audioblazer wrote: ↑Wed Nov 28, 2018 5:05 pm
From my limited experience , Vittoria Pitstop not very effective . Just bought myself a bottle of effeto mariposa expresso & see whether it’s more effective . However is wondering if I use a sealant & it doesn’t work , it will be messy to change the tyre . So might as well just change the tubular & try to repair the tub after the ride
For most sealants you would remove the valve core (easy peasy) when you add sealant such as Orange Seal, Stans, etc. On the other hand, with Vittoria Pitstop you insert it right through the presta valve from its pressurized cannister and if you're lucky, some of the sealant gets in the tube. If you're extra lucky, that sealant that made it's way into the tube will actually seal the puncture. And if you're super super lucky, enough compressed air will have made it into the tire to give you at best a pretty poorly inflated, but sealed tire to get home on. At least that was my experience with it.
So, with the likes of Orange Seal, or other liquid sealant, you do remove the valve core and I usually add about 15ml or so when I get a flat and rotate the tire so that it flows to the area of the puncture. Then replace the valve core and pump it up with a regular pump that I carry (Lezyne Road Drive). I can quite easily get full pressure back. Ok, so while I never seem to get clogged valves (I never add loads of sealant in there and I make sure the valve is located somewhere in the top of half of wheel when I infalte), I have come across some tires that air would just not go into. In fact, I knew one guy who threw away a perfectly good tire because of that. So, one fine day I decided to do an autopsy on a valve that you could not get air "into" the tire to see exactly how the sealant was clogging things up. What follows is my story (which I've posted elsewhere before, but seems appropriate here too)... actual names have been omitted to protect the guilty...
I never use sealant as a "preventative" measure in my tubulars, as it can potentially stick your latex tubes together if they are allowed to go flat, and it also means you would never be able to use that tire as a spare once changed out for a newer tire. But I do use sealant to fix punctures, rare as they seem these days, while on the road. And occasionally, the sealant will ultimately clog a presta valve in a way that prevents you from pumping up your tire. Even though you unscrew the top of the presta valve, it is impossible to pump air into the tire. So, out of curiosity what it was that was actually clogging, I did an autopsy on a presta valve that would not allow any air into the tire.
What happens is the sealant gets in the valve, and for whatever reason, perhaps you didn't quite screw the top back down all the way for example, as I think happened here, the sealant pools and forms a nice little o-ring so perfect that you might think it actually is an o-ring intended to be there....
As it is above, that "o-ring" on top will quickly act just as the valve on the inside of the presta valve acts to prevent air escaping... it immediately blocks the passage of air throught the valve into the tube.
Simple solution... dig that sealant based latex o-ring out of the valve and prest-o... your valve core is free again and good as new. Oh, if you don't see the sealant formed 0-ring as in the picture, that just means it must be dug out of the cavity, as I had to do in this example with a small pick or a needle.