Whether you own a bike or rent one for the day, knowing how to inflate the tires is essential. Here we are looking at the Presta valve, what makes it unique, its advantages, and how to pump a bike tire with a Presta valve.
What is a Presta Valve
The Presta valve is also called the French or Sclaverand valve, though most people call it the Presta valve. It is the valve stem in use on more expensive bikes and mountain bikes that have an inner tube.
Compared to a Shrader valve (another bicycle valve stem), it is thinner in diameter and longer. It consists of the outer valve stem with an inner body. The valve stem at the wheel’s rim has a lock nut and a valve cap to prevent air leakage. The outside of the Presta valve has threads to be used when an adaptor is needed.
The Presta valve’s hole is small enough to accommodate a narrower wheel while supporting the bicycle wheel’s strength. When you properly inflate the tire, the tire pressure keeps the inner valve body closed to maintain the air pressure. The locknut on the top of the valve body screws shut and keeps the valve closed tight.
To inflate or deflate the bike tire, you unscrew the nut. Once you inflate the tire, you must remove the pump and retighten the screw. The valve cap protects the valve from mud and dirt that can gunk up the valve. It doesn’t keep the air in the tire as the valve screw does.
Advantages of the Presta valve
- Their precision design lets you inflate the tire to a precise pressure
- Decreases air loss in the tires
- Maintains tire pressure so it won’t affect the cyclist’s safety, performance, or speed
- No valve cover is necessary when the locknut is closed
- The valve cap keeps mud and dirt out of the valve stem
A word about tire pressure
Manufacturer’s conveniently put the recommended tire pressure on the side of the wheel (as do vehicle manufacturers). Like the car, the pressure is measured in pounds per square inch or PSI. Tire pressures vary by the wheel. Below is standard tire pressures. Always check the manual for the PSI specific to the tires you own.
- Hybrid tires – 40 – 7- PSI
- Mountain bike tires – 25 – 35 PSI
- Road bike tires – 80 – 130 PSI
While most riders squeeze the tire to decide if it needs inflating, using a tire gauge is the best way to check the tire pressure. A pressure below the manufacturer’s recommendation requires inflating.
Checking the Tire Pressure With a Presta Valve
The pump matters…some pumps have two valve holes. The Presta valve uses a smaller hole. The valve hole accommodates the Presta and the Shrader valve if you use a “smart pump.” But if you use a pump from a gas station set up for a Shrader valve, you will need to use a Presta adaptor.
Remember when loosening the locknut, the air escapes the minute it is loose. Opening it too wide will deflate the tire!
Use the following steps to inflate the tires with the Presta valve.
Step 1: Locate the locknut on the top of the valve. Apply pressure on the locknut using your fingertip as you unscrew the locknut.
Step 2: To ensure the valve stem is free of debris, ease the fingertip pressure to let some air escape and blow debris out of the stem. Then press your fingertip back down to stop the airflow.
Step 3: Check the tire pressure using the tire gauge. If the gauge is not part of the pump, your reading may be slightly off due to the air escaping. Pump a minimal amount of air in the tire to compensate before reading the pressure, then let out the unnecessary air.
Step 4: Make sure to tighten the locknut and replace the valve stem cap before riding.
Be sure to increase the tire pressure if you have added weight, such as equipment or a heavier rider—bike pressure decreases in colder weather and increases in hot weather. Adjust the tire pressure with this in mind. Where you ride will also change the tire pressure. Riding on rocky terrain can be uncomfortable, but decreasing the tire pressure can make the ride more enjoyable.
Inflating a Bike With a Presta Valve
Step 1: Remove the valve stem cap (save it!) and loosen the locknut. If you can hear the air coming out as you press on the valve stem, it is open enough to inflate the tire.
Step 2: If you don’t know the recommended PSI for the tire, check the area below the tire’s rim for the numbers. Don’t underinflate the tire, but adjust the recommended PSI if needed.
Step 3: Place the pump on the valve (for pumps with a lever, you need to push it into the open position before placing it on the tire.)
Step 4: Once the valve is seated in the pump, put the lever down to lock it on the valve. Then begin inflating the pressure. If the pump has a gauge, keep an eye on the
tire’s pressure. If there is no tire gauge attached, you must retrace your steps and manually check the pressure as you inflate the tire.
Step 5: When you reached your ideal PSI, remove the tire from the pump, retighten the locknut, and replace the valve cap. Enjoy your ride!
Using a Presta valve adapter to inflate the tire
The Presta adapter turns your valve into a Shrader valve, so you can use any pump to inflate the tire. Adapters are inexpensive and can be purchased in a set of six or more. You can buy one in a bike shop or order one online. Order more than one so you can keep one with your biking gear and another in the car. Here’s how to use the adapter:
Step 1: Remove the valve cap and turn the locknut counter-clockwise, opening the valve.
Step 2: Thread the adapter clockwise on the Presta valve. Place the pump on the adapter and fill the tire as you did in the section above.
Step 3: Once you inflate the tire to the needed pressure, unattach the pump, remove the adapter, tighten the locknut, and replace the valve cap. Then tighten the locknut on the bottom of the valve stem too.
Tire adapter hack
If you need to air a bike tire and you don’t have an adapter, use this adapter hack to make an adapter. This hack will let you use any Shrader valve pump! Most gas stations have a tire gauge you can use. If not, fill the tire till firm but still squeezable.
Step 1: Remove the valve cap. Using a pocket knife or sharp object, cut off the tip of the cap at the rim.
Step 2: Now, unscrew the locknut, place the cap upside down on the locknut, and screw it in place on the valve stem.
Step 3: Place the pump on the adaptor and fill the tire using bursts of air.
Step 4: Once the tire is reinflated, you are ready to enjoy the ride.