Put my first TPU tube in my rear tire to test around town three months ago, a RideNow spec'd at 700/32-47 at an advertised 45 grams. My very uncertified kitchen scale put the weight at 40 gr. 

For me, a gram counter and space miser, they hold promise. I’m currently using Continental Tour tubes, also 32-47, but they weigh in at 150gr each (154 on the kitchen scale). With 2 tubes installed and 2 spares that’s close to one pound in weight savings and approx. ⅓ the storage space for the spares by using TPUs. So far my TPU tubes are holding air very well. 

These are some of the plus features. For years, almost 2 decades I’ve used Schwalbe SV18 extra light butyl tubes at 105 gr per tube. But I Don’t think they export them to the USA anymore, at least I can’t find them.  Amazon seems to have a ready supply of TPUs from various brands and sizes at competitive prices. Schwalbe now is marketing its own TPU tubes at the low, low price of $32.00 USD per!

The unknowns and perhaps negatives: Will they hold up under tourning conditions? How easy are they to patch and will the patches hold over touring road time. I stuck a Park Tools glueless patch over a pinch hole occuring during installation. It’s holding air well and seems to stick, but time will tell. I think it should, the Park patches are also TPU. One negative for me is the RideNow valve cores are not removable. If the brass set screw is bent or breaks off the tube is trash. (They do claim TPUs are recyclable.) My second TPU purchase was for Cyclami tubes with removable valve cores. The glueless patches that came with the Cyclami were a joke. I couldn’t get the patches to separate from their backing without destroying the patch, but the tubes themselves were easy to install and hold air very well. I’ve alway use tubes with removable cores and carried a couple of extra cores on tour.

The TPU claim is that they reduce rolling resistance comparable to tubeless and latex tube levels. I can’t say I’ve noticed the reduction, but maybe under load and distance with TPU tubes in both tires it maybe noticed.

We’re headed to France in a few weeks with a full complement of TPUs installed, and have no fears of finding replacement butyl tubes if the TPUs prove to be a bust.

Wow, that is a big difference. I hadn’t heard of the TPU tubes before. Good to know.

And please be sure to let us know how things worked out on tour.

That looks like a major saving in storage space for spares. We each have different size tires, so carrying two regular spares each really eats the space in the tool bag. On Amazon.ca I see prices for TPU tubes ranging from 2 for $30 to 2 for $123. Almost all seem recommended for narrower, road bike tires. Those that do go up to width 47 (which is just 1.75") state it as 32 (1.25) to 47. That's a lot of stretching for something so light?

Your concern is legitimate, but so far with the two brands I’ve tested it is being too wide for narrow tires. In the picture the Conti Tour measures 30mm and the Cyclami TPU is 44mm. Both tubes are new out of the box and never inflated. The Tour is rated 32-47 and I use them at both extremes. I currently have a Tour tube in my front tire, which is 28mm and was not all that difficult to fit. The Cyclami is also rated 32-47 and I don’t think I could successfully jam one into a 28mm tire without damaging the tube.

I just put TPU tubes on MJ’s Tri bike, which has 23mm tires and narrow rims. The tubes claimed to be span 18 to 32mm. I got a snake bite fitting the tube in the first tire. They were much wider than the narrow tires.

My current concern and yet to be tested is how much “rebound” the TPU tubes have after being used in tires on the wide end of the scale. Will they stay stretched and be too wide for my 32mm street tires after being used in 47mm dirt tires?? I’ll report back in a few days.

As for price, at $10 to $12 USD per, is about what I used to pay for Schwabe tubes. The Continental Tours are only a dollar or two less. As for the $30+ European branded TPU tubes, I think their prices will have to come down to stay competitive.

If you decide to go back to Schwalbe extra lights they are available online in USA from Rene Herse cycles in Seattle.  

They also sell their own branded TPU tubes. From the colour I would guess they are made by Schwalbe. Not inexpensive, but replaceable cores. 

I’ve not used them, but I am seeing more adverts for them pop up on a social media site which seems to have worked out that I’m a cyclist.

The saving in weight and volume appeals to me, but probably only for use as spare tubes at this stage. 

Since you first posted this, and paradoxically got the untechnical Dodie going on the subject, I have watched quite a few Youtubes on the subject. It's hard to know what is factual on Youtube, but I have seen more than one reviewer showing variously that TPU is hard to patch, needs special costly glue in a special patch kit, does not roll appreciably easier, does not hold air well, resulting in easy to get pinch flats, and especially in the case of the Chinese brand is thin and flimsy. So despite all this, we seem ready to buy several, lured entirely by the small packed size. We recently went berserk and bought a large heavy camera, and I am crying about have no space now for extra snacks. So I seem willing to trade possible pinch flats for snacks! Maybe on our coming tour we will develop some actual TPU experience, and then we can become yet another social media review expert!

Interesting. I doubt I will anytime soon because the bike I’ve been using for touring lately is tubeless. My poor road bike, which uses tubes, has barely seen the light of day since I got the titanium bike. Al’s new road bike (he rides his road bikes) is tubeless too, and we have a whole shoebox of tubes to work through before we need to buy any more. Why so many?  Back when we could get things like tires online for half the Canadian retail price, we always topped our orders up to the free shipping threshold with tubes. Now there’s no saving on tires and free shipping thresholds are much higher than they used to be. Luckily we don’t need more tubes!