An alternative to the commercial conversion kits is a bmx tube. I came up with this as a stop gap when I had to replace the Stan's tape on the back wheel at last year's Sabie experience and the bike shop didn't have any kits left. You cut the 20" bmx tube in half along the circumference which produces a rubber 'rim tape' with a valve. It should be wide enough to cover the entire inside of the u shape of the rim's outside. i.e up the sides to just below the thicker edge where the tire bead usually seats. Fit the tire, my case it was a Crossmark LUST, so that the tire bead sits inside the rubber tape 'u', I.e.the 'rim tape' is sandwiched between the tire bead and the rim wall. Lightly coat the surface between the bead and the rim tape with sealant, add sealant to the tire and inflate. This stopgap is still the back wheel setup on my hardtail which has been through 8 weeks of very hard mostly offroad Pioneer training with no leaks or hassles.
