New wheels for my son (13 3/4) and on the first race, they were perfect until 5 laps to go when it “burped”. He still finished though. Wheels are Parcours Rondes designed for 28mm tyres. Tyres are 28mm Continental GP5000TL. He still managed to finish 12th nursing soft back tyre.
I had put about 55 psi in the back and about 53 in the front. He is 61kg + bike, water bottle and kit - a system weight of about 70kg. The roads were typical Belgian concrete and rough (you should see that on the second photo - that is one of the better bits of road. It is concrete with a joining strip. I had thought that pressure to be optimum considering the rough road and 30mm width (actual) of the tyre and the system weight. Silca tyre pressure calculator suggests about that weight for standard tyres and I thought that would be ok for tubeless. Sealant was about 55ml. I had seated the tyre with a Milkit pressure booster and schwalbe easy fit and pumped it to 85 psi and left it overnight before adding sealant and pumping up to about 85 psi again to make sure it was seated. He doesn’t remember hitting anything hard, but it was in the heat of racing with 5 laps to go so who knows. On normal tyres previously in another race, he did hit an object and pinch flatted, so at least this did not happen and he finished.
Do you have suggestions for preventing burping? We had done short rides Tuesday/Wednesday and Thursday and a tune up session Saturday, some with some speed and rough roads and cobbles, without any issues. We had used cycle paths and had been up to 45kmh and had not issues on the cycle paths and one session with sharp bends as “crit training”
Is the sealant too much?
Was the pressure too low? (I’m thinking so??)
Do I need to use more pressure for the initial seating?
Could it be variability in Continental GP5000 TL production?
Could you have variability in production tolerances for rims?
Should I buy another Continental GP5000TL?
Or try another brand?
When pumped up back up to 80psi it appears fine and there is no “bump” when riding, so I am assuming it is seated correctly afterwards.
Any advice greatly appreciated. At least he managed to finish and finish 12th in only his 4th race in Belgium.