Thanks for this advice David.
>From this and other comments I received off-list it seems that I need to take more care mounting the tyres, make sure I'm not using bulky inner tubes when using rims without hooks, and watch out for mis-matches between the rim and bead size.
Wyndham Pulman-Jones Girton, Cambs., UK.
On Sunday, January 25, 2009, at 08:37PM, "david snyder" <dddd@pacbell.net> wrote:
>Wyndham,
>
>Firstly, let me say that I don't see this as rim, or rim-size related.
>
>This is almost certainly a case of the bead area getting damaged during installation.
>
>Avoid using a metal tyre iron of any kind, and I'd say to mount the tyres without tools if at all possible. This can usually be done by "working" the entire length of bead into the "well" of the rim while getting the last few inches of bead tucked into the rim, noting that some air pressure may need to be relieved from the tube during th installation.
>
>I start with an ever-so-slightly inflated tube installed in the tire.
>
>Next, I install the first bead and valve stem.
>
>This is followed by getting the tube centered into the rim well.
>
>The final step of getting the second bead in is done while doing the following two things:
>
>1) Pushing the valve stem momentarily into the tire casing so the surrounding tube isn't trapped under the bead, and:
>
>2) Relieving pressure as necessary while getting the remaining beads setting deep into the rim well as possible. I use a squeeze-and-slide action with my "free" (freed) hand to achieve this last detail while holding tension on the remaining un-mounted length of bead, then use both hands to lift the final bit of the bead over the edge of the rim.
>
>I've mounted many a stubborn tyre using the above method, sans tools.
>
>I've also managed to damage the bead fabric while forcefully pulling tyres OFF of the rim, as there is a bit of a shearing action between metal beads and the rim's edge, if one isn't careful.
>
>Better luck next time!
>
>Apologies in advance if this message gets garbled or compressed by my current psuedo-email applicatiion. This will serve as a test of sorts.
>
>David Snyder
>Auburn, CA usa
>
>
>--- On Sun, 1/25/09, Wyndham Pulman-Jones <simonpj@mac.com> wrote:
>
>> From: Wyndham Pulman-Jones <simonpj@mac.com>
>> Subject: [CR] Tyres blowing off old 27 inch rims
>> To: "classic Rendezvous" <classicrendezvous@bikelist.org>
>> Date: Sunday, January 25, 2009, 11:18 AM
>> I have had bad luck recently with tyres blowing off old 27
>> inch rims - and often splitting the carcass of the tyre from
>> the wire bead - with a very loud bang shocking passers by.
>> This has happened with Panaracer 27 x 1 1/4 and 27 x 1 1/8
>> tyres and with Continental Ultra Gatorskin tyres - on both
>> Fiamme and Weinmann Alesa rims.
>>
>> Are there tyres which don't suffer so badly from this?
>> Or is it just a matter of tyre pressures? My blow-offs have
>> happened with the tyres at about 75 psi. Is it necessary to
>> go lower than this?
>>
>> Wyndham Pulman-Jones
>> Girton, Cambs., UK.