It’s been a few days or weeks since you last rode your bike. And, although you clearly remember topping them up with air on your last ride, the tires have become soft and squishy.
Aside from having to whip out the pump and fill them back up, what does this mean, really? If the tires on your bike are constantly losing air, does that mean you need to go to the bike shop?
All bicycle tires deflate and lose pressure at a rate of 1-30 PSI per day, wether they’re brand new or worn and torn. This happens more so during storage and less so with daily use. It’s also why experienced cyclists check the tire pressure daily.
There’s a simple, logical reason behind all of this.
Tires and inner tubes are made mostly out of rubber. And, although rubber is material that’s solid, waterproof, and relatively dense, air can nevertheless pass through it.
Road bikes with clincher tires and latex inner tubes tend to lose air pressure the fastest, often at a rate of 30 PSI per 24 hours. Without daily top ups, a rice bike’s tire can go flat within a few days.
City bikes and children’s bikes have butyl tubes. Because butyl rubber isn’t as permeable to air as latex, tire pressure is maintained longer on these types of bikes, usually up to a week. (If you leave the bike in the garage for a week, the tires will go flat from sitting.)
Off-road and hybrid bikes, because they tend to have tubeless tires that hold air and maintain tire pressure for longer, can last up 1-2 weeks without needing a top up. But even with that said, it’s still recommended to check the tire pressure before every ride.
Nine times out of ten, especially with a new bike or a new pair of tires, you may think that the tire is punctured or the valve is leaking, when you really should be using the pump more.
What Can Cause Your Bike’s Tires to Lose Air Faster
There’s air loss… and then there’s air loss.
If you topped up your bike’s tires to the correct pressure yesterday and you already have flats this morning, you most certainly have a problem.
The root cause of this problem can be one of several things, depending on the age and the condition of the tires. And knowing how to get to the bottom of it can mean the difference between a quick fix—and wasting time and money on the wrong thing.
What can cause your bike’s tires to lose air faster?
- Age. Rubber tires and tubes have a useful life of 4 to 6 years. After this time, the rubber begins to degrade and the tire must be replaced. Look for dry rot.
- Wear and tear. A relatively new tire can wear out quickly with daily commuting, long touring, or extreme mountain biking. Inspect the cords for damage and the sidewall for cracks.
- Punctures. Thorns, rusty nails, and pieces of glass are the most common causes of punctures. Some punctures and small enough to be patched up or sealed. Others are too big and render the tire useless. Check the tire and tube for punctures.
- Bad bead. If your tire has a bad bead, it won’t be able to fit tightly to the rim. This can lead to punctures on tires with inner tubes and loss of air pressure at a faster rate on tubeless tires.
- Leaky valve. Leaky Schrader valves tend to have loose cores; leaky Presta valves tend to have loose locknuts. Apply soapy water or saliva to the former and look for bubbles. For the latter, remove the tube and submerge the valve under water to see if air escapes.
This checklist should help you track down 99.9% of the problems on your bike. Add this post to your bookmarks and refer back to it when you need a refresher. Remember, though, that the top cause of leaky tires is a forgetful rider.
How Can I Prevent My Tires From Losing as Much Air?
If your bicycle is equipped with clincher or tubular tires, check the tire pressure daily and don’t ride with underinflated tires. The tube can get pinched between the beads on the tire and the edges of the rim—and get snakebite punctures.
Regularly inspect your bike’s tires for cuts, cracks, and punctures, especially if they’re several years old or have high mileage. You can fix inner tubes with patch kits and tubeless tires with Slime sealant.
Slime sealant’s my favorite. You don’t need to remove the tire to install it, it works instantly and doesn’t need time to dry, and it keeps plugging new punctures in your tire (as long as you don’t blow the tire out and they’re not too big) for 1-2 years.
True your wheel. If your wheel needs to be trued for one reason or another, the tubeless tire won’t sit firmly on the rim and will lose pressure to varying degrees as it rolls.
If you find you are pumping your bike tires more than you thought you would, don’t worry! Air loss is normal. Get a good pressure gauge and pump, keep your tires inflated correctly, and keep an eye out for damage and debris.