"Tom Purvis" <
[email protected]> wrote in message
news:[email protected]...
> "Eric M" <
[email protected]> wrote:
> > Fred Fragger <
[email protected]> wrote:
> > >The more I get into riding the more I worry that I bought the wrong frame size.
> > >
> > >I'm 5'10" with a 30.5" (clothing measure so about 32" to the ground) inside leg and my hardtail
> > >has a 20" frame.
>
> Could be wrong, but could be at least close to right, depending on other dimensions of the frame.
> Sounds to me like you're pretty long in the torso. I'm 6'1" with a 36" (jammed up there) inseam.
> You are 3 inches shorter than me, but your legs are 4 inches shorter. I've been on a 19.5" bike
> with a 120mm stem (medium length) for 5 seasons. And it has a fairly long effective top tube for a
> bike it's size, 24.25". Do you know what the effective top tube is for your bike frame? If not, do
> you know how to measure for it? In torso length you're pretty similar to my size. I'd be curious
> about how long your bike's frame is. What length stem does it have?
>
> > Basic bike fitting:
> >
> > First you need to correctly set the fore-aft saddle position. The rule of thumb is that with the
> > crank arms level, the bony bit just below your knee should align with the pedal axle of the
> > forward pedal. You can go back from there but not forward (except maybe for track riders or
> > triathletes).
> >
> > Then make sure that the seat is the right height. The basic LeMond formula is seat above BB axle
> > .866 X true inseam (not clothes measurement, use a book against a wall and really jam it up
> > there). Or use
http://www.totalbike.com/service/frame_size.php If you change the seat height
> > you'll need to re-do the fore-aft position.
> >
> > I prefer a higher seat than the Lemond formula, but not quite as high on a MTB as on road bikes.
> >
> > If your frame is too large, which sounds possible, you may have a longer top tube than you need
> > and thus too long a reach to the bars. That would make you want to sit forward and/or move the
> > saddle forward. That's wrong; you place the saddle where you need it for best pedalling and then
> > buy a different length stem to adjust the reach.
>
> This is very sound advice. Right on about setting saddle placement first, then choosing a stem to
> set bar placement, and abandoning the frame when you find that you can't make it fit without
> drastic frankenbike measures (150mm stems, etc).
>
> But you don't really mention rise. Very important, especially if we have knabular irritation. That
> suggests that the fellow's gonads are being jammed into the saddle nose because his hips are
> pointing forward and down too much. Bar too forward AND/OR too far down relative to saddle can
> cause uncomfortable knabulator/saddle involvement.
>
> There are at lease three ways to get rise: Get a stem with rise, riser bars, or leave steerer cut
> longer and put spacers under the stem. The third option only is available if you have the luxury
> of deciding how long to leave the steerer. New complete bikes usually come with the steerers cut,
> do they not?
>
> Mr Fragger, what level are your bars relative to your saddle. Bars lower than saddle, same height
> as, higher than saddle? Is your saddle flat (horizontal), tipped back, or tipped forward?
> --
> Tom Purvis -
http://www.arkansasvalley.net/tpurvis/ Salida, CO
Tom,
I'll try and answer at least some of your points as well as I can, being a relative newbie.
First thing to point out that my inside leg, wearing shoes, is 31" not 32" (I got it wrong) so
either my nickname is stumpy or yours is giraffe's legs

we need some other reader's measurements to decide which one of us is
"normal" !
My saddle looked perfectly level but I checked it with a spirit level and it's 1/2 an inch up at the
front which I'm guessing won't be helping.
My saddle (when levelled) and bars are at exactly the same height.
I checked my frame size and, measuring from the centre of the crank(?) to the top of the seat tube,
I got 20" which I was expecting
Measuring (horizontally because the top tube slopes) from the centre of the seat tube to the centre
of the head tube I get 22.5" You're right, I don't know how to measure the "effective" top tube
length - perhaps you could enlighten me? I like to learn something new every day!
The stem, measured from the centre of the head tube to the centre of the bars is 4"
Hope that helps you to help me?
Cheers,
Fred