eastern sierra rendezvous, details for sept 22-26 - clearing up

[Chris Krok]

> From: Zachariah Mully > Subject: Re: NKLR-Crash Assist > > Wrong way, on a schrader valve it is possible for the inertia of the > valve core to exceed the valve core spring and open, but only at really > high speeds. Presta valves do not have this problem as the valve is > nutted shut.

You bastards. Now I'm going to have to measure the force required to open the valve, weigh the guts of a core, and figure out exactly how fast you need to go to get centrifugal force to open it. Krokko

[Richard May]

--- In DSN_klr650@yahoogroups.com, Chris Krok wrote:

>You bastards. Now I'm going to have to measure the force required >to open the valve, weigh the guts of a core, and figure out exactly >how fast you need to go to get centrifugal force to open it.

Please also check whether or not this rotating mass would alter the front wheel's gyroscopic inertia in such a manner that it would impact a shaft driven motorcycle's ability to countersteer and/or wheelie. Thanks Yuo, RM

[Dave Watkins]

LOL...... Don't worry Chris..... A little thought here should save you the work. Besides, I doubt there's a centrifuge that can reach the speeds necessary to determine the failure point of a working valve....... First......the spinning forces things outward toward away from the hub. The spring in a Schrader valve will theoretically compress as rotational/centrifugal forces increase. This will not affect the seals ability to do its job. If you look at the old type valves you will se that the spring is actually floating and "pulls" the moveable sealing surface from the non moving surface when a chuck is applied. There are two seals that come into play here. One that seals the stem to the core and the second seal prevents the passage of air out of the tire when the internal spring is not extended either by air pressure or by an object pressing directly on the center pin of the core. Note again that the spring is normally in a near relaxed state and applies very little pressure to the center of the core itself. Just compare the force needed to depress the center pin of the core when inflated and not compresses. ..................The core to stem seal is made by screwing the core into the stem. It's possible to deform this seal by over tightening or some foreign object coming between the two mating surfaces. The core to core seal as you can see in the attached web page will tighten as centrifugal force causes the moveable part to compress against the non-moveable part. If you look closely at the valves on the web page you'll see what I mean. http://www.geocities.com/cyqlist/valve.html Make sense? Dave Watkins

[Alan L Henderson]

> > You bastards. Now I'm going to have to measure the force required to > open the valve, weigh the guts of a core, and figure out exactly how > fast you need to go to get centrifugal force to open it. > > Krokko

Don't over look the fact that the air pressure in the tire also applies force to hold the valve closed. Alan Henderson A13 Iowa

[Jeffery McLaughlin]

But... SOMEONE has to do it...

>From: Chris Krok >To: DSN_klr650@yahoogroups.com >Subject: [DSN_klr650] NKLR valve core leakage >Date: Mon, 13 Sep 2004 08:49:13 -0700 > > > > From: Zachariah Mully > > Subject: Re: NKLR-Crash Assist > > > > Wrong way, on a schrader valve it is possible for the inertia of the > > valve core to exceed the valve core spring and open, but only at really > > high speeds. Presta valves do not have this problem as the valve is > > nutted shut. > >You bastards. Now I'm going to have to measure the force required to >open the valve, weigh the guts of a core, and figure out exactly how >fast you need to go to get centrifugal force to open it. > >Krokko >-- >Dr. J. Christopher Krok >John Lucas Adaptive Wind Tunnel >Caltech MS 205-45, Pasadena, CA 91125 > > >List sponsored by Dual Sport News at www.dualsportnews.com. List FAQ >courtesy of Chris Krok at: www.bigcee.com/klr650faq.html >Unsubscribe by sending a blank message to: >DSN_klr650-unsubscribe@yahoogroups.com . > > >Yahoo! Groups Links > > > > >

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[Chris Krok]

> A little thought here should save you the work. Besides, I doubt there's a > centrifuge that can reach the speeds necessary to determine the failure > point of a working valve.......

No need for a centrifuge, just need the mass of the inner part of the core, and F=ma (a = (angular velocity)^2 * R). Measure the force needed to depress the pin far enough to let air out of the tire (tire pressure at 35 psi, for example) using a spring scale or load cell, plug in the numbers and back out the angular velocity. Convert that to velocity, and voila.

> First......the spinning forces things outward toward away from the hub.

Riiiiiiiiight...

> The spring in a Schrader valve will theoretically compress as > rotational/centrifugal forces increase. This will not affect the seals > ability to do its job.

Why not? If I push on the pin (away from the hub, in the direction of centrifugal force), air comes out. Since the pin (and whatever it's connected to) has mass, then spinning the tire at some (possibly relativistic) speed will generate enough centrifugal force to move the pin and bleed air.

> There are two seals that come into play here. One that seals the stem to the > core

Not worried about the core-to-stem seal. The threaded connection between the two will prevent relative motion between those two parts (for this consideration, anyway). Ergo, that seal will not be affected.

> and the second seal prevents the passage of air out of the tire when > the internal spring is not extended either by air pressure or by an object > pressing directly on the center pin of the core. Note again that the spring > is normally in a near relaxed state and applies very little pressure to the > center of the core itself. Just compare the force needed to depress the > center pin of the core when inflated and not compresses.

Exactly. I could just assume the "holding force" from pressure x area, but actually measuring it would account for any stiction and the miniscule spring force. Last task then is to drive out the pin and its attached components, and weigh it on an analytical scale. Make sense? Krokko -- Dr. J. Christopher Krok John Lucas Adaptive Wind Tunnel Caltech MS 205-45, Pasadena, CA 91125

[Devon]

dave@... wrote:

>A little thought here should save you the work. Besides, I doubt there's a >centrifuge that can reach the speeds necessary to determine the failure >point of a working valve....... >

It's called a racebike wheel.

> The core to core >seal as you can see in the attached web page will tighten as centrifugal >force causes the moveable part to compress against the non-moveable part. >

No, it will force the "inner core" (the moveable part) outwards, and AWAY from its seat. That's the direction it moves in, as you push the core away from the hub to open the valve. Devon

> >

[Dave Meers]

Converting the required rotating forces (angular forces ) to revolutions per hour times the tire cercumferance( say of a 21" wheel) this should result in a required speed of 350-400MPH. THAT SHOULD DO IT. I don't think my KLR WILL GO QUITE THAT FAST. -----Original Message----- From: Devon [mailto:bigfatgreenbike@...] Sent: Monday, September 13, 2004 1:25 PM To: dave@... Cc: 'Chris Krok'; DSN_klr650@yahoogroups.com Subject: Re: [DSN_klr650] NKLR valve core leakage dave@... wrote:

>A little thought here should save you the work. Besides, I doubt there's a >centrifuge that can reach the speeds necessary to determine the failure >point of a working valve....... >

It's called a racebike wheel.

> The core to core >seal as you can see in the attached web page will tighten as centrifugal >force causes the moveable part to compress against the non-moveable part. >

No, it will force the "inner core" (the moveable part) outwards, and AWAY from its seat. That's the direction it moves in, as you push the core away from the hub to open the valve. Devon

> >

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[Zachariah Mully]

On Mon, 2004-09-13 at 13:29, Alan L Henderson wrote:

> Don't over look the fact that the air pressure in the tire also applies > force to hold the valve closed. > Alan Henderson A13 Iowa >

Yes, but the diameter of the valve is so small that only a fraction of 32psi is acting against the stem. -- Z DC A5X A12X

[denis@teachlinux.com]

There you go, killing off a good thread with logic.. Denis

On Mon, 13 Sep 2004, Alan L Henderson wrote: > > > > You bastards. Now I'm going to have to measure the force required to > > open the valve, weigh the guts of a core, and figure out exactly how > > fast you need to go to get centrifugal force to open it. > > > > Krokko > > > Don't over look the fact that the air pressure in the tire also applies > force to hold the valve closed. > Alan Henderson A13 Iowa > > > > > List sponsored by Dual Sport News at www.dualsportnews.com. List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html > Unsubscribe by sending a blank message to: > DSN_klr650-unsubscribe@yahoogroups.com . > > > Yahoo! Groups Links > > > > > >