I’ve just converted the front wheel to tubeless, went up first time without sealant.
Materials:
1.5mm underlay foam (also sold as jiffy packing foam).
50mm Gorilla tape
Tubeless valve (cut from an old tube in my case).
Method:
Remove everything from the rim including the tape.
Cut the foam into 5x ~3.3m strips 60mm wide. Or try and buy some foam 60m wide if it exists, or some ~7.5mm thick foam would need less strips.
Starting just after the valve tape a bit of the foam to the rim and wrap it under a slight tension, the foam was slightly waxy so doesn’t slip around. If you’re using multiple strips like me, tape each one to the end of the last one. Untill you have 5 layers, stop just before the valve (same as all tubeless systems they work best if it’s a bit thinner at the valve). This was enough to get the rim level across it’s width inside with the step at the edges which is what was needed.
Then add a layer of gorilla tape, one on each side, making sure it goes slightly up the wall of the rim so that it’s sealing the rim, I guess if it didn’t you’d pump sealent/air through the foam. A bit of tension helps it stick to the rim and the sidewall without creasing.
Poke the valve through and do the nut up.
Stick the tyre on, it’ll now be quite tight, but it’ll still go on with just fingers and thumbs as the foam’s squidgy enough.
Inflate with a track pump, got it upto 20psi and it stayed up for 20min so should be good with sealent, certainly a lot rounder than it was before 🙂
Total weight was 10g more than the original rim strip according to my kitchen scales.