crank length

Discussion in 'Cycling Equipment' started by Joe, Feb 17, 2003.

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  1. Joe

    Joe Guest

    would I notice a difference between a 170mm crank and a 172.5, I have never been able to pedal any
    distance using a 172.5 & 53t x 12, 13 t gearing. Would a 170 enable me to spin more? Thanks
     
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  2. In article <[email protected]>, Joe <[email protected]> wrote:
    >would I notice a difference between a 170mm crank and a 172.5,

    Nope.

    > I have never been able to pedal any distance using a 172.5 & 53t x 12, 13 t gearing.

    What do you mean, would a shorter crank let you spin a 53x12 or 53x13 gear faster? I think I don't
    understand the question.

    > Would a 170 enable me to spin more?

    It would have a negligible effect on your spinning.

    Bad bike fit and bad saddles can certainly hurt your spin. The rest is basically all practice. Many
    people benefit from using a cadence computer for a while.

    --Paul
     
  3. Mike S.

    Mike S. Guest

    "Paul Southworth" <[email protected]> wrote in message
    news:mKh4a.32670$A%[email protected]...
    > In article <[email protected]>, Joe <[email protected]> wrote:
    > >would I notice a difference between a 170mm crank and a 172.5,
    >
    > Nope.

    MS: I'm going to disagree with this one. I can tell, but then I've been riding for a while and I
    notice things like that. I switch between 165 and 170 cranks between my road and track bikes,
    and can tell which I'm on immediately! Switching between the road and mtn (170 to 175) is
    another big difference in feel. When I'm riding my mtn bike, it almost feels like my old
    Rockhopper with the Biopace chainrings used to.

    Try them both. Decide which works for you and your style of riding. If you're a masher, the longer
    cranks are going to help. If you spin like Lance, then the shorter cranks are going to help. You can
    usually find used cranksets on rec.bicycles.marketplace, or www.roadbikereview.com, or (gasp!) ebay.
    Racing track, I tend to spin more, so I ride shorter cranks.
    >
    > > I have never been able to pedal any distance using a 172.5 & 53t x 12, 13 t gearing.
    >
    MT: Those gears are for when you're really going all out. Downhill or in a sprint is primarily when
    you ride the bigger gears. If your legs aren't spinning 70-100 rpm, you're in too big a gear.
    Going uphill is an exception. Most of the time, you'll find yourself in the larger sized cogs
    on your cassette. This is not a bad thing. Just 'cause the gears are there doesn't mean you
    HAVE to use them.

    > What do you mean, would a shorter crank let you spin a 53x12 or 53x13 gear faster? I think I don't
    > understand the question.
    >
    > > Would a 170 enable me to spin more?
    >
    > It would have a negligible effect on your spinning.

    MU: I'm going to disagree on this one too. It isn't as big an issue as between 170 and 175, but
    you're going to turn your legs over a little slower with the longer cranks.
    >
    > Bad bike fit and bad saddles can certainly hurt your spin. The rest is basically all practice.
    > Many people benefit from using a cadence computer for a while.
    >
    MV: Just to prove that I'm not categorically disagreeing, I do agree with this last point.

    > --Paul
     
  4. Peter Cole

    Peter Cole Guest

    "Joe" <[email protected]> wrote in message news:[email protected]...
    > would I notice a difference between a 170mm crank and a 172.5, I have never been able to pedal any
    > distance using a 172.5 & 53t x 12, 13 t gearing. Would a 170 enable me to spin more?

    No, that's an insignificant difference.
     
  5. Wayne T

    Wayne T Guest

    I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My crank size is a 170. Been riding
    with it for 30 years. Builder thinks I should go to a 175 since I am getting a new crank. What
    exactly would this do for
    me. Would it improve pedal efficiency? Also, would it be harder on the knees?

    "Peter Cole" <[email protected]> wrote in message
    news:[email protected]...
    > "Joe" <[email protected]> wrote in message news:[email protected]...
    > > would I notice a difference between a 170mm crank and a 172.5, I have never been able to pedal
    > > any distance using a 172.5 & 53t x 12, 13 t gearing. Would a 170 enable me to spin more?
    >
    > No, that's an insignificant difference.
     
  6. In article <[email protected]>, Mike S. <[email protected]> wrote:
    >
    >> >would I notice a difference between a 170mm crank and a 172.5,
    >>
    >> Nope.
    >
    >MS: I'm going to disagree with this one. I can tell, but then I've been riding for a while and I
    > notice things like that. I switch between 165 and 170 cranks between my road and track bikes,
    > and can tell which I'm on immediately! Switching between the road and mtn (170 to 175) is
    > another big difference in feel. When I'm riding my mtn bike, it almost feels like my old
    > Rockhopper with the Biopace chainrings used to.

    I think if you did a blind test you would not reliably tell a 172.5 from a 170 if you put them on
    the same bike and did not know which ones were in use. If one arm was a 170 and the other a 172.5 I
    think you would not identify that either in a blind test. Wrong length crank arms have been put on
    experienced (ie, pro) riders' bikes without their realizing it. Perhaps part of that effect is the
    fact that they didn't expect it and therefore didn't consider it. (?)

    I too have been riding for a while (not as long as many here) and my experience is that 2.5mm of
    crank arm difference is nothing to
    me.

    --Paul
     
  7. On Tue, 18 Feb 2003 16:12:07 -0500, Paul Southworth wrote:

    >>MS: I'm going to disagree with this one. I can tell, but then I've been riding for a while and I
    >> notice things like that. I switch between 165 and 170 cranks between my road and track bikes,
    >> and can tell which I'm on immediately! Switching between the road and mtn (170 to 175) is
    >> another big difference in feel.

    Sure, you can tell the difference between track, road, and mountain, but I think you ascribe too
    much of that to crank length.

    > I too have been riding for a while (not as long as many here) and my experience is that 2.5mm of
    > crank arm difference is nothing to me.

    I recently changed cranksets on my track bike, going up to 175. I found a color that matched my
    frame and had to try 'em. Can't feel any difference, and my bb is probably high enough to keep me
    out of trouble as long as I stay away from indoor tracks.

    --

    David L. Johnson

    __o | Enron's slogan: Respect, Communication, Integrity, and _`\(,_ | Excellence. (_)/ (_) |
     
  8. Peter Cole

    Peter Cole Guest

    "Wayne T" <[email protected]> wrote in message
    news:[email protected]...
    > I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My crank size is a 170. Been
    > riding with it for 30 years. Builder thinks I should go to a 175 since I am getting a new crank.
    > What exactly would this do for
    > me. Would it improve pedal efficiency? Also, would it be harder on the knees?

    I'm 6'10", with a 38" (pant) inseam. I have bikes with both 170 & 175 mm cranks. I can't tell the
    difference.
     
  9. I'm 6'2" and rode a 1973 PX10 with 170 mm cranks for 28 years. Last year I sold it and bought a Fuji
    Team with 175 mm cranks and a more slack seat tube angle.

    The difference is very noticeable. My new setup is more comfortable and a recurring pulled
    muscle/tendon in my right back/hip progressively disappeared.

    "David L. Johnson >" <David L. Johnson <[email protected]> wrote in message
    news:[email protected]...
    > On Tue, 18 Feb 2003 16:12:07 -0500, Paul Southworth wrote:
    >
    > >>MS: I'm going to disagree with this one. I can tell, but then I've been riding for a while and I
    > >> notice things like that. I switch between 165 and 170 cranks between my road and track
    > >> bikes, and can tell which I'm on immediately! Switching between the road and mtn (170 to
    > >> 175) is another big difference in feel.
    >
    > Sure, you can tell the difference between track, road, and mountain, but I think you ascribe too
    > much of that to crank length.
    >
    > > I too have been riding for a while (not as long as many here) and my experience is that 2.5mm of
    > > crank arm difference is nothing to me.
    >
    > I recently changed cranksets on my track bike, going up to 175. I found a color that matched my
    > frame and had to try 'em. Can't feel any difference, and my bb is probably high enough to keep me
    > out of trouble as long as I stay away from indoor tracks.
    >
    > --
    >
    > David L. Johnson
    >
    > __o | Enron's slogan: Respect, Communication, Integrity, and _`\(,_ | Excellence. (_)/ (_) |
     
  10. Robin Hubert

    Robin Hubert Guest

    "Peter Cole" <[email protected]> wrote in message
    news:[email protected]...
    > "Wayne T" <[email protected]> wrote in message
    > news:[email protected]...
    > > I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My
    crank
    > > size is a 170. Been riding with it for 30 years. Builder thinks I
    should
    > > go to a 175 since I am getting a new crank. What exactly would this do
    for
    > > me. Would it improve pedal efficiency? Also, would it be harder on the knees?
    >
    > I'm 6'10", with a 38" (pant) inseam. I have bikes with both 170 & 175 mm cranks. I can't tell the
    > difference.

    Most people can't, unless they know beforehand.

    Robin Hubert
     
  11. x

    x Guest

    RE/
    >I'm 6'10", with a 38" (pant) inseam. I have bikes with

    Do you buy off-the-shelf or custom?
    -----------------------
    PeteCresswell
     
  12. Peter Cole

    Peter Cole Guest

    "(Pete Cresswell)" <[email protected]> wrote in message news:[email protected]...
    > RE/
    > >I'm 6'10", with a 38" (pant) inseam. I have bikes with
    >
    > Do you buy off-the-shelf or custom?

    Bikes or pants?

    Actually, I asked around a bit about custom frames. One very well known (and regarded) east coast
    builder said he could make me a big enough frame, but couldn't promise I'd be happy with it. He said
    he just didn't do enough work with large frames. I spoke with a couple of guys nearly my size who
    had custom bikes, both admitted they found the frames a little flexy. I looked at Leonard Zinn's
    tall-specific frames and those of another couple of builders who specialized in over-size frames and
    wasn't much impressed.

    I wound up buying a Cannondale touring frame (68 cm) and building that up. I don't think that custom
    frames can compare with that bike. It's very light (for its size), very stiff, has a longer
    wheelbase, generous frame and brake (canti) clearances, and was an incredible bargain at 1/3 the
    cost of the cheapest customs. I don't think small builders with stock tube sets can offer as good a
    solution to very large riders. All that said, I have a couple of 68 cm steel frames that date back
    to the 70-80's when big frames were in fashion. They're not bad, I just wouldn't want to pay a lot
    of money for the same technology in a custom frame.

    I sometimes buy my pants custom, though. The technology seems the same.
     
  13. Bluto

    Bluto Guest

    "Peter Cole" <[email protected]> wrote:

    > I'm 6'10", with a 38" (pant) inseam. I have bikes with both 170 & 175 mm cranks. I can't tell the
    > difference.

    Have you ever tried long cranks? I have gotten very good results from 196mm Bullseye cranks. I
    believe that such long cranks helped me get higher power output with less perceived effort (when
    that sort of thing was important to me). The bike I'm building now has 205mm cranks.

    The larger radius of motion dictated by long cranks makes me feel like I can pedal with a more
    natural stroke and rhythm. I reckon what feels better is also probably faster and more efficient,
    though this is speculative.

    Since I am no taller than you (I have a 103cm standing inseam), I would not be at all surprised if
    you could benefit from longer cranks too.

    I suppose if you are comfortable with readily available sizes, then the hassle of getting custom
    length cranks would be a disincentive. Most of my bikes sport 185 or 190mm cranks for reasons of
    availability and limited BB height.

    (Some BMX 3-pc cranks are regularly available in 185 and 190mm lengths, and I would be using such
    cranks anyway since I break square-taper spindles.)

    Chalo Colina
     
  14. Wayne T

    Wayne T Guest

    "Peter Cole" <[email protected]> wrote in message
    news:[email protected]...
    > "Wayne T" <[email protected]> wrote in message
    > news:[email protected]...
    > > I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My
    crank
    > > size is a 170. Been riding with it for 30 years. Builder thinks I
    should
    > > go to a 175 since I am getting a new crank. What exactly would this do
    for
    > > me. Would it improve pedal efficiency? Also, would it be harder on the knees?
    >
    > I'm 6'10", with a 38" (pant) inseam. I have bikes with both 170 & 175 mm cranks. I can't tell the
    > difference.

    Thanks. That is very helpful. In that case i will stick with a 170 since it gives more pedal
    clearance when turning corners or going around sharp curves. Allso, I just pulled out a ruler with
    MM on it and I find that 5 mm is very small. It appears that you might be able to detect a
    difference if you went from a 170mm to 180mm.
     
  15. Wayne T

    Wayne T Guest

    "Donald Specker" <[email protected]> wrote in message
    news:[email protected]...
    > I'm 6'2" and rode a 1973 PX10 with 170 mm cranks for 28 years. Last year
    I
    > sold it and bought a Fuji Team with 175 mm cranks and a more slack seat
    tube
    > angle.
    >
    > The difference is very noticeable. My new setup is more comfortable and a recurring pulled
    > muscle/tendon in my right back/hip progressively disappeared.

    After looking at a ruler and seeing how minute the difference between a 170 and 175mm crank, I
    can't help wondering if the increased comfort is due more to the more relaxed seat angle. In fact,
    I believe that the more relaxed seat angle on touring bikes is designed to give more comfort for
    long rides.

    >
    > "David L. Johnson >" <David L. Johnson <[email protected]> wrote in message
    > news:[email protected]...
    > > On Tue, 18 Feb 2003 16:12:07 -0500, Paul Southworth wrote:
    > >
    > > >>MS: I'm going to disagree with this one. I can tell, but then I've
    been
    > > >>riding for a while and I notice things like that. I switch between
    165
    > > >>and 170 cranks between my road and track bikes, and can tell which I'm on immediately!
    > > >>Switching between the road and mtn (170 to 175) is another big difference in feel.
    > >
    > > Sure, you can tell the difference between track, road, and mountain, but I think you ascribe too
    > > much of that to crank length.
    > >
    > > > I too have been riding for a while (not as long as many here) and my experience is that 2.5mm
    > > > of crank arm difference is nothing to me.
    > >
    > > I recently changed cranksets on my track bike, going up to 175. I found a color that matched my
    > > frame and had to try 'em. Can't feel any difference, and my bb is probably high enough to keep
    > > me out of trouble as long as I stay away from indoor tracks.
    > >
    > > --
    > >
    > > David L. Johnson
    > >
    > > __o | Enron's slogan: Respect, Communication, Integrity, and _`\(,_ | Excellence. (_)/ (_) |
     
  16. Peter Cole

    Peter Cole Guest

    "Bluto" <[email protected]> wrote in message
    news:[email protected]...
    > "Peter Cole" <[email protected]> wrote:
    >
    > > I'm 6'10", with a 38" (pant) inseam. I have bikes with both 170 & 175 mm cranks. I can't tell
    > > the difference.
    >
    > Have you ever tried long cranks? I have gotten very good results from 196mm Bullseye cranks. I
    > believe that such long cranks helped me get higher power output with less perceived effort (when
    > that sort of thing was important to me). The bike I'm building now has 205mm cranks.
    >
    > The larger radius of motion dictated by long cranks makes me feel like I can pedal with a more
    > natural stroke and rhythm. I reckon what feels better is also probably faster and more efficient,
    > though this is speculative.
    >
    > Since I am no taller than you (I have a 103cm standing inseam), I would not be at all surprised if
    > you could benefit from longer cranks too.
    >
    > I suppose if you are comfortable with readily available sizes, then the hassle of getting custom
    > length cranks would be a disincentive. Most of my bikes sport 185 or 190mm cranks for reasons of
    > availability and limited BB height.
    >
    > (Some BMX 3-pc cranks are regularly available in 185 and 190mm lengths, and I would be using such
    > cranks anyway since I break square-taper spindles.)

    I suppose I'd be interested in trying significantly longer cranks if they were readily available. I
    know you also have a Cannondale touring frame (my primary bike), which has a low-ish BB to start
    with, that is a bit of a problem. My other main bike is a fixed gear, where long cranks would be
    even more problematic. As things are now, when I'm in the drops the tops of my thighs hit the bottom
    of my ribs at the top of my stroke. I'm not sure I could use a significantly longer crank without
    bashing myself in the chest (twice) every revolution. Given the spotty reliability of cranks, I'm
    also a little concerned that significantly longer cranks might be more failure prone. Anyway, thanks
    for the info, it's another data point.
     
  17. On Wed, 19 Feb 2003 09:22:45 -0500, Donald Specker wrote:

    > I'm 6'2" and rode a 1973 PX10 with 170 mm cranks for 28 years. Last year I sold it and bought a
    > Fuji Team with 175 mm cranks and a more slack seat tube angle.
    >
    > The difference is very noticeable. My new setup is more comfortable and a recurring pulled
    > muscle/tendon in my right back/hip progressively disappeared.

    So, you replaced a mid-to-lower quality 30-year-old French frame, classic though it may have been,
    with a new bike with different angles, new components, new saddle, different frame material --- and
    you ascribe your more comfortable riding to a 5mm difference in crank length? OK.

    --

    David L. Johnson

    __o | When you are up to your ass in alligators, it's hard to remember _`\(,_ | that your initial
    objective was to drain the swamp. -- LBJ (_)/ (_) |
     
  18. Wayne T wrote:
    > I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My crank size is a 170. Been
    > riding with it for 30 years. Builder thinks I should go to a 175 since I am getting a new crank.
    > What exactly would this do for
    > me.

    Proably not a lot. There are those that disagree:

    http://www.nettally.com/palmk/crankset.html

    Judge for yourself. Personally, if I used that guy's formula, I'd be using a 197mm crank (36"
    inseam), which is somewhat difficult to come by. I might need a new frame for that in order to
    maintain ground clearance (it would put my pedals almost an inch closer to the ground which could be
    a problem when pedaling through turns). Right now, I'm sticking with my 175.

    > Would it improve pedal efficiency?

    It will give you very slightly better leverage actually (slightly longer lever). It will reduce your
    gain ratio a bit (effectively lowering your gears slightly) and allow you produce slightly more
    torque with the same amount of effort, which may help you up the hills a little. It's probably not
    enough to be all that significant though.

    > Also, would it be harder on the knees?

    Probably not. They will have a slightly larger amount of movement to account for the bigger pedaling
    circle but we're not talking about a lot here and since you're getting better leverage, it will
    likely be slightly easier on your knees. By the time you get to the power part of your stroke, you
    knee will actually be slightly straighter than with a shorter crank, which should be a good thing.

    --Bill Davidson
    --
    Please remove ".nospam" from my address for email replies.
     
  19. Woody Turgid

    Woody Turgid Guest

    I've actually gone the other way, from 175s to 170s. I did it for knee pain. The 5mm difference is
    none on the knee extension, since saddle height is measured from an extended crank. But there is 5
    times 2, or 10 mm of difference in flexion, since the saddle with a 175 is lower, and yet the other
    crank comes up 5 mm higher.

    Going from a 170 to a 175 gives a longer lever, which means more torque, which has a similar effect
    of adding two teeth to each cog in the rear.

    "Bill Davidson" <[email protected]> wrote in message news:[email protected]...
    > Wayne T wrote:
    > > I am 6'4" with a 34" inseam. I ride a 25 1/2" touring road bike. My
    crank
    > > size is a 170. Been riding with it for 30 years. Builder thinks I
    should
    > > go to a 175 since I am getting a new crank. What exactly would this do
    for
    > > me.
    >
    > Proably not a lot. There are those that disagree:
    >
    > http://www.nettally.com/palmk/crankset.html
    >
    > Judge for yourself. Personally, if I used that guy's formula, I'd be
    using
    > a 197mm crank (36" inseam), which is somewhat difficult to come by. I might need a new frame for
    > that in order to maintain ground clearance (it would put my pedals almost an inch closer to the
    > ground which could be a problem when pedaling through turns). Right now, I'm sticking with my
    175.
    >
    > > Would it improve pedal efficiency?
    >
    > It will give you very slightly better leverage actually (slightly longer lever). It will reduce
    > your gain ratio a bit (effectively lowering your gears slightly) and allow you produce slightly
    > more torque with the same amount of effort, which may help you up the hills a little. It's
    > probably not enough to be all that significant though.
    >
    > > Also, would it be harder on the knees?
    >
    > Probably not. They will have a slightly larger amount of movement to account for the bigger
    > pedaling circle but we're not talking about a lot here and since you're getting better leverage,
    > it will likely be slightly easier on your knees. By the time you get to the power part of your
    > stroke, you knee will actually be slightly straighter than with a shorter crank, which should be a
    > good thing.
    >
    > --Bill Davidson
    > --
    > Please remove ".nospam" from my address for email replies.

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  20. Peter Cole

    Peter Cole Guest

    "Woody Turgid" <[email protected]> wrote in message news:[email protected]...

    >
    > Going from a 170 to a 175 gives a longer lever, which means more torque, which has a similar
    > effect of adding two teeth to each cog in the rear.

    More like half a tooth, I think.
     
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