Originally Posted by
KiwiDallas
1. Watching a mountain stage that featured constant cold rain and 45 mph downhills: is there such a thing as rain tires for bicycles? Like car and motorcycle tires get, some rubber compound that grips better on wet surfaces?
Some rubber compounds are better for wet grip than others, yeah. But the low power outputs in cycling (relative to motorsport) put rolling resistance at a high premium, so manufacturers don't always make top-end racing tires that are specifically optimized for wet grip.
The high tire pressures and relatively low speeds of road bikes make them generally immune to hydroplaning, so there's no point making tires with channeled tread patterns. Some tire manufacturers do put shallow "herringbone" tread on some tires in an effort to improve wet grip by getting the rubber to interlock with road irregularities, but there doesn't seem to be consensus on whether this has any actual efficacy.
Oftentimes racers will run a bit lower pressure in nasty conditions.
2. How come just about every cyclist out there is clean shaven? Athletes in other sports who are in their 20s and 30s have some hip-looking growth. Is it aero something? Or tradition?
If you're talking facial hair, it's mostly fashion. It usually has very little impact on aerodynamics.
Shaving the arms and legs, however, has a tangible aerodynamic benefit. And if a crash occurs with nasty road rash, things clean up
far better if there's no hair.
3. What is the point of "chasing down" a breakaway rider, especially uphill? So the pursuit riders catch up with him ... then what happens? They can't slash his tires.
Drafting. The higher the speeds, the more aerodynamic benefit you get from being behind someone.
If you're well behind someone at the top of a climb, but you want to catch up with them, you'll potentially need to spend a lot of time on the subsequent descent and flats putting out a bigger effort than them in order to do that.
But if you catch someone before the crest, you can use their draft to keep up with them at much lower effort. Or the two of you can work together, trading turns at the front of the pair, so that the two of you are able to ride faster than if you were each solo.
4. After a big crash and pile-up .... how do they sort out or assign times to the riders caught in the pile-up, whether they are injured or not, or their bikes broken or not?
They mostly don't.
There
is the "3km rule": if you crash or suffer a mechanical in the last 3km of a stage, and riders from the group you had been in continue up the road and finish ahead of you, then when you cross the finish line you're awarded the same time as those riders.
Other than that, being in a crash basically just sucks, and any time lost due to injuries or bicycle damage is just lost.
5. Mountain stages: what's a typical rear cassette gear pack? They have big gears for the brutal uphills but also tiny gears for downhills - I see them pedaling for more speed when they're already going 45+ mph.
Nearly all 11/12-speed road cassettes have a 10T (if SRAM) or 11T (if Shimano or Campagnolo) small cog.
On mountain stages, big cogs in the ballpark of 30T or even larger sometimes show up.
Related Q: Do riders ever use triple chainrings?
Not pros in the modern peloton. Even if they wanted to use a triple, there aren't really any options for setting them up with the electronically-shifting groupsets that everyone is using these days, and there really aren't many standard options for triples on 11/12-speed drivetrains period. It would be a substantial kludge.