Maintenance: Bike Tires 101

Tires are one of the major components of a bike. The proper tire, installed and inflated correctly, can be the difference between a comfortable ride from an uncomfortable and even frustrating ride. There is more to tires than colors and tread.

History of the Bicycle Tire

John Dunlop

The first bicycles didn’t have tires. Instead, they had bare rims. Eventually, bicycle companies placed bare rubber on the rims, although over time the rubber cracked. The bare rims and flat rubber tires, however, resulted in a harsh ride. Pneumatic tires did not come into existance until 1887. A man by the name of John Dunlop developed the first pneumatic (or air-filled) tires for his son’s tricycle in 1887 in Ireland. Soon after, pneumatic tires were commonplace on bicycles all across the world.

Thomas B. Jeffery was a bicycle manufacturer in Chicago, Illinois, who manufactured the Rambler bicycle. He developed the clincher rim, which is still used by most bicyclists to this day.

Tubeless tires for bicycles were developed in the later part of the 20th century, after they became commonplace on cars.

Tire Types

Much like how you have different types of bikes and types of brakes, there are many different types of tires to choose from.

Clincher/Tube-type

The Clincher (also known as a “tube-type” tire), as developed by Thomas B. Jeffery in the 1890s, is still the most common type of bike tire to this day. Its popularity remains so great due to the fact that it is cheap to produce parts for and repairing or replacing a tire on a clincher rim is much easier than tubeless or sewn-up tires.

In a clincher, you have two basic components:

  • Inner Tube – The inner tube is essentially a donut-shaped rubber balloon inside the tire. Its job is to hold the air, meaning it is the “core” of the tire. Since the tube is the part that holds the air, the tube also contains the valve stem.
  • Tire Casing – The tire casing is the part you see from the outside (minus the valve stem). The tire casing protects the inner tube and gives you traction with tread.

Clincher tires offer many advantages. They’re cheap to produce and repair, in comparison to tubeless and sew-up counterparts. The technology has been around for over a century, and has been proven.

Another major advantage to clincher or tube-type tires is the ease of repair or replacement, including in the field. While tubeless tires require sealants and an air compressor to install, clincher tires are much easier to replace. And since the inner tube can be easily replaced or patched in the field, clincher tires can easily be repaired from anywhere.

While the clincher has been proven and is still the most popular, it has its disadvantages. Disadvantages of clincher tires include the added weight from running tubes, as well as the often varying quality of tubes. Additionally, tube-type tires are less puncture-resistant; a simple puncture will cause a tube-type tire to rapidly deflate whereas a tubeless tire would take days to deflate in the same situation.

Fun Fact: Tube-type clincher tires were used in the automotive industry from the 1890s well into the 1960s, and even afterwords in limited applications. Modern agricultural and construction equipment tires rely on tube-type tires due to their robustness.

Tubeless Tires

Following the advent of tubeless car tires in the 1950s, tubeless bicycle tires entered the bicycling industry in the later part of the 20th century.

Tubeless tires are found on high-end road and mountain bikes, where weight means everything. As the name would suggest, tubeless tires lack the inner tube. The tire casing itself holds the air, similar to tires found on modern cars and trucks.

The tubeless bicycle tire has many advantages and disadvantages. The main advantage is saved weight. In some scenarios, such as racing, having as little weight as possible is the key and can be the difference between winning and loosing. Therefore, shaving off the couple ounces which an inner tube adds is one place to start. Tubeless tires also offer much better puncture resistance, often offering a controlled, slow leak while their tube-type counterparts would rapidly deflate or even catastrophically fail. (For instance, a small thumbtack may take a couple days to produce a noticeable drop in pressure in a tubeless tire, while a tube-type tire would be completely flat in a matter of minutes.)

However, much like clincher tires, the tubeless tire has its disadvantages. The biggest disadvantage of tubeless tires (and perhaps the largest reason behind why they haven’t become mainstream on bicycles) is installation. Installing tubeless tires on a bicycle isn’t cheap or easy. Tubeless bicycle tires require a special type of rim* and tire combination, sealant, and an air compressor. Installation requires sloshing liquid sealant inside of the tire and quickly inflating it to seat the tire and ensure there are no leaks. But all of this requires a special type of tire and rim.

Tubeless tires, as you can already probably guess, can’t be (easily) replaced or repaired in the field. Many bicyclists who have tubeless tires often carry one or two inner tubes in their repair kit, to quickly fix a flat on the side of the trail.

Tubeless tires, lastly, are more picky about tire pressure. Tube-type tires can be overinflated or underinflated beyond their recommended pressure range (although risky**), whereas underinflating a tubeless tires will just come unsealed while riding, and overinflating a tubeless tire will often damage or destroy the tire as it blows out.

Tubular/Sew-Up Tires

Don’t let this term confuse you. Tubular tires are basically a tube-type tire in a package. A tubular tire, sometimes referred to as a sew-up tire, or a tub, is essentially an inner tube sewed inside of a tire. Most tubular tires have the Presta valve stem and can often be found on indoor track-style racing bike tires.

The advantages of tubular tires are that they can be easily installed. They glue on to the rim, requiring minimal tools to be installed. They can typically be installed in the field. However, tubular tires have many disadvantages. They are difficult to repair, requiring to be unsewn, repaired, resewn, and reinstalled. Tubular tires also are much easier to puncture since the tire casing is typically thin, and are much rarer.

Airless Tires

Airless tires have no air in them, requiring no maintenance, and can’t be punctured. Clincher-style tires can be retrofitted to airless by using a mousse tube. A mousse tube is essentially an inner tube made of foam. They are typically found on motorcross and dirt bikes.

Types of Valves

There are three types of valves commonly found on bicycle tires: Schrader, Presta, and Wood. Since the Wood valve is rarely found, we’ll discuss the popular two.

Schrader

Schrader valve

The Schrader valve is found on most lower-end and older bikes. The Schrader valve is the same type of valve found on car tires. They are short and fat, with black rubber surrounding the outside of the bottom of the valve stem (although some come threaded, with a locking nut, similar to threaded presta valves). A schrader valve uses a valve core to hold the air in, which has a plunger to let air in and out.

They require no special tools or adapters to be inflated with a standard air compressor or tire pump.

Schrader valves can be deflated by using either a valve core removal tool to remove the valve core assembly, or finding an item to fit down inside the barrel of the valve stem, to push down the plunger and let the air out. I’ve used tweezers to remove the valve core, and I’ve also used my fingernails to let air out of the tire, although others have used a tip of the dust cap.

Keeping a dust cap on your schrader valves will keep debris and dirt out of the valve, which will maintain tire pressure. Dust caps typically come with inner tubes or schrader valves themselves, but custom dust caps can be purchased online, automotive or bicycle shops, or even WalMart. Tire pressure can be checked with either a tire pump or air compressor equipped with a tire pressure gauge, or (if the pressure is below 40 PSI) an automotive pressure gauge.

Presta

Presta valve

Presta valves are typically tall and skinny. They are either smooth or threaded, and the threaded variations usually include a locking nut which helps prevent the tube or stem moving around within the tire. Presta valves are typically found on higher-end bikes, such as mountain and road bikes.

Presta valves are much more difficult to inflate, often requring a special adapter or special tire pump to inflate. Tire pressure can be checked with a tire pump or air compressor equipped with a tire pressure gauge, as most tires with presta valves are inflated at higher pressures, often higher than regular automotive tire pressure gauges. Plus, regular automotive-style gauges and inflators will not work with Presta valves without a special adapter.

Pressure valves are easy to deflate. In order to inflate or deflate a Presta valve, unscrew the valve lock nut (top locking nut, commonly covered by dust cap) and place the adapter or pump onto the valve. To deflate, press down on the plunger to let air out. In presta valves, the air will escape much faster than the schrader counterpart. Be sure to screw the valve lock back down tightly, to ensure that no air leaks once the dust cap is screwed back into place.

Be sure to lock the locking nut down tightly flush with the rim, so that the stem is held tightly into place.

Pressure: Underinflation vs. Overinflation

There are three types of bicyclists – those who underinflate their tires, those who overinflate their tires, and those who inflate their tires just right. What are the risks of underinflation and overinflation, as well as the benefits between the two.

Underinflation

Much like underinflating the tires on your car, underinflated tires will require more effort to be exerted to gain speed. However, underinflated tires offer a smoother ride, as the tire cushions the bumps and imperfections in the road surface. Puncture resistance is also greatly increased with underinflated tires. Underinflated tires also offer greatly improved traction, as the surface area of where the tire touches the ground is increased.

However, underinflated tires can offer issues. For one, there are two types of punctures which plague underinflated tires. The first type of commonly found puncture with underinflated tires is the snakebite flat. A snakebite puncture is two parallel punctures in the inner tube, caused by the pressure of the rim poking holes in the thin tube. The other type of puncture is the pinch flat, where the tube is caught between the tire and rim, and bulges outside of the tire. This will often cause the tube to explode.

Underinflated tires can also cause the inner tube to move inside of the tire, which can result in the valve stem coming separated from the tube, which can’t be repaired.

Overinflation

Overinflating tires provides a firm ride that allows you to gain more speed with less effort. However, the ride has very little cushioning – meaning you can feel every bump and pebble on the road or trail.

However, overinflated tires have many problems. Overinflating any tire is much riskier, and is like blowing up a balloon too much. If you overinflate your tire too much, or the tire was improperly installed or has weak spots, the tire can explode. This will ruin the inner tube, and can ruin the tire and even the rim. This will also ruin your day and week, as you experience the constant ringing of your ears that plague anyone who has blown a bike tire.

Overinflated tires also offer less puncture resistance, and fail more catastrophically than underinflated or properly inflated tires.

WARNING: Tubeless tires should NEVER be overinflated. Doing so can ruin the tire, and cause disastrous consequences. Tubeless tires should never be inflated over their recommended pressure rating. Often times, tubeless tires and tubeless rims will feature a sticker or have a warning paragraph molded into the tire warning of the consequences of overinflating a tubeless tire.

Properly Inflated Tires – “Just Right”

Inflating your tires to the proper or recommended inflation pressure is always recommended, as it offers the best of both worlds in most cases.

I typically “air down” – or partially deflate – my tires when riding on gravel trails and in rough conditions, as it offers greater comfort and provides a slight increase in traction. I also have to underinflate the tires on my 1981 Free Spirit Pinnacle, due to the rim issues it suffers from.

Otherwise, it is best to run your tires at the proper inflation. Properly inflated tires will last the longest, produce the fewest amount of headaches and frustrations, and often is the most comfortable while being the most efficient.

Most tires provide a recommended pressure range on the sidewall (see next paragraph), meaning you can still customize your tire pressure. In most cases, you can experiment and see what pressure works best for you by trial-and-error.

Inflating and Maintaining Your Tires

The recommended pressure rating is stated on the sidewall of most tires. The rating is either stated in as “Recommended Inflation Pressure — PSI – — PSI (– kPa – — kPa)” or “Maximum Inflation Pressure — PSI (– kPa.)” Tire pressures are rated in PSI, or Pounds per Square Inch (Imperial/English units) or kPa, or kilopascals (metric unit.)

As previously mentioned, trying different pressures within the recommended range is a great way to see what the best pressure for you is, since many people are different.

When installing my tires, I typically try to position the pressure rating on the sidewall of my tires above or near the valve stem. This allows for easy access to the recommended pressure range while inflating the tires.

It is never recommended to use an air compressor, especially an unregulated air compressor (like one at a gas station), for inflating bicycle tires. Since bicycles tire have a lower volume when compared to car tires, they will be filled faster. It is easy to extremely overinflate bicycle tires with an air compressor.

I typically try to use a tire pump to inflate my bike tires. Other methods exist, though, which include CO2inflators, which are typically used in emergency situations, such as flats in the field far from gas stations or local bike shops (such as off-road and trails.)

It is recommended to check your tire pressure at least once a week if you are running butyl tubes, and every time before riding with latex tubes. Tubeless tires can be checked safely every two weeks. It doesn’t hurt (in fact it is better) to check your tire pressure more often, and I try to check tire pressures before leaving.

When going on a long trip or riding on the trails, off-road, or on the road, bring an emergency backpack. This should have all the tools you need in case something goes wrong on your trip. This emergency backpack should feature all the tools you need to remove your wheels from the bike, a spare inner tube (for tubeless or tube-type tires), a tube patch kit, duct tape, glue, and a First Aid kit. It is a good idea to check your emergency backpack and take “inventory” each time before you leave for a long trip, as being stranded with a flat tire is no fun. If you’re going to extremely remote locations (i.e. where there is no cell service, and the nearest town is twenty or thirty miles away at least), tell friends and family where you plan on going (as well as ETA back) and carry a GPS phonem if possible. In case of an emergency, this can save your life. You should also carry a frame pump at the very least, or CO2cartridges to limp to the nearest town. (Frame pumps often require more energy, and are tricky, to use to inflate tires. However, it can save your life. CO2 cartridges will inflate a tire much quickly, if it is the proper size and properly used. However, CO2 leaks out of tubes much quicker, especially latex tubes, and will often only be able to get you to a gas station or shop to inflate with proper air. CO2 cartridges are also much more expensive and difficult to use.)

Links

Sheldon Brown’s entry on “Tires”