21 January 2009

bikefix Exclusive: An Ode to Tubeless

I am writing this piece to promote what I think is the single greatest advance in mountain bike equipment since suspension. I want to promote it because I feel that strongly and I know that many people still haven’t embraced it yet. I want to clear this all up.

For those of you who don’t know, the tubeless mountain bike tire is similar to a car tire, where the bead of the tire is held against rim by air pressure inside the tire. There is no tube and so the rim has to be air-tight to manage this. It is also extremely helpful (but not actually required) to have a specially shaped rim and specially designed tire.

First: let me point out that I realize a tubeless set-up is not the answer for everyone- lots of people, in many parts of the country, don’t need the advantages that tubeless offers. One might argue that they should go ahead and try it if it cost the same, but it doesn’t. In its cheapest incarnations (converting wheels and tires) tubeless still costs a bit more than a traditional setup, and I personally feel that it has an inferior outcome. I’ll get into the specifics of conversions vs. UST (Universal Standard Tubeless) in a bit.

The primary reason I promote tubeless systems is for puncture resistance. This is hands-down the most winning attribute of the tubeless systems on the market. Originally, when UST was introduced, I don’t think they intended people to use sealant in the tires, but we all do, and I consider it a critical component of the system. The rest of this review describes systems using some type of liquid sealant (such as Stan's). I know that some folks are shaking their head and saying “why change from tubes if I still have to use sealant?” The answer is this: Sealant is much, much, more effective at sealing holes in tire casings than holes in inner tubes. Inner tubes are considerably more elastic than the tire casing and any small hole created in an inner tube flairs open much wider than the object that created the hole- this is difficult for the sealant to stop. In contrast, a thorn hole (or similar) in a tubeless tire casing stays the same small size as the object that created it, and is much easier for the liquid to plug. Not to mention that the strength of the casing often holds the embedded thorn in the hole and all the sealant has to do then is seal the tiny space that air might be escaping around the edges of the thorn- very easy to do. I have many tires that are riddled with cactus quills and goatheads yet still hold air just fine. Unlike tubed tires though, you are better off leaving all the foreign objects lodged in the tubeless tire. Tubeless systems are also much more resistant (almost immune) to pinch-flats- otherwise known as “snakebites,” in which the rim of the wheel contacts the ground beneath it and cuts/splits the inner tube at the contact points. Again, the tire casing is just a much stronger piece of rubber and is almost impossible to pinch-flat. I am aware that a few people can still manage to do this but these are the riders on the freeride or downhill side of mountain biking and are doing things on their bikes that 99.8% (est.- accurate statistics are difficult to come by) of us will not even think of doing. I think that these two types of puncture resistance alone are worth the cost of tubeless. As a side note: I mentioned in the beginning that I didn’t like tubeless conversions as much as UST, but puncture resistance to thorns and cactus type objects is one area where conversions are almost as good. If this alone compels you to try tubeless then a conversion may be an adequate solution.

Another great reason to go tubeless is because you can run less air in the tire and therefore increase your traction. This is a direct result of the near-immunity that tubeless systems have to pinch-flats. If you don’t have to worry about pinch-flats then you don’t have to run 45-50 psi. I can hear the cries of the non-believers as I write this: “I don’t ever run that much pressure”. If you live in a part of the country that isn’t hard on tires and you run normal pressures- then perhaps tubeless doesn’t make sense for you. But let’s make sure we are talking apples to apples (my favorite saying): I am 220lbs with my riding pack on, I am riding up and down some of the hardest and rockiest trails out there, I am doing it on a 5-6inch travel bike, I run between 29 and 34 psi in my tires, and I’ve had two flats in 7 years. If you can say the same in each of these areas, and you are running inner-tubes then let me know what you are doing so I can pass it along. Did I mention that my wheel set-up is the same weight or less than most people who are riding tubes in this terrain? The traction increase from running tires at lower pressures is phenomenal- on steep hills with loose dirt and rocks it can be the difference between riding and walking. I know there is an increase in friction when you do this, but only on the smoothest trails. It is well understood now, that on bumpy trails, lower tire pressures (to a point) are actually more efficient than higher pressures because they deform around, rather than bounce off, the small rocks and roots. The beauty of tubeless though is that you can run higher pressures if you want to. If you are riding a trail that you know is ultra-smooth, pump in a few extra psi and run things that way, but at least you have the option to ride with less psi and out here the extra traction is usually the better way to go.

There are a couple other small reasons to go tubeless: to improve your ride quality, and because they “feel” like they roll quicker. You can increase the ride quality of any bike by going tubeless, and again, it is all due to the lower pressures you can run. You cannot feel a big difference on a full-suspension bike, but on hardtails and such, it noticeably smooths out the ride. This is a nice way to cushion your hardtail and then you also get the more important benefits listed above- a win-win situation if you ask me.

I almost hesitate to mention that tubeless “feels” quicker, but I think it warrants a mention because I immediately noticed this aspect when I first changed over, and many other people also notice this too. It’s hard to do an exact comparison (tire weights and tread are large factors) so perhaps this should be taken with a grain of salt, but it is a real enough phenomenon that engineer types have speculated about the difference we are feeling (between similarly set-up tube-type and tubeless systems). The prominent idea being bandied around is that the tube-type set-up has an extra layer of friction between the tube and tire (known as hysteresis) that the tubeless system skips- so even at roughly the same weights, tubeless “feels” quicker and livelier because tubeless systems have less inherent internal energy loss. I am not saying that this is a reason to switch to tubeless because it is just a tiny difference but if you do convert to tubeless you might just feel this (very positive) difference. The lack of hysteresis also accounts, in part, for tubeless tires' uncanny ability to stick to the ground. Fewer layers working against one another mean that the tire is better able to conform to the trail. Given the same tread and pressure, a UST tire will simply stick to the ground better than its tubed equivalent- which has advantages for both climbing and descending.

Most people I've talked to who don’t like tubeless or worse yet- blast it with a litany of drawbacks are the folks who have little [or no] experience with it, or at least no experience with proper UST systems. Which is the single biggest drawback of tubeless- they require some knowledge and skill to set-up properly. The tubeless system has a short but steep learning curve, and if you are a do-it-yourself type of person this can be aggravating. The main problem occurs when people are trying to convert rims and tires to tubeless using one of the “conversion systems” that are sold as being the quickest and cheapest way to go tubeless. Many of these systems do work but depending on the tire and rim they can be very difficult and frustrating for even experienced tubeless users. The UST system is much easier, but also has some tricks that are important to learn. I’m not going to go into great detail (I’ll leave that to your local shop- unless they're among the haters out there) but the main things to pay attention to are keeping the bead of the tire in the center-depression of the rim when you are trying to pull the opposite side over the edge of the rim- This creates the necessary slack to get it on without breaking your fingers (that’s right, I almost never have to use tire levers on UST). It's not a matter of strength- it's all about technique. Remember to do this again for the other side of the tire. The other thing that is sometimes hard to do is getting the tire inflated. The obvious solution here is an air compressor, but I have gotten to where I can mount 9 out of 10 UST tires (especially new ones) with a floor pump. An air compressor is even more helpful (and often required for conversions). With a little experience you get much better at all of this.

Just to save time I’m going to list the other things that a naysayer might argue are drawbacks: Tubeless is hard to fix in the field, it weighs too much, and it looses air over time. Yes, tubeless is hard to fix in the field, but the really good thing is that you rarely have to. Even if it does, just put a tube in it until you get home- the same fix you would have already had to do and everyone should be riding with an extra tube or two regardless of which system they are using. The argument against the weight of tubeless is not very solid. I like to say that tubeless is “functionally lighter” meaning- that around here with all the things that can pop your tire, the tube-type systems people run are extremely heavy because they use tough (heavy) tires with heavy-duty tubes and loads of sealant, and they still get more flats than those of us on tubeless. Again, if you don’t have to do this where you live then this isn’t a reason to go tubeless for you- and perhaps your tires are lighter, but tubeless weights are coming down quickly as manufacturers get better at making the tires. Finally; it really seems to upset people that most tubeless tire will lose air over longer periods of time (24hrs or more). In my experience this happens with tube tires too, albeit more slowly, but the reality is that everyone should attach their pump and check their tire pressures before every ride. Tubeless systems pretty much require this (although I’ve had some that last a very long time) but it’s a good idea even with tube tires because if you are even a little low on air- it is much more likely that you will pinch-flat. So how big a deal is it to pump some air into a tubeless system right before a ride? Not a big deal and I have found that most of my tubeless systems loose no air for at least 2-3 days. I make a habit of checking before every ride, though.

There are other little tidbits that I could throw at you but I’m going to wrap this up. My argument for using tubeless is for cross-country, trail-riding, and maybe some light all-mountain. I do not have direct experience with freeride or downhill and I am not saying tubeless is better for those types of riding (although it may very well be). For the record, I am in no way connected to a tubeless manufacturer or getting paid to write this. I wrote this entirely because I feel it is the way forward, and more people will have a better riding experience if they run tubeless. There's a lot of nonsense floating around out there regarding tubeless systems that keeps them from getting the credit or chance that they deserve, which I hope that I've been able to set straight.

charlie

8 comments:

Gus said...

I've had one flat in 3 years with tubeless (riding a hardtail!) although that was a pig to fix - tubes that sit in camelbaks for years accumulate holes. Interestingly I have had no air leakage between rides, I can leave it for months and still have pressure. Is this an unexpected benefit of Crossmax wheels with fully sealed (welded) rims?

bikefix said...

Gus, I'm glad to see you are a believer. Your tube mishap is a bummer and has happened to me as well. Now, I make it a point to put a new tube in my pack each year. Actually, it is like spring cleaning- only I just go through my pack and make sure everything is still good. As far as the welded rims being responsible for your lack of air-leakage over time- I don't think the welded rim is the reason. It certainly helps, but I ride welded rims almost exclusively, and some hold air for a long time and some don't. I think it has more to do with the tire and it's bead. Some are just better than others- I have yet to find a way to tell until you install them and use them for a bit. Good luck and thanks for the post.
-Charlie

Brian43NY said...

That was a long lengthy article on going tubeless. I did not read that you mentioned you live in Albuquerque the homeland of GOATHEADS. Of course your going to your going to be all over anti flat tech because otherwise you will spend all day fixing flats. Other parts of the country not as big as deal. But when I upgrade I will head your advice.

bikefix said...

Brian,

I hear where you're coming from, but I got turned on to tubeless while living in Boston- somewhere I never really suffered from pinch flats or thorns. It was the additional traction that did it for me, even at 35psi...

marc

Mikeylikeybikey said...

I have converted regular rims & tires to tubeless using the Stan's conversion. While it's a HUGE hassle due to my tire choice (Kenda Nevegals), once I got it sealed (sometimes it took 3-4 days) I've experimented with different tire pressures and found that 32lbs. is where I liked them best. I never went under 40lbs. when I ran tubes without pinch flatting, so the lower pressure gave me a noticeable boost in traction. I've had no flats for the life of the tire. As the tire was near the end of it's life, I heard a hiss at the bottom of a gnarly, rocky descent. Turns out it was coming from the bead. The seal must have been pried open, but it did seal up again after a little shaking. I replaced the tire with the DTC version of the Nevegal.... call me a glutton for punishment-it took forever to seal, but that tire rides great where I am (North West NJ). I have yet to seal the 2.35 I run up front... although it may be worth it, one tire is hassle enough! My next bike will have the proper UST tires and rims!

bikefix said...

Mikey,

You're almost there! Try some of Geax's new TNT tires- they seal up with a hand pump... There are plenty of *proper* tubeless tires too- you may well be able to run lower pressures in those thanks to the sturdier sidewall. Glad you've made the switch, even if it was the hard way. mb

Mikeylikeybikey said...

So would these Geax TNT tires mount up to non tubeless rims?
Would any tubeless tire for that matter?

bikefix said...

Mikey-

You bet. Tubeless or TNT tires will mount right up to normal rims when using tubes or not. They may take some effort to get seated on a standard rim, but far less than 'converted' tires would...