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

[smontanaro]

I'm a bit confused (nothing new there). If heat was the problem, you'd think the front would have been the tube to explode. Different type of tubes front and rear?

[ridethecliche]

I think the solution is to buy them in bulk and treat them like regular tubes including throwing them away without guilt when necessary.

Like others, I'm also a bit confused by the front being fine and the rear having the issue twice!

[marciero]

Originally Posted by EB

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

The faffing about with tubeless is mostly why I just recently decided to go with TPU.

[fourflys]

Originally Posted by robt57

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.

sometimes it's nice to be either lazy, too cheap to buy the new thing, or both..

I'm too lazy to deal with road tubeless currently (maybe when I get my new to me incoming T-Lab) and I'm too cheap to buy TPU tubes when I still have a decent number of butyl or latex tubes.. folks just seem to have weird issues with TPU tubes.. maybe they're fantastic to ride, but I'm good for now..

[MikeD]

Originally Posted by ridethecliche

I think the solution is to buy them in bulk and treat them like regular tubes including throwing them away without guilt when necessary.

Like others, I'm also a bit confused by the front being fine and the rear having the issue twice!

How many times have you had or seen someone get a puncture and replaced the tube without looking for and removing the item that caused the flat in the first place, and get another flat? That's what probably happened here. The OP has not provided any evidence as to what caused the flat and assumes heat related.

[fourflys]

Originally Posted by MikeD

The OP has not provided any evidence as to what caused the flat and assumes heat related.

he did speak to a seam separation issue above I think..

from pg 2:
"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."

[MikeD]

Originally Posted by fourflys

he did speak to a seam separation issue above I think..

from pg 2:
"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."

OK, I missed that but inconclusive. Lots of the cheap TPU tubes have that problem out of the box. But, I'm not defending TPU tubes. I've got two Cyclamis still in the box and am hesitant to use them.

[ColonelJLloyd]

Originally Posted by fourflys

.. folks just seem to have weird issues with TPU tubes.. maybe they're fantastic to ride, but I'm good for now..

One thing that is interesting to me is that they hold their shape unlike butyl or latex and feel "stiff" for a tube as you inflate them. They increase their size, but hold their shape such that as they inflate you can feel them inside the tire not touching the tire. It's weird to feel airspace between the tread or sidewall and the tube.

Originally Posted by MikeD

OK, I missed that but inconclusive. Lots of the cheap TPU tubes have that problem out of the box.

I have limited TPU experience but recently bought tubes from three different brands. One of the two Barbieri NXT Piuma tubes had a snake bite puncture through the tube at the fold. I successfully patched that with the Barbieri patch kit I bought at the same time.

[chismog]

Wow, I was today years old when I found out about this problem. Have been riding TPU on my disc bike cuz I don't want to dork with tubeless goo. No problems with my Amazon "Wanban" TPU tubes. Was considering putting them on a rim brake bike.

The Wanban box says they're good for rim brake or disc. The owner's manual goes into a bit more detail and says there may be a problem in extreme heat situations, but (their) TPU is only slightly worse than butyl and better than latex.

I'll probably try it eventually. I've had good luck with TPU so far.

[many_styles]

Need to look at my pirelli TPU tubes to make sure they’re ok for rim brake use.


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[marciero]

One thing that is weird is no threads on the valve stem. I am probably in the small minority but I had gotten used to using the valve nut with tubed setups. It makes for more positive seating of press on pump heads, and without the repeated inward deflection of the valve into an inflated tube. Some carbon wheels have a special valve nut and form fit washer/ferrule for this purpose.

[ColonelJLloyd]

Pretty certain it's in the rules.

[dddd]

I think robt57 hit on a good point, about the sizing.

A TPU tube that tenses enough upon inflation to feel firm inside of the still loose-feeling tire may have enough tension to pull itself apart at the seam when the rim side gets hot and starts yielding in tension (so that the balance of the tube's minor perimeter can "relax" some of it's high tension).

But, if the tube size is closer to the actual inside diameter of the tire's cross-section, then it might be orders of magnitude more resistant to heat-induced failure of the more-heated inner "side" of the tube.

I'm in the habit of sizing up considerably on butyl tube size, while also comparing tube's widths that I actually measure (as folded flat) versus any numbers printed on the box or on the tube itself. I've found such numbers to be wildly all over the place versus what I measure!
The added tube width (up to a point where the tube can still be installed wrinkle-free) often allows me to finish a ride on a punctured tube, since the rate of air loss is so much lower when the tube is less-tensed.

All of this reminds me of a few times that I've seen latex tubes split open along a surprising length, those tubes being particularly sensitive to stretching forces that may not even exceed what occurs when fitting them into the largest-rated tire on the tube's package.
So I get the feeling that the upper limit of tire size (width) may be optimistic with perhaps all of these lighter-weight tubes, especially any generic ones sourced from overseas suppliers.

[Clean39T]

Originally Posted by dddd

I think robt57 hit on a good point, about the sizing.

A TPU tube that tenses enough upon inflation to feel firm inside of the still loose-feeling tire may have enough tension to pull itself apart at the seam when the rim side gets hot and starts yielding in tension (so that the balance of the tube's minor perimeter can "relax" some of it's high tension).

But, if the tube size is closer to the actual inside diameter of the tire's cross-section, then it might be orders of magnitude more resistant to heat-induced failure of the more-heated inner "side" of the tube.

I'm in the habit of sizing up considerably on butyl tube size, while also comparing tube's widths that I actually measure (as folded flat) versus any numbers printed on the box or on the tube itself. I've found such numbers to be wildly all over the place versus what I measure!
The added tube width (up to a point where the tube can still be installed wrinkle-free) often allows me to finish a ride on a punctured tube, since the rate of air loss is so much lower when the tube is less-tensed.

All of this reminds me of a few times that I've seen latex tubes split open along a surprising length, those tubes being particularly sensitive to stretching forces that may not even exceed what occurs when fitting them into the largest-rated tire on the tube's package.
So I get the feeling that the upper limit of tire size (width) may be optimistic with perhaps all of these lighter-weight tubes, especially any generic ones sourced from overseas suppliers.

Good thoughts there. I was running tubes that are supposed to be good for 28-32s in nominal 30s, so it should have been fine..

Funny side note. I went to the Trek store in Heber City and got some good ol' rubber ones - the thick kind. Box says 25-28mm. Tubes have 20-25mm printed on them.

Anywho, having those in at least let me feel moderately safe descending Pine Canyon Road at old-lady pace after doing the Guardsman/Empire climb this afternoon. What a hoot.

[marciero]

Originally Posted by ColonelJLloyd

Pretty certain it's in the rules.

And I'm doubly in violation bc I use the cap too. I just think it looks neater.