From: alavalle@seqp4.sequoia.com (Art LaValle)
Newsgroups: rec.bicycles
Subject: Re: Subject: Re: Correct seat height summary
Summary: I don't think it's coincidence
Date: 31 Aug 92 14:03:16 GMT
Organization: Sequoia Systems Inc., Marlboro, Mass.

In article <9208242256.AA17796@ucbvax.Berkeley.EDU>, ericp@VNET.IBM.COM writes:
> Art, one of the bike mags recently had a statement on this from B. Hinault.
> He uses 1.09 times inseam for the heigth from the saddle to the center
> of the pedal with the cranks parallel to the seat tube. It may be
> coincidence, but this is within 1 mm of what the NECA Fit Kit
> recommended for me.
> Eric Pearson

I don't think it's a coincidence at all. I think all the popular methods for
setting seatpost height (NECA (now NASBR) Fit Kit, Eddie B method, the 109%
of inseam method, and Greg LeMond's .883 of inseam method pretty much result
in the same seat height setting. BTW my original posting on this issue was
a complaint about the fact that if you use the .883 (GL) method as is, it
doesn't account for different crankarm lengths. I also concluded that the GL
method was being quoted out of context from his book. Someone sent me e-mail
with the *entire* section in his book which describes his method. Although he
does describe the added variable of Crankarm length, it still is a bit vague
for my liking.

Consider this:

The other night on a ride with a long time biking friend of mine (who coin-
cidently is half owner of the NECA (now NASBR) Fit Kit System) we got into
this discussion about bike fit. He suggessted that after the ride he "fit kit"
me with one of the kits he had in his basement. I've never been fit kitted
before and was a bit nervous that the results would show tha my cherished
16 year old *custom* frame, which was speced out via the Eddie B method, would
turn out to be the wrong size for me. :-{

Well lo and behold the Fit Kit results showed that my frame was right on the
money - that's top tube length, seat tube length, stem length, HB width,
crankarm length, and seat height setting. (Whew :-))

After my relief at the fact that I didn't need a new frame was over, we started
looking at the results from different perspectives. Here are the results:

 - The seat height setting that I was using (as originally determined about
   16 years ago in an Eddie B run clinic) was exactly the same as the seat
   height setting prescribed by the Fit Kit - we already knew this.

 - The seat height setting, if measured from *pedal axle* to seat is close
   enough to 109% of my inseam (I think this number originally came out of
   a study done at a Sports Medicine College in the UK years ago) to be 
   considered correct using this method.

 - The seat height setting, if measured from *bottom bracket* to seat is again
   close enough to .883 of my inseam to also be correct according to the GL
   method. Keep in mind that this is my road bike which is set up with 170mm
   cranks.

My conclusion is that you can use any of these methods and you can't make
a *significant* error. Although if you lack access to an Eddie B clinic the
Fit Kit is equally good at giving you a good overall bike fit - which includes
more than just seat height.