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-   -   Bell puncture resistent tubes? (https://www.bikeforums.net/general-cycling-discussion/58365-bell-puncture-resistent-tubes.html)

think5577 07-19-04 07:25 AM

Bell puncture resistent tubes?
 
I was watching the tube last night and Bell (the helmet company) had a more then normal length commerical on. It talked about of course helmets, but at the end it said something about how they had developed puncture resistent tubes. I went on their site but found nothing about it.

Anyone know anything?

Thanks.

OregonBound 07-19-04 06:55 PM


Originally Posted by MERTON
specialized makes kevlar ones.

Kevlar tubes?

I think puncture resistant tubes are generally just thicker and heavier than normal.

Paul

OregonBound 07-19-04 07:18 PM


Originally Posted by MERTON
nope. they have aramid tubes.

Interesting. Could you post a link?

Paul

slvoid 07-19-04 07:58 PM

There are 3 types that I've seen separated into 2 categories. Active and passive.
Active ones are fluid filled where the fluid pools around the puncture to seal it.
Passive ones include using kevlar strands to resist punctures or just plain using a really really thick tube. I have the latter on the rear wheel of my commuter and I can definitely say the tube is about the same thickness as my road bike's TIRE and weighs about the same amount.
I've never really believed in kevlar (which BTW is in the aramid family of synthetic materials) in resisting punctures. If you've ever stabbed your lover with a sharp ice pick while she was wearing a bullet proof 20 layer kevlar vest in the heat of passion, you'd realize that the shank either slices through the kevlar or pushes the weave aside and gets through. When a bullet hits a vest, the impact converts kinetic energy into heat and deforming the vest. The slug that you pull out of your vest looks like a glob. It works because the glob has huge surface area in which to dissipate impact energy. The term should actually be bullet-resistant, not proof, as kevlar just helps resist penetration of an object. If you were shot with a .50 in the chest, you will probably get knocked down and have a huge bruise if not broken ribs. Armor piercing bullets have a central core that mains integrity as the metal jacket deforms around it, thus allowing it to slice right through the kevlar and penetrate.
I just can't see how the weave can be dense enough in a bike tire to prevent something from puncturing it if it were sharp and hard enough to make it through the rubber thread of the tire, then again I'm no expert YMMV. Plus if it were a piece of glass working it's way into it, several hundred revolutions of compression as the piece hits the ground should be enough to eventually slice it's way through the tire and the tube.
I think first defense inc. or something like that has a really really dense kevlar vest that resists shankings.

OregonBound 07-19-04 08:07 PM

I stand corrected. Thanks for the links.

Paul

supcom 07-19-04 08:31 PM


Originally Posted by slvoid
If you've ever stabbed your lover with a sharp ice pick while she was wearing a bullet proof 20 layer kevlar vest in the heat of passion, you'd realize that the shank either slices through the kevlar or pushes the weave aside and gets through.

Do your lovers often wear 20 layer kevlar vests in the heat of passion? Are you speaking from experience here?

slvoid 07-20-04 12:38 PM


Originally Posted by supcom
Do your lovers often wear 20 layer kevlar vests in the heat of passion? Are you speaking from experience here?

No.. not that I can remember. But I'd imagine that to be quite a sight.


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