Several days before the Willow Springs race found my rear tire flat. Installed a spare WalMart tube. Next morning, another rear flat, checked around for the usual causes, but found none. Assumed the thin WalMart tubes were at fault, bought some slightly thicker Target Dept Store tubes. Ran only about 30miles the day of WS race, no problem though 2 other e-bikes DNF'ed with flats.
Week later, headed out for a pleasure bike ride and rear tire went flat, 3 hard to explain flats inner side of tube in 50 miles! A closer inspection uncovered 1/8" holes in my SunRingle rims. There were 12 holes symetrically placed, 2 sets of 4 aside valve hole and opposite side, and 2 pairs at 90o & 180o, apparently to let moisture/air from the tube chamber. All vent holes are placed between the tire bead and the spoke nipple cover tape.
This 24" rim is generally used for BMX where a rather low PSI is standard. I'm using the rims for motored bike racing (kart tracks/some street use) and run 90 PSI, perhaps 3X's the pressure of BMX
So I think high pressures cause the tube to balloon thru the 1/8" vent holes. Bet 'ya I can put rim tape over the holes, (poke a tiny pin hole in the tape) and not have further flats.
Week later, headed out for a pleasure bike ride and rear tire went flat, 3 hard to explain flats inner side of tube in 50 miles! A closer inspection uncovered 1/8" holes in my SunRingle rims. There were 12 holes symetrically placed, 2 sets of 4 aside valve hole and opposite side, and 2 pairs at 90o & 180o, apparently to let moisture/air from the tube chamber. All vent holes are placed between the tire bead and the spoke nipple cover tape.
This 24" rim is generally used for BMX where a rather low PSI is standard. I'm using the rims for motored bike racing (kart tracks/some street use) and run 90 PSI, perhaps 3X's the pressure of BMX
So I think high pressures cause the tube to balloon thru the 1/8" vent holes. Bet 'ya I can put rim tape over the holes, (poke a tiny pin hole in the tape) and not have further flats.
