"never use the max. PSI pressure from the sidewall"

[spokes]

Following my third visit from the p*nct*re fairy in a week, I was googling
around on 'flat-proof tyres' and came across a discussion
http://www.bikeforums.net/archive/index.php/t-218157.html
featuring the quote in the subject line.

I've got used to standardising on 100psi with my Grand Prix 2000s, which is
well within their supposed max (and I'm about 11 stone, so not a massive
load). And I checked the Sheldon link provided, which seemed to suggest
c.100 would be about right for me. I guess 'try it see' is an obvious
answer, but should I take them down to 80 or something? Any thoughts? What
do other people do? (I'd always previously thought that problems came when
you didn't inflate *enough*.)

 

[Clive George]

"spokes" <[email protected]> wrote in message
news:[email protected]...
> Following my third visit from the p*nct*re fairy in a week, I was googling
> around on 'flat-proof tyres' and came across a discussion
> http://www.bikeforums.net/archive/index.php/t-218157.html
> featuring the quote in the subject line.
>
> I've got used to standardising on 100psi with my Grand Prix 2000s, which
> is well within their supposed max (and I'm about 11 stone, so not a
> massive load). And I checked the Sheldon link provided, which seemed to
> suggest c.100 would be about right for me. I guess 'try it see' is an
> obvious answer, but should I take them down to 80 or something? Any
> thoughts? What do other people do? (I'd always previously thought that
> problems came when you didn't inflate *enough*.)

Tandems routinely use pressures above the max, so I wouldn't worry about
going with what it says.

100psi would be a good starting point - if you're happy with that, stick
with it.

cheers,
clive

 

[Bob]

spokes wrote:
> Following my third visit from the p*nct*re fairy in a week, I was googling
> around on 'flat-proof tyres' and came across a discussion
> http://www.bikeforums.net/archive/index.php/t-218157.html
> featuring the quote in the subject line.
>
> I've got used to standardising on 100psi with my Grand Prix 2000s, which is
> well within their supposed max (and I'm about 11 stone, so not a massive
> load). And I checked the Sheldon link provided, which seemed to suggest
> c.100 would be about right for me. I guess 'try it see' is an obvious
> answer, but should I take them down to 80 or something? Any thoughts? What
> do other people do? (I'd always previously thought that problems came when
> you didn't inflate *enough*.)

I always go with the max, too many punctures otherwise.

Cheers,

--
bob [at] bobarnott [dot] com http://www.bobarnott.com/
------------------------------------------------------------------------
"Crash programs fail because they are based on theory that,
with nine women pregnant, you can get a baby in a month."
-- Wernher von Braun

 

[Pete Biggs]

spokes wrote:
> Following my third visit from the p*nct*re fairy in a week, I was
> googling around on 'flat-proof tyres' and came across a discussion
> http://www.bikeforums.net/archive/index.php/t-218157.html
> featuring the quote in the subject line.

That's a load of crapola. The "max" is often about right, or sometimes a
bit too low, or sometimes a bit too high.

> I've got used to standardising on 100psi with my Grand Prix 2000s,
> which is well within their supposed max (and I'm about 11 stone, so
> not a massive load). And I checked the Sheldon link provided, which
> seemed to suggest c.100 would be about right for me. I guess 'try it see'
> is an obvious answer, but should I take them down to 80 or
> something? Any thoughts? What do other people do? (I'd always
> previously thought that problems came when you didn't inflate
> *enough*.)

You have not stated the width (aka depth) of the tyres. No one can
recommend a specific pressure until that is known. A 23mm tyre at 100 psi
is significantly softer than a 25mm tyre at 100 psi, for example. Basic
physics, innit.

Some theories say tyres puncture more easily the harder they are, and some
the opposite. Certainly tyres will be more prone to the pinch-flat or
snakebite type of puncture when they're soft. Anyway, you should use the
pressure that's the best compromise between grip, comfort and speed for your
liking. If getting too many punctures, consider more puncture resistant
tyres. Using a different pressure is not the answer.

I can't remember what GP 2000s are like. If lightweight racing tyres,
consider something a bit more substantial (but still quite light & slick)
like Vittoria Rubino Pro - and in size 25 if you currently use 23s.
For even more puncture resistance, there's Panaracer Pasela, Specialized
Armadillo, and ultimately, Schwalbe Marathon Plus.

~PB

 

[Simon Brooke]

spokes wrote:

> Following my third visit from the p*nct*re fairy in a week, I was googling
> around on 'flat-proof tyres' and came across a discussion
> http://www.bikeforums.net/archive/index.php/t-218157.html
> featuring the quote in the subject line.
>
> I've got used to standardising on 100psi with my Grand Prix 2000s, which
> is well within their supposed max (and I'm about 11 stone, so not a
> massive load). And I checked the Sheldon link provided, which seemed to
> suggest
> c.100 would be about right for me. I guess 'try it see' is an obvious
> answer, but should I take them down to 80 or something? Any thoughts? What
> do other people do? (I'd always previously thought that problems came when
> you didn't inflate *enough*.)

Lower pressure = more punctures, on the whole. Take 'em up to their max, but
not when there's ice on the road.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; "If I were a Microsoft Public Relations person, I would probably
;; be sobbing on a desk right now" -- Rob Miller, editor, /.

 

[Pete Biggs]

Simon Brooke wrote:

> Lower pressure = more punctures, on the whole. Take 'em up to their
> max, but not when there's ice on the road.

Higher pressure means the tyre is forced harder onto an object, meaning the
object is more likely to puncture the tyre. I don't think pressure should
be reduced for this reason though (see my previous reply).

~PB

 

[Nick]

Pete Biggs wrote:
> Simon Brooke wrote:
>
>> Lower pressure = more punctures, on the whole. Take 'em up to their
>> max, but not when there's ice on the road.
>
> Higher pressure means the tyre is forced harder onto an object, meaning the
> object is more likely to puncture the tyre. I don't think pressure should
> be reduced for this reason though (see my previous reply).
>

Although lower pressures can mean pinch flats.

 

[Rob Morley]

In article <[email protected]>, Pete Biggs
[email protected] says...
> Simon Brooke wrote:
>
> > Lower pressure = more punctures, on the whole. Take 'em up to their
> > max, but not when there's ice on the road.
>
> Higher pressure means the tyre is forced harder onto an object, meaning the
> object is more likely to puncture the tyre.

Or it means the tyre deflects less, so the object is more likely to be
flicked aside than to stick in. I suspect a lot depends on the type and
position of the object, the tread pattern and compound ...

 

[Pete Biggs]

Rob Morley wrote:
> In article <[email protected]>, Pete Biggs
> [email protected] says...
>> Simon Brooke wrote:
>>
>>> Lower pressure = more punctures, on the whole. Take 'em up to their
>>> max, but not when there's ice on the road.
>>
>> Higher pressure means the tyre is forced harder onto an object,
>> meaning the object is more likely to puncture the tyre.
>
> Or it means the tyre deflects less, so the object is more likely to be
> flicked aside than to stick in. I suspect a lot depends on the type
> and position of the object, the tread pattern and compound ...

Altogether it's such a complex phenomenonen that we might as well put it
down to "luck".

~PB

 

[spokes]

>
> Altogether it's such a complex phenomenonen that we might as well put it
> down to "luck".
>
> ~PB

Or to put it another way, noone really has any idea whether it's best,
p*nctu*e-wise, to keep your tyres hard or soft. (Or, more accurately, quite
a few people have firm ideas - but those ideas are often diametrically
opposed.)

I do find it quite surprising that something so fundamental has presumably
never been tested properly in real world conditions, given that it would
have quite significant implications for countless millions of people all
over the world. Strange.

I think I'll stick at 100 and take my chances. (Oh, and in answer to PB's
earlier query - sorry, should've mentioned - 23mm tyres. And these are not
pinch/spoke problems - they're always glass shards coming straight thru'.)

I've had better "luck" the last few days...glad to say.

 

[spokes]

I suggest trying 110 to 120 psi in the rear tyre - for a bit more
> speed and tyre life. (Rear should be harder than front as it takes more
> weight).
>

Ok - thanks for that. I'll give it a try.