TPU Tubes: Learnings after 2 Years
When Velo-News recently talked about ‘7 Road Bike Trends We Expect in 2026,’ TPU tubes were on their list: “You’re going to swap your tubeless setup for a TPU tube,” predicted tech editor Alvin Holbrook. He continued: “Why would someone want to swap to a TPU tube? For some, tubeless tires and the sealants required can be a messy, expensive headache. […] TPU tubes offer some of the same benefits of a tubeless road tire setup, particularly when compared to a standard butyl rubber tube. Both tout lower weight, additional puncture resistance, and improved rolling resistance against a standard rubber tube.”
Since we’ve been working with TPU tubes for over two years now, it’s nice that mainstream media finally see the merits, too. In a way, it reminds me of the wide-tire revolution. We (and our customers) were riding wide tires for years, while the mainstream media ignored “those weirdos in the Cascade Mountains who claim that wider tires roll faster.” It’s the same with TPU tubes—we were testing and riding them while most media were still in the ‘tubeless for every rider’ camp. (Of course, we’ve also been riding tubeless on some of our bikes—it all depends on where and how you ride.)
I just got a brand-new OPEN U.P.PPER 2.0 yesterday, and I have to decide how to build it up. One thing I already know is that this bike will run TPU tubes.
Readers who know how much I love my first-generation U.P.P.E.R. can imagine how excited I was when our friends at OPEN sent me one of their just-released new frames, painted in Rene Herse colors. Thank you, Andy and Gerard! I can’t wait to try this amazing frame… and for the riding I do, TPU tubes are often the better choice: faster and lighter than liquid sealant inside the tubes, and without having to worry about the sealant solidifying if I don’t ride this fender-less bike for a while during the rainy Seattle winter.
If this bike (and its 44 mm tires) was to be ridden by a big, strong racer like Ted King or Brennan Wertz in Unbound, we’d run the tires tubeless. (You’ll read in a moment why and how I rode TPU tubes even in Unbound XL.)
We’ve been testing and riding TPU tubes for more than two years now. Before we introduce a new product, we test it thoroughly. That’s part of the Rene Herse promise: If we sell something, it’s already proven itself in the field. Over the last two cycling seasons, we’ve sold literally thousands of TPU tubes—and got feedback from our customers. So here are answers to some frequently-asked questions, based on those many months and many miles of real-world experience.
Why would someone swap out a tubeless setup for TPU tubes?
People sometimes forget that tubeless sealant adds weight and resistance—all that liquid sloshing around inside your tire. (As a tubeless tire rotates, the sealant gets spun to the outermost point of the tire—under the center of the tread. The tread deforms where the tire touches the road, so the sealant has to move with each revolution. That’s a good thing in the sense that it distributes and mixes the sealant, but moving around liquid also consumes energy, which makes your tire roll slower.)
Compared to the sealant, a TPU tube is lighter and rolls faster. Furthermore, you don’t have to worry about the sealant drying out. With a TPU tube, it doesn’t matter how long the bike has been standing: just inflate the tubes, and you’re ready to go.
What are the advantages over butyl tubes?
The thinner material makes TPU tubes much lighter and also faster. They pack smaller, too, so you can bring more spares. There’s another advantage that we initially didn’t talk about, since it seemed ‘subjective’—until our customers mentioned it: The bike feels different. For lack of better word, it feels more alive. It’s something we’ve long known about latex tubes. The same is true for TPU tubes.
Speaking of latex tubes…Why are TPU tubes better?
TPU tubes roll just as fast as latex. They are lighter. Most importantly, they don’t lose air as quickly as latex tubes, which need inflating at least every 24 hours.
There are many TPU tubes on the market. What makes Rene Herse tubes special?
The challenge of making TPU tubes lies in attaching the valve to the tube. With butyl tubes, the metal valve goes inside a rubber cone that is vulcanized onto the tube. That’s not possible with TPU. Most makers instead use a plastic valve stem that’s glued onto the TPU tube. That can cause problems where the (metal) valve core is screwed into the plastic valve stem: The plastic stem distorts or even cracks. Then you get mysterious air leaks. Tightening the valve core—usually the first step in curing mystery leaks—will make the problem worse.
Rene Herse tubes use patented all-metal valves that trap the TPU material between two metal discs. That eliminates the mysterious leaks.
Leaks can also occur where the ends of the tube are joined. That’s why Rene Herse tubes use ultrasonic welding and are checked individually to ensure they’re airtight.
Recently Silca introduced tubes with all-metal valves, too. How are yours different?
We want to be open and honest: Both tubes are made by the same supplier in Germany. And unlike tires, where our Rene Herse tires differ from others made by the same supplier with respect to casings, tread patterns and rubber compounds, a tube is, well, a tube.
There are some differences, of course. Silca offers two widths, which covers tires from 24 to 64 mm wide. Rene Herse TPU tubes come in three widths for tires from 20 to 65 mm—we don’t want to cut it that close. On wide rims, tires are often wider in reality than the ‘nominal’ width that’s written on the sidewall. We don’t want you to run the risk of your tube bursting because your 43 mm tire has ballooned to 45 mm on a wide rim. At the other end of the spectrum, if your tube is a bit wide for the tire, it will be hard to insert without creases or folds—especially once you’ve run it for a while, and it has stretched a bit. With three widths, there’s a greater margin of safety.
We also figured that, for road bikes with tires up to 32 mm wide—like Andy from OPEN’s own MIN.D. road bike—you don’t want the extra weight of a tube that’ll also work for gravel bikes with much-wider tires. Having a dedicated tube for 20-32 mm tires saves 30%—13 grams per tube. (Andy is running Rene Herse 700×31 Orondo Grade tires with our TPU tubes on his tricked-out, superlight 6.8 kg bike.)
The sizes of Rene Herse TPU tubes overlap. Which size should I use?
If your tire width is covered by two tubes, you can use both sizes. The smaller size will be lighter. The larger size will stretch a bit less and thus be a little stronger. If you run wide rims, use the larger size, since the actual width of your tires may be a bit wider than what’s printed on the sidewall.
What tires and rims are Rene Herse TPU tubes compatible with?
Rene Herse TPU tubes are compatible with all tires—tubless-compatible or not—and all rims—hookless or with hooks.
Can I run TPU tubes with rim brakes? Are they heat-reistant?
TPU tubes have a higher melting point than butyl tubes. They are safe with rim brakes.
Can TPU tubes be inflated with CO2 cartridges?
Inflating with CO2 cartridges is not recommended. The sudden pressure can break the tube. The expanding CO2 is extremely cold, which makes the TPU material brittle. However, TPU tubes are safe to use in sub-freezing temperatures—the tire insulates the tube from sudden temperature changes. (Unless you inflate the tube with freezing CO2.)
How about electric inflators or compressors?
Electric inflators and compressors are fine, as long as you inflate the tube in small steps—like 20 psi (1.5 bar) at a time. There are two reasons for this: 1. You don’t want to overheat the tube. 2. When the tire seats on a modern (tubeless-compatible) rim, the tube suddenly stretches a lot. We want to make that ‘pop’ as gentle as possible to avoid overstretching the thinwall tube.
Are there special considerations when installing a Rene Herse TPU tube?
With modern tubeless-ready rims, the installation techniques have changed for all tubes, but it’s especially important for our TPU tubes. The one thing that needs to be avoided is a sideways pull on the valve. That’s why we recommend inserting the valve into the rim before the tube is inflated (above). Then inflate the tube. That way, the tube eases into the tire, rather than being pulled one way or the other as you insert it. We’ve made a video that shows the installation of TPU (and other) tubes into modern rims. (Link at the end of this article.)
Can TPU tubes be patched?
Patching TPU tubes is simple: Wipe the tube with alcohol, then apply a self-adhesive Rene Herse patch. (Alcohol wipes are included with the Rene Herse patch kit.) That’s much easier than patching a butyl tube, where you roughen the surface with sandpaper and deal with messy vulcanizing fluid. Rene Herse offers a patch kit with 5 patches at moderate cost. The patches are permanent, not just to get you home.
Is there a maximum pressure or maximum rider weight for Rene Herse TPU tubes?
The maximum pressure is determined by your tire and rim. Rene Herse TPU tubes themselves do not have a rider weight limit.
Can I run Rene Herse TPU tubes on aero wheels?
Rene Herse TPU tubes are available with 50 mm and 70 mm valves, so they work on most aero rims. However, we don’t recommend using valve extenders if your rim requires an even longer valve stem. Screwing on the extender can break the valve/tube interface.
Rene Herse TPU tubes have smooth stems and no valve nuts. Why?
It’s not a big deal either way. If you come from a racing background, you know that tubular tires have smooth stems because they work much better with slip-on pump heads. When the gasket inside the pump head is pushed against the serrations of a threaded valve stem, it can virtually lock on, making it difficult to remove. With smooth valve stems, you won’t have that problem.
Then why do most valves have threaded stems and nuts?
On European city bikes, the nut prevents the valve from being pulled into the tire if you forget to pump up your tires until the pressure is almost zero, and ride on almost-flat tires. (Stiff city bike tires remain rideable even with almost zero air.) When the rider finally gets around to inflating the tire, they can’t find the valve because it’s inside the tire! The valve nut prevents that from happening. Obviously, that’s not something you’ll ever do on a performance bike, so there’s no need for a valve nut. (Tubeless is a different matter, as there’s no tube pushing the valve outward.)
What if I use a pump with a hose. How do I screw that onto a smooth valve?
The hose of the pump screws onto the valve core, not the stem. That part is threaded on all valves, so there’s no difference between smooth and threaded valve stems in this respect.
You sell sealant for TPU tubes, but Josh from Silca says sealant doesn’t work in their TPU tubes. What gives?
If the hole in the tube doesn’t align with the hole in the tire, the sealant can run into the space between tire and tube and create a mess, instead of sealing the puncture. In our experience, that can be an issue with stiff tires, where the tube moves against the tire. With supple tires, tire and tube move together, the holes remain aligned, and the sealant works like it does on a tubeless tire.
In his recent TPU video, Josh talks about how he does their product testing on his way to work, riding his e-bike. He found that punctures didn’t seal when he was running TPU tubes and sealant on the e-bike. Most e-bikes have relatively stiff tires, since rolling resistance is less of a concern when an electric motor provides the power. That may be the reason why Josh didn’t have much luck with sealant inside his TPU tubes.
We do our testing in gravel races and on bikepacking trips. We’re running our supple Rene Herse tires, and we’ve found TPU sealant works well in those scenarios. That’s something our customers have also confirmed. One of them, who lives in Albuquerque, New Mexico, “where goatheads are more common than grass,” reported in an online forum: “Came home again today with several goatheads stuck in the casing, but no air loss.”
It’s true that TPU sealant will not seal big gashes in the tube. It’s really intended for small punctures from steel wires, small slivers of glass, goatheads and thorns—all those things that cause 90% of flats. When you encounter those punctures (and are running supple high-performance tires), our TPU sealant works really well.
Can I run Rene Herse TPU tubes on my gravel bikes?
Rene Herse TPU tubes have slightly thicker walls than most TPU tubes, so they are extra-strong. This adds only a few grams of weight, but they resist pinch flats better than butyl tubes. We’ve raced on Rene Herse TPU tubes in Unbound XL (above) and set FKTs on ultra-tough bikepacking routes, without any problems tire/tube problems.
Wait, above you said that you’d recommend tubeless for Unbound. What gives?
We’re running ultra-wide 54 mm tires on our gravel race bikes, so the risk of pinch flats is much-reduced. At Unbound XL and during solo FKTs, there’s no huge pack like you get in the 200-mile pro race at Unbound, so you can see the road ahead and avoid the biggest rocks, which reduces the risk of sidewall cuts.
Every rider and scenario is different—that’s why we offer TPU tubes, but also our Supple Tubeless Sealant—and that’s also why most of our tires are tubeless-compatible. That gives you choices based on your preferences, riding style and terrain.
More information:
- TPU tubes in the Rene Herse program
- Video: How to install tubes in modern rims
