Rim damage - worth saving old bike or not?

[Yellow Saddle]

Whilst we are on the subject, how best to get a dented rim straight again?

First thing to realise is that aluminium work-hardens. In other words, if you bend it, the bended part is harder than the adjacent bit. When you then attempt to bend it back, you get an S-bend because what you are trying to do if you don't know this little quirk, is to bend the bend. The bend will refuse to bend (fully) and a new bend will form next to the old bed.
Therefore aluminium should be beaten into submission. On a rim you do it as such: Remove the tyre and tube and solicit the help of a helper. The helper's job is to keep the flat part, in this case the brake track, flat on a flat anvil of sorts. It could be the little flat anvil on top of a vice or something like that. It has to be harder than the rim, so wood won't do.
Now, from the inside of the rim's U-shape, you hammer the dent outwards and flat onto the anvil.
The anvil should be smooth so that you don't leave abrasive marks on the rim. Also, your tool should be a hammer and hard stick or preferably a nylon rod about 25mm in diameter and 200mm long. A stick works, but only once or twice before it splits.

That rim in the picture is only pinned in place and it was quite fortunate that the damage was done right on the joint, so that it is easy to repair. It gets mor difficult if the dent is further towards the centre of the rim. That's because the spoke bed is highly stressed and hitting it with hard blows makes it settle towards the spoke tension direction. To avoid that the spokes should be loosened in that region before hammering away.

A skilled mechanic can fix the rim in the picture in 20 seconds. It is a shame to have to throw it away since the brake track is still good, the spokes seem fine and there's not much corrosion at all.

Save the rim. Yet, I'm not convinced it even needs work. If the brake doesn't pulse when applied, leave it.