Originally Posted by
63rickert
I will bow to your cross experience but do use sealant in road tubulars and have used cross tires as road tires in winter. Just no problems for three years. Has sealed every flat. Flats prevented - no idea. Sealant goes in tube after first flat. Still lots of useful life on tires not in daily use. I do not use extenders. The only time a valve core became badly fouled simply holding it under running hot water cleared it.
Sealant needs pressure to direct it to the hole. Perhaps the problem is CX runs at such low pressure sealant does not know where to go. Or something else is different because of low pressure.
Yeah no telling. We use sealant extensively in tubulars once they flat and it usually works but mostly in tubeless tubulars (someone's head just exploded).
I won't say adding sealant to a tubular that has a tube never works but I have absolutely had it fail more often than not. On the cross ones we have them blow out at high pressure. Will hold at 25-30psi but blows out at 40 psi. In those cases we let it sit with the hole down at 20psi as long as we can before we take it to race pressure.
It used to be standard for old school racers to put sealant into their cross tubulars in advance. I've never had great results that way. On the road I would say it's more likely the smaller holes than the larger pressure.