Sunday, I participated in a group bike ride, riding just for the heck of riding, not riding to get somewhere, a rare thing for me. At the farthest point from the ride start/end point, someone in our group got a flat. Not me (that would have actually been better).
I pulled up next to the hobbled bicycle with great intentions of quickly remedying things, only to find out that the rider didn’t have a spare tube. My spare tube was the wrong size (and wrong valve type) and the only other spare tube in the group was also the wrong size. No big deal, I had a patch kit.
(As you will see below, unless you get lucky and find an obvious puncture-causing agent in the tire and the corresponding puncture in the tube, a patch repair kit will do relatively little good on the road. There’s a good chance you’ll need access to a sink full of water to identify the hole in the tube.)
I whipped out my flat repair kit, we removed the wheel, and I inspected the outside for offending objects. Finding none, I removed the tube and inspected it. No great, huge, obvious gashes to patch, just this area of roughness and wear that I thought may have indicated a pinch flat (what you get if you ride on under-inflated tires). I proceeded to apply three patches to cover the entire suspicious area.
Long story short, we rode a bit farther, and the tire went flat again. At this point, getting closer to the end, we switched to the “add more air and keep riding” approach. Either my [hastily applied] patches didn’t hold, or I misidentified the problem.
Moral of the story? Whether you’re a novice or professional biker, if you only carry one repair-related thing on you when you ride, carry an extra tube (of the proper size). Even if you’re not carrying tire levers and a pump, with a properly-sized spare tube you at least stand a chance of someone else being able to help (more likely if you’re riding in an area with lots of other bikers). If you ride in areas where you rarely see other bikers, or you just want to be prepared (a good idea), invest in a decent hand pump ($30-$40, get one with an inline pressure gauge), tire levers ($3), and a patch repair kit ($3).
Also. Check your tire pressure and keep your tires properly inflated (see sidewall of tire for pressure range for your bike). Bicycle tubes naturally lose air very quickly, so it’s a good idea to check, and most likely add air, once a week (or before every ride if you ride less frequently).