Schwalbe Marathon 700x32c - Failure/tear?? HELP!

Pete Biggs

Colin wrote:
> Hello All,
>
> Last year, I noticed that the rear tyre on our tandem had developed
> rips in the rubber just beyond where the rim meets the tyre. The tyre
> was still holding its shape OK & there were no other symptoms. Seeing
> this as a bit dodgy & unsafe I took it back to the local bike shop
> where I bought the tyres & they promptly gave a replacement, but no
> explanation.

It won't be unsafe if the casing under the rubber is unaffected. After all,
a lot of tyres don't have any rubber coating on the sidewalls at all. It's
just there to supposedly provide some extra protection.

/snip
> Tyre pressures – I normally inflate to 5/10 psi under the max – never
> higher. We have never ridden the bike on flat/ low tyres, nor has it
> been stored with flat tyres.

The lower the pressure, the more the sidewalls flex and and chafe. The
"max" will be set with solo bikes in mind. You might want to try a higher
pressure. And different tyres if the casing is getting damaged or the bead
starts separating.

There is an article on the CTC website that advises keeping tyre pressure
high to avoid sidewall problems, and I've had sidewall problems myself that
I now suspect was caused by under-inflation.

~PB

Colin

Hello All,

Last year, I noticed that the rear tyre on our tandem had developed
rips in the rubber just beyond where the rim meets the tyre. The tyre
was still holding its shape OK & there were no other symptoms. Seeing
this as a bit dodgy & unsafe I took it back to the local bike shop
where I bought the tyres & they promptly gave a replacement, but no
explanation.

I have just been checking the bike over before we go on holiday on it
next week & I have noticed that the same thing has started happening
to the front tyre. It has only done about 600 miles it was bought at
the time of the original back tyre).

I shall go through the things that I have thought of that maybe
causing this & hopefully someone will be able to let me know what I am
missing!

I have checked over the rims & neither seem sharp/ rough – where there
was a slight edge were the rim was joined, did not correspond to any
of the damage to the tyre. Also, the rims are fairly old – if they
were the source of the problem, I would have thought it would have
been noticed before now (the tandem I second hand – build in the 80s).

Tyre pressures – I normally inflate to 5/10 psi under the max – never
higher. We have never ridden the bike on flat/ low tyres, nor has it
been stored with flat tyres.

Heat – I keep a good eye on the temperature of the rims after long
descents – to my knowledge, they have never got hotter than it is
comfortable to hold my hand against. Also, had this been heat related,
I would have expected the damage to be all around the tyres, not just
in fairly small areas.

Anyways, here are some pics. More can be provided if necessary. I hope
someone can shed some light on this…preferably before next weekend!

Many thanks

Colin.

You should find pictures of the damage\defect at this link.....

http://picasaweb.google.co.uk/detproperty/Tyres

Jonathan Campbell

Colin wrote:
> Hello All,
>
> Last year, I noticed that the rear tyre on our tandem had developed
> rips in the rubber just beyond where the rim meets the tyre. The tyre
> was still holding its shape OK & there were no other symptoms. Seeing
> this as a bit dodgy & unsafe I took it back to the local bike shop
> where I bought the tyres & they promptly gave a replacement, but no
> explanation.
>
> I have just been checking the bike over before we go on holiday on it
> next week & I have noticed that the same thing has started happening
> to the front tyre. It has only done about 600 miles it was bought at
> the time of the original back tyre).
>
> I shall go through the things that I have thought of that maybe
> causing this & hopefully someone will be able to let me know what I am
> missing!
>
> I have checked over the rims & neither seem sharp/ rough – where there
> was a slight edge were the rim was joined, did not correspond to any
> of the damage to the tyre. Also, the rims are fairly old – if they
> were the source of the problem, I would have thought it would have
> been noticed before now (the tandem I second hand – build in the 80s).
>
> Tyre pressures – I normally inflate to 5/10 psi under the max – never
> higher. We have never ridden the bike on flat/ low tyres, nor has it
> been stored with flat tyres.
>
> Heat – I keep a good eye on the temperature of the rims after long
> descents – to my knowledge, they have never got hotter than it is
> comfortable to hold my hand against. Also, had this been heat related,
> I would have expected the damage to be all around the tyres, not just
> in fairly small areas.
>
> Anyways, here are some pics. More can be provided if necessary. I hope
> someone can shed some light on this…preferably before next weekend!
>

Chafing by improperly aligned brake blocks?

Happened to me and the symptoms seem very similar. However, I note that
at the time I was an inexperienced returnee to cycling and let the
problem cause a number of punctures before the penny dropped.

And no thanks also to the LBS (*) that sold me the bike --- they missed
the problem when the bike was sold and on a 500 mile free service (which
was undertaken so grumblingly that I might have expect the nothing I
received).

(*) Apologies to the two other LBSs that I use, I guess they will not
take offence.

Jon C.

Rob Morley

On Sun, 1 Jun 2008 09:45:49 -0700 (PDT)
Colin <colinj.wood@ntlworld.com> wrote:

> Tyre pressures – I normally inflate to 5/10 psi under the max – never
> higher. We have never ridden the bike on flat/ low tyres, nor has it
> been stored with flat tyres.

You probably need more than the rated pressure for tandem use - the
tyres can't be expected to take twice the design load without a bit of
extra air. You've effectively been running them under-inflated (unless
you and your stoker are real lightweights) which causes increased
sidewall flex.

> You should find pictures of the damage\defect at this link.....
>
> http://picasaweb.google.co.uk/detproperty/Tyres

How has the bike been stored? This looks typical of the sort of
degradation that occurs when a tyre is kept in sunlight or on a damp
floor. As long as the casing threads haven't started to fray it
shouldn't be a safety problem.

Sam Salt

Colin wrote:
> Hello All,
>
> Last year, I noticed that the rear tyre on our tandem had developed
> rips in the rubber just beyond where the rim meets the tyre. The tyre
> was still holding its shape OK & there were no other symptoms. Seeing
> this as a bit dodgy & unsafe I took it back to the local bike shop
> where I bought the tyres & they promptly gave a replacement, but no
> explanation.
>
> I have just been checking the bike over before we go on holiday on it
> next week & I have noticed that the same thing has started happening
> to the front tyre. It has only done about 600 miles it was bought at
> the time of the original back tyre).
>
> I shall go through the things that I have thought of that maybe
> causing this & hopefully someone will be able to let me know what I am
> missing!
>
> I have checked over the rims & neither seem sharp/ rough – where there
> was a slight edge were the rim was joined, did not correspond to any
> of the damage to the tyre. Also, the rims are fairly old – if they
> were the source of the problem, I would have thought it would have
> been noticed before now (the tandem I second hand – build in the 80s).
>
> Tyre pressures – I normally inflate to 5/10 psi under the max – never
> higher. We have never ridden the bike on flat/ low tyres, nor has it
> been stored with flat tyres.
>
> Heat – I keep a good eye on the temperature of the rims after long
> descents – to my knowledge, they have never got hotter than it is
> comfortable to hold my hand against. Also, had this been heat related,
> I would have expected the damage to be all around the tyres, not just
> in fairly small areas.
>
> Anyways, here are some pics. More can be provided if necessary. I hope
> someone can shed some light on this…preferably before next weekend!
>
> Many thanks
>
> Colin.
>
> You should find pictures of the damage\defect at this link.....
>
> http://picasaweb.google.co.uk/detproperty/Tyres


Colin,

The underinflation suggestion may be correct.We have the same tyre on
our tandem and always keep it pumped up to at least 100psi ( I think it
recommends 90psi on the sidewall ) and we have never had a problem.

Sam Salt


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