TPU tubes, rim-brakes, a 4500ft descent -- and a near epic self-own.. #facepalm

[mhespenheide]

Shameless/gratuitous photo:



King's Peak, in the High Unitahs. (Backpacking, not cycling!)

[verticaldoug]

Yes, you are lucky. I thought about TPU tubes for their compactness and abrasive resistance. But I ride rim brakes on some of my road bikes, and saw the warning recommended for disc brakes not rim brakes.

I looked up the Thermo-Plastic (TP) part and saw at around 80 C these start to breakdown.

Even on a disc road bike, I can see a situation when it is 40 C outside, and maybe just the road surface temp gets the tire too hot for comfort.

Glad you are okay

[JMT3]

I use the TPU tubes. Had one that flatted a week ago from this past Saturday. Was on a team ride and rode over a recently placed reflector in the pavement that was epoxied in a pretty shallow groove that was not cut as deep as the others. Put a new TPU tube in and for three or 4 days after the CO2 molecules escaped pretty quickly and now it maintains pressure. When I used latex I would have to pump up my tires to pressure daily. With the TPU tubes its every three or four days and then they are usually down 10 to 15 psi. I still do tubes on the road. Fat, gravel and mountain I do tubeless.

[mcteague]

I had a front tire blowout going down a steep hill when running TPU. I'm still not sure how I managed to keep from hitting the deck. At least with mine it was clear what caused the puncture.

https://forums.thepaceline.net/showthread.php?t=297030

Tim

[Tall]

I don't know about your braking technique, but my assumption would be that you get much higher temperatures in the front on a steep descent. So I don't know about the heat theory. Did you carefully inspect the rim tape? I recently had two successive TPU tube failures caused by a subtle shift of the tape (fortunately not while I was riding).

[MikeD]

I'm unconvinced that heat tolerance is a problem with TPU tubes or not. Jan Heine says that they have the same temperature tolerance as butyl. Latex is worse. YMMV. OP did the tube look melted?

Rubber doesn't actually melt, it chars. TPU melts. Not sure if that makes any difference to the situation or not.

Are TPU tubes heat-resistant? Can they be used with rim brakes?

TPU stands for thermoplastic polyurethane, which means they are made by melting and extruding polyurethane. Does this mean that the heat from rim brakes can cause the material to melt again? Actually, that’s not a problem: TPU tubes have a higher melting point than butyl tubes. They are safe with rim brakes.

BITD, Panaracer had these plastic tubes. I used them on a hot day and got a flat during a ride on a 100° day. I stuck the tube under water and discovered tiny leaks all over the tube on the rim strip side (Velox rim strip). Maybe they weren't exactly the same material as these new tubes are or not.


Continental offers high quality TPU tubes. They say on their website that they shouldn't be used with rim brakes. They say also that latex and thin butyl tubes shouldn't be used with rim brake rims that have no rimstrip. They seem to be the most conservative with regard to heat effects on tubes.

[phishrabbi]

If it is really true that you can't use your brakes while riding downhill when using this product, why would anyone purchase this product?

I've been keeping a tpu in my saddle bag as a just in case solution to a catastrophic flat situation with my tubeless setup, but this thread is making me reconsider.

[robt57]

Rated for disc only, where rim brake heat buildup non issue. The mistake was overlooking putting them on rim brake bike.

The disc TPU I have are 23grams. The TPU rim brake ones I use are double to triple that depending on which ones.

The 23 gram Tubilito is for 23-28mm tires. Imagine how thin they get in 28 tire that runs a bit large as well.

Originally Posted by phishrabbi

If it is really true that you can't use your brakes while riding downhill when using this product, why would anyone purchase this product?

I've been keeping a tpu in my saddle bag as a just in case solution to a catastrophic flat situation with my tubeless setup, but this thread is making me reconsider.

[verticaldoug]

https://yellowcrank.com/2022/01/05/t...rket-overview/


I think it depends on brand, as there are also variations in TPU with one being better than the other with heat.

All I know is when I looked at the Conti TPU, it definitely said no RIM Brakes.

If TPU does start to soften at 80C, I can see all sorts of little issues. I figure it isn't worth it for me.

If you look at the TPU tubes on the Vittoria website,

The ultimate tube for racing with disc brakes 
The lightest, fastest inner tube available, engineered for racing on disc brake wheels only. The highest speed available with the convenience of clinchers tires.

[exapkib]

Sorry to hear about the mechanical issues! Glad they didn't ruin your day. Let me know if you want to stop by for supplies while you're out here.

[Clean39T]

Update: took a close look at the Tubolito and it appears to have lost its integrity at the seam.. which I'd say is consistent with overheating, but I guess could be an unrelated failure.

[2metalhips]

Some Tubolito tubes are rated for rim brakes and some are not.

[ColonelJLloyd]

Interesting and timely. I just installed different TPU tubes in three bikes over the weekend.

Disc brakes, carbon rims, Revoloop.cc gravel tubes. Recommended for disc only.

Rim brakes, carbon rims, Barbieri NXT Piuma. Recommended for disc only.

Rim brakes, alloy rims, Schwalbe Aerothan. Approved for rim brakes.

[EB]

Forget all this faffing about with TPU, I'm going back to tubeless

[robt57]

Originally Posted by Clean39T

Update: took a close look at the Tubolito and it appears to have lost its integrity at the seam.. which I'd say is consistent with overheating, but I guess could be an unrelated failure.

I think another lesson is to look at these and replace as necessary when moving or replacing tires, exercise prudence.

I have more Schwalbe in play by a margin. Somehow I feel like the 60-65 gram tube is going to be more durable than a 35 gr one. Plus of the ones I have used thus far, the Schwalbe that is speced to go to 28mm starts out being bigger, more material than the tubolito.

Just like with Tubeless clinchers I think I will revert to butyl once TPU scare me. Hopefully before death. Or the latex I still use and have for 10 years or more.

Of course I mean for clinchers, I still run Tubeless tubular on a few wheelsets...