FWIW: I've been running folding Micheling Pro Race 2 tires at about 100psi on (very similar to those Grand Bois, no hooks) Rigida rims (sold by Velo Orange a while ago) without any problems. OTOH, I had a traditional steel bead tire (Schwalbe 26 x 1 1/4) blow off a similar hook-less rim (Conloy) during pumping up @ about 90-100psi - but I must admit that that tire is rated to 85psi max so I was pushing my luck (not by much though)... so, while Kevlar-beaded tires may be more flexible, my (very limited of course) experience does not indicate that they are more "stretchy".
-- Cheers, Dmitry Yaitskov, Toronto, Canada.
Tuesday, December 16, 2008, 11:51:12 AM, Fred Rednor wrote:
> In my experience, if you keep the pressure below 85psi (about 6
> bar) the hook bead-seat is unnecessary. I believe hook beads
> were invented so that you could use very high inflation pressures
> with flexible (i.e. Kevlar)bead tires.
> If the pressure isn't so high, the rim does not require a hooked
> bead-seat. With steel bead tires, I've even run 95psi
> (nearly 7 bar) without any problems.
> Best regards,
> Fred Rednor - Arlington, Virginia (USA) - and about to grab
> a drink from the other kind of bar...
> --- On Tue, 12/16/08, John Betmanis <firstname.lastname@example.org> wrote:
>> From: John Betmanis <email@example.com>
>> Subject: Re: [CR]Grand Bois Rims
>> To: firstname.lastname@example.org
>> Date: Tuesday, December 16, 2008, 11:18 AM
>> At 08:23 AM 16/12/2008 -0600, email@example.com
>> >It looks like the Grand Bois Rims are not a hook bead
>> >Any reason to not have a hook bead rim?
>> As I recall, hook bead rims were a relatively recent
>> invention, used for
>> folding tires with "stretchy" beads that would
>> otherwise blow off regular
>> straight sided rims. It seems that modern clincher bicycle
>> tires no longer
>> have strong wire beads, or their beads don't sit deep
>> enough, so that they
>> need hook bead rims to keep them in place. So to answer the
>> question, those
>> Grand Bois rims are probably of traditional vintage design
>> meant for
>> traditional vintage tires. Of course, this is all
>> conjecture on my part and
>> I'd like to know exactly how it came about that modern
>> clincher tires
>> degenerated to where they required hook bead rims to keep
>> them in place.
>> John Betmanis
>> Woodstock, Ontario