Forks that are bent are bent because of an incident. ("Just riding along" being a common one. (no, really, running into something)). Been there, done that, twice, on Aluminum forks. You get them replaced, and it's fine.
Bending the rear triangle out 2mm on a side is well known for steel bikes, first in the 6sp->7sp transition (120->126 mm) and then in the 8+ 126->130mm transition. There are even bikes with a 132.5 spacing so that they can take 130 or 135mm hubs.
You can absolutely make metal bikes stiffer or more flexible, directionally. Titanium pivotless bikes are the poster child for that, but people have been monkeying with tube shapes and sizes forever.
Descending at 30, 40 or 50mph really isn't that big of a deal on a competent bike. They track, they're more stable at speed, and sitting up will be a hell of an airbrake to start. You often don't even need the brakes. Just be careful if you do it where you have a T junction at the bottom or side traffic. (e.g., queen anne hill in seattle)
Bending the rear triangle out 2mm on a side is well known for steel bikes, first in the 6sp->7sp transition (120->126 mm) and then in the 8+ 126->130mm transition. There are even bikes with a 132.5 spacing so that they can take 130 or 135mm hubs.
You can absolutely make metal bikes stiffer or more flexible, directionally. Titanium pivotless bikes are the poster child for that, but people have been monkeying with tube shapes and sizes forever.
Descending at 30, 40 or 50mph really isn't that big of a deal on a competent bike. They track, they're more stable at speed, and sitting up will be a hell of an airbrake to start. You often don't even need the brakes. Just be careful if you do it where you have a T junction at the bottom or side traffic. (e.g., queen anne hill in seattle)