Originally Posted by
bruce19
Just a couple of thoughts. I use the LeMond-Guimard method of frame sizing. Basically .665 X inseam in CM and it gets me in the ball park. Before I got old and then broke my neck and had C1 & C2 I was also 5'10". My inseam is 32.5" With your unusually long inseam I'm guessing you could ride a 60-62 frame. (I should note that I measure frame size using a virtual TT rather than the sloping TT.) I'm also guessing that you have a short reach and would need a shorter stem. As for saddle height. I don't measure from the BB. That can give you a false reading since crank length varies. I've checked that with people who do professional bike fits and they agree with me. Better to measure from top of saddle to pedal spindle.
Ok, so the OP said his inseam measured with help is 35.5. To get the frame size, multiply by 0.665 to get a frame size of 23.6, rounding up to 24. So the nominal frame size is 24. To get the saddle height, BB center to top of saddle for 170 mm cranks, multiply 35.5 by 0.889 to get 31.56 from BB to saddle top. Lower the saddle by 0.1 to account for the longer 172.5 mm crank arms. So your Lemond-Guimard frame size is 24 and the saddle height from the BB center is 31.46. From the pedal axis its 38.23 saddle height.
I think I got all the Guimard factors right, but these are, like KOPS, only starting points. Ill leave the rounding up or down to you guys. 510 tall? Im 55.5 tall, and I like my bikes 52 to 55 cm, depending on the rest of the geometry.
If the OPs cycling inseam really is 36, Id say 24 is still the suggested frame size, and the saddle height goes up to about 38.6 above the pedal axis.
I also use heel on pedal as a saddle height starting point, wearing the shoes and shorts I usually ride in. I usually have to adjust from there, down a bit.