I’m going to run some power/speed trials comparing two bike setups. I set up my road bike to match the tri bike, insofar as how my joint angles are arranged. The tri bike has the saddle nose 3cm in front of the bb, and the armpads 19.5cm down for this test (about how I would ride a half IM or longer). I measured everything, in particular the angle from pedal axle to greater trochanter to outside end of collarbone (at the AC joint). That angle is a little greater than 90 degrees, with the AC about 8cm above the 90 degree line passing through my shoulder.
I then set up the road bike to match. All joint angles are as close as our measurement tools can allow. The saddle height is tweaked in each case to be as close as I can tell, but I pedal more heels-down on the roadie, so my knee looks a little more extended. The road bike saddle nose is 8.5cm behind the bb. I have had my road bike set up for many years at 11cm behind, but I moved it forward a little for this test to make everything work. The armpads are 9cm below the saddle. Pretty normal road-bike triathlon setup.
Photos:
I’ll being doing some trials in the early mornings over the next few weeks, and I’ll post results. The one thing I cannot control for is aerodynamic differences in the frames and handlebars. No big deal though, since what I’m really trying to do is to find out roughly how much advantage there is in buying a basic tri bike and setting it up aggressively, versus just using the trusty old road bike.
Another interesting outcome will be whether or not I end up with the same Crr figures. I should, of course, but if I don’t it would tell us something about the reliability of the tire testing I did last month.