Tires again!

Stephen (aka steford) <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Sorry if this is getting a bit boring but after reading yesterday's thread on punctures and
gloating that I'd not had one for ages I did this morning on Oxford Street! I've never really
taken much notice of pressure before, other than the fact that even at it's lowest recommended
pressure it's

rock

Quoted message said:

hard and I daren't go any further (using garage compressed air). Using Schwalbe Marathons and
whatever tubes are going at the moment and do exclusively road commuting with the odd bump up a
kerb and maybe over the occasional bit of grass in a park or whatever.

Thanks for any advice.

Advice on what? - you haven't asked for any !

and they're tYres

Russ :-)

"russell.pinder" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Stephen (aka steford) <[email hidden]>

wrote

Quoted message said:

in message "]news:[email hidden]...

Quoted message said:

Sorry if this is getting a bit boring but after reading yesterday's

thread

Quoted message said:

Quoted message said:

on punctures and gloating that I'd not had one for ages I did this

morning

Quoted message said:

Quoted message said:

on Oxford Street! I've never really taken much notice of pressure

before,

Quoted message said:

Quoted message said:

other than the fact that even at it's lowest recommended pressure it's

rock

Quoted message said:

hard and I daren't go any further (using garage compressed air). Using Schwalbe Marathons and
whatever tubes are going at the moment and do exclusively road commuting with the odd bump up a
kerb and maybe over

the

Quoted message said:

Quoted message said:

occasional bit of grass in a park or whatever.

Thanks for any advice.

Advice on what? - you haven't asked for any !

and they're tYres

Russ :-)

Tyre/tube combinations and pressure to avoid punctures. I always used to write tyre then saw someone
had written "tire" so put that instead!

Stephen (aka steford) said:

Tyre/tube combinations and pressure to avoid punctures.

The Marathon is a good tyre and reasonably resistant to puncturing. As long as you've got a
competent inner from a decent manufacturer (most of mine have been Specialized or Michelin) then it
should go in any decent tyre, Marathon included, with no particular consideration about any
combination effect AFAICT.

What pressure you use depends on the exact version of the Marathon, but assuming it's one of the
ones that will take up to 100 psi, for road use you're looking at at least 60, preferably 80+ and no
reason not to run at 100 assuming you can pump reliably to that. Any less than 60 and you're just
making a lot of work for yourself pedalling. Higher pressures give a little less suspension effect
and will skitter more over obstacles if you go off-road at all, but also give lower rolling
resistance on a good road (I run my Marathons at 100 psi on both bikes that have them, a Brompton
folder and a touring recumbent).

Note that despite its kevlar belt the Marathon isn't completely puncture proof: no tyre is, or at
least no tyre that you'd really want to use (there are some solid ones, but I haven't come across
any serious cyclists that use them, ever). A dagger shaped shard of glass will work its way through
just about anything if you catch it at the wrong angle: it's just bad luck. But I've ridden across
quite a bit of broken glass in my time on Marathons, and they'll generally deal okay with the more
typical lumps of the stuff.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

"Peter Clinch" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Stephen (aka steford) said:

Tyre/tube combinations and pressure to avoid punctures.

The Marathon is a good tyre and reasonably resistant to puncturing. As long as you've got a
competent inner from a decent manufacturer (most of mine have been Specialized or Michelin) then
it should go in any decent tyre, Marathon included, with no particular consideration about any
combination effect AFAICT.

What pressure you use depends on the exact version of the Marathon, but assuming it's one of the
ones that will take up to 100 psi, for road use you're looking at at least 60, preferably 80+ and
no reason not to run at 100 assuming you can pump reliably to that. Any less than 60 and you're
just making a lot of work for yourself pedalling. Higher pressures give a little less suspension
effect and will skitter more over obstacles if you go off-road at all, but also give lower rolling
resistance on a good road (I run my Marathons at 100 psi on both bikes that have them, a Brompton
folder and a touring recumbent).

Note that despite its kevlar belt the Marathon isn't completely puncture proof: no tyre is, or at
least no tyre that you'd really want to use (there are some solid ones, but I haven't come across
any serious cyclists that use them, ever). A dagger shaped shard of glass will work its way
through just about anything if you catch it at the wrong angle: it's just bad luck. But I've
ridden across quite a bit of broken glass in my time on Marathons, and they'll generally deal okay
with the more typical lumps of the stuff.

Thanks for that. I still can't believe though that my tyre that feels rock hard at 45psi will go up
to 80psi without blowing my head off in the garage forecourt. What difference am I going to see/feel
at 80 as opposed to 45? Of course I can see a problem running them at very low pressure (eg hand
pumped) as it must increase wear and tear on the tyre walls - but 80-100psi?

Cheers.

Stephen (aka steford) said:

Thanks for that. I still can't believe though that my tyre that feels rock hard at 45psi will go
up to 80psi without blowing my head off in the garage forecourt. What difference am I going to
see/feel at 80 as opposed to 45?

Considerably less rolling resistance. The more pressure you have the fewer square inches of tyre
contact you need to take the weight, so the less the tyre will spread over the road, so it'll be
easier to push it round. You'll go quicker, and use less effort in the process. If you find 45 psi
"rock hard" on a bicycle tyre then you've clearly got weaker fingers than me! ;-)

Quoted message said:

course I can see a problem running them at very low pressure (eg hand pumped)

See the thread on pumps currently running. There's no reason why a half decent hand pump can't push
pressure well beyond 45 psi in a bike tyre. Pumps have come a long way, and it pays to have a good
one so you're not reliant on having an open garage with an airline handy.

Quoted message said:

as it must increase wear and tear on the tyre walls - but 80-100psi?

It depends on the tyre. The Marathon[1] is *designed* for that sort of pressure and so it's well
within the engineered limitations of the material and construction. If you run an inferior tyre at
that sort of pressure it'll probably go pear shaped (literally, right before it explodes), but
that's quite a normal pressure for a quality bicycle tyre

Pete.

[1] some versions, like the 20 x 1.75", won't take 100 psi, but most of the ones people would likely
be using will.

--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

"Peter Clinch" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Stephen (aka steford) said:

Thanks for that. I still can't believe though that my tyre that feels

rock

Quoted message said:

Quoted message said:

hard at 45psi will go up to 80psi without blowing my head off in the

garage

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Quoted message said:

forecourt. What difference am I going to see/feel at 80 as opposed to

45?

Quoted message said:

Considerably less rolling resistance. The more pressure you have the fewer square inches of tyre
contact you need to take the weight, so the less the tyre will spread over the road, so it'll be
easier to push it round. You'll go quicker, and use less effort in the process. If you find 45 psi
"rock hard" on a bicycle tyre then you've clearly got weaker fingers than me! ;-)

Quoted message said:

course I can see a problem running them at very low pressure (eg hand pumped)

See the thread on pumps currently running. There's no reason why a half decent hand pump can't
push pressure well beyond 45 psi in a bike tyre. Pumps have come a long way, and it pays to have a
good one so you're not reliant on having an open garage with an airline handy.

Quoted message said:

as it must increase wear and tear on the tyre walls - but 80-100psi?

It depends on the tyre. The Marathon[1] is *designed* for that sort of pressure and so it's well
within the engineered limitations of the material and construction. If you run an inferior tyre at
that sort of pressure it'll probably go pear shaped (literally, right before it explodes), but
that's quite a normal pressure for a quality bicycle tyre

Pete.

[1] some versions, like the 20 x 1.75", won't take 100 psi, but most of the ones people would
likely be using will.

OK I'll get some decent tubes in this weekend and pump them up hard. Will repaired tubes take the
same sort of punishment?

Stephen (aka steford) said:

OK I'll get some decent tubes in this weekend and pump them up hard. Will repaired tubes take the
same sort of punishment?

If you've done them properly, yes. Higher pressures will just push the tube against the tyre harder.
It's the tyre that's doing most of the serious containment work, the tube just needs to be
non-porus.

Most tubes are basically okay, so I'd try your existing ones first: you're fairly unlikely to have
them explode as the tyre stops them expanding to the point where they'll fail.

Pete.
--
Peter Clinch University of Dundee Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net [email hidden]
dundee.ac.uk~pjclinchOpen ↗

"Stephen \(aka steford\)" <[email hidden]> wrote

Quoted message said:

Sorry if this is getting a bit boring but after reading yesterday's thread on punctures and
gloating that I'd not had one for ages I did this morning on Oxford Street! I've never really
taken much notice of pressure before, other than the fact that even at it's lowest recommended
pressure it's rock hard and I daren't go any further (using garage compressed air). Using Schwalbe
Marathons and whatever tubes are going at the moment and do exclusively road commuting with the
odd bump up a kerb and maybe over the occasional bit of grass in a park or whatever.

"Rock hard" is a relative term. The first time I used a proper floor-standing bike pump with a guage
in it I was surprised to find that I'd been pumping my tires up to only about half to 2/3 of what
they should be! I vowed to get a proper pump and inflate them correctly. And a good floor standing
pump (like a Silca) will easily inflate to 100psi, and then the guage will tell you how much you've
got in there. You may think they're rock hard, but in fact they should be even harder! And good
tires like the Marathons will without a doubt handle the pressure levels molded into the sidewalls
(I inflate my 28mm Marathons to about 85psi) without a problem.

And to answer your other question, yes, tubes with patches on them will take high pressures without
a problem, as long as you've applied the patches correctly.

-Myra