Sailorman

I'm talking 700C 25s here and tired of the hassle of the Presta valve stems. I'm sure there are good reasons why these stems predominate the 700c market but WHAT ARE THEY?

jim-bob

What's the hassle?

AndrewP

Prestas have a simple non-return valve in them that is closed by the pressure of the air in the tire. It doesnt open till the pressure in the pump is greater than in the tire. This reduces the leakage of air when you remove the pump from the valve. I also think they are easier to pump to high pressure, but this is only my feeling and I dont know if this is really true. The Schraders are closed by a spring which is opened by a bump in the middle of the pump head - this means the valve is opened for air to leak out as you attach the pump and also as you remove it.

cycletourist

I have used and like both. Prestas take longer to bleed down and the lock-nut prevents the valve stem from slipping.

For long distance riding I prefer Schraeder because I can air them up at any gas station. A well prepared bicycler always carries a pump but pumps can get broken or lost so it is reassuring to know I can get air at a gas station if I need to.

madpogue 

You can get the best of both worlds by running prestas, which you can indeed pump more easily to higher pressure (one problem with Schraders is that, since the valve is open the whole time you're pumping, it's harder to keep the pump tight on the valve). For long rides, carry a Schrader-to-presta adapter in case of a situation where your only choice is to fill from a gas station.

1oldRoadie

And where do you buy 700C 25 Schraeder's?

jhota

presta valves are lighter than schrader also, if i remember correctly.

also, on a narrow 700c rim, it can be very difficult to mount a clincher tire with a schrader tube (since the stem is like twice as thick)...

Sailorman

OK guys, you have convinced me - I'll stick with the prestas!!

shokhead

I think its all crap.

trekkie820

I use the presta to schrader adapter, and it rides with me everywhere, just in case.

steveknight

I put a little locktite on the knob in the open posision and put on the presta adaptor. this way I can use my compresor or service station to air it up. or take off the adaptor to use co2 to pump the tire. you need locktite in this case because the knob tends to get screwed down.

randya

May be BS, but something I heard once: skinny rims are weakened by the big hole required for the Shraeder valve - the smaller hole required for a Presta valve maintains more rim strength...

shokhead

Never seen rim failure because of value hole.

DieselDan

Not BS. Think about it. A smaller hole is less damage to the rim that supports your bike. The spokes do most of the work, but a smaller hole makes a more strucually sound item.

Also, Scharder valves have a srping in them that can jam open. The jam is easy to fix, but can sometimes be irresverable, making you replace the valve core.

cerewa

Not 4 days ago, i saw a guy ask a mechanic whether he should try to salvage an old road bike rim or toss it out and switch the hub and spokes over to a new rim, and the mechanic looked at the rim and pointed out that it was deformed right next to the schrader valve hole. That rim might have been ok, but i wouldn't take the risk of putting it on MY bike.

shokhead

You do what?

siggy_lxvi

I think he keeps the presta-to-schrader adaptor on the stems full-time, so he loctites the presta's open so that when he has to use a gas-station pump, he doesn't have to worry about the presta valve being screwed closed.

RacerX

A schrader valve is too fat for a typical road rim. If you were to drill a hole that big, it would go into the sides.
Also the bigger the hole, the weaker the rim is at that point. If you don't think it's true, go ahead and drill a nice big hole in your road rims and tell us how your ride goes.

CRUM

I have, and more than once. But to be fair, it has been a long time. The rims of today are way stronger out of the box than the rims from even 10 years ago. Hence, the ability to market rims with less than a sane number of spokes. Just yesterday on a road ride, a guy riding the spiffy Shimano Wheel set hit a big pot hole at 35+MPH and his wheels came through just fine. I was impressed.

I think the biggest reason for presta is tradition and they do take air faster. Just my opinion though.

deliriou5

Wow... you've really replaced the valve before!!?? I would think it much easier to replace the whole tube...

sch

Delirious: schraders have an inner core which can be unscrewed and replaced by
using those caps that have a ~2.5mm cylinder on the end that is notched. I had
a German presta with a somewhat similar construction but most are not designed to
be repaired. A not unusual failure mechanism with a presta is for the whole valve to
tear out of the tube. Steve

Phatman

nashbar...and I think walmart.

deliriou5

wow... did not know that. another bit of useless (to me at least) trivia to add to my collection

Avalanche325

I will get usefull really quick when it happens on your car! Come to think of it, it hasn't happened to me in about 20 years. OK usless trivia.

bandaidman

does everyone use those little locknuts on presta s???

i never have...seems to be no problem....is there a reason i should?