Background: I’m desperately trying to make my tubelss setup loose less air. Last year I used it with the original rim tape that came with the tires and they lost roughly 1 Bar per day. As far I can tell the rim tape that came with the rim was a 19mm width tape.
This year I want to fix the problem. So I redid the rims with 19mm tape, 2 full layers, but they still lost air to the side. Then I redid them with a 25mm width tape (after having read good things about the tape partially going up the sidewalls of the rim). Unfortunately they still loose air, especially where the tape goes up the full sidewall to the overhang. (See foam picture).
What would be the ideal width of the tape? I have attached the spec sheet of the rim and a few pictures of different width rim tapes 19, 21, 23, 25mm. Too me it looks like the 19mm tape is not wide enough and the 25mm tape is too wide. I’m not sure what strategy to try next. 1 layer? Which width? Any other potential problems that could prevent the tire bead from sealing perfectly?
by vienna_city_skater
6 Comments
Forgot to mention: Tesa 4289 rim tape, muc-off sealant and valve, Conti GP5000 S TR 30mm tires, valve hole was cut with a solder iron, rim tape 15cm overlap in valve area
Just to fully troubleshoot, are you entirely sure you’re losing air along the rim, and not, for example, at the stem?
I hate that manufacturers don’t list the proper size tape. It should just be printed right on the side of the rim. Right next to the iso or any other information that they provide. They will put the 622×19 or whatever it is on there. Why not the proper tape size?
21 will fit if it really is a width issue, but I’d check the stem, the valve core, and make sure the whole tire is seated
I’d try the 19mm again with two layers but just slightly offset from each other so as to achieve adequate coverage on each side of the rim. I’d imagine going too far up the wall would disrupt the seal which is probably what you got with 25mm. Hoping this helps.
So you’re losing air out the sides of the rim/tyre not through the spokes/valve area that’s good. Add another layer of tape and fully seat the tyre without sealent. If it holds air for 10-30 minutes without sealent then deflate add sealent your then good to go. If it doesn’t hold air dare I say it add one more layer of tape… this will make the tyre sit on the rim tighter. If that then fully seats and holds air without sealent it’s setup right and good to go. If your tyre leaks from the side wall it might be one that needs sealent added to fill in the gaps and become fully air tight.
Going to 21mm tape could help and if 4 layers of 19
Does not make the tyre sit tight enough 3 layers of 21 could do the trick.
1. Double check air loss is not from valve area
2. Redo tape with 3 layers of solid tape firmly press into rim and allow no air to be trapped in bubbles at all tape kept up high tension, use your bike frame or a stand.
3. With tubeless valve in place and air tight (add small bit of oil/chain lube to edges of valve rubber seal inside rim and push into hole tight if you need a better seal) proceed to seat the tyre make sure it is fully seated use air compressor if needed.
4. Pump tyre up to minimum ride pressure and check for leaks, leave it sit for 10-30 minutes with no sealent if it holds air deflate and fill with good amount of sealent (little more than you need) and inflate to riding pressures. If it doesn’t hold air add another layer of tape and double check valve and tyre seating.