Tyres for non-hooked rim

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emleyman
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Tyres for non-hooked rim

Postby emleyman » 4 Mar 2009, 6:34pm

I need to get some new tyres for some old 27" wheels where the inside of the rim is flat, ie. not hooked. What should I be looking for?

I'd like to get something with decent puncture protection. I've found some Conti Ultra Gatorskins in the right size (27 x 1 1/4). Does anyone know if these can be used?

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hubgearfreak
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Re: Tyres for non-hooked rim

Postby hubgearfreak » 4 Mar 2009, 7:05pm

sheldon says.

Note on tire/rim compatibility:

Traditional 630 mm (27 inch) rims were straight side design, but in the late '70s they evolved to a "hook edge" design which would permit the use of higher pressures.

These days, many 630 mm (27 inch) tires are marked "For hook edge rims only" (some companies use the term "crochet type" instead of "hook edge"...this is the result of poor translation.)

The fact is that modern 630 mm (27 inch) tires will work on older straight-side rims, but they won't handle as much pressure as they are capable of with hook edge rims.

Generally, the "rule of thumb" for traditional 630 mm (27 inch) tires is that they should be inflated to 70-75 psi. This shouldn't be a problem with any tire, despite whatever disclaimer the manufacturer puts on the sidewall. However, if you're restricted to this pressure range, you probably shouldn't be running tires narrower than 1 1/8, or preferably 1 1/4, unless you're a very lightweight rider

emleyman
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Location: W Yorks.

Re: Tyres for non-hooked rim

Postby emleyman » 5 Mar 2009, 12:58pm

Thanks for the info Hubgearfreak. I looked on Sheldon but couldn't find anything about this.

I'm not a lightweight (13st+) but I was intending to get 27 x 1 1/4 to replace what is currently on there. The only thing is the recommended pressure for the Ultra Gatorskin is 85PSI (max 102PSI).

Do you think I'd be better going for the Ultra Sport which has a recommended pressure of 70PSI for the same size tyre. I don't really want to do this as I'd lose some of the puncture protection, but I'd rather that than risk a high speed tyre failure.

pigman
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Re: Tyres for non-hooked rim

Postby pigman » 5 Mar 2009, 1:12pm

from personal experience, I'd never have a non hooked rim. i remember once having steel 27"'s on a bike I built up, pumping the tyres and keeping to low pressures, and both blew off the rims splitting the tubes within the first 5 mins. Maybe it was a bad tyre combo, cant remember.

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hubgearfreak
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Re: Tyres for non-hooked rim

Postby hubgearfreak » 5 Mar 2009, 1:35pm

emleyman wrote:The only thing is the recommended pressure for the Ultra Gatorskin is 85PSI (max 102PSI).


my guess is that if you asked continental, they'd say not to fit them to unhooked rims. if sheldon says 75psi, then you'd be a fool to go to 85psi, IMHO. what you do with the info that's there however, is entirely your choice. i'm sorry if i sound stroppy, i'm really not :D ...but i can tell you that i rode for hundreds of miles on unhooked rims no bother, but never at high pressure.

it's from here, if you wish to see it

http://sheldonbrown.com/harris/tires/630.html

emleyman
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Location: W Yorks.

Re: Tyres for non-hooked rim

Postby emleyman » 5 Mar 2009, 2:57pm

Hubgearfreak. I don't think you sound stroppy at all. I'm grateful for any advice, and I realise it's up to me what I decide to do with it.

It's just a case of deciding whether to go for replacement 27" tyres on non-hooked rims, with a very small choice of tyre, or spend a lot of extra cash to replace the wheels. The reason I've been looking to get replacement 27" tyres is that it's an old bike I've been doing up, and I don't want to spend a lot of cash on it in case I decide I'm not keen and want to sell it.

Pigman's view would obviously be not to risk using these rims at all.

I guess I could just get another set of the Michelin World Tours that are on it at present (the existing ones are falling apart), as these are £6 each from Chain Reaction, and then replace the wheels at a later date if I decide to keep the bike. The problem is these tyres are cheap for a reason. They appear to be as puncture proof as a large balloon!

PinkPanther
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Re: Tyres for non-hooked rim

Postby PinkPanther » 5 Mar 2009, 3:47pm

I've run Schwalbe Marathons on an eighties Raleigh with Weinmann rims for the last 18 months (about 4,000 miles) without a problem, think I've had them at about 80psi.

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hubgearfreak
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Re: Tyres for non-hooked rim

Postby hubgearfreak » 5 Mar 2009, 11:03pm

PinkPanther wrote:an eighties Raleigh


if your bike is 80's
and
if sheldon is correct
then you'll have hooked rims.

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hubgearfreak
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Re: Tyres for non-hooked rim

Postby hubgearfreak » 5 Mar 2009, 11:06pm

emleyman wrote:I don't want to spend a lot of cash on it in case I decide I'm not keen and want to sell it.


why not try a wanted advert on this very forum?

i'll bet that there's many here (like me) who can't bear to throw things out and may just have what you want cluttering up their sheds 8)