On 2017-01-16 21:51, Jeff Liebermann wrote:
On Mon, 16 Jan 2017 23:05:43 -0000 (UTC), Duane
wrote:
The idea of two pounds worth of tubes to avoid putting air in my tires
doesn't parse at all.
Let's do it by the numbers.
The tubes I usually buy are these:
http://www.nashbar.com/webapp/wcs/stores/servlet/Product_10053_10052_175629_-1___205038
26x1.5" for $4.79ea. They weigh 176g (0.39 lbs) and they leak air.
The proposed leak proof tubes:
https://www.amazon.com/Sunlite-Thorn-Resistant-Presta-Valve/dp/B0063R2GJW/
26x1.5" for $15.36ea. These weigh 572g (1.26 lbs).
For two tires, that a difference of:
2 * (1.26 - 0.39) = 1.74 lbs (789g)
Not quite 2 lbs but close enough.
The average 26x1.5" tire
seems to weigh about 550g (1.2 lbs). Ignoring the weight of the
wheel, with these tubes the rotating weight will increase by:
1.74 / (2 * (1.2 + 0.39)) = 55%
Offhand, it seems a bit too heavy to be worthwhile.
Please note that my original problem was not to find the best thorn
proof tire, but rather one that doesn't leak out of the box. I don't
seem to experience any sudden releases of air, but instead get slow
leaks. On the wheels in question, I ride on pavement.
You won't see slow leakage anymore after switching to the thick tubes. I
believe you do not live in hilly terrain but in the Bay Area and there
the increased weight won't matter much. The increased rotating mass
might but only if you have lots of stop and go traffic, with a lot of
braking.
As for me, I'll never buy a thin tube again no matter where I ride and
currently I live in a very hilly region.
The only downside is if a tube does go because a tire side wall failed
it is an expensive affair because that generally can't be patched. It's
also a rather loud scenario. The advantage on the road bike: I managed
to ride home sans air because the tube already looks almost inflated
without air. It and the tire were shot anyhow so it was ok (at reduced
speed). Doesn't work on the MTB though, I had to walk it all the way
home but the tire was so shredded anyhow that chunks flopped around.
--
Regards, Joerg
http://www.analogconsultants.com/