Due to a very small cut I fixed my Pirelli TPU with a patch from another TPU brand. As I pumped it up to 0.5 bars after some time 2 really big bulges show up. My question, can I still use this tube or is it dead?
by LongjumpingPay904
Due to a very small cut I fixed my Pirelli TPU with a patch from another TPU brand. As I pumped it up to 0.5 bars after some time 2 really big bulges show up. My question, can I still use this tube or is it dead?
by LongjumpingPay904
7 Comments
If it holds air it’s still usable. The bulge straightens itself out once it’s in the tube due to compression. When I use cheaper tubes I always get bulges (especially the ones from Decathlon). I never have any issues when riding.
Tubes are not structurally sound. Small variances in thickness will cause such effects. The tyre is what provides the structure. The tube is just there to hold air.
If it holds air it’s good
Yep, it is fine. TPU tubes come with a warning not to inflate outside of the tyre for that reason.
0.5 bars is too much. Never pump up TPU tubes outside the tyre so much! And don’t keep them inflated outside for long. In theory 0.5 bar might still be OK, but many pump pressure gauges are inaccurate, especially in the low pressure range.
A more realistic maximum is 0.3 bars or 5 psi.
I’d still rock this tube, but please never do that again.
I’ve found that basically all inner tubes are best not inflated outside the tyre, apart from a little air to check for leaks.
I’m not experienced with TPU, but my experience with butyl is that swelling outside the tyre is no indicator that it’ll fail when actually inside a tube.
Having said that, don’t inflate your times outside the tyre, they’re not designed to be strong without pressing against an outer layer.
I had tpu tubes on my old bike(35c tires). They never deformed, but now I run 28c continental gp5000 and I tried 3 different brands of tpu tubes and they were all are specked up to 32c, but all of them developed small bulge around the seam or around the valve. On my last ones(ridenow with metal valve stem) rear one seems to be fine with very minor deformation.. but the front has some. I am running them like that maybe for 200km, they hold air but I’m not very confident. I am carrying an extra co2 cartridge and a spare inner tube and patches 😀 I think they are just too narrow for 28c tire. Can someone recommend a wide enough inner tube? Excuse me for hijacking this post, there are some answers to my question already, maybe :))
That Turbolito patch kit works great for TPU tubes, still running tubes patched multiple times with it after months. In future though, don’t inflate them outside the tire to check, as that tube is now ruined.