Since april, i tried to ride tubeless with my road bike.
I have Continental GP5000 sTR 28 mm tyres.
I weight 162 lbs (73.48 kg) and i was told to put like 80 psi rear and 76 psi front. The problem is that i had already 2 punctures since start of summer and it didnt close with the scellant. I use mucc off standards sealant.
When i looked at the puncture, it make 3 mm length on the inside.
Im about to switch back to tube but i am taking a chance here to see if someone know what im doing wrong. Is it my sealant? My tyre pressure?
In my experience running tubeless at “road” pressures, the sealant isn’t going to seal any significant puncture and usually requires a plug. Works great for those tiny holes from glass or wire, but not going to seal anything significant. You really need to be under 40psi before sealant works on bigger stuff without plugging. Again, just my experience(mostly w orange seal), maybe there are some magical sealants out there that work better.
If you can run 30/32mm tires I definitely would. My old bike was initially set up with 28s tubeless and while it would seal it was not nearly as reliable as when I moved to wider tires.
At those pressures I would say the best sealant is Stan’s Race. Not really supposed to be for long term use but lasts a long time for me in moderate UK temperatures. May not work so well if you’re dealing with very hot temperatures that dry it out quickly. The wider the tyre and the lower the pressure the better tubeless works. Cross over point for me is about 65-70psi. Higher than that I’d probably err towards tubes. But even if running tubeless you should always carry plugs (seems close to unanimous that Dynaplug are the best) to deal with those bigger cuts that won’t seal (and which would also ruin your day if running tubes).
Pressure sounds way to high. I’m heavier than you and run 60 psi.
I’m using normal Stan’s sealant, and have found the same as above - it’s not sealing well at high pressure, but it does seal at 30 - 40 psi. That’s enough for me to ride on, its feels slightly more draggy than 60 psi, but also more comfy, hah.
A few things might be working against you here. First, the Mucoff standard sealant isn’t known to handle larger punctures (over 3 mm), you might get better results switching to a sealant like Orange Seal or Stan’s Race, which are thicker and seal bigger cuts more reliably
As others have said your pressure is way too high. I’m your weight and with those tires I run 58/63 give or take. Using Orange Seal and generally have no issues and have been using that for many years. Tried Muc Off and threw it away after realizing it absolutely seals nothing and leaves a mess on the frame that is very hard to remove once dry.
I would have expected sealant to seal that. I have had holes like that not hold at low pressures with Peatys/ Finish line but instantly seal with Orange Seal/ Stans Race.