Originally Posted by
staehpj1
Thanks, That is helpful. When you say "start to soften" do you think that is actually close to failure? Or is there yet more room for error?
I can’t say for certain but if the tube were heated outside of a tire, it likely would deform permanently. Inside a tire, the tube is constrained and likely wouldn’t blow out. The tire would have to come off the rim which is unlikely.
[QUOTEIt is possible to get a rim above 185 F but I am pretty sure it isn't the norm. I have seen a rim hot enough to make spit sizzle when a wetted finger touched it, but that was an extreme case that could and should have been avoided. That wasn't on my bike. I am thinking that if I do decide to run TPU tubes I'd have the heat issue in the back of my mind and never go that far without stopping to let the rims cool if there was ever a need to. Not that I ever expect to heat the rims anywhere close to that hot by braking. I have gone down some pretty long and steep grades with a load and checked the rims halfway down and they were sometimes pretty warm, but never all that hot that I'd be worried they were close to 185 F.
I see that some brands say they are for rim and disc brakes and some say disc only. I doubt the difference is the tubes and figure it has more to do with how worried they are with avoiding possible lawsuits.[/QUOTE]
It would be possible to get the rim hot but you’d also have to get the tire that hot as well. Rubber doesn’t conduct heat all that well