So what does a bad bolt look like? The following diagram shows a number of old bolt fixtures. It is unlikely that any of these ancient bolts or hangers would hold body weight...much less a fall.
The question then becomes, what should you do if you come upon an ancient bolt?
First, remember where you found it. Keep track of bad bolts and report them on you local climbing website. There are a few good Samaritans out there looking for bolts to replace.
Second, decide whether or not you need it. In some cases, there is good natural gear nearby. In others, you will have to commit to using the bolt. If you do have to use it, continue climbing and try to get something solid in as soon as possible. If it doesn't look like solid gear is a possibility and the terrain above the bolt is difficult, consider bailing.
If the bolt is part of an anchor system, you may be required to "beef-it-up." Some climbing instructors use a 12 point rating system to evaluate an anchor. Different pieces of gear are given a value of 0-12. Once you reach 12, your anchor is considered "bomb-proof." In other words, a good cam is worth 4 points, a good bolt is worth 6 points and a giant tree with a good root base is worth 12 points. Most of the time climbers have to equalize a number of different pieces in order to bring the value of their anchor up to 12.
Bolts like those in the diagram above should only be given a value of 1 or 2. Many people have been taught that an anchor is composed of two bolts or three pieces. The reality is that an anchor should include whatever you need in order to make it worth 12 points. If two bad bolts are equalized, the anchor would only have a value of 3 or 4. In such a case more pieces would have to be added to supplement the bolts.
What then, does a good bolt look like? The following diagram shows a series of bolts that will hold a substantial fall if they are placed correctly:
Don't get lulled into a sense of complacency by shiny new-looking bolts, a small percentage of these are bad too. Some bolters use substandard equipment because it's cheaper. Others may place a bolt incorrectly. These are hard things to evaluate on the sharp end of the rope when your forearms are completely pumped out and you're about to whip.
There are three ways to evaluate a route with new-looking bolts prior to climbing it. First, look through the guidebook and see how many routes the first ascentionists put up. The more routes they have to their names, the less likely it is that they made a mistake bolting. Second, the more popular the route is, the more likely it is that the bolts have been evaluated by people who have placed a lot of bolts. Indeed, on a popular route it is also more likely that the bolts have held falls. And third, question the locals. If there is something amiss on a route, local climbers are usually aware of it.
People laugh when I tell them that I trust traditional gear more than I trust bolts. The reality is that with trad climbing I can always assess my own placements and I can always adjust them until they're perfect. There is little that I can do with a bolt that was placed by a stranger. And even less that I can do if it's thirty years old. That's not to say that I don't trust new-looking bolts. I do...but I do so with reservations.
(Diagram Credits -- "Bolts: Bomber or Time Bombs" by Todd Vogel. Rock and Ice #62, July 1994 -- Reprinted at the American Safe Climbing Association website.)
--Jason D. Martin