Ping!

Crapaud

A 'ping' sound from wheels usually means that the tensioning of the spokes is out; some are too tense and others are loose, IME. When repairing / getting the wheel repaired, get the wheel re-tensioned. It's likely that the other wheel will need attention as well, so get that checked too.

With one spoke missing, the wheel would buckle anyway. In the past what I've done is use the front brake only and braked early, and gently, and limped home. If the brake is rubbing against the rim, loosen off the brake.

You should be fine for 4 miles, but one spoke going puts other spokes under greater tension and it would only be a matter of time until more spokes fracture.

ris

i had a rear spoke go with a 'ping' over the summer, and despite trying to get the weight more forward and coasting downhill for 2 miles the rear wheel went out of true very quickly.

i walked the last 3 miles to work and got a new rear wheel (it wasn't the first spoke to go in the wheel that summer and the rim was dead).

andrew_s

The effect of a broken spoke depends largely on how many spokes there are in the wheel. If it's what used to be a standard wheel, made up from hub, unrelated brand of rim,and 36 spokes, then there won't be all that much effect. You should just be able to carry on riding until you can get it fixed. If it's a modern factory wheel with not very many spokes, like a Mavic Ksyrium or whatever, then a broken spoke can put the wheel so far out of true that the bike is unrideable.

Assuming a standard wheel, get the spoke replaced as soon as possible. The sooner it's done, the easier it is, and the less effect there is on the other spokes in the wheel. If done immediately (eg by the roadside when on tour), then truing the wheel afterwards is just a matter of tightening up the new spoke so it's as tight as the old one was. If you've left it a while, or if you had to adjust spoke tensions to allow the buckled wheel to fit between the brakes so you could get home, then a full re-trueing will be required.

It's usually the hub end of a gear side rear spoke that breaks, and it's usually due to metal fatigue in a wheel that wasn't built all that well in the first place.
If you get more than 2 or 3 spokes go in the same wheel, all the others are probably already on the way out and it will be better to get the wheel rebuilt with a full new set of spokes rather than carry on replacing spokes one by one as they break.