Stubby Legs

Discussion in 'UK and Europe' started by Danny Colyer, Jun 3, 2003.

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  1. Danny Colyer

    Danny Colyer Guest

    Are there any short people out there who've experimented with different crank lengths?

    My wife is 5' with a 27" inside leg. She's currently using the 170mm cranks that the bike came with,
    but I reckon she'd be better off with 150mm cranks (if I can find some).

    I haven't yet determined whether I can replace the right crank without also replacing the chainring.
    Either way wifey isn't convinced that it will be worth the cost, particularly given that she only
    rides about 100 miles/year. However, we intend to improve on that figure significantly this year.

    I'd be interested in the opinions and experiences of similar height people who've tried different
    crank lengths. Does 150mm sound about right? Does it make a significant difference? My wife's bike
    is a Dawes Special Edition 26" wheel mountain bike, but has slick tyres and seldom goes offroad.

    --
    Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny ) Recumbent cycle page:
    http://www.speedy5.freeserve.co.uk/recumbents/ "He who dares not offend cannot be honest." -
    Thomas Paine
     
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  2. On Tue, 03 Jun 2003 17:43:39 -0400, Danny Colyer wrote:

    > Are there any short people out there who've experimented with different crank lengths?
    >
    > My wife is 5' with a 27" inside leg. She's currently using the 170mm cranks that the bike came
    > with, but I reckon she'd be better off with 150mm cranks (if I can find some).

    165 are pretty common, sure to be better than 170 for stubby legs. TA cranks come in vast
    array of sizes.

    >
    > I haven't yet determined whether I can replace the right crank without also replacing the
    > chainring.

    why not? rings separate on all but cheapest junk cranks. need to make sure bolt circle diameter the
    same. or just go buy new, forget cost.

    Either way wifey isn't convinced that it
    > will be worth the cost, particularly given that she only rides about 100 miles/year. However, we
    > intend to improve on that figure significantly this year.

    too long cranks would make it less fun to ride. but best measure is not cost per mile, is about
    health, fun, fitness, adventure, not transportation.
     
  3. Pete Biggs

    Pete Biggs Guest

    Danny Colyer wrote:
    >
    > My wife is 5' with a 27" inside leg. She's currently using the 170mm cranks that the bike came
    > with, but I reckon she'd be better off with 150mm cranks (if I can find some).

    That's a big, big difference. I've not got short legs but I find even 5mm makes a difference (175 v
    170) to pedalling comfort & efficiency. I think it might be wise to try 160mm first.

    ~PB
     
  4. "Danny Colyer" <[email protected]> wrote in message news:[email protected]...
    >
    > I haven't yet determined whether I can replace the right crank without also replacing the
    > chainring.
    >
    >
    Remember that shorter cranks will give her less leverage, so you may be better to replace chainrings
    anyway, to compensate.
     
  5. Sabineuk

    Sabineuk Guest

    "Danny Colyer" [email protected] said:

    >My wife is 5' with a 27" inside leg. She's currently using the 170mm cranks that the bike came
    >with, but I reckon she'd be better off with 150mm cranks (if I can find some).

    St John St Cycles offer their own cranks down to either 140 or 145mm - couldn't spot them on the
    site but they're generally listed in their print ads.

    They've also got some Suntour XR cranks listed in both 152 and 162mm - £29.99 with rings, so not
    exactly bank-breaking.

    150 seems an awfully big drop from 170 though - worth trying say 160mm first, to see how much of a
    difference that makes?

    John
     
  6. Dave Kahn

    Dave Kahn Guest

    "Danny Colyer" <[email protected]> wrote in message news:<[email protected]>...
    > Are there any short people out there who've experimented with different crank lengths?
    >
    > My wife is 5' with a 27" inside leg. She's currently using the 170mm cranks that the bike came
    > with, but I reckon she'd be better off with 150mm cranks (if I can find some).

    Any difference in leverage caused by crank length variation can be compensated for by gearing, so it
    seems perfectly reasonable that the ideal crank length will be mainly a function of the rider's leg
    length. Shorten the cranks and you may have to gear down slightly to maintain the same speed for the
    same effort on the same bit of road. This means spinning a bit faster, but this is just what the
    smaller pedal circle promotes.

    There are a couple of sites that explore the crank length issue in some detail.
    http://www.cranklength.info/ is by Andrew Bradley. http://www.nettally.com/palmk/Crankset.html by
    Kirby Palm is rather eclectic, also explaining why men should pee sitting down, how to build a
    high-rise apartment for pond fish, and an improved version of badminton.

    Sheldon also goes into this issue on his site and even gives an improved scheme for calculating gear
    sizes that takes crank length into account. Of course as every 10th word is a link you will be
    forced into spending several hours reading about Sturmey Archer gears or some other topic you had no
    idea you were so interested in.

    Changing the crank length will also mean adjusting the saddle height, which might mean an adjustment
    in handlebar height is also required to get the ideal position. Increasing the crank length would
    reduce the pedal clearance for cornering which is something tall people need to be aware of.

    --
    Dave...
     
  7. Dave Kahn

    Dave Kahn Guest

    "Martin Bulmer" <[email protected]> wrote in message
    news:<[email protected]>...

    > Remember that shorter cranks will give her less leverage, so you may be better to replace
    > chainrings anyway, to compensate.

    They effectively increase the gearing right across the range. But she's hardly likely to run out of
    low gears on the bike she has.

    --
    Dave...
     
  8. Danny Colyer

    Danny Colyer Guest

    Dave Kahn wrote:
    > They effectively increase the gearing right across the range. But she's hardly likely to run out
    > of low gears on the bike she has.

    Quite - the bike's undergeared anyway, to the extent that on the flat she tends to ride on the big
    ring and the 5th sprocket of 7 (42/15, roughly a 70" gear).

    I'm aware of all the issues raised so far (but thanks for mentioning them). You don't spend long
    doing Muni or riding a Coker without learning a little about crank length and effective gearing, and
    I've spent enough time tinkering with riding positions on both our bikes to know what adjustments
    are likely to be needed.

    I think the biggest concern I have about fitting shorter cranks is that if I then put the saddle up
    it'll become harder for Catherine to reach the floor. I shall take a closer look at her current
    riding position with regards to that before I try shorter cranks.

    The suggestion to try 160mm cranks first seems reasonable (Richard Ballantine suggests 165mm for
    anyone with an inside leg of 29" or less, but I preferred the formula I found of leg length in
    inches * 5.48 to find something that might allow her to spin comfortably at a decent cadence).

    And thanks to those who mentioned SJSC, as well. I hadn't spotted anything less than 165mm when I
    looked a couple of days ago, but if I know they do them then I can phone up and ask (after I've
    asked at a couple of LBS').

    From the RHS it looks as though I should be able to separate the right crank and the chainring with
    no problem, but I'll know for sure when I get round to lifting the bike off the wall, removing the
    chainring and cleaning it up a bit! Which, come to think of it, I could probably do this evening.
    (Bugger, maybe I won't, as it turns out that the retaining bolt is absurdly tight and my 10" wrench
    doesn't provide enough leverage to shift it. Time for a squirt of GT85, methinks).

    --
    Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny ) Recumbent cycle page:
    http://www.speedy5.freeserve.co.uk/recumbents/ "He who dares not offend cannot be honest." -
    Thomas Paine
     
  9. Peter

    Peter Guest

    "Danny Colyer" <[email protected]> wrote in message news:[email protected]...
    > Are there any short people out there who've experimented with different crank lengths?
    cut: Elderly overweight with an inside leg of 28" I occasionally get twinges in the knees when
    riding (for me) long distances or after riding several days in succession. Normally use "standard"
    170 long cranks that come with most bikes, but when fitting larger rings to a bike I increased the
    crank length to 175 for the mechanical advantage longer cranks would give. Sharp increase in
    occasions of and severity of pain, so did some research on the net that suggested 165 cranks might
    suit me better. This is correct, pain now rarely happens and rather than a loss of power there seems
    to be an increase in my ability to (slowly) grind up hills. peter
     
  10. Tim Woodall

    Tim Woodall Guest

    On Wed, 4 Jun 2003 21:17:24 +0000 (UTC), peter <[email protected]> wrote:
    >
    > "Danny Colyer" <[email protected]> wrote in message news:[email protected]...
    >> Are there any short people out there who've experimented with different crank lengths?
    > cut: Elderly overweight with an inside leg of 28" I occasionally get twinges in the knees when
    > riding (for me) long distances or after riding several days in succession. Normally use "standard"
    > 170 long cranks that come with most bikes, but when fitting larger rings to a bike I increased the
    > crank length to 175 for the mechanical advantage longer cranks would give. Sharp increase in
    > occasions of and severity of pain, so did some research on the net that suggested 165 cranks might
    > suit me better. This is correct, pain now rarely happens and rather than a loss of power there
    > seems to be an increase in my ability to (slowly) grind up hills. peter
    >

    Does anyone know where you might be able to "hire" cranks to try with. I've got an inside leg of
    just over 29" which most websearches seem to imply would want a 165 crank.

    In order to maintain the same speeds at the same cadence I would have to push harder. I'm limiting
    my speeds because of the odd twinge in my knees and can't comfortably spin any faster on the
    windcheetah. Do shorter cranks make it easier to spin a bit faster? Or mean that people with short
    legs can push a bit harder without straining their knees? Or does it all depend on the person?
    Hence why I would like to have a month to try shorter cranks. OTOH, it's only 70GBP to hopefully
    limit the effects of arthritis in old age. Why do I find it impossible to limit my effort when
    riding on my own? :)

    Regards,

    Tim.

    --
    God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.

    http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/
     
  11. On Wed, 04 Jun 2003 16:23:06 -0400, Danny Colyer wrote:

    > I think the biggest concern I have about fitting shorter cranks is that if I then put the saddle
    > up it'll become harder for Catherine to reach the floor.

    when you dismount you step down and magically one's foot teaches the pavement. surely you don't
    expect to keep one's arse on saddle and touch pavement??
     
  12. Dave Kahn

    Dave Kahn Guest

    Tim Woodall <[email protected]> wrote in message
    news:<[email protected]>...

    > In order to maintain the same speeds at the same cadence I would have to push harder.

    The idea is to maintain the same speed and effort but spin a bit faster.

    > I'm limiting my speeds because of the odd twinge in my knees and can't comfortably spin any faster
    > on the windcheetah. Do shorter cranks make it easier to spin a bit faster?

    Yes.

    > Or mean that people with short legs can push a bit harder without straining their knees?

    Possibly. At any rate shorter cranks will reduce the amount by which your knees have to flex with
    every pedal stroke.

    > Or does it all depend on the person?

    To some extent, almost certainly.

    > Hence why I would like to have a month to try shorter cranks. OTOH, it's only 70GBP to hopefully
    > limit the effects of arthritis in old age.

    If you don't get on with them you should be able to get some of your money back selling them on
    eBay. If you do like them you may still be able to get some of your money back by selling the
    original ones on eBay.

    > Why do I find it impossible to limit my effort when riding on my own? :)

    Because you are a cyclist.

    --
    Dave...
     
  13. Danny Colyer

    Danny Colyer Guest

    peter wrote:
    > so did some research on the net that suggested 165 cranks might suit me better. This is correct,
    > pain now rarely happens and rather than a loss of power there seems to be an increase in my
    > ability to (slowly) grind up hills.

    Thanks Peter. I think I might try a set of 160's, then go up or down from there depending
    how it goes.

    --
    Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny ) Recumbent cycle page:
    http://www.speedy5.freeserve.co.uk/recumbents/ "He who dares not offend cannot be honest." -
    Thomas Paine
     
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