TL;DR: Who's done testing, and what were the results, finding the maximum amount of traction a road bike tire can generate.
After watching some videos of TdF descents, and discussing them with some of my friends, we have some questions.
First, the lean angles achieved are less than spectacular. MotoGP bikes are getting all the way down to 63 degrees of lean. I do understand that is.. remarkable, requiring tuned flex in the sidewalls, headstock, and swingarm, along with some hilariously sticky tire compounds.
I've read tire reviews, and they almost never seem to concentrate on traction. Traction seems to come as an afterthought, after rolling resistance, aerodynamic benefits, noise, tread life, and even color.
I've never run into a ... I was about to tell a lie, but I'll share that story at the end... I've almost never run into a bicycle tire without enough traction to allow me to pick the back tire up with brake force alone. So longitudinal traction isn't a question. But I have been caught out and lost traction horizontally.
So, has anyone done testing, and reported the data, on how far a road bike can lean over?
My hunch, is that a road bike, with sticky tires would be able to get well past 45deg. Everything on a bike is set up to lead to good traction, and good recovery from slides. The rider is high up, so the CG is a long distance from the tires, that makes the pitch moment long. The wheels are high rate springs, and the rims and tires are light, so should be able to follow the road well. I think the biggest failure would come from the headstock not being stiff enough to allow the wheels and fork to do their thing.
Since I teased it.. I bought a folding bike. A clone of the Sinclair A-Bike. It came with solid foam rubber tires. The brakes could lock either tire up. And even a fast application of steering would cause the tire to slide. That wasn't the bikes only problem.. but that is still another story.