2 Pack CYCLAMI Bike Tire Tube for 700C Road / MTB26/27.5/29 / Gravel, TPU Bike Inner Tube with 45/60/65/80/85mm Presta Valves, Ultra-Light TPU Inner Tube(Include Patch Repair Kits)

Super

Facts first: they are lightweight and stow compactly in an under saddle bag. They are also puncture resistant.That's where my experience diverges from the marketing hype and the glowing online articles about how TPU is the New Great Thing and butyl rubber is dead.I have bought multiple of these so I feel that consistent experience can be established. I have ridden different routes each time. I already use Gatorskins tires. I use tubeless compatible rims, so there is NOT a spoke strip problem.And in the past, with butyl tubes, I might get one flat in an entire season. Today I got 2 flats on one ride. The ride before that was cut short by a flat. And the ride before that was cut short by a flat. The common factor: cyclami TPU tubes. Even when they are not flat, they leak as much as 30 psi overnight. I usually top off to 110 psi in 700c tires around 11 pm before a ride. By morning these tubes are typically down to 80 psi.That is, when they aren't spontaneously blowing or emptying themselves of air. When I have test filled them underwater, the leak is ALWAYS at the base of the valve stem. I checked into this online and it was recommended to cut a hole in a piece of felt and insert the valve stem through it so that there is a cushion for where the stem goes through the rim. Maybe that helps, I don't know.Another thing to notice is that when you press the release on the valve stem to vacate a little air so the tubes can be pumped, it almost always bends the interior of the stem. Again, it's not that I don't know what I'm doing... NO PROBLEM with butyl tubes, even the cheap ones. And I have ridden tens of thousands of miles on butyl tubes.One final point: these are super thin tubes, so when your tube goes, you don't have an elastic layer of shot butyl tube for your rims to ride on until you can find a driveway to pull safely into. You feel Every. Bump. in. The. Road. And it is VERY difficult to steer, moreso than with flat butyl tubes.I feel duped. I believed the positive press on these tubes but the articles were clearly puff pieces from some weight weenie geeking out over grams.:-(I'll probably use the remaining 4 tubes as pressure ties for some woodworking project. That's all they are good for at this point.

Work great on my 700x28 Continental GP5000 road tires! The main advantage is that they are lightweight and very compact, so you can carry two spares in less room than it takes to carry a single butyl tube spare.

Update 3: a third tube also failed in exactly this way. I've installed one more. Before installing, I cleaned the failure area and applied one of the included patches, preemptively. I've ridden about 350 Km over the course of 9 rides and it seems to be holding.Contacting Cyclami directly is no good, however contacting the seller, SoRider, was amazing! They responded within a day, asked a couple of questions, then shipped two more tubes to replaced the 3rd failed one. The reinforced ones continue to hold. I'm cautiously optimistic to the point where I may install them on another bike.Update 2: the second tube failed in exactly the same place about 60 miles after being installed. At least one other review had photos with exactly the same failure. Reducing rating to 1 star.Update: after riding these for about 100 miles (5 rides in 4 months) one of the tubes failed when crossing a railroad track. Tires were just pumped up 10 minutes before, not overinflated. I put in my spare and rode another 20 miles. When I checked the bike two days later, the replacement tube was flat. I pumped it and it seems to be holding for now but I'm pretty disappointed with the apparent lack of durabiltiy.I installed these tubes when replacing tires, just to try. Installation was simple - the bright green color makes it easy to verify that the tube isn't being pinched between tire and rim. Carried as a spare, the truly tiny size takes up much less space in my bike bag. The bright green aluminum valve caps are a bit over the top for this old guy, but I'm very pleased with the initial experience. Will update this review over time if my opinion changes.I've reached out to cyclami but they are not responding at all.