So i poped my tire the other day and I took everything apart to fix the tube and for some reason i removed that thin rubber strip that runs on the inside of the rim. I have no idea why i did that but now its lost and i can’t find it for the life of me. So after tearing my room apart looking for it with no luck I just put my uni back together with out it. It seems fine for the little riding i just did, but is this something i should stress about, like getting a new one?
Yes, be concerned. The tube will pop, and probably sooner rather than later.
That rubber strip keeps the tube from bulging through the spoke holes inside the rim. There are sharp edges down there and something will end up cutting the tube. On high pressure tires (60 psi and up) you likely wouldn’t be able to get to full pressure before the tube blows.
There are two styles of rim strips. There are the rubber or vinyl plastic loops that you stretch on the rim like a rubber band. Then there is rim tape that you apply just like tape. Both work. The rim tape is generally more reliable because the adhesive keeps it in place.
You can get rim strips or rim tape at your local bike shop and probably at shopping stores like Wal*Mart and other places where they sell bikes (assuming you have a standard size rim like a 20" or 24", they wouldn’t have a rim strip to fit a 19" trials).
i believe it protects the tube from the rim, so as long as your rim is nice and not bumpy or sharp, i dont think it should be too crazy, maybe if you took some hockey tape or something and replaced the rubber with that it might work?
i might be wrong though so you should check with someone else first.
I think, and I’m pretty sure, that the thin rubber strip that you’re talking about is to prevent the spokes from popping the innertube through the rim. It’s not REALLY important to have one, but I’m sure it helps. I don’t think I have one, and I ride light trials/freestyle and have never had a problem.
My advice, don’t worry yourself and keep on riding!
If the innertube pops unexpectedly, then I guess you’ll know why. But, really, I don’t think it’s something to lose sleep over 
EDIT: John_Childs post wasn’t there before! Okay, now I know I was wrong. Thanks, John, for clearing this up. hehe.
It is important to have a rim strip but depending on your rim you might get away without one. What I use though is electrical tape just wrap two or three layers around your rim and you are good to go, it’s thin and stays put and you probably have some around the house.
if you cut thin duct tape strips that could work I guess
Without that strip your current tube is doomed. Each spoke head will take turns having it’s way with your tube until one of them finally rubs through. It will happen a time when it is most inconvienient.
If you can’t find a rim strip then for now you could take an old tube and cut a long thin strip out if it. Wrap it once around the rim (with some extra length) and use some patch cement to help keep it in place. I’d use about 4 inches of overlap at least. Use an Exacto knife to round out a hole for the air stem. Not a permanent fix but it will save your existing tube while you’re hunting for a new strip.
Just use elecrical tape. that works just fine. I have it on mine…
Yeah, what everybody else said.
I don’t think rim tape’s too expensive, your LBS should have some.
19" trials strip??
Get rim tape like the Velox tape. Your bike shop will have it. With the tape you just cut off the excess so it will fit anything from an 8" wheel on up to a Coker (a Coker wheel actually takes about 1-1/2 rolls). Easy to do and the Velox style tape works well.
Velox tape comes in at least two widths. Make sure you get the one suitable for your rim (probably the wider one).
As for electrical tape, you’d have to be a bit more careful applying it because the edges are fine enough to eventually wear a hole in your tube. I know - it happened to me when I used some to effect a temporary repair to the side-wall of my road bike trye!
Hooked
u never should pope your tires