TUBELESS TIRES 101
Truth and lies in the air
The year 2001 will be remembered as the year that tubeless tire technology for mountain bikes, pioneered by Mavic, found widespread acceptance among the major bicycle manufacturers. To keep you up on developing events, we put together the straight story on the most common questions we hear on the trails.
Q1: What are the advantages of tubeless tires for mountain biking?
A1: Pinch flats are no longer a concern, because a tubeless tire can be ridden with lower air pressure. The lower air pressure gives the tire a better bite and aids your bike’s suspension. Finally, you don’t have to buy as many tubes anymore. On a weird science note, one manufacturer claims that the friction created by a tube rubbing against the inside of the tire slows you down and that the tubeless system eliminates this friction. We doubt most riders would feel the difference in the saddle.
Q2: Can tubeless tires be mounted on conventional rims?
A2: Yes and no. Tubeless tires won’t work on standard rims. There are, however, companies that offer kits to transform your rims so they will accept the new tubeless technology. These kits include a special rim strip that seals the spoke area so air cannot leak out and tires that are designed to work with the rim strip.
Q3: Can a tire and tube combo be used on a tubeless rim?
A3: Yes, but you will need to remove the tubeless tire valve from the rim.
Q4: Are tubeless tires more dificult to mount than tires with tube?
A4: Yes. Tire companies require mounting tubeless tires without the use of tools (so you won’t damage the material that seals to the rim, called the bead). It is best to apply soapy water before working the tire onto the rim. Once mounted, the wheel needs to be slightly rotated to assure both beads are seated properly. Air need to be added “energetically” to get the tire to inflate.
Q5: I run a 2.10 tire now. Should I run the same size if I switch to tubeless?
A5: Yes. The trend right now is bigger is better. Small, light and quick tires that were the rage just a few years ago are somewhat passe now. The nice thing about the tubeless tire is that you can run lower tire pressures and therefore increase your traction. Tubeless tires put a lot of rubber on the ground.
Q6: Is a tubeless tire system lighter?
A6: No, but they are closing the gap. The rim assembly is slightly heavier than a conventional rim, and the tires are heavier because they are made with an inner liner. This liner is what keeps the tire from leaking air and protects against punctures. Some tire companies coat the outside of the tire instead of using an inner liner, but either design adds around 200 grams over a tire-and-tube combo. Since the technology is rapidly developing, expect weights to be reduced.
Q7: Why do I have to pump up my tubeless tire everytime I ride?
A7: Companies hve manufactured their inner-liners as thin as possible to keep the tires weight reasonable. The thin inner liners have porous holes that allow air to seep out over time. Air can also escape from where the tire mates with the rim due to production tolerances. Improvements are reducing the seepage problems of the past.
Q8: Will lower air pressure increase rolling resistance?
A8: Tubeless tires add some rolling resistance because you are putting a bit more drag in the tire by running it softer. But increased traction easily offsets any rolling resistance penalty. A tubeless tire rider needs to find the right balance of air pressure to rolling resistance. We are running between 38 and 45 psi in either the front or rear tire. Running too low pressure may result in damge to the rim flange. Once you cause damage to a tubeless rim, you’ll have trouble sealing a tubeless tire to it. Running too high of a pressure negates the tire’s performance gains over a conventional tube-tire combo.
Q9: Will I get fewer flats with a tubeless tire?
A9: Yes. You won’t pinch flat and the lower air pressure will help reduce punctures. When you roll over something, the tire has more give than a tire running high pressure.
Q10: Do tubeles tires leak more slowly once they are punctured?
A10: Yes. We have finished rides with numerous goathead punctures. The goathead stays stuck in the tire and effectively seals the hole. However, there is no advantage when it comes to big punctures or rips.
Q11: Can a punctured tubeless tire be repaired on the trail?
A11:It is a delicate process that is best accomplished in your workshop. The inside of the tire has to be clean and dry for a patch to seal it properly. It is best to carry a tube, and if you puncture, remove the tubeless tire valve and insert the tube to get home. We have not found plug-type patches to be effective. Automotive tires have four or five plys, so there is a lot of material for a plug to adhere to. That is not the case with a bicycle tire.
Q12: Should I upgrade to a tubeless system?
A12: Serious racers may be able to justify the expense of building a tubeless tire wheelset, specially if their results have suffered because of pinch flats or they are looking for an edge in technical terain. But the industry is adopting tubeless technology at an alarming rate, so your next bike will most likely come with a tubeless system. It you are not a racer, wait until you buy your next bike to begin your tubeless experience.
source: 2002 Feb, MountainBike Action
