Wheever

Hey all, happy 4th of July.

tl;dr : road tubeless tire and rim combo blew off while being set up. Made a mess and blew my eardrum out. Need help figuring out why before I attempt it again.

So last night I took the plunge and started converting to tubeless on my Domane. I had acquired all the various bits over the prior couple of weeks, and decided that, since I had the next day off, I would do lit ast night so I could ride them today. Didn't go as planned!

I got the the front tire mounted, and checked the bead was solid all the way around. Inflated and deflated it a couple times. Seemed well sealed and locked in. Was holding are surprisingly well without sealant. So I injected sealant, and put about 20psi in and wobbled them around to distribute it, etc. Didn't see any leaks, really, just a little oozing by the bead, as expected. Seemed well sealed. So I left it for a bit and came back and it had lost a little air. Put more air in, about 40 psi, and flopped it around some more. Came back a bit later and pressure had held! So I started putting more air in...and then disaster struck!

At around 80 psi the tire blew off the rim! Sealant everywhere, and I think it punctured my left eardrum it was so loud. (No, seriously, I'm going to go to urgent care later and have it checked out.) So I need input on what I did wrong.

The rims are bontrager Affinity Comps, which are supposed to be tubeless ready. The tires are Challenge Strada Biancas, which are also tubeless ready. I used Stan's 21mm yellow tape, two layers, fit well and didn't wander into the bead hook area as far as I could see.

Now, here's one thing: Bontrager has their own tubeless rim strip, but after talking to the guy at the local trek store, he said I didn't need to use it, stans was fine, and he used it all the time. I also couldn't find ANYTHING online that said the rims HAD to be used with the bontrager rim strips. So I proceeded, since he didn't have the rim strips in stock, and in his experience I didn't need them.

So, can someone tell me what the heck happened? I didn't even know this was a possibility if the tire and rim were locked together well enough to not really showing much weeping of the sealant!

I'm not going to attempt this again until I have an idea of what happened. Actually, might just give it up as an idea entirely.

Has anyone else had experience with using Stan's tape on bontrager rims? Has anyone else had the tire blow off like this for apparently no reason? Help!