I've worn my cycling shoes, with cleats, onto the plane on quite a number of occasions, and I know lots of others who have as well. Sometimes they set off beeping when I went through, sometimes they didn't (scary thought!). When they did, I just told the person with the wand that I was wearing cycling shoes with cleats, and they sent me on my way.

A friend of mine had his trigger the sensors in Singapore, and he had a few rather frightening moments trying to explain his cleats to them ... but after a few minutes, they seemed to understand and let him through.

For some reason, the officials have seemed much more concerned when I inadvertently tried to board with a rat-tail comb, and a teensy little eyeglass screwdriver that was 75% flimsy plastic.