Hi Bruce,
A couple of theoretical thoughts;
i) Do you know if the wheel chairs will even have spokes? These days, I thought racing chairs had 'composite' disk filled wheels, for lower aerodynamic drag.
ii) The top of the hill will mean low ground speed; yes, more strain showing on faces perhaps, but less speed on wheels or limbs.
I haven't shot such an event for many years though and even then, it was a conventional Triathlon, without wheelchair participants. I was lucky enough to be able to move about behind the barriers as crowds not too thick, allowing me to try several positions during the event.
Here's one shot you might like to try for: the classic
Sunglasses reflection from June 2009.
Shot on Nikon D5000 at 200mm (FFE 300mm) 1/1500s, f/8, iso400.
Good luck, Dave