Title says it all, how do I keep my bicycle tires from going flat easily? I live in an area with a lot of sharp stuff (think glass shards, nails, cactus, etc)...
There are a number of things you can do:
- Puncture resistant tires. These have kevlar/aramid belting in the tire, thicker rubber or other features that make them harder to puncture. Would need to know more specifics about your bike (especially wheel/rim size) to be able to suggest specific tires, but Specialized, Continental, Schwalbe, and pretty much every other major tire manufacturer have a wide range of puncture-resistant tires. You can probably just go to your local bike shop and ask about puncture resistant tires, or you can order them online a number of places. There's a bunch of good suggestions here for specific types: What type of tires can prevent goatheads?
- Puncture resistant tubes. These seem to be harder to find.
- Slime/goo in the tube. Personally I don't care for this, but some people swear by it. This is a sort of thick goop that goes inside the tube; small punctures will get filled in by the goop.
- Tire inserts. These are kind of like a belt that goes between the tire and the innertube, stopping sharp pointy things from going into the tube.
- Keep tires well-inflated (near the top of the recommended pressure). This reduces the size of the contact patch and makes it more likely stuff will glance off the tire. You didn't mention them in the question, but this also prevents pinch-flats.
- Avoid riding over sharp pointy things, especially when there's water around. It's much easier to cut or puncture rubber when wet, since dry rubber tends to grab glass and metal.
Also, if you do get a flat, make sure to check both for remaining pointy bits and gashes in the tire large enough for the tube to herniate out through.
The question was asked in 2010. I believe tubeless tires were fairly widespread on mountain bikes at the time. However, tubeless tires on road, gravel, and cyclocross bikes were in their infancy in 2010.
It is 2019, and things are substantially different. Tubeless tires with sealant do address the original question. Tubeless products have advanced enough that some riders may wish to consider them. Many performance-oriented gravel riders have adopted tubeless, in part for the flat protection that sealant affords. Possibly some commuter riders could see benefits. Professional road and cyclocross racers seem to be adopting them much more slowly. This is a side discussion, but conventional wisdom appears to be that they are still inferior to tubular tires in those two highly specialized settings. These are for safety reasons in pro road (tubulars will stay on the rim if flat and if properly glued, and can even be ridden while flat) and performance reasons in CX (conventional wisdom is that tubulars can take even lower pressure than tubeless, thus providing more traction).
Tubeless tires are similar to standard clinchers. However, tubeless tires and tubeless rims (with tape, mind you) are designed to form an airtight seal, all on their own, without a tube inside. A standard clincher tire + wheel + tape doesn't need to be airtight. Some relevant reading here.
There is a substantial learning curve to learning how to use tubeless tires, e.g. they can be hard to mount. Actually, they need to be hard to mount so that they're airtight. They require some different logistics from clincher tires, e.g. sealant, tubeless repair products. Also, tubeless standards are still evolving, and some combinations of rims and tires won't seal properly - and it's hard to predict which combinations don't work.
With sealant, they are more puncture resistant than tubed clinchers
You can (and mostly should) add latex sealant to tubeless tires. When the tire sustains a small puncture, sealant often plugs the hole without much air loss. This factor could address the original question about riding a bike in an area where the roads have a lot of glass and other sharp objects. This video by the Global Cycling Network demonstrates sealant in action. (Note: the video had a paid promotion by Mavic, and was demonstrated on Mavic wheels and tires.) Additionally, you aren't at risk of traditional pinch flats - there's nothing to pinch. These two factors could address the original question about riding a bike in an area where the roads have a lot of glass and other sharp objects.
The following paragraph mainly applies to performance-oriented riders rather than more casual riders or commuters. You can run lower pressures in a tubeless clincher than in a tubed one. This matters for gravel and cyclocross riders: it increases traction at no greater risk of pinch flats. Last, some argue that tubeless tires with sealant have lower rolling resistance than clinchers. This point may be in disupte. Clinchers with latex tubes should generally have comparable rolling resistance to an equivalent tubeless tire. The last link by Bicycle Rolling Resistance compares 3 tests on one (tubeless-ready) MTB tire. The same group found similar rolling resistance between the 25mm Continental Grand Prix 5000 tubed clincher version with a latex inner tube and the 25mm tubeless specific version of the same tire with sealant.
With large punctures or cuts, sealant won't work, and you'll have to insert a tube or a boot into the tubeless tire (they do work with tubes) and pump it up. However, many punctures that sealant won't quite seal can be plugged with a quick, easy to use tubeless plug that you can just stab into the tire without having to dismount it. One example here. A large cut will obviously defeat a tubeless tire, just as it would defeat any tire.
Why not put sealant in tubes?
You could. The folks at Slowtwitch.com tried this in 2014. I don't believe tubeless sealants have advanced night and day in 5 years, so the results may not hold entirely. Sealant in tubes actually did seem to work, despite not technically having been designed for use in tubes. Slowtwitch observed that the sealant seemed to work better in latex tubes rather than your usual butyl tubes. Also, this 2015 Q&A on StackExchange addressed the issue. One poster there thought you would be better off with Slime tubes.
Latex is used by racers, as its lighter and lowers rolling resistance. However, it does require you to pump your tires up more frequently.
Tubeless sealant can eventually clog your tube's valves. Tubeless riders will replace the valves or else just the cores on the valves. Many tubes are available with removable valve cores. If you must use tubeless sealant in regular tubes, make sure you have removable valve cores.
They have downsides
Tubeless tires can be hard to mount onto rims in general. You do need to add sealant periodically. Also, in general, your wheels need to be tubeless compatible. Many current performance road, gravel, and cyclocross bikes are sold with tubeless compatible wheels.
With caution, some rims that aren't specifically tubeless compatible may be convertible to tubeless use. If you are on road rims, I would urge you not to try this under any circumstances. In the cyclocross setting, some rims may be convertible. If you are a commuter rider, then if your tire widths and pressures are closer to CX and gravel tires, it may be worth doing some research. Please do not do this lightly.
You'll need tubeless-compatible tires. In the early days of tubeless, riders frequently converted used mountain bike tires and rims that weren't specifically designed as tubeless. For performance road tires, I would not even consider this because the pressures are much higher. On cyclocross bikes, in the early 2010s, people did have success converting some not-technically-tubeless tires to tubeless use. For commuter tires, I suspect your success will vary depending on your tire width and pressure, but I haven't found any specific recommendations.
For tubeless tires on performance road bikes, it may be possible to burp the tire (i.e. cause the sidewalls to momentarily gap the rim when you hit a hard object). On a mountain bike tire, the pressure is low and the volume is high, so they only lose a few PSI when burped. Road tires have low volume and high pressure. Lennard Zinn (link above) feels that because of the high pressure and low volume, you're likely to lose a lot of pressure, and that can cause you to lose control of the bike. I haven't got any experience with road tubeless and I have no idea how widespread this phenomenon is.
One larger issue: there is no universally accepted tubeless standard at the time of writing. One thing such a standard would do is state acceptable an acceptable mean diameter and variance of the diameter for both rims and tires. Right now, you can have some tires that fit too loosely on some rims to seal (like this Stack Exchange poster), or some tires and rims that are too tight to mount at all. It is possible for your tires to blow off your rims entirely if they don't fit well. It should be rare if they were mounted by knowledgeable mechanics. One engineer thinks that blow-offs may be an issue inherent to the high pressures in road tubeless, and he doesn't recommend that his company's tubeless tires be inflated over 60 PSI lest you stretch the tire bead too much. That pressure recommendation should only be an issue for performance road bikes and tubeless tires, but loose fit could potentially affect all bike types. Industry bodies are reportedly quite close to finalizing a standard. Issues of tire-rim compatibility should gradually disappear.
Who could tubeless tires work for?
Subjectively, riders I talk to seem to think that for mountain bikes and gravel bikes, tubeless is clearly better than tubed clinchers. "Better" includes flat resistance and all other performance characteristics.
For tubeless tires on performance road bikes, the benefits aren't as clear. Most of the roadies I know don't have tubeless road yet, or have tried it and not found it to be worth the advantage. One person I talked to said it didn't seem to seal that well on his road bike, but others have disagreed.
I'm not sure about commuters. I suspect that tires on commuter and hybrid bikes span the width from wide road tires (about 28mm, 60-80 PSI?) to gravel-ish size (40mm or thereabouts?), with corresponding air pressure. If you run pretty wide tires, and you're willing to accept the learning curve and logistics involved (i.e. carry spare tube, carry a tubeless plug, replenish sealant, have tubeless ready wheels), then maybe this is worth considering for some commuters. Some of these riders probably already have a performance bike with tubeless, so the learning curve and logistics aren't relevant. If you commute on tires closer to road bike pressures, e.g. 28mm tires, then I think it's less likely that tubeless has an advantage over clinchers. I realize this is a subjective opinion; I haven't found any other expert opinions to back this up.
Side note on tubulars
Tubular tires are not the same as tubeless. You glue tubulars onto your rim. Tubulars can accept sealant as well. Alternatively, they can be safely ridden for some distance when flat. I'm only including this for completeness; they require specialized rims and you need to glue the tires on, and you need to carry a pre-glued tubular for flat repair rather than just a tube. When you puncture a tubular, if sealant doesn't repair it, you'll need to cut the tire open, patch the tube inside the tire, then sew it back up (or you can pay someone to do this; Google tubular tire repair for options). I'm including this for completeness. It's not an option most people should consider. Pro road racers still use them, and current opinion seems to be that they have performance advantages over tubeless in cyclocross (although this may be slowly changing).
There are good puncture-resistant tires. I personally use Schwalbe Marathon Plus.
I used to get flats all the time. Then I started to notice that most of the time there were two small holes in the tube. This is the classic "snake bite" or "pinch flat" that results from under inflation. On my road bike I now keep at least 100 PSI in the 20mm or 23mm wide tires and (knock on wood), I haven't had a flat in years. Wow, I hope this doesn't jinx me.
Additionally old timers will sweep their tires when they notice that they just ran through glass. This is a tricky maneuver where you hold a gloved palm on each tire as you ride along to sweep any glass from the tire. The thought is that on the first time around the glass is just sitting on the surface and it takes a couple of rotations to fully push the glass shard through the tire and into the tube. I shouldn't have to say you need to be extremely careful with this, one slip up and you'll break a wrist or worse. I typically stop and manually sweep the tires, a lot safer. There used to be some company that sold little wire units that would lightly rub the tire as it rotates with the thought that it would keep the surface clean and reduce punctures. Does anyone remember who made those and what they were called? This was in the late 80's early 90's when I remember seeing them.
Just contributing my two cents, I learned the hard way that the reason for frequent flats could be that the Rim Tape (tape that sits between the Rim Spoke nipples and the tube) has aged and the tube is getting poked by the spokes - causing micro punctures. Filing down the spokes that poke through the spoke nipples, or using a good Rim Tape (sometimes clear medical tape also helps - wound 2-3 times around the rim) should help.
Also - see if you can get Butyl tubes - tougher and better.
Obviously you need to solve the puncture problem first. But once you've resolved that, you can use nitrogen to inflate your tires and solve the leakage problem as well. It doesn't leak out as fast as air. My riding buddy keeps a tank handy and over the last couple years he's been gradually "converting" my bike tires over to nitrogen as/when they need air. They are definitely losing pressure more slowly.