Airless Tires in our Future

A Colorado engineer has come up with a new tire design. Not just another new tread pattern but a whole new approach. Instead of the usual threads encapsulated in rubber he has gone for the latest in carbon nano-tube technology. Result is a tire that mounts directly to the rim and requires no tube or air pressure to give it shape. The nano-tubes can be adjusted to give different ride characteristics, much like adjusting air pressure, and are covered in the rubber coating with the tread pattern. Not available as of yet but I am sure it will not be long before they are filtering through into the bike shops. In the meantime have a look at the video. If nothing else they look cool.

To Powder or Not to Powder...

          

A recent post on inner tubes "Latex v Butyl" has created interest in another of those topics which can stir passionate debate, whether to use talcum powder on inner tubes. So I shall offer my views on the subject and you can make your own decision.

           I shall state from the outset that I do not usually use powder when installing tubes. That being said I have customers that do and I have a canister of 'Johnson's' in the cupboard so, if requested, I can powder up a tube to keep everyone happy.

           Firstly, what are the reasons behind some people’s choice of using powder? Well, powder can make the tube easier to glide around against the tire when you are trying to wedge everything together. I know many people have trouble when trying to poke a tube into the tire and pinching the tube under the bead of the tire is a common problem for some. Also, when removing a tube from a tire, it is easier when dealing with a tube that was powdered. I have also heard the argument that when a tube is powdered there is less friction between tube and tire and less likelihood of failure from abrasion. Finally people see that there is often some trace amounts of powder when you get a new tube out of the box so therefore powder must be good.

            Okay, I think that covers most of the arguments that commonly get mentioned for the use of powder, now for my rebuttal.

            Starting from the bottom of the list, the reason manufacturers use powder is actually during the manufacturing process itself, it is not as some suggest them pre-powdering the tube for you. When the tubes are made the rubber becomes very hot, even by the time the process is over there is still considerable heat left. The powder is actually used on the inside of the tube so that when the tube is folded flat and pressed into the packaging the two sides of the tube will not bond together. Next time you have an old tube at hand cut through it and you will see a fine white powder coating the inside.

            Friction. I have never quite got my mind around this one. If anything you are creating a scenario to create more friction by using powder. When a tube is correctly inflated inside of a tire there really is no room for any movement between touching surfaces. Also we have all seen how a tube bonds slightly to the tire, if there was a need for any movement it would be very slight and the tube would be much better flexing instead of sliding against the surface as the powder argument suggests. And before the cries of tubes completely bonded to tires rises to crescendo, this never happens to the extent of tossing a tire away because of a tube that cannot be removed. I have replaced more tubes in my life than I have eaten hot dinners and never have I had a tube that refused to “Part Company” with anything more than a sharp tug. In fact that slight bonding helps out in another way too. When a puncture does occur, due to an errant thorn or some such, having the tube attached to the tire means that the air only comes out through the hole at that spot around the thorn, if you powder the tube and there is no bonding the air will escape from the tube into the cavity and be gone much quicker.

             Lastly, the installation. Here at least I do see a benefit for those who struggle with tube replacements. However, if you follow a set of rules such as, inflating the tube enough to give it body, make sure to get it seated up into the tire before popping the final bead on and never sticking tire irons in there, you should be fine. Most issues come when popping the last 6 inches of bead on and no amount of talc is going to help you there.

Butyl versus Latex. The Great Debate

Every year, as sure as leaves turn and fall, the perennial debate of "what are better butyl or latex tubes?" rears its head in the store. This year is no exception, brought to life by a group of riders traveling across the country and looking for a mediator.  Now I have learnt long ago when to keep my head down and look busy and this was one of those times. The rest of their trip gives me a headache just thinking of it. Anyway I thought that I might offer my thoughts on the subject here, where it is quiet…

                Firstly a little history, back in the day, the only game in town was latex rubber, basically latex is the stuff you pull out of trees and plants that can be formed into a rubber. Most plants exude some form of latex when they are cut or injured in some way. One tree in particular ‘Hevea brasiliensis’ was found to have great potential for commercially made latex rubber. Now I am no chemist so I will cut the lesson short on manufacturing natural latex, suffice to say it is produced from trees.  I should say that natural latex is, as it can be synthetically manufactured as well but originally everything from gloves to tires to condoms were made of natural plant based latex. Now everything was progressing fine until the advent of WWII. Amid worries about supply of rubber for everything from tire tubes to condoms a push was made for a substitute. Along came butyl, proper name Isobutylene Isoprene Rubber. The basis for this compound was developed by the German company BASF in the early thirties but was developed into what we know as butyl today by a couple of guys at Standard oil just before the onset of the war. Anyway I think that covers the how and the why but what is the difference and benefits of the 2 when it comes to your bike.

                I will agree that there are benefits to a latex inner tube and paired with a suitable tire they can be felt by most competent riders. The benefit comes in the form of better rolling resistance due to better or faster elasticity. When rolling, the tube is compressed and then, as it rolls along it springs back to its original profile. At the contact point the tire has a portion of its profile squashed to the road, obviously tire pressure and profile all factor in but as it is rolling the section that is leaving contact has to bounce back, the quicker this happens the less contact patch there is and by default the less drag. Latex is like a huge tight spring and it snaps back quickly. Butyl on the other hand acts like a hydraulic shock and bounces back slowly and in a controlled way, the energy is absorbed along with the heat.

                Other benefits include better feel when generally riding, for the reasons mentioned above, the tube also benefits cornering and basic feel.

A few things to consider when running Latex tubes.

·         Compared to butyl air leeches out quicker from a latex tube. Get used to pumping them up before the event to ensure proper psi.

·         Because of the high permeation rate, as mentioned above, do not use CO2 to inflate them. CO2 permeates through latex much quicker than regular air which is predominantly nitrogen.

·         They are lighter than a regular butyl tube, although some of the ultra-lite butyl are comparable. I have never been a big fan of the ultra-lite butyl tubes, they are extremely flimsy and the failure rate on them is very high which in my opinion negates any gain, especially on race day. Latex tubes in comparison, despite their delicate nature are surprisingly durable. They will shrug off lots of abuse. They will find any weaknesses in your rim tape though so be careful to install good tape well.

A standard Latex tube.

A latex tube will be beneficial to any good road race tire to a certain degree. That gain can vary from about 1.2 watts to about 2.8watts. Using a supple, high thread count tire makes a big difference. On tires utilizing some form of protective aramid belt or a thicker rubber tread the benefit will be considerably less.

Over the years latex has been definitely pushed under a rock when it comes to bicycle inner tubes and, honestly, that is probably the best for most riders. Butyl is much more suitable to the needs of most cyclists. It is thick and offers a little more protection and durability than latex. Butyl holds air better, it still needs topping off regularly but compared to latex it is significantly less permeable.

 Latex still has a place though, for those riders looking for ultimate performance from body and machine latex tubes can be a benefit. At this level any performance gain is always minimal but it is there. Running a quality latex tube in a quality race tire on race day is another of those gains.

Re-Inventing the Wheel.

The bike business is a business like many others, ideas come and ideas go, some good some bad and many are just there to let people know that the company ain’t dead. Every once in a while an idea comes along and just kind of hangs in the periphery, just waiting for their time to come. One such idea is 650b wheels, not that the 650b wheel is a new idea, hell it’s not even an old idea it has been around for decades, but to mountain bike designers and riders it is relatively new. There are some people, and I myself am one, that contend that if we had designed mountain bikes from the ground up in the beginning instead of modifying road bikes and cruisers to go biking in the woods, we would probably have opted for 650b wheels right from the start, however modifying frames led us to the smaller 26 inch wheels that then became the mountain bike standard for so many years.

        A few years ago we made the quantum leap to the 700c wheel, more commonly referred to as the 29er, which has made a huge impact with off roaders. This has made it difficult for the 650b though. Going so long with one choice, the 26, then adding the 29er quite recently has meant some reluctance from mass manufactures to add yet another wheel size and different bike geometry to already swollen product lines. Luckily the fear of being left behind by the competition has won out and we are seeing many choices from frame companies along with tire and rim manufacturers for 650b. This is very good news. And here's why; Choices.

As mentioned before the industry standard 26inch wheel MTB has been around since the start of mountain biking, the 29er or 700c MTB wheel is a relative newcomer and the 650 b is the new kid in town. The important thing to keep in mind here though is to not disregard any of the old wheel sizes just because there is a new one. They all have their place when looking for a new bike.

During this bike season we have seen a lot of new customers, which is very nice, a lot of new MTB’ers have come through the door as well and a good deal of them have opted for the 29er. Now don't get me wrong a 29er is a fantastic machine but it is not for everybody.

Designing frames and frame geometry for big wheels is tough, sure anyone can build a bike to accept big wheels but getting the handling and feel dialed in is a very different matter and it is especially difficult getting it right on mid to small frame sizes. We have seen many, many riders lately that look like they have been swallowed whole by their bike and, while this arrangement is fine for a gentle trail ride, on a more MTB specific trail or good single-track it must be akin to riding a bull elephant with colic.

Before I carry on let me clarify what we actually mean when we talk about these different sizes. Below are the measurements, in millimeters across the wheel, bead to bead. The bead of a rim is about 3mm down from the top of the rim.

26        559mm

650b    584mm

29er     622mm

As you can see the 650 falls about midway between the other two you will also note that the bead seat diameter of the 29er is the same as a standard road 700c so why do we call it a 29er when it is really only a modern 27inch road wheel. Well it is because some bright spark decided to measure the diameter outside to outside with a fully inflated mtb tire on, which gives you a measurement of roughly 29inches. Confused yet?

Anyway, back to the business at hand.  If you are a tallish or leggy person the big wheel option is definitely a choice for you. The frame size will be plenty to accommodate the extra clearance while still maintaining the ride characteristics of a good mtb. All the rules of bottom bracket height and head and seat tube angles still need to be obeyed and they can be with a mid to large frame size. However, if you are, shall we say a little vertically challenged, this is where problems arise. The rules of designing a bike to perform well for the rider tend to get thrown out the window and it all becomes about designing a small enough frame to at least reach the pedals on while the design is sacrificed to fit a big set of wheels. This really does not work. The cut off for a bike designed for the rider instead of the wheels generally falls somewhere around the 5’6” mark. There are exceptions for those with exceedingly long legs in relation to body height but generally speaking this is where sticking with the 26” wheels tends to be the better option.  Now though we have another option 650b.  This is where the slightly smaller size gives us, as frame designers, much more scope to still design the bike for the ultimate ride and handling but still giving the option of bigger wheels.

A Soma "B-Side" Built and ready to roll.

For those wanting to know more about the options available in the 650 or 29er range stop in or fire me an email. There are lots of choices. At the moment some of the best 650b frames tend to be from companies like Soma who offer the B-side. I expect some of the major names to start producing complete 650 bikes in the next year’s product line.

Tire Sealant, Our Recommendations.

       Tire sealant has been around for a good many years now and has certainly improved greatly in that time. What started as a thick sludge suitable only for a lawn tractors or wheelbarrows has now progressed to a foaming lightweight liquid suitable for a race wheel tubular. When I was mountain biking regularly in England I had great success avoiding punctures by using a bottle of the green slime in each tube. When the tires wore out and were removed from the rims there had been so many punctures sealed that the tubes had welded themselves to the tires, made me a fan of the stuff for life. It is still sold today and is still Martian green and still works great in a tube setup.

        Basically all the sealants work in the same way. When the casing is breached air rushes out through the hole taking the sealant with it, as the sealant flows through the hole, particles in its formula seal the gap. Although the principle is the same throughout the range of products on the market we have found some of these potions are more successful than others at getting the job done.

        For a comfort on hybrid bike or even a fat tire mountain bike running regular tubes Slime is still hard to beat. It is easy to install in a Schrader tube and, with a little patience and a removable valve core, it can be used on skinny valves too. Although it can be put in road tubes I find that it does not work quite as well under high pressure. Although Slime is about the beat of the bunch when using a tube, making the switch to a tubeless system can offer up a whole new set of possibilities.

       When using a tubeless system, such as the one offered by Velocity or the similar Stan's method, we prefer to use the Cafe Latex brand of sealant and the Stan's sealant. When putting a tubeless mountain setup together we prefer the Stan's sealant. This stuff works great on big tires, it seals quickly almost any puncture from thorns to nails and helps seal any areas around the valve and along the beads. It will not seal a cut or slit, none of the brands will, and like other makes, it does lose its effectiveness over time. Any punctures sealed stay sealed but after around 3 months the mixture dries up considerably and ceases to work sealing new holes and needs replacing.

      When it comes to tubeless road systems we prefer the Cafe Latex brand. This stuff is great on high pressure skinnies and seals quickly and permanently any punctures. Like the Stan's it also helps seal values and beads however we do find that it tends to keep its effectiveness a little longer.

Velocity Tubeless Road.

The good folks at Velocity have produced some great rims over the years and anyone that I have talked wheels to knows that I am a big fan. A little while ago there was a bit of a re think in the way road tires performed best, the general consensus was that a road tire of 700x23 performed best when mounted on a rim of around 19mm wide however the footprint of a 23 tire seems to favor a rim that is a little wider. The Velocity A23 is a good example and now we can mount it tubeless.  The tubeless system is very similar to the Stan’s mtb method. A special rim tape is used and a tubeless valve mounted in the rim finishes the job. You can use any sealant in there for added security, the Stan’s is good but we prefer the Caffe Latex brand. Once mounted this setup will give you as close to the ride of a tubular wheel as you can get without getting out the glue!

www.Velocityusa.com