Latex tubes most likely. Latex is more porous than butyl. Better tubulars use latex tubes, some of the cheaper ones use butyl. Most clincher tubes are butyl.
David Bilenkey Ottawa, Ontario, Canada dbilenkey@sympatico.ca
http://www.wooljersey.com/
> -----Original Message-----
> From: classicrendezvous-bounces@bikelist.org
> [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Simon PJ
> Sent: November 14, 2006 2:49 PM
> To: Classicrendezvous@bikelist.org
> Subject: [CR]Simple one: why do sew-ups lose air more quickly?
>
>
> What is it about sew-up tubes that means that they 'leak' in
> a different way to the tubes in clinchers?
>
> Thanks,
>
> Wyndham Pulman-Jones,
> Girton, Cambs.,
> UK.