Dunbar

Towards the end of my ride I noticed my rear tire was low. Fortunately I was only a few blocks from home so I was able to limp it back but the tube was down 40-50psi. I took the tube out and confirmed it was a slow leak from 180 degrees opposite the valve (at 12 o'clock in the first picture.) It looks like the tube was rubbed through but I can't figure out how? This is a ~3 week old Challenge Corsa latex tube.



The tube looks to be pretty concave opposite the presta valve.

Homebrew01

Looks like some sort of seam failed. That's an odd looking tube. Looks like they put the valve reinforcement opposite the valve by mistake.

Dunbar

The black oval looking mark is not a seam. It looks to me like it was caused by rubbing or a stress point. The black oval seems to correspond to the shape of the concave portion of the tube opposite the presta valve.

tomacropod

Looks like the wear caused by Mr tuffys or similar. In my experience they always wear through the tube eventually.

- joel

Dunbar

No tire liner was used in the GP4000s tire.

TiHabanero

That is weird. An oval shaped rub area for sure.

My experience with latex tubes has been valve stem leaks where they are "vulcanized" to the tube, but not opposite the valve stem base like yours. After many attempts and dollars to make 'em work, I gave up and went back to butyl. No complaints since.

xenologer

folded tube. straight line in middle is the fold. oval is from surrounding rubber stretching up around it to fill up tire at pressure. present concavity is from the folded area not being stretched out as rest of tube was. be more careful with install next time

cny-bikeman

The oval seems too perfect to be a result of rubbing or stretching. I do think it's a seam, possibly allowing installation of the valve. The leak is right at the seam but that does not mean a defect was the cause. More likely it's a result of either installation or expansion/rubbing of that portion of the tube at a spoke hole, which would occur at about that distance from the valve. The seam was just slightly weaker than the rest of the tube so that's where it failed.

xenologer

regarding sharpness/deliberateness of oval. consider two normally smooth soap bubbles forming a flat edge/wall when they stick together. center line is a fold, effectively separating tube into a bubble on each side. pressed flat where they meet. border lines then sharpened by time and abrasion

miamijim

Improper installation of the tube. It was overlaped or scruntched up when installed.

Dunbar

I think I understand now. The tube was folded over there and got pinned up against the tire while inflating (probably while installing the chuck head since the valve isn't threaded.) I'm guessing a buytl tube isn't elastic enough to do that and would pop back into shape.

If latex tubes are that finicky then it looks like I'll be going back to butyl.

Dunbar

Update: So I removed the other latex tube to replace it with a lightweight butyl tube (didn't trust it after the first one failed so quickly). Lo and behold I see the same marks on the other tube. It wasn't leaking yet but it was only a matter of time. I really doubt that I made the exact same mistake installing both tubes. I think the problem is during manufacture when they glue the presta valve on it creates that concave sunken portion opposite the valve. That concave portion creates a stress point which eventually wears through the tube causing a leak.

Anyways, thanks to all the BF'ers who blamed it on my installation. I expect that in the 41 but not on this forum

Pictures of the other tube:

xenologer

test:
take fresh tube , inflate outside of tire to verify no marks
deflate
install as normal
ride a while
uninstall
???
profit


looks to me like the rubber near the valve is less stretchy, doesn't inflate evenly there, so wear problems

Dunbar

I would actually like to partially inflate a brand new tube to see if it looks the same. But latex tubes are expensive to buy (especially in the US) so I didn't buy any spares.