Quote Originally Posted by zoom-zoom View Post
That's interesting...I'm generally a relatively aggressive-positioned spinner. I wonder what this means in terms of vibration sensitivity. I was maybe a hair more upright on my aluminum Synapse, relative to my Redline.
My conjecture is based on my limited experience:

When I lived in Houston and Florida, which are both relatively flat, I was predominantly a spinner (a consistent 88 RPM). Because I was only applying medium to low force on the pedals, my butt was fully weighted on the saddle and all the vibration was ultimately transmitted to my butt and girly bits through the saddle. After riding a while, my pain threshold would be reached and the butt/bits would become even more sensitive to subsequent vibration. Here in Austin, I’ve had to change my style to make it up the long and never-ending hills. Now that I’m mashing the pedals almost constantly with near maximum force, my butt is noticeably unweighted from the saddle with each pedal stroke and I’m not even aware of the saddle and the vibration/jolts transmitted to it.

Position-wise, on my old road bike I was really stretched out and my upper body muscles (shoulders, arms) were always working to help support my torso. The vibrations would cause those already-tense muscles to involuntarily react, with the result that after a while they’d get fatigued and become even more sensitive to subsequent vibration. My new road bike has a shorter top tube so I’m not as stretched out. My core muscles provide most of the torso support, and because my upper body muscles do not have to work quite so hard, they can endure a lot more vibration. The result is that I have yet to experience any upper body discomfort on my new bike from vibration and jolts.