Why am I getting all of these flats?

Often people wonder why they get so many flats on their bikes.  I’ve heard things like, “This is my third flat in just under a year.  This is so frustrating!”

Flat tires are (to some extent) a part of cycling.  There are things you can do to minimize the number you get, and with a little luck you can ride with very few flat tires.

One reason that bicycles get so many more flats than cars is that their tires are much, much thinner.  Bikes don’t have the same suspension that cars have (if they have any suspension at all) and they rely mainly on their tires to absorb road shock.  A thin, supple tire casing allows the bike to absorb small irregularities in pavement and improves overall handling and feel.  A bike with tires as thick as car tires would ride like it was on solid rubber.  Solid rubber tires have been tried various times since the invention of the pneumatic tire.  They generally just remind people why we went away from solid rubber tires in the first place.

Tubes are generally punctured in one of five ways:
1. A foreign object enters from the tread or sidewall
2. The tube is punctured by a spoke head from the inside
3. The tire pressure is low enough that on a bump, the rim compresses all the air out of it and cuts two tiny holes in the tube, also known as a “snakebite” flat.
4. The tube was installed incorrectly and gets pinched between the tire and rim before being inflated.  This will cause it to split wide open and generally makes a very loud bang.
5. The tread has a large enough hole in it that the tube can push through.  You’ll often see a star-shaped hole where it burst.

So, how do you prevent flats?

Always ride at the recommended tire pressure.  Also, ride on tires that are in good shape.  As the tread wears down and gets thin, the tire when viewed from in front or behind will look squared off rather than round where it would contact the road.  More tread = fewer flats.  If the side walls have large cuts, you can see threads, the threads are cut, or there is a suspicious lump or bulge, the casing has been damaged enough that you need a new tire.

Make sure your rim strip is in good shape.  If the cloth or rubber strip covering the spoke heads inside the rim is worn or torn so that you can see the sharp metal heads, it needs to be replaced.

Finally, don’t ride over glass, staples, tacks, thorns, sharks’ teeth, pitchforks, etc.

I’m still having problems/I want bulletproof tires!
If the regular methods aren’t enough for you, you have a few options.

1. Sealant
Some people like to fill their tubes with Slime or other sealants.   Generally, bike tires run at higher pressures and the sealant gets pushed out before it can do its job.  It works better in things like wheelbarrow tires.  Don’t be surprised if you still flat, and get a green, goopy mess.

2. Tire liners
Tough, plastic tire liners that go between the tube and the tire can help prevent punctures.  They do reduce ride quality.

3. Kevlar/Puncture Resistant Tires
You can also purchase tires that are built with a puncture-resistant belt inside of them.  This is the same concept as the tire liner, but its built into the tire itself.  They work reasonably well; the best tires we’ve seen are Continental Gatorskins (which are tough to mount), and Specialized Armadillos which are backed by a puncture-proof warranty.  Neither is cheap, but they beat the most expensive options which is…

4. Tubeless tires
Ditch the tubes.  If you have rims built for tubeless tires or buy a conversion kit you can run high-quality tires that use a high-end latex sealant.  The big difference between this sealant and the kind you typically see in Wal-Mart is that it works.  It’s designed to work with the tubeless tires and we’ve seen it seal holes from large nails.  It’s truly impressive stuff.  The conversion (if you need it) will run $90+ and is a one-time expenditure.  For road bikes the tires are around $120 each or so, but they ride like butter.  Mountain bike tires are cheaper.  Some sealant manufacturers claim that their particular brand will work with any tire, even regular, non-tubeless designs, but we’ve seen mixed results.

Final Thoughts
Punctures are a part of biking.  No system is bulletproof, and eventually you will get a flat.  The best thing to do is to learn how to deal with them out on the road and carry a spare tube and mini pump or CO2 inflater.  When flats become a manageable bump in the road rather than a ride-ending crisis, they become far less frustrating.