XTERRA Couch to Trail - Tires Part 2

Aug. 9, 2017

By Mimi Stockton

Tubes or Tubeless?
The tube vs. tubeless debate is very common in mountain biking circles. Avid mountain bikers are as passionate about their tire system as they are about their trails. After all, it's the tires that keep the adventure rolling and the rider upright. Once wielded solely by elite racers, tubeless tires are gaining popularity with more and more riders. Car tires made the evolution to tubeless eons ago, so it’s not surprising to see the same shift happening in the bike world. 

In a nutshell, in order to have a tire without a tube, you need the tire's bead to lock onto the rim. You also need the tire, rim and seated valve stem to be absolutely airtight. A special sealant is key to making it all work.  

While both systems are reliable and have their own sets of advantages, it may really come down to a rider's preferences and peace of mind. 

Let’s talk tubes first. This well-known system is based on having a separate inner tube within the tire that inflates with air and dictates the performance characteristics of the tire. Some advantages of tubes are that they are easy to repair in the field, can be carried in a tool kit, and are inexpensive to replace. Tube tires are lightweight, but when coupled with tubes, they become heavier.  

The downside of using tubes is that sharp objects can easily puncture them. Additionally, when running lower tire pressure, they can "pinch flat" - a kind of snake-bite rupture caused by air pressure building up in one area of the tube. This is common in off-road biking.

Repairing a ruptured tube is relatively easy, but takes practice and skill to be quick and efficient. A patch kit/spare tube and some basic mechanical skill are necessary for these repairs on the trail. Furthermore, the tube tire set-up does weigh more than a tubeless set-up.  If you’re trying to shave some weight off your bike, this is a fairly easy place to do it.  

Tubeless Tires
First, it’s important to understand what a tubeless set-up is and how it differs from using a tube tire and tube. Tubeless mountain bike tires require a compatible, deeper hooked rim, allowing for the bead of the tire to seal, eliminating the need for a tube.  Also, the side walls are stiffer, thicker and heavier than conventional tubed tires. 

Furthermore, a valve stem is necessary for the tubeless rim and most riders choose to add a liquid seam sealant of some kind to avoid air loss and to protect against punctures.  Mounting tubeless tires is more difficult than tubed tires.  The biggest challenge is getting the tire bead to seat on the rim correctly—the seal has to be airtight. The process requires you to carefully add sealant, then pump in a lot of air in a hurry!  This usually means using a compressor or CO2 cartridge.  And removing tubeless tires can be more difficult (and messy, thanks to the sealant) because the stiff bead designed to grip the lip on the rim can be hard to get off. 

However, it’s not hard to get the hang of mounting and removing a tubeless tire. It just takes a little practice.  Riding on tubeless tires is also more expensive. Expect to pay anywhere from $400-$1,000 to convert a bike to tubeless. And, perhaps most important is the fact that flats in a tubeless tire are a bear to fix on the trail (hello sealant!).  In comparison, tube tires are a relatively simple fix.  You can however, put in a tube in a tubeless tire during a ride (or even a race), so it’s always crucial to carry one with you.  

There are numerous benefits to going the tubeless route. Tubeless tires are somewhat more durable. They are slightly heavier than normal tires, but lighter overall when you consider no need for a tube.  But the two main advantages that tubeless tires offer are:

1 They eliminate pinch flats 

2 They allow the rider to run a lower psi

There is no doubt you will get fewer flats with a tubeless system.  A tire deforms when you hit a hard object like a rock. With a big impact and a tubed tire, that rock and your rim can squeeze together forcefully enough to tear a tube. Whether you call it a “pinch flat” or a “snake bite” (a pair of pinch holes), you’ve got a flat to fix. 

If you switch to tubeless tires you’ll never have to fix a "pinch flat" again. Also, thanks to the sealant put in during mounting, tubeless tires suffer far fewer puncture flats. Tubeless riders who discover a tire riddled with shiny spots after a ride can smile knowing that their sealant fixed all those thorn pricks on the fly. 

You can also ride with less air in your tires. What's so great about that? Less air equals better traction!  Decreasing air pressure in the tire increases the surface area of the tread in contact with the ground, resulting in better grip, or traction, of the tire.  Riders can run with up to 15 percent less air pressure in tubeless tires, providing terrific traction in the most demanding conditions.

You might find that eliminating the tube also gives you a better feel for the trail, especially while cornering. Running a lower psi helps maintain your bike’s momentum, too, because tires are able to conform to obstacles, rather than bounce off of them. That also allows a tire to absorb small bumps and trail debris, giving you a smoother, more comfortable ride. Using lower tire pressure is the easiest way to allow the tire to deform over irregularities in the trail instead of forcing the wheel upward. When using tubes, there is friction between the tube and tire, and this friction has to be overcome to allow the tire to deform. By getting rid of the tube you get rid of that friction and reduce the energy needed to deform the tire, thus resulting in a faster bike!

So You Want to Convert? 

Option 1:  Get tubeless-ready wheels and tires

Look for a tubeless designation like “UST” (Universal System Tubeless), the original standard. You’ll also see similar, though different, terminology like “tubeless ready” or “tubeless compatible” from some brands.

UST-designated rims and tires are considered slightly easier to mount, in part because of how well the tire bead locks onto the rim. They typically require less sealant, too, because they are inherently more airtight. UST components are a little heavier, though, which is one reason why alternative tubeless-compatible systems are gaining popularity.  Your current wheels or tires might already be tubeless ready, so double-check before assuming that they’re not. Most top-end bikes come with tubeless-ready tires and rims.

Getting new rims and tires is the most expensive way to upgrade, but it also offers the easiest installation and the most reliable bead-to-rim seal. You’ll need sealant and perhaps some valve stems to do the installation, but that should be the extent of your additional expenses.

Option 2:  Convert your current tires and wheels to tubeless

Almost any combination of wheels and tires can be transformed using a tubeless conversion kit. The setup ranges from simple to challenging, because air can find more places to leak in non-tubeless-ready components. 

Conversion kits cost between $50-$70, though you can cut that cost by purchasing components individually. At a minimum, you need sealant, rim tape and a valve. Kits will not give you the lightest set-up, and getting the tire bead seated and holding air usually cannot be done with a floor pump. For that you’ll need an air compressor or a visit to your local bike shop. Some rims convert more easily than others, as do some tires. If you decide to go this route, it is crucial to do some research before you buy.  

When the Rubber Hits the Trail

A tubeless set-up offers several advantages to the hardcore enthusiast, but might not be worth the extra cost or hassle for the beginner mountain biker.  With that said, if you rode and raced your first XTERRA season with tubes and plan to be involved in XTERRA down the road, then I definitely recommend at least considering going tubeless. In my humble opinion, the pros of tubeless tires definitely outweigh the cons.  I haven’t used a tube in 8 years!

The XTERRA Couch to XTERRA training series is presented by SheriAnne Little, Jeffrey Kline, and four-time XTERRA age group world champion Mimi Stockton of PRS Fit.  Their new 12-week “Couch-to-XTERRA” training program is designed to do just that, get aspiring athletes off the couch, into training, and to the start line of an XTERRA.  

Read past training articles from PRS Fit at http://www.xterraplanet.com/training/couch-to-trail and learn more about their coaching programs at prsfit.com.

Couch to Trail