I headed off from my house one Saturday early in my biking career, drooling with excitement for the mountain bike ride I’d been awaiting all week. Then, before I had reached the trailhead, I noticed my rear tire was significantly low. I felt like I was riding through mud – on the pavement! Remembering a gas station with an air pump on my way to the trailhead, I figured I could easily pump up my tire without a wasted trip back to my house.
But, when I tried to inflate my mountain bike tire… AAACK! Foiled! The gas station had a standard car pump and, new biker that I was, I forgot my bike tires have a presta valve. A week of hungering for a mountain bike ride… RUINED! All because of a puny little valve. Oh, the angst. Do NOT let this happen to YOU!
Unless you grew up biking, most of us are so familiar with car tire valves, we assume it’s the only type of valve. In truth, car tires use what’s called a Schrader valve. It’s about the diameter of a pencil and has a tiny “button” in the center that, when pressed, allows air in or out, but holds air pressure relatively steady when not compressed.
Presta valves, on the other hand, are significantly skinnier than Schrader valves. They don’t have a button in the center of the valve and instead have an attached screw mechanism at the tip. When screwed closed, it holds air pressure in the tire. When unscrewed, you can pump air in or release air out.
Presta ValveCurrently, presta valves are the most common type of valve on high-end mountain bikes. Racers and high performance cyclists prefer them. They’re becoming increasingly common – even on mountain bikes on the low-end of the price spectrum.
Why, you ask. (Perhaps with a significant number of swear words as you kick your flat mountain bike tire or throw your useless Schrader pump.) Why use an uncommon, obscure valve that doesn’t fit a standard pump? Is it just to make mountain bike newbies suffer? Why? Why?
No, it’s not just to frustrate you.
Presta valves are generally more reliable and allow pumping your tires to a more precise pressure. By virtue of design, all Schrader valves release tiny amounts of air over time, requiring occasional “topping off”. Having a cap on the valve can significantly decrease the air loss, but it still means, at any given moment, your tire may not have the pressure you pumped it to.
A casual mountain bike rider may not know what pressure they should be riding or even notice when the pressure is off. But for high-speed riders, tire pressure can have a significant impact on speed, race performance and riding safety.
The screw on the tip of the presta valve allows a rider to close off the tube at the desired pressure and not require a cap. Barring an unnoticed leak or a puncture during a ride, the tire will now reliably hold the pressure you want.
You can inflate a presta valve with a common air pump, such as at a gas station or portable air compressor.
However, you need an adaptor that’s ridiculously small in size but huge in importance: a presta valve adaptor.
Here are the steps to inflate a presta valve with a standard pump:
Since more and more mountain bike tires use presta valves, most bike pumps are either universal (meaning one hole works on both presta and Schrader valves) or they have two separate holes, one for each valve type. However, you should always carry a valve adaptor when you ride for situations when a standard pump is the only option. Some cyclists do this by keeping a valve adaptor screwed on their tire valve all the time. Just make sure the valve is screwed closed before putting the adapter on!
Presta valve adapters are extremely tiny and portable.
This also means they’re easy to lose. The good news is they’re fairly cheap. I usually buy a handful at a time and keep one in my garage bike tools and one in my portable tool kit for rides. Having one in your glove box isn’t a bad idea, either!
All bike shops sell valve adapters and some general sporting goods shops and hardware stores carry them as well. You can also buy valve adapters online easily and cheaply.
This simple question actually does not have a straightforward answer. The simple rule is to refer to the tire manufacturer’s specs on tire pressure that are printed on the sidewall of your tires. Consensus of riders is that mountain bike pressure should be 30 psi on the front tire and 33 psi for the rear tire. This information should serve you well if you have only a casual interest in mountain biking and are doing entry-level to intermediate trails two or three times a month.
However, if you spend a significant amount of time on your bike (and an equally significant amount of time dealing with pinch flats, blowouts or skidding out on corners), you’ll want to dive deeper into the science of bike tire pressure.
DIY Mountain Bike has a fabulous, in-depth article and survey results examining appropriate bike tire pressure.
The fastest and easiest (and cheapest) way to check your tire is with your hand. When you squeeze it, it should be hard in the center with only a tiny bit of give farther out on the tire near the treads. A hand test, however, is – not surprisingly – not very accurate!
If you want to be precise, a tire pressure gauge will be necessary. But be warned: tire pressure gauges are notoriously unreliable and the sensitive sensors are easily broken. For my recommendation, read my tire pressure gauge product review.
If you’re in a pinch (perhaps literally!), and you don’t have a universal pump or a valve adapter, you can modify a tube cap to create a functional adapter using a presta valve CAP.
Find the place on the valve cap where it gets smaller. Cut at that spot with scissors or whatever you have that will do the trick. Throw the tiny tip away.Remember to screw the tire valve shut after inflating! I know you’re tired of hearing that, but it’s important.
Now that you know everything you need to about how to inflate a presta mountain bike tire, you’ll never find yourself hungering for a ride and find yourself deterred by a standard tire pump!
And don’t forget to screw the presta valve closed…
Professional writer Kat Jahnigen was 2 miles from the nearest village – and roughly 2,310 miles – from the nearest English-speaking town – when her bike tire burst. At that time, she was a college student on a bike trip across the desolate, rocky island of Crete. It suddenly occurred to her that it would’ve been good to learn some basic bike repairs before setting off on a solo bike trip.
Check out Kat’s website WriteHire at writehire.net.
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All bike tires slowly leak air every day. Even if you’re an occasional rider, and you only take your bike down from the bike rack once a week, the tire pressure will still decrease. Before you ride, you should always check your tires’ PSI and, if needed, inflate them with a floor bike pump or a handheld pump.
On the sidewalls of your tires, you’ll see the manufacturer’s recommended pressure range for PSI (pounds per square inch). Different bike tires have different ranges, and narrow tires need more pressure than wide tires. The recommended PSI for different tires are:
Experienced cyclists can often estimate whether their tires need to be pumped by pinching the tire between their thumb and forefinger.
The more accurate way of knowing when your tire should be pumped is by measuring its pressure with a pressure gauge; if the air pressure is measured below the recommended PSI, it’s time to pump.
First pump your bike tire to the middle of the range for the recommended PSI. You also need to take your body weight into account. Tires that bear a heavier rider need more PSI. Weather conditions and terrain also affect how a bike rides, so you’ll need to experiment with different PSIs to feel what’s most comfortable to you.
A Schrader valve is the type of valve you’ll find on car tires, older bike tires and mountain bikes. It consists of a metal pin in the center of a threaded valve, and a rubber cap that’s screwed onto the valve. Most bike pumps like those we reviewed have a dual head to accommodate both Schrader and Presta valves or a single head with an adapter.
A Presta valve is found on road bikes and some mountain bikes. It’s a slender valve with a nut at the top that is loosened and tightened before and after inflation. Almost all new bike pumps have a head with openings for both Schrader and Presta valves, or they have an adapter for switching from Schrader to Presta, like one of our top picks, the Topeak – Road Morph G.
If you’re out riding and your tires need air, you could give them a quick inflate with a CO2 injector, like the one we reviewed. But if you don’t have a CO2 injector in your bag, and you forgot your mini pump, then you can pull into a gas station and inflate your tires there.
If you don’t have a pressure gauge, ask the station attendant for one. Inflate your tires to optimal pressure in short bursts; a gas-station air pump has very high pressure, and you run the risk of popping your tire.
A gas-station air pump will only fit a Schrader valve. But if your tires have Presta valves and you don’t have a Presta valve adapter, there’s still a way to inflate them.
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Gene Gerrard, Writer
Gene has written about a wide variety of topics for too many years to count.
He's been a professional chef, cooking-appliance demonstrator, playwright, director, editor of accountancy and bank-rating books, Houdini expert and dog lover (still is). When he's not writing for Your Best Digs, he's performing as a magician at the Magic Castle in Hollywood.
Air pressure in bicycle tires is one of the most underestimated parameters, which, as practice shows, is often neglected by many inexperienced riders. Under-inflated or, conversely, over-inflated bicycle wheels significantly affect the riding characteristics of the bike, contribute to accelerated wear of rims and tires, cause discomfort, and in some cases, emergency situations. That is why maintaining the optimal pressure in bicycle tires is an important component of comfortable and safe movement for every cyclist.
Proper tire inflation depends primarily on the class of the bike and, accordingly, the specifics of the rubber with which it is equipped.
For example, for road bikes, this figure will be significantly higher than for mountain bikes and road bikes.
Bicycle tire manufacturers always indicate the recommended pressure range on their products. For non-professional riding, the wheel should be inflated with an orientation towards the average value from that indicated on the product. This marking is located on the side of the tire, and it can use different units of measurement. Usually these values are specified in three values:
The recommended pressure range for most mountain and city bikes is between 2.3 and 4 atmospheres (35-60 psi), for road bikes it is higher - from 6.
4 to 9.1 atmospheres.
For people who are new to cycling, adjusting tire pressure is often a problem. In this case, it is recommended to use either pumps with a pressure gauge or a stand-alone pressure control device. Having learned by eye to determine the optimal degree of inflation of the wheels in the future, you can do without additional devices. Also, every cyclist can always get to the nearest gas station or car service station, where it is usually possible to measure pressure and pump up for a minimum amount, and more often for free.
When preparing the bike for the ride, you do not need to be afraid to pump the wheel. The upper pressure limit for most tires is quite high. But, nevertheless, you should not overdo it in this matter, because. you can harm your comfort while driving.
Over-inflated wheels have less traction, which negatively affects traction and steering response.
This is especially noticeable on mountain bikes when riding on dirt roads. Overpressured wheels are less able to absorb small bumps in the terrain and compress impacts when driving over curbs and other natural obstacles. When driving on asphalt, over-inflated tires wear out faster, which causes premature tire changes.
Riding on under-inflated tires can cause more problems for both the rider and the bike. In this case, the likelihood of tube punctures increases several times, and insufficient shock compression often causes damage to the rim and the formation of eights. A poorly inflated tire on an asphalt road is subject to even more wear than an over-inflated one. Also in this case, rolling resistance is significantly increased, which worsens the roll and makes the cyclist spend more energy in the process of riding. And, finally, low tire pressure can lead to extremely unpleasant and emergency situations, when the tire breaks off the front wheel and the chamber bursts on sharp turns.
These incidents almost always involve falls and severe rim damage requiring costly repairs.
The wheels of road bikes are pumped up to 6.4-9.1 atmospheres. This is due to their specifics: a smaller volume of air in the chamber and features of contact with the surface. By choosing the average value from the tire indicated on the sidewall, you will ensure driving comfort, excellent rolling and be safe from force majeure situations associated with improperly inflated wheels.
Due to the larger volume of air in the chamber, the pressure in the mountain bike tires is controlled within 2.3-4.08 atmospheres. To achieve optimal pumping performance, the preferred riding style is taken into account. If you are a fan of aggressive riding on rough terrain, with broken primers, potholes and other natural obstacles, stick to the average pressure settings indicated on the tire. Cyclists who use mountain bikes for moderate city riding and groomed paths can safely inflate the wheel to the upper limits prescribed in the marking.
In the case of road bikes, things are much simpler. They are always inflated to the maximum values specified by the wheel manufacturer.
Ambient temperature also affects the optimum pressure. In high heat, it makes sense to reduce it, because. otherwise, the risk of overheating of the wheels increases. In the cold season, it is recommended to pump up the bike more strongly. This will not only improve the bike's snow handling, but also minimize the risk of tire and tube damage in sub-zero temperatures.
It may be elementary, but being able to inflate bike tires is an essential skill for any cyclist.
Many of you already know how to do this, but for those who don't, the different types of valves, pumps, and more importantly, how much pressure to inflate your tire can be a little overwhelming. Let us help you through this process.
Contents
Pneumatic tires were invented to overcome the harsh "ride quality" of massive wheels.
The air inside acts like a spring, giving you suspension and allowing the tire to adapt to the terrain for better traction.
Tire inflation is a quick job that can easily improve your driving pleasure. Incorrect tire pressure will adversely affect cycling and make it more prone to punctures.
If you've never repaired a puncture before, you may not have thought about how your tires hold air in.
The vast majority of bikes will use a tube. It's a donut-shaped airtight tube that sits inside the tire with the inflation valve you see on the outside.
An inflated tire rests on the ground and provides puncture protection.
You may have heard of tubeless tires which do not have a tube but use a special rim and tire to seal air without using a tube.
This usually requires a tubeless sealant, which is a liquid that plugs any air outlets.
Tubeless tires are more commonly used on mountain bikes, but the technology is moving to road bikes.
Tubeless sealant also seals punctures, and no tube means much less risk of pinching flat surfaces - that's when your inner tube gets pinched by the rim, causing a puncture. Thus, tubeless tires can run at lower pressures than inner tube tires to improve comfort, speed, and traction.
At the highest level, you also get tubular tires. They are essentially a tire with a tube built into it, but they are rarely seen or used outside of professional racing.
Inflating tires to the correct pressure is an important part of bike maintenance.
Running your tires at too high or too low pressure can be potentially dangerous and can also affect your bike's handling.
We will discuss correct pressure later, but for now let's look at possible problems.
An under-inflated tire will reduce your efficiency and leave you vulnerable to annoying punctures.
If you drive with tires at too low pressure, the tire may wear out prematurely. Excessive sidewall deflection can lead to carcass cracking and tire brittleness. This can eventually lead to tire blowout.
Excessively low pressure also increases your susceptibility to punctures and can even cause your tires to literally jump off the rim if you turn at speed (the pressure inside is what keeps your tire on the rim).
Damage can also be caused by tire deflection all the way to the rim. This can lead to dents or cracks, which can compromise your wheel and require a costly replacement.
Conversely, too high pressure can cause the tire to come off the rim with explosive consequences. This pressure can also compress the wheel because if it is too high, the compressive force on the wheel can be too great.
From a drivability point of view, low pressure can lead to poor drivability due to the tire squirming under load.
Your bike will be difficult to control and will be slow and sluggish.
On the other hand, too much pressure can lead to poor traction and a rough ride, leading to fatigue and in turn poor handling.
There are two possible reasons for your flat tire. Either you have a puncture or your tire has deflated over time.
The adhesiveless patches are great for a quick fix, while the more traditional kit is a versatile option when you have a bit more time.
All tire systems will bleed slowly because the tubes are not completely sealed. For example, standard butyl tubing retains air fairly well compared to lightweight latex tubing, which bleeds relatively faster. Even tubeless setups will slowly leak air.
Old tubes will pass more air than new ones, so if they haven't been replaced in a while, it's worth taking a look at them. It is less likely, but also possible (especially on older tubes), that the valve is no longer sealing properly.
The best way to check what's going on is to try pumping up the tire. If it's holding air, you probably have nothing else to do. If this does not happen, most likely you have a puncture.
If air leaks slowly overnight, you have a slow puncture or just an old tube that needs to be replaced.
The first thing you need to know before inflating a tire is the valve type.
The valve is the key part that keeps the air in the tire but also allows the tire to be inflated (or deflated).
Schrader valve also used for car tires.
Schrader valves are more common on lower end bikes and in the past on mountain bikes. The same valves are used on car tires.
The valve assembly is a hollow tube with a spring loaded valve that automatically closes and screws into the outer housing. The pin comes out of the valve and is usually flush with the end of the outer tube.
This pin can be pressed to release air.
The dust cap on Schrader valves is an important part of the design that can help close the valve completely if it is not fully sealed. Essentially, it provides a secondary "backup" seal.
The spring-loaded design of the valve is slightly susceptible to contamination from dirt or sand, so it is important to protect it as well.
These Presta valves are longer and narrower than the Schrader type valve.
Presta valves are only found on bicycles.
They originated on road bikes, where a narrower valve (6mm versus 8mm for the Schrader) meant a smaller valve hole (usually the weakest part of the rim).
These days you can find them on both mountain bikes and road bikes. Instead of using a spring, the valve is held in place by a nut that holds it closed, although the valve itself seals "automatically" when the pressure inside the tire forces it to close.
With a schrader valve you can simply press the pin to release the air, but with a Presta valve you first need to unscrew the small lock nut.
Don't worry about the nut coming off the end of the valve body because the threads are rounded to prevent this from happening.
There seems to be a myth that Presta valves handle high pressures better - this is probably not true given that there are Schrader valves that can handle many hundreds of psi (much more than you'll ever need). in your tire).
However, Presta valves are definitely a bit more fragile than Schrader valves. It is very easy to strike the threaded inner body of the valve, bend it or break it, so care must be taken. However, valve cores are easily replaced with standard tools.
Compared to Schrader valves, this requires a special tool.
Presta valves can be supplied with a retaining ring that secures the valve body to the rim. This can make them easier to inflate. The dust cap is not essential to sealing it, but helps keep the valve clean.
The only other type of valve you may encounter is the Dunlop (also known as Woods) valve.
The base diameter is the same as the Schrader valve but can be inflated with the same pump as the Presta valve.
They are very popular on city streets in Europe and elsewhere in the world, but you are unlikely to find one in the UK or the US.
The tubeless valve is difficult to distinguish from a regular Presta valve.
Valves for tubeless tires are attached directly to the rim, not part of the inner tube.
Most often they are of the Presta type, but there is also a Schrader.
If you have a Schrader type valve like the one shown above, the first thing you need to do is remove the dust cap (if present).
Simply unscrew the cap counterclockwise to open the valve.
Now attach the pump head.
Inflate the tire to between the minimum and maximum indicated on the tire sidewall and remove the pump.
Ready!
If your bike has a Presta style valve like this one, you will first need to remove the plastic valve cover (if any).
The plastic cover will open another threaded valve cover.
Loosen the threads, but be careful not to damage them in the process.
Now attach the pump head of your choice to the open valve and inflate the tire to between the minimum and maximum pressure indicated on the sidewall of the tire.
Inflate the tire to the desired pressure and remove the pump.
Finally, close the valve by turning it clockwise and install the plastic valve cover.
If you have a tubeless tire or a tube with sealant inside, there are a few extra steps you should take to avoid contaminating your pump.
Turn the wheels so that the valves are at the bottom and leave for a few minutes to allow the sealant to drain.
Turn the wheels so that the valves are up and inflate the tires. The same thing happens when the tires are deflated to prevent the sealant from splattering all over the place.
We would say that if you can only own one type of pump, get a foot pump for home use because it is efficient, fast and easy to use.
However, there is no doubt that having an extra mini-pump for the duration of the trip is very useful - otherwise you risk getting stuck on the side of the road in case of a puncture.
There is no limit to pump selection. Basically, they all do the same job, some of them look better than others.
From budget to outrageously expensive, you'll find something to suit your needs.
Mini pumps work but are much more difficult to use. Again, there are many options that will fit in your pocket. We prefer hose mini pumps because it reduces stress (and potential damage) on the valve.
Another option for your inflation needs is the CO2 pump. They use compressed carbon dioxide in a small cartridge to inflate or fill a tire very quickly. Not something you would like to use on a regular basis, but perfect for emergency repairs.
The first thing to do is attach the pump to the valve.
Remove the valve cap, and regardless of valve type, we find it useful to let some air out to make sure the valve doesn't stick and opens and closes cleanly. Screw on the chuck, or push it in and lock it.
If your tire is completely flat, it may be difficult to install the cartridge at first because the valve tends to move back into the rim. Simply hold the valve at the back while pressing down on the outside of the tire so you can lock the cartridge in correctly.
The locking ring on Presta valves (if equipped) can also help by preventing the valve from dropping, holding it in place for you.
The connection to the valve must be tight. It is normal for a small amount of air to escape when installing the pump, but this should not last long. If so, remove and reinstall cartridge. If the problem persists, it might be worth checking the rubber seal in the chuck to make sure it's not worn out and needs to be replaced.
Remember to be careful with the valves - they are fragile. This is especially true if you are using a mini pump without a hose.
Be sure to secure the pump by hand to avoid applying too much force to the valve, which could cause damage.
When you start pumping, make sure you use the full stroke of the pump. You will find that most of the stroke is compressing the air to the point where it will be forced into the tire.
If you don't use the pump all the way, the air won't be forced out of the bottom - you need to pressurize to move the air from the pump to the tire. Instead, you'll just end up wasting your energy to no avail.
With a floor pump, don't just use your hands, use your body weight to push down and pumping becomes much easier.
Sometimes you may find that the pump does not hold pressure, especially when inflating a tire from a fully deflated position. This may especially apply to older pumps where the seals may be slightly worn.
We find that vigorous inflation first helps to create enough back pressure (i.e. tire side rebound) in the system to ensure the valves actuate properly and seal the tire. Keep going until you get the right pressure.
When the cartridge is removed from the valve, a hiss of air loss can usually be heard. This usually happens on the pump side, not the valve side. The pressurized air from the hose and cartridge just comes out.
The pump pumps air into your tire. The principle of operation is simple; you increase the pressure inside the pump until it exceeds the pressure inside the tire.
This "overpressure" forces air into the tire, which also increases tire pressure.
The pump is simply a manually operated piston. As the pump moves down, a check valve (allowing air flow in one direction) seals the piston chamber, causing the air pressure to rise as the pump is compressed. This pressure increases until it exceeds the pressure inside the tire.
At this point, the second one-way valve will allow air to flow from the pressure pump chamber into the tire. You extend the pump again, the check valve opens to fill the chamber with air, and you repeat the process.
To prevent leakage of tire pressure, the second check valve at the base of the pump closes. If it wasn't there, the pump would just open up again.
Presta valves close automatically, but spring-loaded Schrader valves are usually held open by a pin in the valve mount (meaning you don't need any additional inflation force to overcome the pressure exerted by the spring).
The pump head is also known as the cartridge.
The cartridge is the part that attaches the pump to the valve and forms an airtight seal over the valve. There is one of two designs: threaded or push-on with a locking lever. Most pumps nowadays can also be adapted to Schrader or Presta valves.
They will either have two different mounting points or a cartridge that can be changed for both types.
For large pumps (and many mini pumps too), the cartridge is often on the hose, preventing your force from damaging the valve.
Pumps are often equipped with a tire pressure gauge.
Correct tire pressure is perhaps one of the most controversial topics, but there are a few guidelines you can use.
As a rule of thumb, your tire should be strong enough to prevent it from flexing all the way to the rim, yet malleable enough to provide some suspension - after all, the beauty of a pneumatic tire is that you don't have an incredibly hard ride.
Most tires have minimum and maximum pressures marked on the side. It is advisable not to go below or exceed these limits, because manufacturers have indicated them for a reason. Of course, this means there is still plenty of room to play around with the pressure and what works for you.
For mountain bikes, the problem is relatively easier to solve, as the goal is usually to improve traction, cornering, and damping.
As a rule of thumb, riders try to run as low pressure as possible without making it so soft that the tire squirms under load in a corner or flexes enough to damage the rim.
Things get a little more complicated for road bikes because along with grip and comfort, rolling resistance (how efficiently the tire rolls) is an important factor.
On all but the smoothest of surfaces, a stiff tire will have no advantage, and instead of the tire being able to lean and conform to the bumps, making the bike move forward, you will bounce.
On all but the flattest surfaces, lower tire pressures can provide greater comfort and efficiency.
Testing showed that 20 percent tire compression (the amount of tire compression when a load is applied, measured by the height from the ground to the rim) was the optimal balance.
By the way, some manufacturers recommend the same level of tire compression, although this figure is somewhat controversial.
This value is indeed a good starting point for experimenting with tire pressures.
You don't always have to remove the pump/gauge to check tire pressure.
It is recommended to check the tires before every ride. Usually, you just need to squeeze them with your hand to check the pressure.
No, it's not very accurate, but you will quickly feel the pressure in your tires and be able to tell if they need to be inflated or not.
If you get serious about this, you can end up with a pressure gauge that can read your tire pressure very accurately.
