Mountain bike punctures - valve being torn off.

"Wm..." wrote in message
]...
Mon, 14 Sep 2009 10:48:34
uk.rec.cycling Doki


Yep, I know what you mean. Never heard of them being available for
pushbikes though - I suspect most racers use higher pressures and ride
full suspension, or go tubeless, so there's no real market for something
like that (extra weight).

Just curious, why don't you want to increase the pressure if that would
solve the problem?

"Mountain bike" is a clue. Low pressures provide more grip in some
conditions, and more comfort over bumpy stuff, at the expense of a bit more
effort.

I wonder if a bit of light glue would do it? Something like one of the
display board adhesives - ie sticky, but able to be released. Fasttack?

"Doki" writes:

I keep getting punctures on my mountain bike, where the Schraeder valve has
been pulled off the tube. Clearly, the tyre is rotating slightly on the rim
under braking, and pulling the tube along with it, which eventually rips the
valve off.

You could try talcing the inside of the tyre.

Jon

Mon, 14 Sep 2009 12:16:01
uk.rec.cycling Clive
George

"Wm..." wrote in message
]...
Mon, 14 Sep 2009 10:48:34
uk.rec.cycling Doki


Yep, I know what you mean. Never heard of them being available for
pushbikes though - I suspect most racers use higher pressures and ride
full suspension, or go tubeless, so there's no real market for something
like that (extra weight).

Just curious, why don't you want to increase the pressure if that would
solve the problem?

"Mountain bike" is a clue. Low pressures provide more grip in some
conditions, and more comfort over bumpy stuff, at the expense of a bit more
effort.

I wonder if a bit of light glue would do it? Something like one of the
display board adhesives - ie sticky, but able to be released. Fasttack?

Or even flour and water. I'll probably roux saying that.

--
Wm...
Reply-To: address valid for at least 7 days

On Mon, 14 Sep 2009 10:48:34 +0100
"Doki" wrote:

Yep, I know what you mean. Never heard of them being available for
pushbikes though - I suspect most racers use higher pressures and
ride full suspension, or go tubeless, so there's no real market for
something like that (extra weight).

Easy enough to make some, I'd have thought. I don't think a straight
adaptation of the motorcycle type would work, because of the difference
in the tyre/rim interface and the difficulty of avoiding chafing, but a
nicely smoothed lump of alloy, resin or even hardwood might be made to
do the job. Or it might just spread the walls of the rim. Maybe a
light smear of tubular tyre adhesive on the tyre bead would be a better
idea.

On 14 Sep, 08:18, "Doki" wrote:
I keep getting punctures on my mountain bike, where the Schraeder valve has
been pulled off the tube. Clearly, the tyre is rotating slightly on the rim
under braking, and pulling the tube along with it, which eventually rips the
valve off.

Tyres are 2.25" Panaracers, running at a fairly low pressure, and are well
within the maximum specs for the rim (I think the max is 2.5"). I don't want
to increase pressure, unless I really have to.

Any ideas on possible remedies? I don't really want to superglue the tyres
to the rim... The tyres are also about 4 years old, if that makes any odds.

Pressure too low. This is one of the primary symptoms of pressure too
low (the other is snakebytes). If you really want to ride with
pressure this low, the only solution is to go for tubeless tyres (and
rims).

"Simon Brooke" wrote in message
...

Pressure too low. This is one of the primary symptoms of pressure too
low (the other is snakebytes). If you really want to ride with
pressure this low, the only solution is to go for tubeless tyres (and
rims).

Can't you go tubeless with normal rims? Stan's No Tubes?

Clive George wrote:
"Simon Brooke" wrote in message
...

Pressure too low. This is one of the primary symptoms of pressure too
low (the other is snakebytes). If you really want to ride with
pressure this low, the only solution is to go for tubeless tyres (and
rims).

Can't you go tubeless with normal rims? Stan's No Tubes?


You don't need to give much grip, do you think that a bit of tub cement
around the bead would do it? Just don't blame me when you come to take
the tyre off!

--
Roger Thorpe

....Wait a minute, It's stopped raining/
Guys are swimming, guys are sailing.....

Doki wrote:
I keep getting punctures on my mountain bike, where the Schraeder valve has
been pulled off the tube. Clearly, the tyre is rotating slightly on the rim
under braking, and pulling the tube along with it, which eventually rips
the
valve off.

Tyres are 2.25" Panaracers, running at a fairly low pressure, and are well
within the maximum specs for the rim (I think the max is 2.5"). I don't
want
to increase pressure, unless I really have to.

Any ideas on possible remedies? I don't really want to superglue the tyres
to the rim... The tyres are also about 4 years old, if that makes any odds.

My daughter and husband have had this happen to them with Panaracers,
especially when using them at the bottem end of the pressure range.

Ace wrote:
On Mon, 14 Sep 2009 08:18:07 +0100, "Doki" wrote:




Any ideas on possible remedies? I don't really want to superglue the tyres
to the rim... The tyres are also about 4 years old, if that makes any odds.

Haven't seen these for years, and TBH I'm not even certain they were
ever made for pedal cycles, but some trials motorbikes, running very
low pressures in tubed tyres, would have a retaining device bolted
through the rim. This would be a shaped flat plate, sized to fit
between the beads of the tyre, but within the rim, and would be
securely tightened from the outside.

Not the best description, so I'll try some ASCII art instead.

| | ---- Tyre
| plate |
\ | /
\ \ V / / ---- Rim
\ \============= / /
\ \ || / /
\______||______/
[||]

Not sure that helps, nor where you would find such a thing, but
hopefully you'll get the idea.

A "security bolt" is the motor cycling name for them - reasonably
simple to make. I seem to remember that standard practice was to fit
them 90 degrees round the rim from the valve but can't remember:
A: why
B: 90 degrees in which direction.

--
Andrew

"Wm..." wrote in message
]...
Mon, 14 Sep 2009 10:48:34
uk.rec.cycling Doki


Yep, I know what you mean. Never heard of them being available for
pushbikes though - I suspect most racers use higher pressures and ride
full suspension, or go tubeless, so there's no real market for something
like that (extra weight).

Just curious, why don't you want to increase the pressure if that would
solve the problem?

It's a fully rigid mountain bike, and it rides the way I like it with no
suspension and big soft tyres. Most of the riding around here is fairly
gentle, so riding rigid means you can still have fun, but the soft tyres
take the edge off. I could fit my suspension forks back on and raise the
pressures, but it isn't really warranted around here.