Greetings,
I am curious as to why my legs are more comfortable with 72 degree or less seat tube angle?
Riding two bikes with the same parts and frame material; with a steeper seat tube angle (72 degrees versus 73 or 74 degrees) . . . my shins, knees seem to feel beat up. That one or two degrees on a 57 cm seat tube moves the seat forward more than a cm toward the bottom bracket. What is the issue? Is it just because of size 47/48 feet?
More sizing anecdotes.
The last bike shop I worked at sold c-dale, giant, and khs. The go fast racer boys and girls bought what ever they wanted and rode for a while.
When they came in to bum some free work, often they would tell me their bike was great . . . but they were always trying/buying stuff to get comfortable . . . it hurt to ride it.
The bike was too small, top tube too short and the handlebars were too low and too far from the saddle. (Just like the pictures in Bicycling Magazine) I'd refit them on the frame they had with a 17 degree or more stem that would classically position the bars. Comfy but they thought it was dorky and they would suffer the scorn of their fellows. Scorn and fashion apparently precede function and certainly comfort.
A bit ago there was a thread about the importance of top tube length. I wouldn't go so far as to say that it is more important than stand-over height BUT consider the following.
I have a 57 cm Serotta from 1976 with slack angles and a 10 and 3/8 inch bottom bracket that has the same stand-over height as a 53 cm cdale 3.0 criterium. To get the bars high enough I have to use a mountain type stem. UGLY, I agree with the racer boys about that.
I like low bottom brackets as I don't race criteriums (just the dog on ridge road) and start with 1.09 and end up adding some to take in account size 47 or 48 feet.
I have a long torso, broad deep chest and subsequent shorter arms. So I balance a closer fit on the stand over height because generally you spend more time riding than standing over. Any bike with shorter than a 57 cm top tube is going to be really cramped especially if the top tube angle is less than 72 degrees. After my age hit 40 I went from a target of the bars around 1/2 of 1 inch below the seat to now I just add a Nitto Technomic stem.
Just be careful on the stops boys and girls!
Howard Darr
Kinsman OH USA