Fenwick’s Airtight Sealant

Fenwick’s Airtight Tubeless Tyre Sealant is a gel incorporating a non-toxic, glycol free, non-thickening anti-freeze. It is thick when stationary but once the wheel starts rotating it will flow; this ability for a liquid is called thixotropic. Fenwick’s claim it will fix a puncture up to 6mm in diameter with the added benefit of forming a permanent repair, unlike competing latex sealants. Fenwick’s also claim that Airtight is superior to latex by being usable in cold conditions, usable with CO2 cannisters, and lasting up to 6 times longer in the tyre.
 

Fenwicks Airtight Tyre Sealant

 
Airtight can be injected through the valve core into an inner tube, tubular or tubeless tyre; as long as you have a Presta valve with a removable valve core it’s pretty straight forward. Or you can apply it with a brush or similar direct to tyre and rim.

Being able to remove the valve core is essential…

Initially it was the tubeless claims that really appealed to us. Fenwick’s claim that Airtight can be used to convert non-tubeless tyres to tubeless by painting it straight onto the tyre wall or placing it in the tyre-well and then rotating the tyre, sounded great. And sure enough we managed to convert a number of cross tyres to tubeless. But then we failed with a number of others, where the sealant bubbled out of the very porous sidewalls. The key it would seem, is to choose a wheel and tyre combination which is tight to fit and hard to get onto the wheel. Tyres with a lower TPI count seem to work better, as they are less prone to leaking sealant.

Going tubeless – trying to make tubeless valve stems

We wanted to go the whole hog and do a real DIY job, creating our tubeless from wholly homemade parts; it seemed logical to replicate what many riders might be trying at home themselves and see what could be done. So we chopped up some old inner tubes to make some tubeless valve stems…