But the feeling for movement getting over the top of the pedal stroke is now easier than it was with the 170mm cranks where my leg angle was cramped at the top due to needing the seat lower to avoid over stretching at the bottom of the stroke.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • John.T
    John.T Posts: 3,698
    We are all different. I am 5' 11" with a short reach. I ride 56 cm frames with quite a bit of seat post out. 172.5 are the norm on this size but I prefer 175. I have used 180 with no problems and have used 165 on the track. They are fine after a few minutes.
    I have considered going to 170 for TTs to maybe have a faster cadence but this could bring on cardiovascular problems so am staying with what I know works for me.
    My Fleet.
  • pinno
    pinno Posts: 51,371
    This thread is longer than a pair of 185 crank arms...
    seanoconn - gruagach craic!
  • Ringpeace
    Ringpeace Posts: 105
    All a load of bollos IMO.

    I'm 6'1" tall - all my bikes have come with 170 - bikes I have had built have 170.

    I do have short legs for my height - 32" inseam but so what? How much difference is it gonna make?

    I get dropped by guys 10X as fit and using big gear ratios. Then again I don't get dropped by some guys I know who have spent near on £5K on their bikes.

    Too much posing and fannying about in the road scene IMO. I'd be embarrassed to ride full Ultegra, Dura Ace or Di2 unless I was leading. Constantly.

    See way too many people that have these set ups - yet don't have the ability to smash them. Or are riding compacts - LOL.

    I'm a beginner and my biggest aim is to be getting back on the big chainrings - which I used to have - and ride that quickly.

    I'm a long way off - just too easy on the compacts...
  • drlodge
    drlodge Posts: 4,826
    I have a posh bike, with a compact setup and Campag Super Record. So what? Oh, and 172.5mm cranks.
    WyndyMilla Massive Attack | Rourke 953 | Condor Italia 531 Pro | Boardman CX Pro | DT Swiss RR440 Tubeless Wheels
    Find me on Strava
  • dennisn
    dennisn Posts: 10,601
    Ringpeace wrote:
    I'm a beginner and my biggest aim is to be getting back on the big chainrings - which I used to have - and ride that quickly.
    I'm a long way off - just too easy on the compacts...

    I think the word "beginner" says it all about your post. :lol::lol:
  • Ringpeace
    Ringpeace Posts: 105
    dennisn wrote:
    Ringpeace wrote:
    I'm a beginner and my biggest aim is to be getting back on the big chainrings - which I used to have - and ride that quickly.
    I'm a long way off - just too easy on the compacts...

    I think the word "beginner" says it all about your post. :lol::lol:

    You must of missed the title thread that says " road beginners".....

    Ooops.....
  • w00dster
    w00dster Posts: 880
    Ringpeace wrote:
    All a load of bollos IMO.

    I'm 6'1" tall - all my bikes have come with 170 - bikes I have had built have 170.

    I do have short legs for my height - 32" inseam but so what? How much difference is it gonna make?

    I get dropped by guys 10X as fit and using big gear ratios. Then again I don't get dropped by some guys I know who have spent near on £5K on their bikes.

    Too much posing and fannying about in the road scene IMO. I'd be embarrassed to ride full Ultegra, Dura Ace or Di2 unless I was leading. Constantly.

    See way too many people that have these set ups - yet don't have the ability to smash them. Or are riding compacts - LOL.

    I'm a beginner and my biggest aim is to be getting back on the big chainrings - which I used to have - and ride that quickly.

    I'm a long way off - just too easy on the compacts...


    I take it you're a WUM / troll? The comment by dennisn was showing you that your post was of no relevance to the discussion between riders with differing views on crank lengths.
    With regards to your smash them comments, WTF are you on about? I ride a nice bike with full ultegra for one reason only - I can afford it. If my budget dictated a bike with a lower groupset then I would happily ride that. The bike and groupset nothing to do with my ability. If I see a guy on a much better bike than me, then I don't get the need to smash him and nor do I feel upset when I get overtaken by a guy on a bike that may be regarded as being lower in the chain than mine. I ride with lots of good riders, some have very posh bikes, others not so posh.
    I'm not even going to get into the debate you're trying to start regarding gear ratio's and your comment about compacts.

    Enjoy riding in your big chainring, us oldies would quite like to do that, but father time shows no mercy!
  • StillGoing
    StillGoing Posts: 5,211
    w00dster wrote:
    Ringpeace wrote:
    All a load of bollos IMO.

    I'm 6'1" tall - all my bikes have come with 170 - bikes I have had built have 170.

    I do have short legs for my height - 32" inseam but so what? How much difference is it gonna make?

    I get dropped by guys 10X as fit and using big gear ratios. Then again I don't get dropped by some guys I know who have spent near on £5K on their bikes.

    Too much posing and fannying about in the road scene IMO. I'd be embarrassed to ride full Ultegra, Dura Ace or Di2 unless I was leading. Constantly.

    See way too many people that have these set ups - yet don't have the ability to smash them. Or are riding compacts - LOL.

    I'm a beginner and my biggest aim is to be getting back on the big chainrings - which I used to have - and ride that quickly.

    I'm a long way off - just too easy on the compacts...


    I take it you're a WUM / troll? The comment by dennisn was showing you that your post was of no relevance to the discussion between riders with differing views on crank lengths.
    With regards to your smash them comments, WTF are you on about? I ride a nice bike with full ultegra for one reason only - I can afford it. If my budget dictated a bike with a lower groupset then I would happily ride that. The bike and groupset nothing to do with my ability. If I see a guy on a much better bike than me, then I don't get the need to smash him and nor do I feel upset when I get overtaken by a guy on a bike that may be regarded as being lower in the chain than mine. I ride with lots of good riders, some have very posh bikes, others not so posh.
    I'm not even going to get into the debate you're trying to start regarding gear ratio's and your comment about compacts.

    Enjoy riding in your big chainring, us oldies would quite like to do that, but father time shows no mercy!

    Nicely put.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.

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