Like a car’s wheels, bike tires also need numerous pieces of equipment and accessories to maintain just the right amount of pressure (neither too much nor too little), ensuring your ride is smooth and seamless.
One of those devices is the valves, which – despite their seemingly small size and simple structure – arrive in quite various types and models!
So what exactly is a bike tire valve, and how many types of valves on bicycle tires are there on the marketplaces? Our article will address all these burning inquiries for you.
Table of Contents
What Are The Different Bike Tire Valves?
1. Schrader Valves
Schrader valves (often known as American valves) are pneumatic products present in almost every vehicle you can find – including bicycles – ever since August Schrader’s 1844 invention.
A Schrader valve contains a complex valve stem threaded into a core. This core is a poppet supported by several springs; meanwhile, the rubber seal on the top of these cores prevents fluid from flowing through the bike’s threads. Whenever the cores encounter technical problems, you only have to extract them from the stem to install new ones.
There’s also a metal tube threaded externally through the cylindrical hollow, usually made of brass nickel. Go to the end’s exterior center, and you will easily find metal pins running along the stem’s axis. They are placed flush against the valve bodies’ back.
All Schrader products have bodies and threads of single standard sizes, so all tools and equipment used on these tubes are popular applications. The only major distinctions between them are the core variants and diameters, which vary across different purposes like propane, refrigeration, and more.
There have been many changes and updates since 1844. Today, thanks to the development of miniature electronic fields, Schrader stems can work well with integrated transmitting devices to better monitor tire pressure.
Lastly, we cannot ignore the valve caps, which prevent contaminant entries that might wreak havoc on the sealing surface and lead to leakage.
Hard plastic and metal caps often include an O-ring or rubber washer inside, both of which prevent the lids from slacking and falling due to excessive vibration. They also work as mechanical seals that protect the valve against air leakage from faulty cores. Of course, some zero-seal caps are available if you want to buy them – but trust us, they are unreliable.
While other applications (AC or refrigeration) consider the cap secondary, bicycles regard them as the primary/fundamental seal.
Recently, colored stem caps have been introduced, with numerous tire dealerships claiming that they incorporate dry nitrogen that can inflate tires much more quickly.
Their common consensus is that a reduction in water and oxygen will lengthen the lifespan of both wheels and tires. Hence, the color (green) on the caps is to signify that they contain pure nitrogen (about 95%).
Other colors aside from green are also accessible, but unlike green, they are mainly for decorative purposes. Certain types of caps even light up and blink whenever your bikes move.
Professionals classify Schraders based on shape, length, rim hole’s intended diameter, and material.
- TR4: straight metal stems (8 mm)
- TR6: straight metal stems (8 mm)
- TR13: straight rubber stem (11.5 mm)
- TR15: straight rubber stem (16 mm)
- TR87: 90° metal stems, short (10 mm)
- TR87C: 90° metal stems, tall (10 mm).
About the threads, we have external and internal:
- External Metric: 7 mm OD, with a root diameter of 6.9 mm x 0.794 pitch.
- External American: 0.30 in OD, root diameter 0.302 x 32 threads per inch
- Internal metric: 5.3 mm OD x 0.7 mm pitch
- Internal American: 0.2 in OD x 36 threads per inch
These valves thrive on every motorcycle/bike tire – especially tires with wider rims. Even better, they can also be used as recharging ports for fuel rails or installed on bicycle shock absorbers to enable more air pressure adjustments that fit riders’ weights.
See also: How Much Does A Bike Weigh?
2. Presta Valves
Presta valves (other names: Slaverand/French valves (FVs) are commonly found in pressure road bicycles and inner tubes within mountain bikes.
Structure And Support Accessories
Overall, Presta valves comprise outer stems and inner bodies, with lock nuts to tighten the stems at wheel rims. In some cases, there are also valve caps.
The outer stems are manufactured in numerous sizes and lengths for varied purposes – but overall, their diameter (6mm) is narrower than Schrader and Dunlop’s (8mm).
In most cases, a bike rim’s weakest point lies in the stem’s hole – a dilemma that Presta can fix. Its small hole allows your bikes to enjoy narrow tires while still sustaining enough wheel strength during the trip.
Inner Bodies and Nuts
In inflated tires, air pressure keeps the body shut; meanwhile, a captive nut and small screw on the body’s top enable the valve to be screw-locked, ensuring it always stays tightly closed.
For more airflow, you must unscrew the nut to open entries from all directions. But remember that the screw will still stand on the body even after full unscrewing. It will tighten again once the pump is removed and your tires have been inflated.
This cap protects the body, keeps mud and dirt out of your way, and prevents further tube damage when you roll it for storage. Some claim it also contributes to reducing pressure loss – though we have not yet been able to confirm this theory.
The rims’ holes in Prestas can get enlarged to fit in wide Schrader valves – a common but not advisable practice since they can weaken your rims. Similarly, if you slot Presta valves into large rim holes built for Schraders, reducers and grommets are needed to fill the remaining space.
Since every valve has external threads, riders can purchase adapters and fit them onto these threads, allowing the valves to connect to pumps via Presta chucks.
Due to the similar thread sizes, one can use this adapter to convert Presta pumps and link these devices to various adapter types.
While every Schrader valve has removable cores, only some Presta versions do the same. Riders can use these cores with tubeless setups to pour more sealant into the valve. Another way is to add these sealants to the tires directly.
Valve Extender (Optional)
Thick and deep rims (as with aerodynamic racing wheels) work better with long valves; hence, you should adopt valve extenders to lengthen your short Presta. Two extender variants are acknowledged – which depend on whether your Presta cores are removable.
External threads at both “un-threaded” and “threaded” valve tips are 5V2 (12-24 TPI), measuring 5.2×1.05 mm – similar to Dunlop valve tips. Meanwhile, internal threads on “threaded” valves’ main bodies are 6V1, equaling 6×0.8 mm
These Presta products are specifically produced to enhance bike types. You will not see them anywhere on other vehicles (like motorbikes or cars).
3. Dunlop Valves
Among the three different bike tire valves, Dunlop is obviously the least popular one, which is why we do not delve into it too much.
Nevertheless, novices and beginners should have a quick overview of how it functions and performs. Overall, Dunlop valves (also called English or Woods valves) are pneumatic systems used mostly for bicycle inner tubes.
How Do They Work?
Dunlops have wider bases than Prestas and similar sizes to Schraders. If desired, you can use Dunlop and Schrader interchangeably for rim holes; Dunlops can also get inflated using Presta adapters. Its mechanisms are also easily replaced without specialized tools.
In the past, Dunlops incorporated tight rubber sleeves that riders had to force-open using pumping air pressure. Not only are these inflation methods difficult, but the rubbers also wear down over time, leading to leakage and inevitable failure.
Thankfully, modern versions use different cores/plugs – rubber spring-loaded and internal-bearing – that can become unseated in seconds via basic pumping.
The external threads of Dunlops are about 0.305 in (equal to 7.74 mm) x 32 threads per inch (0.793 mm pitch or 1/32 in)
As previously mentioned, these bike tube valve types thrive best in inner tubes. You can also use them for other bike compartments – though they will not be far less efficient than Presta and Schrader.
4. Schrader Valve vs. Presta vs. Dunlop: How Do They Differ?
So we have gone through long guides about these tire valves’ structure and usage. But at the end of the day, what are the major distinctions that set them apart? Let’s have a quick summary of what we have discussed so far:
- Schrader: Schraders are wider than Prestas but have similar circumferences over their entire lengths. Often drafted in rubber, their outer walls are threaded to strengthen the pump’s head or valve cap. The middle pins are non-return, regulating air flow to and fro the tires via the check valves.
- Presta: Presta is only half of Schrader’s width, made mostly from metal. They run a bit upwards with several threads hung down. To open them, you must unscrew the toothed nuts on the top.
Unlike Schrader, Prestas have no check valves. Instead, they close with the help of exerted pressure from the tubeless straps and inner tubes.
And while they allow riders to extract the valve’s core entirely, you should refrain from doing so; only unscrew their knurled nuts. Otherwise, the air will come out all at once.
- Dunlop: Dunlops are mostly used for city bikes. Despite looking like Presta valves (but thicker), they are made of cheap material – and hence, never enjoy the same popularity as the other two.
Signs of Bad Tire Valves and How to Diagnose It
Signals of Bad Tire Valves
Valve Stem Damage
New tires should go with new stems – since old ones tend to wear down at inappropriate times. So for bikes with older stems, do not be surprised if they start breaking down due to dislocation, frequent usage, and chemical exposure on the road (ex: road salts). As a result, corrosion is inevitable.
Damaged stems often lead to constant (but slow) leaks from the valve, the body, or the base (where it connects with the tires).
Damage on Your Tire’s Mounting Surface
The wheel’s mounting surface – where your tire bead sits – might become destroyed with over-time corrosion. Once the tires pull off the mounting, leaks will occur.
Such catastrophes might also stem from bumpy riding trips, particularly if you often stumble across potholes, step bumps, or curbs. The metal surfaces will deform, causing slow leakage.
Here comes the most popular reason behind bad valves and tire leaks. When your bike runs over nails, sharp pieces, glasses, screws, or other debris types, these substances will get stuck within the tire.
And unlike most people’s belief, they do not trigger immediate blowouts or flat tires. Instead, the process will transpire more slowly – as the object lodged within the rubber prevents air from quick leakage.
How to Diagnose Bad Valves?
When signals of mounting, rim, or puncture damage catch your attention, it’s time to stop the bike for a proper diagnosis process!
These methods could be of help to you:
Manual Pressure Reading
Manual Pressure Reading is a good way to confirm the damage for riders with leaking tires. More specifically, you will check the tires regularly to verify whether one of them (or both) seems underinflated.
TPMS – Tire Pressure Monitor Sensor
Most commercial, passenger, or high-end vehicles are armed with TPMS (Tire Pressure Monitor Sensors) to discover the tire’s air PSI levels. They are wonderful choices for anyone who wants to determine whether the tire pressure is too low. If the devices are switched on, your tires might be underinflated.
After inflating the tires, use TPMS to check again. Are they still on? Then that means the valve is experiencing problems.
Spray Bottle Methods
One last option for tire leak diagnosis is to turn to spray methods. The process is simple: first, mix water and dish soap into one liquid. After that, pour this soapy water combination into one bottle. Then spray it over the sidewalls of your bike tires.
Are there bubbles popping up on the surfaces? You have your answer: the valve is malfunctioning.
How Should You Replace A Bad Tire Valve?
This guide will discuss steps to replace valve stems expensive biking.
Step 1. Check to See Whether Your Stem Is Truly Leaking
Before starting your replacement, do not forget to confirm whether the leaks truly come from the valves. Otherwise, you will waste an entire afternoon struggling with the car for nothing!
Use the diagnosis methods we have already listed above. Our favorite is the last option: pour soapy water into the valves (their caps already removed) to see whether bubbles show up.
And what if there are no bubbles – yet you can still recognize the air leak? Chances are the problems come from somewhere else, not the valves.
Step 2. Prepare All The Necessary Tools Before Beginning
After confirming that your bike needs valve replacements, it’s time to prepare the required equipment to ensure a smooth process. Experts suggest the basic tools listed below – all of which are accessible at any large store/market:
- New valve stems (to replace your current one)
- Stem removal device for the valves
- Tire irons
- Big hammers (any type is accepted, though we prefer sledgehammers)
- Needle-nosed plier
- Nut wrenches to remove/mount the wheels
- Jack stands
- Air compressors (with proper nozzles that fit into the tires)
Have these under your fingertips already? Time to get started!
Step 3. Decide Which Wheel You Want to Work With First and Loosen Its Nuts
How to loosen the nuts effortlessly? We suggest picking a wrench, holding the wheel firmly in place, and loosening every lug nut one by one. Note that the bike must still stay tight on the floor.
The wheel nut might also have anti-theft rings for certain vehicles or bike models. Is that also your case? If yes, you must remove those locking nuts with special keys.
Step 4. Use A Jack to Raise The Bike. After That, Remove Its Wheel
First, remember to apply the handbrake, rendering your bike completely immobilized. After that, lift it off the ground using the jack. Make sure you have positioned the bike on the chassis’ right part, which gives it more proper support and prevents both you and the bike from injuries/damage.
Once you have lifted the bike, secure it firmly on the jack stand. Unscrew all the wheel bolts to remove that wheel. Lastly, put this wheel on flat ground – in a way that makes its outside face up.
Step 5. Use Removal Tools to Extract The Stem Core. Once Done, Leave The Tire to Deflate On Its Own
Have you removed the cap? Do so immediately if you haven’t!
After that, please use the stem removal device to extract the stem core, releasing all of the wheel’s internal airflow. That should be more than enough to help the tire deflate by itself without interference.
Step 6. Separate The Wheel From The Tire Beads
Remember the sledgehammers we mentioned earlier? It’s time to call for their assistance!
With your hammer, hit the sidewalls of your tires (all the hits must be directed at the same place) and stop when a popping/cracking sound is heard.
At this point, the tire’s inside lip will break loose, detaching from the rim. Congrats; you have successfully separated the tire beads and wheels!
After the beads break down, continue using the hammer to hit around the tires, pulling the wheels’ sidewalls off the circumference.
Step 7. Separate The Rim and The Tire
The tire’s side walls must have been now detached completely from the rim’s outer edge that lies around the wheel’s entire circumference.
Your next task is to insert tire irons into the slot between the rim’s edges and the tire’s inside lip. Then, pry them upward, pulling the lip over the wheel’s edge. Keep working this iron around your rims until the whole lips are completely off.
Check whether the tire sidewalls are now above the wheels. If yes, grab them at the lips, pulling upwards to ensure the opposite lips (at the wheel’s bottom) touches the rim’s top edges now.
After that, insert the tire iron between the wheel’s edge and lip once again, prying your fingers to drag the lips over the rim’s edge. Like before, work around the wheel’s edge till your tires are removed from these wheels entirely.
Step 8. Extract The Old, Malfunctioning Stem and Install The New One In Its Slot
After you have separated the rim and the tire, it’s time we removed the old valve stem.
First, pull the stems free using the pliers. Next, insert your replacement stem (remember to do so from the wheel’s inside).
Has it settled down to the empty slot? Pick your plier again, pulling it across the wheel to tighten its position.
Step 9. Reinstall Your Tire. Then Inflate It
Double-check that your new stem has been settled tight. Once certain, return the tires to their original rims.
Kick-start the process by pressing your tire over the rims. Keep exerting force until the base bead has cleared the rim’s edges. Our goal here is to bounce back the tire’s lower sidewalls to their initial positions on the wheels.
Next, press the tire’s upper sidewalls beneath the wheel’s edges. Tuck the iron between the rim edges and the sidewalls, using them to make opposite movements compared to those you just performed. This method will pull the sidewalls off the rim.
After the beads have cleared the wheel’s lips, work your irons around the wheels till these tires are installed completely.
The only thing left to do is to use an air compressor and inflate it back to the right pressure.
- Determine how much pressure your tires require. The calculation often involves KPa (kiloPascals) or PSI (pounds per square inch).
- Remove the stem’s valve cap. Twist the cap counterclockwise till it comes off.
- Press your intended gauge portion onto this stem. Do not feel surprised if some air escapes when you try to adjust your gauge for a better fit with the stem. Once the gauge is already in place, that will stop immediately.
- Scan the gauge to confirm the current pressure level in the tire. On standard gauges, you will see a stick popping at the base. The number it stops at will imply the amount of pressure your tire currently has.
- Keep adding air till the desired pressure has been reached. Finally, return the cap to the stem; turn the cap clockwise, and you are all set! Do not worry that you must use the exact same cap; all caps work well with these stems.
- Check the remaining tire using these steps. Though it might seem that only one tire malfunctions, you should not skip this golden opportunity to confirm all tires are properly inflated at this point.
Step 10. Confirm No Other Leak is At Play, Then Mount Back The Wheel
After inflating the tire, double-check for other types of leaks. All is well? Great! Mount the wheels to your bike. Lower the jack stand’s level to bring it to the ground. When it safely touches the floor, remove the jack.
1. Can You Use Regular Pumps for Presta Valves?
Yes! For safe and effective valve inflation, you only need to purchase air pumps (regular or premium is alright) and special adapters.
Shipping fees depend if you buy them from online shops; meanwhile, purchasing these devices directly from physical bike shops only costs about one or two dollars.
2. Is It Possible to Drive Without Valves?
Yes, you can; but with no valve to protect your tires against debris and dust, don’t be surprised that the bike will crumble a few months (or even weeks) later.
3. How Much Will It Cost for Valve Replacements?
The answer is $10 if you buy the new stems and replace them at home). For those who turn to professional services, expect at least $30.
4. How Often Should You Replace These Stems?
There’s no fixed answer. You should do so every time there are clear signals of leaks and damage. And whenever you replace the tires, remember to install new stems as well.
Our readers have been given a detailed guide on bicycle tire valve types and how these three differ. Concise tips on recognizing bad valves and replacing them are also provided, guaranteeing your bike can carry you across multiple terrains without hassles or challenges.
And as usual, the best way to confirm your tires (and the bike in general) are always in good condition is to check them frequently and keep a consistent maintenance schedule.
Contact professional services immediately once unusual signals are detected, so that they can help devise a good solution for whatever dilemma you encounter!