Bret Cahill wrote:

It had turned into a great day. After about 55 miles into my 95 mi.
trip I had a slight wind pushing me along and I was going to make some
time. The asphalt had buckled against the expansion joints but no
need to slow down or swerve. I was double tubed.

The first bad bump was about 5" above the bridge deck. The front
wheel came down not quiet properly aligned with the direction of
motion and the water bottle flew out. I recovered the water bottle
and quickly resumed riding in the same fashion. A mile later the same
happened again except with a softer bounce. The water bottle stayed
put. The front tire was definitely softer than when I started out. I
thought, finally an opportunity to ride on one tube but it quickly
became clear that _both_ tubes had pinch flat punctures.

This brought up one advantage of double tubing. If the innertube
rubber is pretty thick and if you shift as much weight as possible to
the back wheel, you can more or less ride on the flat tire for short
distances.

I'll check to see if the punctures on each tube are side by side
indicating that both pinch flats happened on the same bump.

If not then the usage other cyclists have been recommending may hold.
Once one tube goes down then inflate the other tube, at least on
longer trips.

Two punctures lined up, side by side, but a shard of glass still in
the tire indicated it wasn't a pinch flat over one bad bump. It
wouldn't have been a likely scenario for me to get the glass out
before the 2nd tube went down.

it's not really likely that any sharp will not puncture both in a very
short space of time.

which kind of begs the question whats the point?

What's really curious is the 2 tubes only leak in two places each
after 33 miles of rim riding.


Bret Cahill

Sorry but I really can't see this being anything but a solution looking
for a problem.

tubeless tyres seem to be catching on slowly or simply robust tyres.

Roger
--
www.rogermerriman.com