you cannot compare bicycles to cars
it's like saying "yesterday i had to push my car, it was so heavy! why cars aren't as light as bicycles!"
car tires are thicker, made of different materials (tpi is not the same), pressure is different, cars and bikes ride on different part of the road (the side of the road is full of gravels and other crap and in fact most of the flats i had happened outside of the road) etc...
sometimes you can have a flat on a bicycle but nothing went trough the tire.
for example if you ride on a sharp stone or if you hit the edge of a sidewalk, it pinches the inner tube.
car tires don't have inner tubes, and mtb equipped with tubeless tires have less flats than those mounted with inner tubes.
pressure is important too: for a long time now i inflate my tires 5 or 10 psi above the recommended max pressure and even with standard (non kevlar) tires i have really less flats.
it is known that flats occurs more often if your tires have low pressure.
concerning kevlar tires, i had bad experiences with them:
i've been touring from geneva to bangkok and i had to change tires in tehran.
i was so happy to change for 'punchproof kevlar tires' (i can't remember the brand i got then)
but the second day, after less than 200km i had my first flat with those tires...
it was the dry thorn of a desert plant that can pierce almost anything i guess (i had a few other flats with this particular plant actually)
then i discovered two things:
- plants in tropical dry climate have thorns really tougher than elsewhere.
- kevlar is over-rated due to its use in bulletproof jackets: these jackets stops bullets because bullets rotate and stop by entangling in the kevlar mesh. But thorns pointy enough just go through the mesh!
also tiny sharp objects (like glass chips) get caught in the little scratches of the tire and finally go through because of vibrations.
quality of the tires and the weight carried are certainly also very important.
but...
in australia i bough a new bike equipped with schwalbe marathon kevlar and i had some thorns that made flats also (but riding in the bush in a straight line is not the best idea maybe...
)
in carnarvon i bought some punchproof bands to put inside the tire.
that was a very good idea... the pointed corners at the ends of the band can also pierce the tube!
then i rounded theses corners... and the overlapping of the ends of the band pinched the tube and made another flat!
then i put duct tape to stick the ends together... and the melted glue of the duct tape corroded the tube and made another flat...
hopefully, in bali, after 7.000 km my back tire exploded because it was too worn.
then i could change for the schwalbe marathon XR i was carrying from perth.
(in fact i put this one on the front and put the former front marathon kevlar at the back)
i've heard some cyclotourers saying they had flats with marathon kevlar, but none with marathon XR.
everything has his own problems, i already hear people moaning about XR because they think they are too sticky to the road
flats are part of the trip, my flats made me met people i would never have encountered with perfect tires!
well this post is becoming to be too long, see you later!
(now, i have two of my bikes to repair: 2 flats, including one on Hudchinson kevlar)
