I've gotten heavily into the comment threads of a few bicycle-oriented essays here recently, and got to thinking that with all these comments I've added to them, I could probably come up with an essay or two on the subject. I decided to start with the deceptively simple subject of changing a bicycle tube. That's what you're really doing, changing a tube...but we think of it as changing a tire, hence the title of this essay.
Your average bicycle repair staffer can change a bicycle tube in a few minutes, and it's not just because of having that handy rack to set the bike up on. There are a number of steps involved, and none of them take much time or are very complicated, but if you know them all, you're much more likely to safely change your tube and have it stay solid for some time to come. But it takes a bit of practice to get handy and fast at all of this.
However, knowing how to change the tube isn't all there is to it. Knowing how to protect the tube is also important.
I'll try to take a shot at all of this here, and will of course greatly appreciate any feedback or corrections with regards to my technique and information.
Protecting the tube
- Types of tubes
Cheap tubes, better tubes, thorn-resistant tubes, solid rubber tubes.
Solid rubber tubes are not going to give you an easy ride, but they are the last word in fool-proof. They probably don't come in all sizes of wheel diameter, but I've often thought of buying a standard 26" wheel diameter bike and installing them, just to have a bike that's more foolproof here where I have a lot of trouble with thorns (more below about thorns).
Thorn-resistant tubes may help a bit; basically they're tubes with slightly thicker rubber. I haven't been all that impressed with them, though.
Cheap tubes I stay away from. A good standard tube with a good strong valve that won't break easily, is what I look for. You can get tubes with Schrader valves or Presta valves; tubes with Presta valves may leak less; I've never been clear what the advantage was there. However, if you want to use Slime (tire sealant) and you get a bike that requires Presta valve tubes, and you can't unscrew the valve core, then you'll have more trouble using the slime, unless you buy pre-Slimed tubes. You can inject Slime directly into the wider, open-mouthed Schrader valve, but the Presta valve must have its core removed, and not all Presta valve tubes have unscrewable valve cores, and those not available in all sizes.
Your bicycle's wheels will be drilled for Presta or Schrader valves. The latter are the larger holes. Presta valves are thinner and have a little screw-on thing at the end that helps to seal the valve.
Schrader valves are more common with less expensive bicycles. Sometimes people redrill Presta wheels to fit Schrader valves.
In any case, flat tires can be a result of valve problems as much as punctures, so it's good to have your valve be (a) good quality, well made, and (b) stabilized and centered, as your bike tube will potentially shift slightly while riding and put stress on the valve.
- Types of tires
I like a tire with a heavy tread, that won't wear down fast, as I tend to use my tires a little longer than I should. I also like higher-end tires with Kevlar linings. They're worth the investment. In some cases, for some tires, there may even be better, more high-tech linings around. Keep this in mind when you buy your bike - wheels with a 26" diameter are pretty easy to buy parts for. That's about the standard diameter. I have a lovely 28" diameter wheel bike, but there are only so many kinds of tubes and tires I can find for it.
I also ideally like a "hybrid" bike with semi-mountain bike tires, but not really wide. About halfway between a touring bike and a mountain bike. I find this ideal for the street, as the tires have reasonable traction and don't get caught up too easily in crevices (grates, railroad tracks, etc) but at the same time aren't overly high-friction.
- Tire liners
These are dense plastic strips you put between your tubes and the tire. I really recommend them if you live where there are a lot of bad thorns or other really hard and sharp road debris. I'm not really sure what they're made of, but they're pretty standard and very tough. I've never seen anything go through them; my problems with punctures are with sharp pointed objects that get into the tire (and then puncture the tube) above the liner, which is barely an inch wide and only covers the bottom inside of the tire.
Slime is tire sealant; this is a trademarked product, and I thusly link their site here. Some people swear by it, others don't find it useful. It does pick up the weight in your tire, and it does go bad after maybe a year or so. However, it does work, to at least some extent, with smaller punctures.
I would recommend using it by hand more than buying pre-slimed tubes, though, unless the Slime people have started buying tubes with better quality valves than they were a couple of years back. It is, though, an inventive and useful product, if used wisely. If I was riding a bike with Schrader valves, I'd definitely use it. But I like a good quality light tube, and the Slime people were using lousy quality tubes for their light product a couple years back (I read other complaints about this on teh net) and the valves were crappy. I hope they've fixed that. However, their heavier pre-Slimed tubes, though a bit pricey, were very reliable in my experience, but I found them hard to obtain after awhile, and I just got into buying good tubes, using tire liners, etc. I do have 28" wheels, as I said, so it's not always that easy to find parts. I don't want to diss Slime at all, it's just a matter of combining it with good tubes.
Okay, here's where we get into how to change a tire. First, either you have quick wheel release levers or not. If you don't, get a couple of good adjustable wrenches (or sized crescent wrenches) for each nut on either side of the axle. Don't just try to remove the wheel by unscrewing the nut on one side; it will hang up on the other side. Go back and forth to gently remove the wheel.
Okay, now you have the wheel off. What you need now is a set of three plastic tire levers, not screwdrivers or other sharp things. Tire levers have an angled flat end that hooks into and under the rim of the tire, and then you pull out and back, and hook the other (curled) end onto a spoke.
Then you move a bit down the tire and do it again with the next tire lever, and walk it down or back from the other side with the third one.
I have best luck starting around the valve, and I usually only need two to get the rim free, but sometimes need the third one.
Once you get enough of the rim out, you can pretty much extricate the rest of the tire with your fingers.
I won't go into patching tubes here because I have no experience with that. But if you are putting in a new tube, first go over the inside of the tire by hand, look for any sharp intrusions. Use a big needle or something similar to pick them out, if necessary.
Replace your tire liner, which I strongly recommend you invest in, and then dust the inside of the tire & liner with baby powder. This will help keep the new tube from getting hung up, since it will shift slightly as you inflate it and start using it, especially if the tire assembly gets hot.
When you put in the new tube, start by putting the valve loosely into the hole in the wheel. If you have a Presta valve, put on the valve ring but only loosely. In either case, seat the valve carefully, make sure the tube is well lined up with the wheel's valve hole.
Then take your bike pump (I recommend getting a good floor-standing pump, and probably a good little lightweight one for travel) and inflate the tube loosely. This will help you seat it in the tire and within the rim of the wheel, and help keep the tube from having any flattened edges getting caught up between the wheel rim and the tire rim.
Then you work the tire and tube onto the wheel. I don't use my tire levers much at that point but beginners may find them useful.
Now you are ready to test your seating. Inflate the tube a bit more, and check and work around the rims. Make sure that there is no bit of the tube caught between the wheel and the rim of the tire. If you're new at this, it doesn't hurt to let some air back out of the tire and retry it, if you didn't get the tube seated right within the tire and the rim on the first try. You don't want a "pinch flat." You can tell when you're risking one, btw, if you take your bike out and it starts bumping, that's a sign that you didn't seat the tube right.
- Things that pierce tubes and tires how to avoid them
Wire. Hard to avoid that, and it's one of the worst, because a bad piece of wire can get up into your sidewalls and thus around your plastic tire liners, and right through some of the built in tire lining in the tires themselves and then into the tubes.
Goatheads. Similar to wire. Tribulus terrestris is actually a medicinal plant, and has all sorts of other fascinating history as well; but its seedheads are much hated by bicyclists, as these "caltrops" (another common name for T. terrestris (because of their caltrop-like thorned structure) have extremely strong little thorns that can get through all sorts of things...including bike tires, including Kevlar lined ones, in my experience.
How to avoid goatheads and wire: ride out away from the gutter, especially during goathead season (latish summer). Wire is more hit or miss, but if you live where Tribulus is happy, goatheads are guaranteed. Note that they will wash out of roadsides during heavy rains, so be especially careful then. I like to stay off the roads a bit then, when I can, until the automobile tires pick them up (those tires are too thick for goatheads to pierce.)
I hope this is a helpful piece. I hope other people can add some comments with suggestions about things I missed or didn't know about. Thanks in advance, and happy bicycling!