Frame sizes

Discussion in 'Cycling Archive' started by Nick Maclaren, May 5, 2015.

  1. A while back, I said that they were smaller than they used to be,
    despite people being larger, and that was disputed. I now have
    evidence (though from a bit earlier than I was looking for).
    'Cycling Manual By The Staff Of "Cycling"' (c. 1920) advised
    people with leg lengths (in shoes) of 34" or more to buy a 25"
    frame, use 6 3/4" or 7" cranks and sprung saddles. Either that or
    another reference said that seat posts should be raisable by at
    least 3".

    Well, saddle+frame+crank-pedal/2 comes to 35", so they were
    recommending AT LEAST an inch longer than leg length - probably
    something in the range 1-3", which is (if I recall) what I said.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 5, 2015
    #1
    1. Advertisements

  2. In uk.rec.cycling.moderated on Tue, 5 May 2015 17:28:29 +0100 (BST)
    Knowing nothing about how uprights are sized.... Are the frame
    geometries the same?

    BB height from the ground, ratio of top tube to seat tube?

    Are we really comparing like with like?

    Zebee
     
    Zebee Johnstone, May 5, 2015
    #2
    1. Advertisements

  3. Not entirely, but this is all diamond-frame, and about leg length,
    reach and ankling. The other aspects you mentioned are irrelevant,
    to a first approximation.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 5, 2015
    #3
  4. Nick Maclaren

    Rob Morley Guest

    On Tue, 5 May 2015 22:53:51 +0100 (BST)
    A very slack seat tube, as was common in the first half of C20, will be
    longer for the same stand-over height (assuming the same bbkt height)
    than a steeper modern one. The saddle position is similar because the
    old bikes' seatposts were cranked forwards.
     
    Rob Morley, May 5, 2015
    #4
  5. In uk.rec.cycling.moderated on Tue, 5 May 2015 23:09:21 +0100
    eg
    http://www.oldbike.eu/museum/1920s-3/1920-1923/1920s-la-lionne-truss-frame-racing-bicycle/

    http://www.oldbike.eu/museum/1900s/fashion-costumes/1890s-bicycles/
    has a few more pics of non-racers but most of the geometry is
    obscured by bods in caps standing in front of the bike...

    They do seem to have seat tubes leaning back compared to say
    http://classiccycleus.com/home/?page_id=230 but whether it is possible
    to get decent measurements to show if the angle accounts for the
    differences Nick finds is hard to know.

    Guess Nick needs to go down to a cyling musuem with a protractor and a
    long steel rule...

    Zebee
     
    Zebee Johnstone, May 6, 2015
    #5
  6. Yes, but that's even less relevant. Stand-over height is relevant
    only when getting on and off. The issue I was talking about is
    the LEG length when RIDING. I was hoping not to bore people by
    reiterating the background, but I suppose I had better :-(

    The point is that a LOT of people who try cycling give up, won't
    ride at above 8-10 MPH and then only on the flat or won't ride for
    more than 2-3 miles, citing knee pain. Based on everything I have
    read and the people who say that I have talked to, by FAR the main
    cause of tha is the modern rule for 'correct' saddle height. I have
    already referred to the physiology and physiotherapy information;
    this was the one I hadn't found.

    Yes, I know that at least some people have no trouble cycling with
    very bent knees (my wife is one) and others can adapt, but a hell
    of a lot of people have serious trouble unadapted and some probably
    cannot adapt. And why should they be forced to, anyway? So the
    current rule is a MAJOR obstacle to any resurgence of cycling for
    medium-distance transport (recreational or utility), both by getting
    bicycles set up inappropriately and by making it damn-near impossible
    for taller riders to buy bicycles that are big enough in the UK.

    And, lastly, you CAN'T just use a longer seatpost, because that
    forces the rider into even more of a crouch, which causes upper body
    pain and sometimes breathing problems. And those are also reasons
    that people give up cycling, or ride the say I describe above.
    There is no substitute for a big enough bicycle. I have helped a
    few people, by advising them to ignore the pundits and salesdroids,
    but most have simply said "I am just one of the people who can't
    cycle." Well, in the 1920s, there were damn few such people; it
    makes no sense that there are today, and I am explaining what is
    a major factor in that.

    Because I am one of the people who cannot ride with a modern setup
    without pain, I can witness how often bicycle shops promote setups
    and, MUCH worse, frames and components that are too small for the
    rider. As I have posted, more than once they have actually refused
    to set up a bicycle according to the traditional rule.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 6, 2015
    #6
  7. Nick Maclaren

    Peter Clinch Guest

    The "modern rule" as I know it is /start/ at the leg very close to
    straight with the heel on the pedal at 6 o'clock and try it up or down
    from there in increments until it's right for you, thobut.

    So I start there, and go up a bit until riding is very uncomfortable,
    back off a little and then it's fine. The "rule" is a guideline for a
    start point, not a pontification of an end point.
    FSVO "very bent"... If I drop my saddle by as much as half an inch on
    the Brom I can tell something isn't quite right, so I'm reasonably
    sensitive to low saddles and feel it in my knees. But my saddles aren't
    significantly different from the start point of the "rule", so I suspect
    the issue is not the "rule", but saddles just put far too low.

    I do cycle instruction and coaching part time. I very, very, very often
    advise people to move their saddles *up* (which will far more closely
    comply with the "rule"), I don't recall /ever/ coming across one set by
    it's owner that seemed too high by said "rule".
    Most people set the saddle themselves IME, and they set it to make
    touching the ground easy, not to make pedalling optimal. They are
    furthermore highly resistant IME to advice that will push them further
    off the ground, and this is particularly the case with relative beginners.
    That would very much depend on the handlebars. If they're relatively
    high and/or swept back (typically easy to do with butterfly bars) it may
    make little or no difference.
    In the 1920s I suspect there were far fewer rationalisations of
    "actually, I think I'll just stick to what I know, and that'll be the
    car". People don't ride so much these days because they aren't in the
    habit of riding. And because they're not in the habit they dream up
    excuses to justify doing what they actually do instead. Prove to them
    that they /can/ ride and then there won't be enough cycle lanes, or
    there won't be showers at work, and so on.

    Pete.
     
    Peter Clinch, May 6, 2015
    #7
  8. Yes. And that length was traditionally recommended ONLY for people
    learning to cycle. The rule I was referring to and found in that
    manual is more like measure that, move the saddle up 1" and then
    continue raising it (sic) until it is right for you. Remember that
    people can extend the ball of the foot 2-3" with their ankles, and
    their legs are 0.5-1" longer when not carrying their weight.
    I wish :-( Because (due to knee issues) I need to be at the high end
    of the traditional spectrum (i.e. 4+" longer), I encounter the dogma
    every time I want to even sit on a bicycle to try it, let alone a
    test ride. As I said, several shops have point-blank refused to set
    up a bicycle for me to try or test.
    VERY bent, as far standard physiotherapy rules and physiology references
    go. The former effectively recommend not pushing with knees bent more
    than about 75 degrees, and the latter say that the blood and lymph flow
    in some people's knees only when the leg is completely straight and
    relaxed. ALL natural sustained exercise leg uses have those properties.
    Precisely :-( They used to be common, and there are a lot of people
    who can ride hard without pain only if they do - but they don't know
    that! You are probably correct that most people set them low for
    ease in putting their feet on the ground, but that is what learners
    need to do. We used to be taught to rise up off the saddle and put
    one foot on the ground keeping the other on the pedal, which allows
    a 1.5-2" larger frame size.

    And remember that the people I am talking about are the huge number
    who give up cycling, or won't ride above (say) 10 MPH or for more than
    2-3 miles because they find it too painful. I have met lots, and
    almost all had had advice from 'experts', and sometimes training.
    Actually, it does. A traditional hand position for an upright was
    c. 6" behind the stem line, and up to 4" higher than the saddle.

    I don't need that, but for long rides, I would very much like another
    2" on the stem. Unfortunately, it can't be done :-( However, back
    to the population I am talking about. It usually CAN be done, but
    usually needs a stem extender and new cables (for taller riders,
    often cut-down tandem ones). Get real. Casual cyclists aren't going
    to do that, so many give up or ride only short distances because of
    the upper limb or neck pain.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 6, 2015
    #8
  9. All very well, but unless you live in Germany, you don't see many bicycles
    in shops with butterfly bars. H. has a bad back and no budget, and it's
    only by chance that I could get the bars up to somewhere vaguely suitable
    for her.

    I suspect one of Nick's tall frames with a slack seat tube would serve her
    well - especially since she _has_ to be able to put feet down from the
    saddle, and a slacker seat tube means that the bottom-pedal distance
    doesn't have to be so badly compromised.
     
    David Damerell, May 6, 2015
    #9
  10. Yes. Ones of 60 degrees used to be fairly common.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 6, 2015
    #10
  11. Nick Maclaren

    Tosspot Guest


    I'm a bit confused by what a 'slack angle' means. Closer to vertical as per

    http://www.ecovelo.info/2010/11/14/the-problem-with-numbers/

    Or the other way around?
     
    Tosspot, May 6, 2015
    #11
  12. They seem to be using it to mean "closer to horizontal" - "as the seat
    tube angle slackens, a bike becomes shorter".

    The confusion may be because Nick isn't proposing "the other dimensions
    remain the same".
     
    David Damerell, May 6, 2015
    #12
  13. The other way round. Less vertical. Like:

    http://www.mbzponton.org/n2awa/bikes.htm#1950_Raleigh

    On another aspect, note the position of the handlebars relative
    to the saddle in that one, and remember that a roadster was NOT
    a bicycle ridden by old fossils going to the pub but for riding
    fairly long distances to work or touring, as the name "Tourist"
    implies. At 16, I rode from Salisbury to Helston on a Hercules
    (see earlier on that page).


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 6, 2015
    #13
  14. Nick Maclaren

    Tosspot Guest

    Blimey, they have changed. While perusing the interweb I found this;

    http://cyclingabout.com/understanding-bicycle-frame-geometry/

    Which at least seems to give all the variables you could ever want to
    obsess over during those long sleepless nights. I'm going to try and
    compare my LHT Disc (modern) with my LHT (rather older) and see if they
    compare.
     
    Tosspot, May 6, 2015
    #14
  15. Nick Maclaren

    Rob Morley Guest

    Looking at those the saddle to handlebar distance seems pretty short
    too - perhaps mostly dictated by the shallow head angle.
     
    Rob Morley, May 7, 2015
    #15
  16. Okay, so now... which (if any!) of these measurements is the "frame
    size", as Nick is referring to in the original post with a 25" example?

    Is it the "stack" height?

    Cheers - Jaimie
     
    Jaimie Vandenbergh, May 7, 2015
    #16
  17. Yes and no. It is short, and that's because they were and are
    ridden mostly upright, not in a crouch or semi-crouch. But it's
    not dictated by anything - that's a desirable property for most
    riders, which is precisely why swept back handlebars are good!


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 7, 2015
    #17
  18. Yes, precisely. Because of the swept back handlebars, the top tube
    can be longer, and roadsters typically have longer wheelbases than
    road racers. That helps a lot with stability, because increasing
    the size (to Jaimie: that is the seat tube length) without doing
    so pro rata to the wheelbase usually reduces stability. Now some
    people like 'responsiveness', but most ordinary cyclists find that
    it makes them feel unsafe.

    Basically, the traditional roadster is staid (the opposite of
    'sporty'), which does NOT mean slow or limited in range. They aren't
    as fast as road racers, for those people that can handle the latter,
    almost entirely due to the extra windage due to riding upright.
    So they correspond to the riding equivalent of walking, including
    brisk and long-distance walking, rather than running.


    Regards,
    Nick Maclaren.
     
    Nick Maclaren, May 7, 2015
    #18
  19. Nick Maclaren

    Sam Wilson Guest

    Usually one of the variants of seat tube length - there are potential
    ambiguities at either end of the measurement as shown on that page.

    Sam
     
    Sam Wilson, May 7, 2015
    #19
  20. That was what I'd always thought, and my earlier comment in the previous
    thread was based on this - modern frames are often squashed and have
    much shorter seat tubes, so of course they're smaller - but when I saw
    that page specifically calling out the seat tube as "This length will
    not matter too much" I started to wonder if I'd just been wrong all this
    time.

    My own bikes have seat tubes of about 24" (Galaxy) and 19" (Scott MTB),
    and both fit me nicely. I'm pretty sure the Scott was sold as a 24" as
    well - presumably in a virtual or equivalence sense? It's clearly not a
    useful direct metric.

    Cheers - Jaimie
     
    Jaimie Vandenbergh, May 7, 2015
    #20
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.