Is it just my bad eyesight or is that really a Weinman alloy rim such as what we all rode BITD if we were lucky enough?.....
I would say that it is. Either that or a Birmalux, (which the weinmann was a copy of). Those rims had a welded joint and were indeed rather soft. Single walled rims lack torsional stiffness/strength, so can 'recover' from a dramatic fold-up like that (although they are more likely to suffer one too, of course).
Roadside repairs of any kind that allow the bike to be ridden are 'good enough' to get you home but usually the spoke tensions are all over the place. If you remove a rim like that from the wheel completely, often it can be rendered straight again, using devious bending. Once reinstalled the wheel is likely to be just fine, provided you have not left any sudden kinks in the rim.
The strain in a single wall rim to change its shape isn't very great, and provided the material is soft and ductile, you won't hurt it. However many modern rims are made differently eg
- twin walled
- alloy that work hardens very quickly
- heat treated alloy (for more strength but less ductility)
- (unevenly) machined braking surfaces
all of which make you chances of straightening a bent rim somewhat less.
FWIW is you have a deep section rim and not many spokes, it is possible to make a wheel with adequate radial stiffness. However even if the rim is pretty stiff, the wheel is unlikely to be particularly stiff laterally. When you are giving it full gas up hills and in sprints (which not everyone does for sure), this lack of stiffness is likely to be costing you, even if the brakes don't actually start rubbing (which they often do). A simple test is to see how easy it is to push the rim onto the brake block using your fingers. Obviously this isn't exactly the same as when riding but it is fairly close. Very many modern wheels fail this simple test, because they are basically a load of flexy nonsense. They 'feel wonderful'? Emperor's new wheels...?
cheers