Originally Posted by
Jimi77
No it doesn't work for me. How did you divine that my saddle is too high? Sure wasn't PBH x 1.09. That formula increases my saddle height to 36-37 inches. I guess I fall in between the formulas, which have a ~26% difference.
What tells me my seat is too low??? The fact that my knee is bent significant at the bottom of my downstroke is a big clue, knee pain and of course the fact that I'm 6ft tall guys don't belong on 17" frames. My Allez (that fit properly) was a 56cm (aka 22') frame. The manager at the LBS set me up on a ~21" frame today. I think that covers it.
I'm sticking with the old heel barely reaches the peddle when fully extended method, but the mathmatical approach is interesting.
Some of your numbers do not make sense, you said too high or low and now you say low instead of high**********? If I were to fit you I would have to measure you for myself etc
. Not arguing, I am sincerely interested, you ride a 22 inch (56cm) frame that fit or a 21? Hmm, I am 5-11 (and shrinking due to getting older) and I ride a 56cm also. I run my seat at 76cm center of BB to crown of seat give or take a little since some of my bikes have a 170 crank and a few have 175 cranks and one a 172 crank. Plus, of course there is seat setback differences due to frame angle differences and so on. My cycling inseam, PBH is 86cm.
I used to fit bikes some years back. I was fitted by a cycling coach myself, back in 1984, he had been a cycling coach for several pro teams and was doing a fit clinic at a local shop. I was fitted another time by yet another pro level coach, nearly same result. I am not entirely sure how they came to their fit but the first one set my saddle at exactly what 109% rule would predict, the later fitting, he left it alone but did shift my seat and stem length a bit.
The 109% is not new, it goes back a long ways. It is not just opinion, it is based on experimentation and measuring power output over distance and comfort over distance. It has been found that the 109% rule, which is sorta similar to the PBH minus 10cm method, for most cyclist produces the greatest power output over time. Of course, it is also true that in triathlons, they tend to run their saddles higher, same in time trials, but, take a look at a tri/trials bike and figure why that might be.
So, you are 6 feet tall and you are on a 21 inch frame? Interesting. At 6 feet, without knowing your PBH or any measurements, I would probably start with a 58cm frame, 58cm TT.
Good luck.
LC