On tours and brevets I carry a couple of these kevlar Fiber Fix emergency spokes. They are easy to use without having to remove your cassette if a driveside spoke breaks. They are light, cheap and reusable. You can ride on one just like it was a regular spoke until getting a replacement is possible. They will fit any bike so you don’t have to stock spare spokes of every conceivable length you might have in your bike fleet.
Now I must admit although I’ve owned 4 or 5 of these spokes for 10yrs or so I have never used one. I don’t break spokes – due to my equipment choices, the amount of gear I carry and the fact I get my wheels built/checked by a professional wheel builder. Having said that it can and does happen. Even if it’s not my bike I want to be able to get a friend rolling as quickly/easily as possible. You never know when you might get a stick in your wheel and no matter how well it was built – if that happens some spokes will break!
I have spoken to folks that have used these spokes in emergencies and reports have been favourable. I hope my luck continues and I am not able to review this product for you myself…=-)
Now that I am thinking about it I’m going to add a Fiber Fix spoke to my mountain biking tool kit!