heat failure TPU tube

[JakobM]

Yesterday I was riding in about 38°C down a very steep descent (800m vertical with 13% average) with rim brakes on alu brake tracks.

I tried to release the brakes as much as possible, but at 13% with lots of turns, a lot of braking is required.

At the bottom I stopped at a fountain, and when I wanted to continue, my front tire was flat.
The welt of the TPU tube had separated. I am very very glad that it didn't happen while riding down.
These are some random TPU tubes from Amazon, which are around 40g, so not the super-light type. Rode them for around 1000km.
I changed the flat with a spare 28g TPU tube and rode home without issues.

I think I will switch to butyl while this heatwave in Europe is continuing and, afterwards, might try the Ridenow 38g tubes with alustem.

Has anyone of you ever had a similar issue?

[gribs]

It's a known issue. My spare rim brake road bike has butyl tubes for this reason as the weight saving isn't worth the risk.

[Dan S.]

Has anyone of you ever had a similar issue?

Yup, that’s a known issue with rim brakes. The brake surface just gets too hot and the TPU cannot handle it. Does not matter what brand you use.

[JakobM]

But it is not the TPU itself but the glue at the joint.
I only read that the thin tubes are not allowed with rim brakes. But I guess my descent was a bit of an edge case. Also without stopping I might have been fine. But I guess once the active cooling stopped the heat creeps further into the rimbed.

[ZacItaly15]

it's not an issue, it's a clear reccomandation given by the producer.
That's why I never swap to TPU with rim brakes but I kept tubeless

[Tasthal]

Hi, I wanted to comment that I'm not sure it's the rim brakes causing your problem. I think I have the same brand TPU tubes as you (at least also orange AliEx ones) but on a disc brake bike. Both front and rear have had this exact thing happen to them the past two weeks, after no issues for 3-4 months prior. Indeed, in the summer weeks I've been riding at 38C weather. Tires are catching sun at the cafe stop, which is when the first lost all pressure. Second one lost pressure at home after a ride. So both in the exact same manner as you: hot tires (due to weather), no problem when riding (and applying pressure to the tubes) but when you get off and the pressure eases, the gap is created.

TLDR: I think its just a very shitty brand and I'm gonna check if I can contact the seller and/or AliEx to report the issue. Too bad I got 6 tubes from them which I'm hesitant to use at all now...

(nb I know TPU + rim brake is not the most heat resistant, but as long as you don't go full braking down Ventoux it should be manageable in my experience)

[JakobM]

Hi, I wanted to comment that I'm not sure it's the rim brakes causing your problem. I think I have the same brand TPU tubes as you (at least also orange AliEx ones) but on a disc brake bike. Both front and rear have had this exact thing happen to them the past two weeks, after no issues for 3-4 months prior. Indeed, in the summer weeks I've been riding at 38C weather. Tires are catching sun at the cafe stop, which is when the first lost all pressure. Second one lost pressure at home after a ride. So both in the exact same manner as you: hot tires (due to weather), no problem when riding (and applying pressure to the tubes) but when you get off and the pressure eases, the gap is created.

TLDR: I think its just a very shitty brand and I'm gonna check if I can contact the seller and/or AliEx to report the issue. Too bad I got 6 tubes from them which I'm hesitant to use at all now...

(nb I know TPU + rim brake is not the most heat resistant, but as long as you don't go full braking down Ventoux it should be manageable in my experience)

thanks for your feedback. That makes me feel a bit better about trying the ridenow tubes on my rim-brake bike.
I also got some turquoise Spongo tubes of Amzon with metal valves. They look good, but I am hoping they don't have the same issues as the orange ones. I might try them on the backwheel first. 😅