puncture resistant tubes are thicker than standard tubes and therefore weigh alot more. they do an ok job, but on previous experience they dont pay for themselves
the principle is quite simple - if you run over a shard of metal or glass, or a thorn etc. the compounds protecting the pressure within the tube must be either thick, dense or inpenetratable enough to stop it piercing through. if you want to, you could wack on everything in the book, and it would pretty much eliminate the chances of getting a puncture, but at the same time make your wheel set weigh a lot more.
My advice would be to just get an affordable kevlar tire, and make sure you take all the precautions while putting it on and changing flats - im pretty sure most are aware of the main points but -
*check for sharp objects and damage in tire and rim
*inflate tube a bit before putting it in
*check that rimtape covers the spokes, and use material tape if you have double/triple wall rims
*be careful when using tire levers, and try not to use them at all when putting the tire back on
*dont under/overinflate
*check the angle of the valve - rims can cut valves sitting at wrong angle
*check the bead is sitting properly in the lip! there is a guideline along the side of most tires, but alot of people forget to check
*check glue is dry on patches, so it doesnt stick to the tire once inflated. put some dirt or chalk on it to stop it sticking
flats are just a part of the sport. dont go riding through glass and the tubes should last long enough.
aidan
Edited by Pro_rider 2004-04-10 4:53 AM