It's due to injuries from a car wreck. Busted up my back and neck, cracking six vertebrae -- two in each major section -- and permanently splintering the C2. That neck damage is the main hindrance. Not really much more can be done short of fusing or extensive surgery, which I'm not willing to risk.

A somewhat lighter bike with more options for hand and body positions may help. I can't ride drops for long because I can't crane my neck upward to look ahead, but I may be able to manage for brief periods on low risk sections of road.

And if all else fails I may consider a recumbent for longer rides and keep the standard bikes for short hops.