This is a new one on me. New bike has come with WTB STs i29 tubeless compatable rims.
Anyone seen this before? Is there any way of remedying it? Try diferent sealant etc.
Have to question the strength of the weld too.
The front holds air fine btw. There was a tiny amount coming from the weld area but it has sealed OK.
[video]https://youtu.be/gnu36db-87E[/video]

My pinned superstar rim did this the first time I taped it. Ended up redoing it better and it stopped the leak. Sealant shouldn’t be getting inside the rim.

It looks like your tape is allowing air to leak into the rim. Probably the tape needs re-doing.

This suggests that the rim joint is sleeved, rather than welded, so the joint won’t be air tight.

I had some rims do that. Nirmal taping then a spin of lecky tape sorted it.

Is the ST welded? I thought it was pinned?

Something wrong with the taping. Once sealant gets into the rim it can escape anywhere. Are you using full-width tape?

It came taped. I guess I could redo it myself. To me it looks like it is seeping through the rim wall. Are you suggesting taping all the way to the top of the rim wall?

What tape did it come with? Most tubeless-ready rims I’ve seen still need tubeless tape applied (WTB may be different).

WTB recommend a tape wider than the rim so that it covers the full width of the rim and goes somewhere up the rim wall.

Looks like Stans tape to me. The front is holding fine.
That’s interesting re WTB advice, I’ll give that a try with the tape I used to tubeless my fat bike rims. It has plenty width to spare.

WTB tape is yellow and does look and handle very much like Stans. It’s probably the same in different widths.

WTB recommend a 34mm tape for i29’s. It does come quite a way up the wall.

CRC sell WTB tape in most sizes and while it’s not peanuts it seems better value than Stans’.