A few weeks ago, I squirted some Stan's sealant into the tubular tires on my fixed gear bike. I was out riding yesterday and got a front puncture. Sprayed sealant all over for about 30 seconds, then stopped. Only lost about 20 psi (90 down to 70); didn't feel that my gimpy shoulders could pump it any higher, and didn't feel like blowing a CO2 cartridge for that little pressure loss, so I kept riding. No problems; worked fine, got home fine, etc. Topped it back up to 90psi for today's ride, did the same route (34 mile loop), and it held up fine.