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Goodbye Presta Valves, and good riddance.

NickD on Thu June 14, 2012 11:06 PM User is offline

With three tires to constantly inflate on my recumbent, finally found Schwalbe Scharder valve inner tubes with the threaded valve stem.







Existing hole size was 6.5 mm, reamed that out to 7.5 mm. Some claim this causes weakness, what removing just a 20 mil radius? Would be far more concerned about hitting pot hole.

This is a photo of a Presta valve stem with two conventional Scharders.



Presta is on the left, thread diameter is 4.5 mm, the two Scharders are on the right with 5 mm thread diameter, okay, 20 mils larger, but the threads on the Scharder are far more robust, also the valve stem seal on the Scharders is far superior to that of this Presta, no wonder why these Presta leak down so quick requiring you to pump up your tires each day.

Some claim air pressure is what closes the Presta valve, but the cup size that holes the valve seal between the two different types are identical! Only difference is a stiff spring holds the valve closed in the Scharder whereas a nut that constantly comes loose hold the valve shut on the Presta. If you try and tighten that nut with a tad too much force, will break that very thin brass rod that goes down to that cupped seal.

Other claim its easier to use a hand pump with the Prestas, since I have a portable bike pump, portable air compressor, and a shop air compressor, all the chucks have valve depressors. Have no idea what they are talking about. The only application I could find for Prestas is on higher end bikes, so why don't we find these on R-12 systems if they are so good, or aircraft tires? Some also claim Prestas can withstand higher pressures. My 27 X 1.25 bike tires pump up to 105 psi, on the trike these Prestas came on are only good to 70 psi.

Is a metal flange on at the bottom of both the Presta and Scharder valve stems, larger than the hole I reamed out on the Presta flange. So still can use them if I ever decide to go back or buy or make a bushing for the slightly larger Scharder hole.

But for now, goodbye Prestas, been a constant PITA for me. Let you know how the Scharders hold air pressure, can't be any worse than the Prestas, but if they are just as bad, least I can refill them in seconds instead of hours.


Edited: Thu June 14, 2012 at 11:08 PM by NickD

TRB on Fri June 15, 2012 12:21 AM User is offlineView users profile

If it works for you run with it. I lose maybe 5 psi a tire over a 2 week period running tubeless and presta valve.

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NickD on Fri June 15, 2012 6:24 AM User is offline

Did commit a high end bikers sin with this modification, Schwalbe Scharder valve tubes have roughly the double thickness of their Presta tubes. I didn't look at tubeless tires, but perhaps a bit fugal since my trike has 170 bucks worth of tires and tubes on it. Want them to last, so did add around 200 grams of weight to my trike. That is really a major sin in the bikers world.

But my function is to reduce my own body weight by biking, since this spring, lost five pounds of winter fat, with another five pound to go yet.

Wouldn't bother if I was only losing 2.5 psi per week, more like 10-15 psi per day. Tried Schwalbe and Kenda tubes, Kenda's were a bit better as the valve stem is not removable. Whenever I tried loosening that nut on the Schwalbe, the entire valve stem would come out. Maybe using the wrong brands. Which brands are you using?

NickD on Mon June 25, 2012 12:58 PM User is offline

June 14 through June25, same Schwalbe tubes, but Scharder instead of Presta, just checked the tires today, didn't lose a single pound. Maybe I got bad Presta's, but in all three wheels?

TRB on Mon June 25, 2012 3:03 PM User is offlineView users profile

Where you closing the presta valve after filling it with air? They have heavy dude tubes in Presta also. One type or the other is not a big deal, except on some high end rims.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

NickD on Mon June 25, 2012 5:38 PM User is offline

Not to the point of breaking that tiny brass stud that I did once, but to the point where I can feel tension. Call it snug, or more appropriately, snug plus a tad.

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