Fabric tire liner
I changed out a tire yesterday that had a layer of fabric between the tire and the tube. It was yellow felt, about 1 1/2" wide and adhesive on the tire side. Fairly thick as fabric goes, but no more than 1/16" when it was compressed by the tube.
I know that tire's been on the wheel about 15 years, but I don't remember seeing anything like this 15 years ago either. The tire was a smooth treaded 20"x1.75" Avocet FasGrip Freestyle mounted on the front of a Bike Friday. I don't think it was stock as the bike has a lot of aftermarket parts including hubs and spokes. The bike's in Arkansas now, but I'm pretty sure it was built up in NW Washington. The previous owner got it used from a guy from there, and he didn't know about the liner.
What was it for? Some kind of smoother ride maybe, or an attempt at flat protection, tho it doesn't look like it'd do much good? Was the tire sold that way, or it it a regional way to build up wheels? I don't need to know this, but I sure am curious.
Kevlar Felt maybe?
Just a guess on this old post, but did anyone ever see Kevlar felt marketed as a flat guard for bike tires?
It might keep a piece of glass from reaching far enough through the tire to cut the tube.
Thanks man, that was just the hint I needed. They're called SpinSkinz Kevlar Tire Liners and they're still available. I had been Googling for Felt tire liners and coming up blank. They must work, the tube I pulled out didn't have any patches.
I tested the stuff by poking it with a pushpin. It went thru, but not nearly as easily as the collar of my flannel shirt with two layers of fabric and a plastic stiffener. Wondering if it was really Kevlar, I also tried to burn some. It chars but won't hold a flame. The burning adhesive on the back, however, got me invited to get that crap out of the kitchen.