Drag

Alistair rode the Dunlap TT in Davis on Sunday. He used my Griffen with the Renn disk and the Hed 3 spoke in front. I had to change the gearing to conform to junior restrictions (max gear 52X14) but other than that we use the same setup. He ended up 7th in his age group (15-16) but he was the second 15 yr old.

He is now 5'10'' and weighs about 115 lbs. I am 6'1'' and weigh in at 174 lbs.

I rode the bike afterwards on the 30K course. Not officially, because you had to preregister and I missed the deadline, but I took advantage of the road marshals anyways. I rode the 30K loop, whereas Alistair did the 20K out and back. But the initial parts of the course overlapped. 

I gathered some interesting data on the outbound, headwind section. Since we both rode the same setup, with everything being equal and both of us riding in aero, the comparison is interesting. The section was flat so weight did not matter here. Data was averaged over several minutes, although we both rode very steady in that stretch.

My speed upwind was 20.6 mph for a power output of 332W. His speed on the same stretch was 22.9 mph for a power output of 294W. The difference is all due to frontal area. Despite putting in and extra 38 watts, I traveled 2.3 mph slower than he did on the same road.

It is possible that the wind picked up slightly when I rode (I rode at 10:45 and he rode at 9:00) but all else was the same.

On Saturday I swam 162 laps (3,000 m).