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15-10.-2005, 01:18 PM
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#1 |
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Registered User
Join Date: Aug 2005
Posts: 16
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Over-inflating
Having only a fairly new and efficient mountain bike, i have taken to only using the thing on longish road rides - and not taking the thing offroad. I'm planning on getting a road bike in a few months - but until then, since i am only on the road the whole time, i have inflated the tyres to obviously high pressures.
I'm not exactly sure what the point of over-inflating exactly is (what psi figure), but IF i have overinflated them, what is the danger? Aside from bursting an inner tube? Does it put more pressure on the rims? Could i have a catastrophic failure at high speeds? What is the problem? |
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15-10.-2005, 01:57 PM
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#2 |
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Registered User
Join Date: Jan 2004
Location: Sierra Madre, CA, USA
Posts: 34
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Re: Over-inflating
You didn’t say how much you over inflate. However for years on my road bikes I have made it a habit to inflate my tires to 130 PSI. I started this with tires that were rated at 90 PSI. However my modern tires are rated at 120 PSI. The higher your tire pressure the less is the rolling resistance or friction. Years ago the Bicycle magazine contacted tire manufacturers to find out how they determined the recommended tire pressure for their tires. They only got a response from one and that one essentially said it was just a guess. That is when I started over inflating my tires. At the time I liked the feel of crisp tires rolling over the pavement with my steel framed bikes. However today with my carbon framed bike and the bad pavement I am riding on, I do not think it is such a good idea. As far as danger of blow out, I think that depends on your rims. If they have a lip that engages the bead of the tire, I don’t think there is any danger of blow out no matter how high you go.
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15-10.-2005, 02:21 PM
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#3 |
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Registered User
Join Date: Apr 2004
Location: Perth (Basso), West Australia
Posts: 3,515
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Re: Over-inflating
My sugggestion is buy some MTB slicks, Conti make 2,
GP in 26x1 and Sport Contact in 26x1.3 Use the GPs for road only, the Sport contact are ok on road and light off-road. http://www.conti-online.com/generat...rix_mtb_en.html All Conti tyres have the max pressure printed on the tyre. Rims can stretch with high pressures if they are the real cheap roll-formed alloy ones and not extruded. What brand is the bike?
__________________
Cheers, George. |
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15-10.-2005, 04:55 PM
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#4 |
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Registered User
Join Date: Aug 2005
Posts: 16
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Re: Over-inflating
It's a Trek 4700.
And the reason i didn't say how much i overinflated - was that with my French valve adapter - i can't get a reading. |
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15-10.-2005, 05:56 PM
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#5 | |
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Registered User
Join Date: Jul 2005
Location: Strathfield, (Sydney), Australia
Posts: 813
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Re: Over-inflating
Quote:
I can - French valve. No probs. Scotty Last edited by scotty72 : 15-10.-2005 at 06:16 PM. |
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15-10.-2005, 06:03 PM
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#6 |
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Registered User
Join Date: Apr 2004
Location: Perth (Basso), West Australia
Posts: 3,515
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Re: Over-inflating
Trek rims will be OK.
Buy a decent floor pump with a gauge. Know your tyres, they are your only point of contact with the road. Read this topic: http://www.cyclingforums.com/t287868-.html it's not rocket science!
__________________
Cheers, George. |
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15-10.-2005, 06:38 PM
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#7 | |
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Registered User
Join Date: Jul 2005
Location: Strathfield, (Sydney), Australia
Posts: 813
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Re: Over-inflating
Quote:
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16-10.-2005, 07:55 PM
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#8 | |
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Registered User
Join Date: Mar 2004
Location: Sydney, Australia
Posts: 2,183
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Re: Over-inflating
Quote:
If you overinflate the tyre, it can blow off the rim. If this happens at speed, your rim can fracture and jam in your brakes or frame. How do I know? - I've done it. Any rim has a maximum rated pressure. Not just cheap rims, but all rims. It is not usually written on the damn thing. All tyres have a maximally efficient pressure which is usually within the rated pressure range. Exceed that and the wheel bounces around on the road suface and wastes energy. For fat tyres, the most efficient pressure is quite low, well under 100psi. |
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