fitting a bike

Discussion in 'Australia and New Zealand' started by Denis W Ellem, Mar 26, 2006.

  1. As a newbie I have read many of the posts while lurking.
    I have read about a bike shops setting up a bike to suit you. Obviously this
    was not done for me when I purchased my first new bike since the last one
    about 40 years ago.
    What is actually involved in setting up a bike for the rider. Any help would
    be greatly appreciated. But don't forget to type real slow for this old
    fart.
    Thanks,
    Denis
     
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  2. "Denis W Ellem" wrote:

    > What is actually involved in setting up a bike for the rider. Any help
    > would be greatly appreciated. But don't forget to type real slow for this
    > old fart.


    Just my 2c. Others on the group will no doubt be able to add more technical
    measures.

    1. Frame size - the most crucial of course, difficult to change: Stand over
    the top tube, feet flat on the floor. You should have clearance between
    frame and crotch of at least 8cm, more for a MTB for off-road use.

    2. Saddle height: Get someone to hold the bike, sit on the saddle and put
    your heels on the pedals. At the bottom-most point of the pedal stroke your
    leg should be pretty well straight. Adjust the seat post to achieve this.
    Put your feet on the pedals in riding position (ball over pedal axle) and
    back pedal. Your hips should stay level, no rocking as you pedal (get
    someone else to check from the rear). With this saddle height you will
    probably just be able to touch the ground with the tips of your toes, but
    that's OK, you move off the saddle when you stop

    3. Pedals: Position your cleats, if you use them, or get toe-clips of a
    suitable length, so that your pedal axle lies immediately below the ball of
    your foot.

    4. Saddle: Position the saddle so that the a vertical line from its nose
    falls about 5-6cm behind the crank axle. When sitting with feet on the
    pedals, crank arms horizontal, a plumb line from your kneecap should pass
    through the pedal axle.

    5. Saddle tilt: The saddle should be level as a general rule or the nose may
    be tilted up 5 degree. Adjust the clamp underneath the saddle. Some ride
    with the nose down for comfort, although this may produce sore shoulders and
    forearms.

    6. Frame/stem reach: Put your elbow at the nose of the saddle, your
    fingertips should fall about 8cm behind the handlebar (straight bars) closer
    for a bike with drop bars, maybe 5-6cms.

    7. Handlebar: Ideally should be about the same width as your shoulders,
    allowing you to ride wtih your fore arms parallel. I find with MTB bars they
    can be a fair bit wider, as the different grip and arm position means your
    arms are parallel in a wider grip.

    A few other position 'rules'
    - when riding a well setup bike you should find in all positions that the
    line between your upper arm and your torso forms a right angle
    - in your normal riding position you should be able to sight your font hub,
    just behind the handlebars
    - move forward on your saddle when spinning fast, slide back on the saddle
    if you grind the pedals slower up a hill.

    All of these should be treated as guides. They will vary for some people
    with different body proportions, and always go by what is comfortable for
    you, but the first four measures are pretty crucial.

    I am sure that others can suggest more ideas.

    --
    Cheers
    Peter

    ~~~ ~ [email protected]
    ~~ ~ _- \,
    ~~ (*)/ (*)
     
  3. Bleve

    Bleve Guest

    Denis W Ellem wrote:
    > As a newbie I have read many of the posts while lurking.
    > I have read about a bike shops setting up a bike to suit you. Obviously this
    > was not done for me when I purchased my first new bike since the last one
    > about 40 years ago.
    > What is actually involved in setting up a bike for the rider. Any help would
    > be greatly appreciated. But don't forget to type real slow for this old
    > fart.


    There's no one right way to do it, and there's a lot of myth and mumbo
    jumbo too.
    Some general principles :

    As Peter says, frame size is important, but within certain values it's
    maybe not as important as it may seem at first - you can get all sorts
    of funky seatposts & stems to move you around.

    KOPS is a myth (knee over pedal spindle) that won't go away and it
    sometimes works by co-incidence (see :
    http://www.aboc.com.au/docs/kops.html ). I look at how a rider stands
    when pedaling and then try and replicate that when they're seated, then
    move them fore or aft on the bike depending on how much weight they can
    handle on their arms, as a general principle. But, there's no one
    right way to do it, the only "right" way is the way that doesn't cause
    discomfort or injury.

    Sorry to be vague, but you cannot get a fit over the 'net.
     
  4. sinus

    sinus New Member

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    8cm is a bit extreme. You'd have me on a 24 inch kids bike :eek:

    Standover height is not a great indicator of bike fit, particularly with compact frames. There are a few well known formulas based on simple measurements, but a good bike fit should be able to take all factors into account. This includes leg length, height, back flexibility, shoe size, power output and others. The formulas are only a starting point.

    One of the well known fomulas is Lemonds. Frame size = inseam * 0.67.
     
  5. rooman

    rooman New Member

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    absolutely spot on...

    plus I'd add ...formulas are for babies to drink & scientists to postulate over.
     
  6. Resound

    Resound New Member

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    While I certainly wouldn't suggest that fitting formulas are infallible and the be all and end all of bike fitting, they will provide a damn good starting point. There is an enormous swathe of middle ground between perfect and useless. I'd agree that 8cm of standover room is a bit much but other than that in the absence of someone who knows what they're talking about (and in order to work out whether the assistant in the LBS knows what they're talking about) a few basic rules can be extremely valuable.
     
  7. DaveB

    DaveB Guest

    rooman wrote:
    >>
    >>Sorry to be vague, but you cannot get a fit over the 'net.

    >
    > absolutely spot on...
    >
    > plus I'd add ...formulas are for babies to drink & scientists to
    > postulate over.
    >
    >


    When I bought my OCR2 I had it fitted and have been very happy with it
    from day 1. Out of interest I made some comparisons between the OCR and
    my old road bike which had taken me a year of tinkering with to feel
    comfortable. Although the frame sizes were quite different (the old
    frame was a donation from a mate), various modifications to headstem,
    seatpost etc on the old bike meant that for seat to pedal, and seat to
    handlebars measurements, I had almost identical measurements for the two
    different bikes. So although formulas are only for babies and
    scientists, once you have a good fit, can that be translated to another
    bike through measurements or does an experienced opinion still play the
    major part?

    DaveB
     
  8. Resound

    Resound New Member

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    There's probably a degree of horses for courses going on with fit. Different types and intensities of riding would determine a different approach as well as unusual proportions. One of my friends has a very long torso and short legs. She's also very much a novice cyclist and so would ride at a much lower intensity. So despite being essentially the same height as me, she'd want a distinctly different fit. Someone who's experienced in dealing with different cycling styles and body types would probably be able to make some pertinent changes to a basic formula straight off. A basic formula would still be a good starting point in the absence of such a person though.
     
  9. rooman

    rooman New Member

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    your physiology, riding style and aspirations dicate your position in space that is most comfortable or provides max performance or whatever in between you have arrived at that feels perfectly fine to you...you managed to replicate that ...well done... that is what it is all about...your position never changed, you adapted your ride to that position you had comfort with...that is achieved by adjusting the many and almost infinite variables at play...what doesnt change is you and your subjective feeling about riding comfort/performance you have settled on as optimum for you...still with me?

    so you can get any new frame within dimensional limits and adapt it to place you in space where it feels right...some do this the hard way and play and twiddle for ages till they get what they perceive as fine for them...others seek experienced professionals to help them along the journey...and far too many never find nirvana for whatever reason...that's why we have this Forum I guess

    whatever...ride..to enjoy and if it don't fit, fix it, then ride and enjoy..and ride and enjoy................
     
  10. Donga

    Donga Guest

    Denis

    Noticed from your posts that you were a car-boy. Good to see a convert.
    I hope this wasn't a troll, seeing all of these nice people have worked
    so hard to answer your question!

    Donga
     
  11. smartie

    smartie New Member

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    Thy this website. Makes perfect sense to me. After tinkering around for a while to get myself a comfortable position, i then read the article and found it to almost be spot on to this guys recommendations.

    http://www.peterwhitecycles.com/fitting.htm
     
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