I have had a Specialized mountain bike for a couple of years now, it came tubeless-ready so in theory all I had to do was remove the innertubes, fit tubeless valves, put some sealant in and away I go… It has not been quite so easy.
I purchased some Mariposa tubeless valve stems (which I have used previously with success on another mountain bike) and set to converting the wheels, they already had “2Bliss” tubeless rim tape (2Bliss is what Specialized call their tubeless system) and 2Bliss tyres so I didn’t pay much attention to that, all looked hunky dory, but after adding some sealant for the life of me I could not get the wheels to seal; sealant kept bubbling up the side of the valve stem, nowhere else. I shook the wheel up and down with the valve at the bottom, I wrapped PTFE tape around the valve stem before and after installation (which actually gave a little bit of success but I didn’t trust it), I even fitted an o-ring around the base of the valve stem (seated against the rim tape inside the wheel) but nothing would stop the bubbles coming out, this eventually led me to believe there was a problem with the valve stem itself so I replaced that, same thing happened.
I was about to order some Specialized 2Bliss Roval Valve Stems and 2Bliss Rim Tape when I happened across a forum post about the 2Bliss Rim Tape, and how some people have had problems and do not rate the tape at all; this changed my thought pattern – perhaps it is the tape after all that is leaking, no amount of valve stem jiggery pokery would fix that, and it made sense too that when I managed to seal it with PTFE it was only by winding it around the stem between the wheel and the washer / nut on the outside of the wheel.
A plan was hatched – I would look very closely at the rim tape for any tiny slots or gaps where the air and sealant could be escaping, starting at the valve hole. I soon discovered that the rim tape was not actually tape at all but more like a large elastic band that had been fitted over the wheel, and while it did form a nice tight fit it was the join at the valve hole that disturbed me, and gave me the firm believe that this was the weak point where the air and sealant was leaking. I decided that I would go the traditional route of sticky rim tape so set forth to remove the 2Bliss rim tape and sealant.
Continues in my next post!