Not seen this before, It’s on the Borani rims on the loop. Hard epoxy resin. Is it a permanent rim tape solution or something to help make the rims take tubeless tyres?
Cheers
Shrunk rim.JPG
How do you adjust the spoke tension if the tape is solid?
Perhaps it used to be rubber and time has taken it’s toll!
Indeed, more questions than answers… 
It’s definitely epoxy - like the resin you get for fibreglassing
I think your thoughts on making it tubeless might be possible as I remember seeing an article somewhere on thisoldtractor, I’ve just had the wheels on my project Eldorado checked over and whilst still in good order all spokes needed tightning hopefully yours won’t!
Ian
Whoops just corrected my typo! 
Yeah I suppose if the spokes need tightening I’ll need to chip it off - which’d be a sod but fine for now. I’m putting on new Dunlop K70’s and tubes so no need for it to hold air.
Cheers
Knew you would.
Thanks. 
I would say it is a very old rim tape that has gone very hard with age. It looks a bit like the one that was in my Stornello. Get something underneath it and it should come off.
Concur Don…
I never had a tyre off, so can’t say what’s going on. There was a lot of talk on the Yahoo site a while back about running tubeless tyres, so could be that, or as said tape gone hard. Never seen tape rock hard before though.
Pretty sure that tubeless rims are a different profile?
Thanks, well it all seemed smooth enough and it wasn’t going anywhere without a fight so I just threw on the new tubes and tyres
Cheers
Tubeless rims are a different profile, but it seems relatively common in the US for folk to seal the spokes and use tubeless on spoked rims.