What's the advantage of presta valves?
08-02-05, 07:29 PM
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What's the advantage of presta valves?
What's the advantage of presta valves?
08-02-05, 07:33 PM
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Don't take this as gospel, but I remember reading somewhere that the smaller diameter of presta valves makes for less of a weak spot in the wheel 'cause of the smaller hole.
--gordy
--gordy
08-02-05, 08:09 PM
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Originally Posted by 135crewchief
What's the advantage of presta valves?
08-03-05, 08:11 AM
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My understanding is that the presta valve does a better job sealing with the higher pressures one sees on a bike, as opposed to automobiles, where the schrader standard comes from. Schrader valves are also a bit more susceptible to problems if dirt and gunk get under the plastic cap.
08-04-05, 07:32 PM
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Yeah, the presta uses an active force to shut the valve, whereas the shraeder only uses the spring-pressure. I've had a couple instances at Bonneville where the rotational inertia of the valve spinning around actually forces the schraeder innards open against the spring. Not fun losing tire-pressure at 185mph... The solution was to lock-tite on some steel valve-stem caps.
Last edited by DannoXYZ; 08-04-05 at 09:49 PM.
08-04-05, 09:50 PM
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Nope, look at the direction that the valve moves to open and seal. The valve points towards the axle of the wheel. The spring pushes the valve towards the axle to seal. To open the valve, you push it outwards towards the outside of the wheel (towards the tyre), in the same direction centripedal force pushes the valve. Get enough RPMs spinning and you'll open the valve.
08-05-05, 11:02 AM
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Originally Posted by DannoXYZ
Yeah, the presta uses an active force to shut the valve, whereas the shraeder only uses the spring-pressure. I've had a couple instances at Bonneville where the rotational inertia of the valve spinning around actually forces the schraeder innards open against the spring. Not fun losing tire-pressure at 185mph... The solution was to lock-tite on some steel valve-stem caps.
08-05-05, 01:36 PM
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less likelihood of bursting tubes through over-enthusiastic use of air compressor to fill tires.
though this is less of an issue with these 100+ psi tubes...
though this is less of an issue with these 100+ psi tubes...
08-05-05, 05:26 PM
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Originally Posted by DannoXYZ
Yeah, the presta uses an active force to shut the valve, whereas the shraeder only uses the spring-pressure. I've had a couple instances at Bonneville where the rotational inertia of the valve spinning around actually forces the schraeder innards open against the spring. Not fun losing tire-pressure at 185mph... The solution was to lock-tite on some steel valve-stem caps.
On a serious note, that's interesting. Never thought of it...
08-05-05, 06:08 PM
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Originally Posted by DannoXYZ
Nope, look at the direction that the valve moves to open and seal. The valve points towards the axle of the wheel. The spring pushes the valve towards the axle to seal. To open the valve, you push it outwards towards the outside of the wheel (towards the tyre), in the same direction centripedal force pushes the valve. Get enough RPMs spinning and you'll open the valve.
08-06-05, 11:41 AM
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Originally Posted by DannoXYZ
Yeah, the presta uses an active force to shut the valve, whereas the shraeder only uses the spring-pressure. I've had a couple instances at Bonneville where the rotational inertia of the valve spinning around actually forces the schraeder innards open against the spring. Not fun losing tire-pressure at 185mph... The solution was to lock-tite on some steel valve-stem caps.
Al
