Schwalbe Aerothan inner tube

Schwalbe has released the Aerothan tube, made from a thermoplastic material that's completely different to that used for most standard tubes. Available in various sizes for road, gravel and mountain bike markets, it's an extremely lightweight tube that is claimed to be more puncture resistant than butyl tubes and to improve rolling resistance, but might not be possible to repair.

How can you test an inner tube? It was a question that was raised immediately when the new Aerothan tube came in for testing. It is a valid question, so I came up with a plan to attempt to test it fairly and compare it to a traditional butyl tube.

• Step 1 - A back-to-back ride to see if any difference in ride quality
• Step 2 - Attempt to check puncture resistance
• Step 3 - See if it will hold a high pressure over time

The Aerothan is a thermoplastic tube and Schwalbe has been working with chemical company BASF for over five years, developing and refining the material. It is available in eight different sizes, designed for road, mountain biking and gravel/trekking. All versions are claimed to be incredibly light, with the SV20E road version, which is designed for 23-28mm tyres, just 43g on my scales.

To put that into perspective, a standard tube for the same size will be 100-120g and a lightweight butyl tube around 80-100g. There are also some incredibly light butyl tubes such as the Continental Supersonic at just over 50g, but they are fragile and usually classed as race-only items.

Thermoplastic style tubes are not new and there are a few other companies making similar types, including Tubolito with the Tubo, which Neil reviewed a few months ago.

All the Aerothan tubes are only available with a single valve length of 40mm, so valve extenders will be needed for deep rims. The valve core is removable, so both types of extender could work, although the valve stem is plastic so extra care is required if changing the valve core or installing an extender.

Schwalbe claims the new Aerothan offer increased puncture resistance over a standard butyl tube, which would be impressive given the weight. Another popular option for racers are latex tubes; these are usually lighter, but also offer an improved ride quality and lower rolling resistance. The downside to latex tubes is that they do lose air far quicker, usually around 10 per cent lost within the first 24 hours, so checking and adding air is required before every ride.

The Aerothan is also considerably lighter than a tubeless setup when you factor in the heavier tubeless tyre, sealant and valve stem, and the claims for improved ride quality and extra puncture resistance are very similar to the benefits of going tubeless – if they prove to be true.

To find out, I used a 10km loop on a local road that has a mix of surface conditions but is mostly flat. Initially I rode a bike with standard butyl inner tubes, then after completing the loop I went to swap the tubes, before another lap of the circuit.

Unfortunately, in my haste I caught one of the tubes in the bead when inflating, and punctured it, creating a small hole. This my error, no fault of the tube, and almost certainly would have happened to either a butyl or latex tube. It did mean I could fast forward to Step 2, testing the puncture repair.

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Repairing is apparently possible using Schwalbe glueless patches. The tube needs to be clean and dry before applying. However, when inflating with the repaired tube, the patch blew off well below riding pressure. I tried a second patch, this time pushing harder to ensure the glue had worked. It pumped up OK to my riding pressure of 80psi and I went to complete another lap.

Immediately, the difference in ride quality was noticeable, giving a smoother ride and muting road imperfections. Things didn't go so well with the repair, though, and less than 3km into the loop the patch failed again. Given that it was the front wheel and I had lost all confidence, I replaced it with a butyl tube and headed home unimpressed.

I later tried a third patch, this time pushing the glueless patch harder and then leaving it for 30 minutes to see if it needed time to set. This isn't practical for a roadside repair, but I wanted to see if it would work. Again, it was inflated to 80psi, and within five minutes the patch had failed.

I continued with the testing, though, now with just the single tube and on to step 3.

For this, the tube was inflated to 120psi and left for two nights to test its air-holding ability; over that time it lost no pressure, which is a big benefit over latex tubes for everyday use.

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I continued to use the Aerothan in just the rear at my usual pressure of 80psi, and the performance – the comfort in particular – was brilliant. Around where I ride the hedges are being cut now it is autumn, and the risk of punctures is a little higher than normal. Okay, it might be more luck than anything else, but I did not suffer a puncture. I also tried to ride small, rougher lanes to see how it might cope and again it was fine. At times I would bounce on the wheels, look behind me and check to see if there was a slow puncture, as sometimes the ride just seemed too comfortable, or rather, significantly more comfortable than I am used to. It was almost exactly the same feeling as when I first used latex tubes, as they also improve the ride comfort.

While the material itself may be very tough, it can still be punctured, even if accidentally as I did, and given that the repair is not safe or strong enough, it essentially would mean that you still need to carry spare tubes and not rely upon the ability to fix it. I can imagine other people doing what I did, which is then £25 wasted. Schwalbe claims the glueless patch is the correct way to repair it, but this was not the case for me. I also tried using a Tubolito tube repair patch that I had, but this, too, failed.

Is there still a place for a tube like this? And would I recommend one or use one myself? This is where I am completely torn. If you had asked me the day after the first test I would have sworn no, but as I have continued to use it, the benefits have grown on me. It might be expensive for a tube, but for those looking to drop weight it offers better savings per gram than most other options.

It could also be a good option for a lightweight, very small spare, although disc brake riders might also look at the Tubolito S Tubo, which is half the weight again at just 23g and absolutely tiny. How reliable it would be I do not know, as although I own one and carry one mostly for events and big rides, I have not yet been unlucky enough to have to use it. The standard Tubolito Tubo that Neil reviewed is almost the same weight as the Aerothan, and available with three different valve sizes, with very similar claimed benefits.

Schwalbe really needs to find a viable repair solution to make the Aerothan tube a better option, even if the repair is only good as a 'get you home' type repair, but currently, in my experience, it is not even that. All that said, assuming you are far more careful than I was when installing and still carry a butyl spare tube, then the extra comfort it provides may be enough to make it worth it, and for those looking to save weight, it offers a good saving and for decent gram per £ cost.

Verdict

Beautiful ride quality and very lightweight, but question marks over the ability to repair