are my femurs short?

Discussion in 'Cycling Equipment' started by Kbh, May 1, 2003.

Thread Status:
Not open for further replies.
  1. Kbh

    Kbh Guest

    This is a continuation of my riding posture thread from below:

    Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was about 1.5"
    - 2" behind KOPS. My bike has a 73 degree seat tube angle, and I'm using a seatpost with no setback
    and the saddle rails in the middle. My saddle height is 79 which results in a setback of
    23.1 cm. Only by putting the saddle almost as far forward as it can go on the rails can I get near
    KOPS. I'm going to try this for a while. I can't fathom the need for a saddle with setback, or a
    bike with a shallower seat tube angle.

    Is this setup unusual? Short femurs?
     
    Tags:


  2. Jim Edgar

    Jim Edgar Guest

    KBH at [email protected] wrote on 5/1/03 1:14 PM:

    > This is a continuation of my riding posture thread from below:
    >
    > Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was about
    > 1.5" - 2" behind KOPS. My bike has a 73 degree seat tube angle, and I'm using a seatpost with no
    > setback and the saddle rails in the middle. My saddle height is 79 which results in a setback of
    > 23.1 cm. Only by putting the saddle almost as far forward as it can go on the rails can I get near
    > KOPS. I'm going to try this for a while. I can't fathom the need for a saddle with setback, or
    > a bike with a shallower seat tube angle.
    >
    > Is this setup unusual? Short femurs?

    Before you follow that too far, read Keith Bontrager's article on the "Myth of KOPS" -

    (of course, there's a version on sheldon's site) http://www.sheldonbrown.com/kops.html
     
  3. Kbh

    Kbh Guest

    I realize that KOPS is nothing but a reference point, and I was only referring to it as such. My
    desire to try KOPS actually has to do with back problems, and general experimentation with bike fit.
    It just seems odd to me that I can only get to this common rider position with a 73 degree seat
    tube, saddle forward on rails , and no seatpost setback.

    "Jim Edgar" <[email protected]> wrote in message news:BAD6D621.3FFE4%[email protected]...
    > KBH at [email protected] wrote on 5/1/03 1:14 PM:
    >
    > > This is a continuation of my riding posture thread from below:
    > >
    > > Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was about
    > > 1.5" - 2" behind KOPS. My bike has a 73
    degree
    > > seat tube angle, and I'm using a seatpost with no setback and the saddle rails in the middle. My
    > > saddle height is 79 which results in a setback
    of
    > > 23.1 cm. Only by putting the saddle almost as far forward as it can go
    on
    > > the rails can I get near KOPS. I'm going to try this for a while. I
    can't
    > > fathom the need for a saddle with setback, or a bike with a shallower
    seat
    > > tube angle.
    > >
    > > Is this setup unusual? Short femurs?
    >
    > Before you follow that too far, read Keith Bontrager's article on the
    "Myth
    > of KOPS" -
    >
    > (of course, there's a version on sheldon's site) http://www.sheldonbrown.com/kops.html
     
  4. Mike S.

    Mike S. Guest

    "Jim Edgar" <[email protected]> wrote in message news:BAD6D621.3FFE4%[email protected]...
    > KBH at [email protected] wrote on 5/1/03 1:14 PM:
    >
    > > This is a continuation of my riding posture thread from below:
    > >
    > > Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was about
    > > 1.5" - 2" behind KOPS. My bike has a 73
    degree
    > > seat tube angle, and I'm using a seatpost with no setback and the saddle rails in the middle. My
    > > saddle height is 79 which results in a setback
    of
    > > 23.1 cm. Only by putting the saddle almost as far forward as it can go
    on
    > > the rails can I get near KOPS. I'm going to try this for a while. I
    can't
    > > fathom the need for a saddle with setback, or a bike with a shallower
    seat
    > > tube angle.
    > >
    > > Is this setup unusual? Short femurs?
    >
    > Before you follow that too far, read Keith Bontrager's article on the
    "Myth
    > of KOPS" -
    >
    > (of course, there's a version on sheldon's site) http://www.sheldonbrown.com/kops.html
    >

    KOPS is a guideline, but too far off either way and you run into biomechanical issues with the pedal
    stroke. Too far back and you don't use the hamstrings as much, too far forward and you loose some of
    the butt muscles effectiveness.

    Have you ever had anyone fit you to your bike? I see lots and lots of people that are riding bikes
    that "fit" according to them, but when really fit gain several miles per hour with no additional
    effort. I would recommend that you start there.

    "Self-fitting" properly is almost impossible. You can't really look at yourself without moving out
    of the proper riding position. (unless you're using a video camera and playing back the tape later)

    Without seeing you riding, its hard for us on the 'net to diagnose your fit. We're just taking stabs
    in the dark. Go have a fit done, let a local expert help you determine your optimal position.

    Mike
     
  5. Kbh

    Kbh Guest

    I hear ya about the fitting (speaking to the many r.b.t er's recommending the same), but I'm of the
    opinion that individual's bodies (or maybe just mine) are too unique to really benefit from a single
    session. A fitting makes sense for the non-techie bicycle buyer, but I'm a geek and I'm fully
    capable of adjusting the three human/bicycle interface points and then seeing how my body responds.
    Unless the fitter wants to see me once a week for the next 3 months, its just not worth it.

    "Mike S." <[email protected]> wrote in message news:[email protected]...
    >
    > "Jim Edgar" <[email protected]> wrote in message
    > news:BAD6D621.3FFE4%[email protected]...
    > > KBH at [email protected] wrote on 5/1/03 1:14 PM:
    > >
    > > > This is a continuation of my riding posture thread from below:
    > > >
    > > > Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was
    > > > about 1.5" - 2" behind KOPS. My bike has a 73
    > degree
    > > > seat tube angle, and I'm using a seatpost with no setback and the
    saddle
    > > > rails in the middle. My saddle height is 79 which results in a setback
    > of
    > > > 23.1 cm. Only by putting the saddle almost as far forward as it can go
    > on
    > > > the rails can I get near KOPS. I'm going to try this for a while. I
    > can't
    > > > fathom the need for a saddle with setback, or a bike with a shallower
    > seat
    > > > tube angle.
    > > >
    > > > Is this setup unusual? Short femurs?
    > >
    > > Before you follow that too far, read Keith Bontrager's article on the
    > "Myth
    > > of KOPS" -
    > >
    > > (of course, there's a version on sheldon's site) http://www.sheldonbrown.com/kops.html
    > >
    >
    > KOPS is a guideline, but too far off either way and you run into biomechanical issues with the
    > pedal stroke. Too far back and you don't use the hamstrings as much, too far forward and you loose
    > some of the butt muscles effectiveness.
    >
    > Have you ever had anyone fit you to your bike? I see lots and lots of people that are riding bikes
    > that "fit" according to them, but when really fit gain several miles per hour with no additional
    > effort. I would recommend that you start there.
    >
    > "Self-fitting" properly is almost impossible. You can't really look at yourself without moving
    > out of the proper riding position. (unless you're using a video camera and playing back the
    > tape later)
    >
    > Without seeing you riding, its hard for us on the 'net to diagnose your
    fit.
    > We're just taking stabs in the dark. Go have a fit done, let a local
    expert
    > help you determine your optimal position.
    >
    > Mike
     
  6. Jim Edgar

    Jim Edgar Guest

    KBH at [email protected] wrote on 5/1/03 2:28 PM:

    > I hear ya about the fitting (speaking to the many r.b.t er's recommending the same), but I'm of
    > the opinion that individual's bodies (or maybe just mine) are too unique to really benefit from
    > a single session. A fitting makes sense for the non-techie bicycle buyer, but I'm a geek and I'm
    > fully capable of adjusting the three human/bicycle interface points and then seeing how my body
    > responds. Unless the fitter wants to see me once a week for the next 3 months, its just not
    > worth it.
    >
    >
    A decent fitting session from a qualified person will tell you where you should ultimately position
    yourself - not just where you can go at that moment. The person doing the work should be certified
    or at least have considerable pedigree for proper fitting.

    A knowledgeable fitter should probably give you an indication of how long to take to move to a new
    position, so as not to injure or stress your bits. If you need to move an inch, you probably don't
    want to do that all in one fell swoop, and then go out and ride a century.

    I can't help but think your body will not respond particularly pleasantly to the 1.5 - 2" shift in
    position you describe in your post (below) - you might want to think about moving more gradually to
    that position.

    >>>> KBH at [email protected] wrote on 5/1/03 1:14 PM:
    >>>>
    >>>> This is a continuation of my riding posture thread from below:
    >>>>
    >>>> Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was about
    >>>> 1.5" - 2" behind KOPS. My bike has a 73 degree seat tube angle, and I'm using a seatpost with
    >>>> no setback and the saddle rails in the middle. My saddle height is 79 which results in a
    >>>> setback of
    >>>> 23.1 cm. Only by putting the saddle almost as far forward as it can go on the rails can I get
    >>>> near KOPS. I'm going to try this for a while. I can't fathom the need for a saddle with
    >>>> setback, or a bike with a shallower seat tube angle.
    >>>>
    >>>> Is this setup unusual? Short femurs?
     
  7. x

    x Guest

    RE/
    > I can't fathom the need for a saddle with setback, or a bike with a shallower seat tube angle.
    >
    >Is this setup unusual? Short femurs?

    Maybe it's a combinatin of the bike's dimensions and body proportions.

    I'm on the tall side (6'5") and to get KOPS on my Ellsworth Isis I need a HellBent seatpost (2" of
    additional setback) and my Brooks B-17 set as far back as the rails will allow. And I could *still*
    use another half-inch...

    My shins don't seem proportionally short - if anything, it's the other way around.
    -----------------------
    PeteCresswell
     
  8. Kbh

    Kbh Guest

    > I can't fathom the need for a saddle with setback, or a bike with a
    shallower seat
    > >tube angle.
    > >
    > >Is this setup unusual? Short femurs?
    >
    > Maybe it's a combinatin of the bike's dimensions and body proportions.
    >
    > I'm on the tall side (6'5") and to get KOPS on my Ellsworth Isis I need a HellBent seatpost (2" of
    > additional setback) and my Brooks B-17 set as far
    back
    > as the rails will allow. And I could *still* use another half-inch...
    >
    > My shins don't seem proportionally short - if anything, it's the other way around.

    Wow.

    I thought about that but the ONLY dimensions of the bike, excluding the seatpost/saddle, that
    determine KOPS are seat tube angle, saddle height, and crank length - that's it. So its gotta be the
    upper to lower leg ratio, not the absolute length of the femur.
     
  9. "KBH" <[email protected]> wrote in message news
    > > I'm on the tall side (6'5") and to get KOPS on my Ellsworth Isis I need a HellBent seatpost (2"
    > > of additional setback) and my Brooks B-17 set as far
    > back
    > > as the rails will allow. And I could *still* use another half-inch...
    > >
    > > My shins don't seem proportionally short - if anything, it's the other way around.
    >
    > Wow.
    >
    > I thought about that but the ONLY dimensions of the bike, excluding the seatpost/saddle, that
    > determine KOPS are seat tube angle, saddle height, and crank length - that's it. So its gotta be
    > the upper to lower leg ratio, not the absolute length of the femur.

    But this man is 6'5" so on standard cranks he will need to sit way back to get KOPS.

    Andrew Bradley
     
  10. Kbh

    Kbh Guest

    > > > I'm on the tall side (6'5") and to get KOPS on my Ellsworth Isis I
    need a
    > > > HellBent seatpost (2" of additional setback) and my Brooks B-17 set as
    far
    > > back
    > > > as the rails will allow. And I could *still* use another
    half-inch...
    > > >
    > > > My shins don't seem proportionally short - if anything, it's the other
    way
    > > > around.
    > >
    > > Wow.
    > >
    > > I thought about that but the ONLY dimensions of the bike, excluding the seatpost/saddle, that
    > > determine KOPS are seat tube angle, saddle height,
    and
    > > crank length - that's it. So its gotta be the upper to lower leg ratio,
    not
    > > the absolute length of the femur.
    >
    > But this man is 6'5" so on standard cranks he will need to sit way back to
    get KOPS.
    >

    That argument would only be true if we all rode the same saddle height. Since he is tall, his saddle
    height will be larger, resulting in more "built-in" setback as a result of the seat tube angle.
    Assuming that the relationship between total pubic bone height and saddle height is roughly constant
    (rule of thumb is 0.883 x PBH), then this brings you back to the conclusion that weather you're 5'2"
    or 6'5", it is the ration of upper leg to lower leg that determines KOPS and therefore how much
    seatpost setback you may need and where the saddle may need to be on the rails.
     
  11. kbh-<< Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was
    about 1.5" - 2" behind KOPS. My bike has a 73 degree seat tube angle, and I'm using a seatpost with
    no setback and the saddle rails in the middle.

    Yes, I would say you would benefit from a frameset with a steeper seattube angle.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  12. Kbh

    Kbh Guest

    I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike territory? I
    wouldn't have guessed I was an outlier physically. I would love to see some stats of upper/lower leg
    length for people close to my height - although I don't think my friends would appreciate me
    measuring their legs.

    "Qui si parla Campagnolo" <[email protected]> wrote in message
    news:[email protected]...
    > kbh-<< Put my bike on the trainer to do a self fitting, using my plumb bob
    I
    > verified that I was about 1.5" - 2" behind KOPS. My bike has a 73 degree seat tube angle, and I'm
    > using a seatpost with no setback and the saddle rails in the middle.
    >
    > Yes, I would say you would benefit from a frameset with a steeper seattube angle.
    >
    >
    > Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    > (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  13. FWIW, Competitive Cyclist has added a decent fit calculator to their website. It's based on the
    Guimard/Lemond methodology with some of their own tweaks, and looks to work pretty well. The TT/Stem
    recommendations it gave me pretty much matched the ones from Lennard Zinn's basic fit calculator, as
    well as matching what I've arrived at as best for me over the years. Plus, it does take into account
    femur/tibia ratio and gives a saddle setback recommendation in addition to the usual Seat
    Height/ST/TT/Stem Length output of most fit systems.

    You might give it a try to see what it suggests for you.

    http://www.competitivecyclist.com/

    SB

    "KBH" <[email protected]> wrote in message news:[email protected]...
    > I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike territory?
    > I wouldn't have guessed I was an outlier physically. I would love to see some stats of upper/lower
    > leg length for people close to my height - although I don't think my friends would appreciate me
    > measuring their legs.
    >
    >
    > "Qui si parla Campagnolo" <[email protected]> wrote in message
    > news:[email protected]...
    > > kbh-<< Put my bike on the trainer to do a self fitting, using my plumb
    bob
    > I
    > > verified that I was about 1.5" - 2" behind KOPS. My bike has a 73
    degree
    > > seat tube angle, and I'm using a seatpost with no setback and the saddle rails in the middle.
    > >
    > > Yes, I would say you would benefit from a frameset with a steeper
    seattube
    > > angle.
    > >
    > >
    > > Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    > > (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  14. "Mike S." <[email protected]> wrote:

    > KOPS is a guideline, but too far off either way and you run into biomechanical issues with the
    > pedal stroke. Too far back and you don't use the hamstrings as much, too far forward and you loose
    > some of the butt muscles effectiveness.

    This all sounds familiar, but whats "muscle effectiveness" and where's the data on these
    "biomechanical issues" or explanation of them?

    Records are broken well forward of KOPS, people have won TDF KOM sitting well forward (though they
    may be behind KOPS on hills).

    Forget KOPS as being some kind of true "norm" when inching the saddle forward or back, your upper
    body and the muscles crossing the hip joint won't let you stray too far.

    > "Self-fitting" properly is almost impossible. You can't really look at yourself without moving
    > out of the proper riding position. (unless you're using a video camera and playing back the
    > tape later)

    Eyeballing for fine tuning isn't great either. When i had a 73 degree frame with saddle forward,
    they said "too far forward". On a 75 degree frame no one noticed anything untoward.

    Take away the seat-tube reference point and a rider can look nice over a range of fore aft
    positions.

    Andrew Bradley
     
  15. Kbh

    Kbh Guest

    Thanks! This is exactly the type of reference I was looking for.

    "Steve Blankenship" <[email protected]> wrote in message
    news:[email protected]...
    > FWIW, Competitive Cyclist has added a decent fit calculator to their website. It's based on the
    > Guimard/Lemond methodology with some of their own tweaks, and looks to work pretty well. The
    > TT/Stem recommendations it gave me pretty much matched the ones from Lennard Zinn's basic fit
    > calculator, as well as matching what I've arrived at as best for me over
    the
    > years. Plus, it does take into account femur/tibia ratio and gives a
    saddle
    > setback recommendation in addition to the usual Seat Height/ST/TT/Stem Length output of most fit
    > systems.
    >
    > You might give it a try to see what it suggests for you.
    >
    > http://www.competitivecyclist.com/
    >
    > SB
    >
    >
    > "KBH" <[email protected]> wrote in message news:[email protected]...
    > > I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike
    > > territory? I wouldn't have guessed I was an outlier physically. I would love to see some stats
    > > of upper/lower leg length
    for
    > > people close to my height - although I don't think my friends would appreciate me measuring
    > > their legs.
    > >
    > >
    > > "Qui si parla Campagnolo" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > kbh-<< Put my bike on the trainer to do a self fitting, using my plumb
    > bob
    > > I
    > > > verified that I was about 1.5" - 2" behind KOPS. My bike has a 73
    > degree
    > > > seat tube angle, and I'm using a seatpost with no setback and the
    saddle
    > > > rails in the middle.
    > > >
    > > > Yes, I would say you would benefit from a frameset with a steeper
    > seattube
    > > > angle.
    > > >
    > > >
    > > > Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    > > > (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
    > >
    >
     
  16. Andres Muro

    Andres Muro Guest

    KBH: This has always been a problem for me. I have short femurs, long torso, short arms. The ideal
    body not to do cycling. Good cyclists tend to have longer legs, shorter torso's and long arms. This
    is why you see them riding with small bikes and with the stem all the way down in pictures. They can
    put the seatpost all the way up, they need a smaller bike with a short top tube, and they can easily
    reach the handlebars with their long arms. There is an advantage in aerodynamics and in having
    proportionally more weight in the lower bodies than upper bodies.

    We all want to look like good cyclists, so we buy bikes designed for them, but our bodies do not
    fit. I had to look for a bike that wasn't too tall but had a long top tube, for a long time.
    American bikes are designed this way more than european bikes. While it solved my torso problem, I
    always felt that I was too far back in relation to the pedals. This has been a problem for me when
    ridding for a long time, or when I wanted to get aerodynamic for a long time, as in a triathlon. By
    being too far behind my pedals, I created a very acute angle between my back and my thighs, when my
    leg was on top of the circle. After a while, I would get pain on my lower back. I would have to
    dimount after 40 miles or so, to stretch. I am reasonably flexible and I swim a lot which helps, but
    I would still get a sore back.

    About a year ago I purchased a bike with a steeper seat angle of 76 degrees, a long top tube and
    farily short seat tube. It is perfect. I can ride forever, and my back does not hurt. I set my
    handlebar around the same height as my saddle and I can get pretty aerodynamic. Last year I rode a
    century and stayed on the aerobars for most of the ride. I was too lazy to get up and it felt really
    confortable staying aero. while the bike has similar dimensions of a triathlon bike, for my body
    type it fits well as a rode bike and rides great. Good luck,

    Andres

    "KBH" <[email protected]> wrote in message news:<[email protected]>...
    > I realize that KOPS is nothing but a reference point, and I was only referring to it as such. My
    > desire to try KOPS actually has to do with back problems, and general experimentation with bike
    > fit. It just seems odd to me that I can only get to this common rider position with a 73 degree
    > seat tube, saddle forward on rails , and no seatpost setback.
    >
    >
    >
    > "Jim Edgar" <[email protected]> wrote in message
    > news:BAD6D621.3FFE4%[email protected]...
    > > KBH at [email protected] wrote on 5/1/03 1:14 PM:
    > >
    > > > This is a continuation of my riding posture thread from below:
    > > >
    > > > Put my bike on the trainer to do a self fitting, using my plumb bob I verified that I was
    > > > about 1.5" - 2" behind KOPS. My bike has a 73
    > degree
    > > > seat tube angle, and I'm using a seatpost with no setback and the saddle rails in the middle.
    > > > My saddle height is 79 which results in a setback
    > of
    > > > 23.1 cm. Only by putting the saddle almost as far forward as it can go
    > on
    > > > the rails can I get near KOPS. I'm going to try this for a while. I
    > can't
    > > > fathom the need for a saddle with setback, or a bike with a shallower
    > seat
    > > > tube angle.
    > > >
    > > > Is this setup unusual? Short femurs?
    > >
    > > Before you follow that too far, read Keith Bontrager's article on the
    > "Myth
    > > of KOPS" -
    > >
    > > (of course, there's a version on sheldon's site) http://www.sheldonbrown.com/kops.html
     
  17. Lee Hurd

    Lee Hurd Guest

    "Road Racing Technique and Training" by Bernard Hinault and Claude Genzling ISBN 0-941950-13-1

    Good book with sizing info on what adjustments to try when you don't have average proportions.
    Hopefully it's still in print.

    Don't worry about what angles bikes are supposed to have, if it works good it is good.

    "KBH" <[email protected]> wrote in message news:[email protected]...
    > I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike territory?
    > I wouldn't have guessed I was an outlier physically. I would love to see some stats of upper/lower
    > leg length for people close to my height - although I don't think my friends would appreciate me
    > measuring their legs.
    >
    >
    > "Qui si parla Campagnolo" <[email protected]> wrote in message
    > news:[email protected]...
    > > kbh-<< Put my bike on the trainer to do a self fitting, using my plumb
    bob
    > I
    > > verified that I was about 1.5" - 2" behind KOPS. My bike has a 73
    degree
    > > seat tube angle, and I'm using a seatpost with no setback and the saddle rails in the middle.
    > >
    > > Yes, I would say you would benefit from a frameset with a steeper
    seattube
    > > angle.
    > >
    > >
    > > Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    > > (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  18. Rick Warner

    Rick Warner Guest

    "KBH" <[email protected]> wrote in message news:<[email protected]>...
    > I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike territory?
    > I wouldn't have guessed I was an outlier physically. I would love to see some stats of upper/lower
    > leg length for people close to my height - although I don't think my friends would appreciate me
    > measuring their legs.
    >
    >

    74 steep? Depends on your body. My new custom bike will be 78 degrees, and this on a relaxed frame.
    If I were racing the builder would go even steeper. I have short legs, and a relatively short
    femur, so ....

    - rick warner
     
  19. Mike S.

    Mike S. Guest

    <snip>

    > > I thougt 73 was on the steep side already, and that 74 starts to get you into tri bike
    > > territory? I wouldn't have guessed I was an outlier physically. I would love to see some stats
    > > of upper/lower leg length
    for
    > > people close to my height - although I don't think my friends would appreciate me measuring
    > > their legs.
    > >
    <snip> for brevity

    For my height/leg length (5'8" & 30" inseam), I find that the slackest frame I can ride is about 73
    degrees. 73.5-74 and a no offset seatpost work better for me.

    Mike
     
  20. "KBH" : I thought about that but the ONLY dimensions of the bike, excluding the
    > > > seatpost/saddle, that determine KOPS are seat tube angle, saddle height,
    > and
    > > > crank length - that's it. So its gotta be the upper to lower leg ratio,
    > not
    > > > the absolute length of the femur.
    > >
    > > But this man is 6'5" so on standard cranks he will need to sit way back to
    > get KOPS.
    > >
    >
    > That argument would only be true if we all rode the same saddle height. Since he is tall, his
    > saddle height will be larger, resulting in more "built-in" setback as a result of the seat tube
    > angle. Assuming that the relationship between total pubic bone height and saddle height is roughly
    > constant (rule of thumb is 0.883 x PBH), then this brings you back to the conclusion that weather
    > you're 5'2" or 6'5", it is the ration of upper leg to lower leg that determines KOPS and therefore
    > how much seatpost setback you may need and where the saddle may need to be on the rails.

    This argument doesn't make sense unless you factor in a slacker than normal seat tube. Traditionally
    they are a bit slacker on a larger frame. We would need to know what it is at any rate.

    He might also have short feet.

    Andrew Bradley
     
Loading...
Thread Status:
Not open for further replies.
Loading...