PDA

View Full Version : Presta and Schrader valves


Alan
04-07-2011, 07:18 PM
So I've had a few flat tires recently. I'm to add a needle to my seat bag so I can pick out deep shards of glass/rock.

I do have a question for some of you inner-tube changing pros. I sometimes struggle with holding the valve stem out away from the rim as i'm trying to get a good "bite" on the valve stem with my frame pump. I know needle nose pliers will do the job. Do you guys have any tricks to hold that stem firm without using a tool? I was trying to push sideways on the stem so It would grip the side housing of the hole and hold in place while I pushed the air pump housing onto it.

A few thoughts from a slightly seasoned amateur...

Presta valves have a threaded lockring to hold them to the rim, keeping them from pushing in, making it easier to apply the pump.

Presta valves don't have a spring closure like Schraders, so you don't have to push the pump down so hard against the valve.

Schrader-to-Presta rim adapters are about a buck. You'd also need either a Presta pump or a Presta-to-Schrader valve adapter, another buck. So for under $10 (adapters+tube) you could try out a Presta tube on your Schrader rim.

Both my floor pump and my mini-pump have gizmos that clamp onto the valve stem. I sorta figured all pumps had those...different thingies on different pumps. Maybe not all, huh?

Even with the clamp, sometimes I hold the valve stem and pump base with one hand while I get enough pressure into the tire to hold the valve solid enough that the clamp doesn't slip off. It's a bit awkward but it works.

CO2 cartridge inflators leave one hand free to hold the valve.

(Quote added from dmc's post (http://bikeportland.org/forum/showpost.php?p=26127&postcount=738) in the Daily Commute Thread (http://bikeportland.org/forum/showthread.php?t=1490). No objection if K'Tesh were to move these posts into a new thread in Tips & Advice.)

K'Tesh
04-07-2011, 08:41 PM
(No objection if K'Tesh were to move these posts into a new thread in Tips & Advice.)

Done...

And visual aids from http://www.sheldonbrown.com...

The valves:

http://www.sheldonbrown.com/images/valveprc.gif http://www.sheldonbrown.com/images/valvepro.gif http://www.sheldonbrown.com/images/valvesch.gif (http://www.sheldonbrown.com/brandt/presta-schrader.html)
The Presta Valve (closed and opened), and the Schrader valve.

The Adapter:

http://www.sheldonbrown.com/images/valvepra.gif (http://www.sheldonbrown.com/brandt/presta-schrader.html)

whiney
04-08-2011, 05:07 AM
Continental's schrader tubes come with the threaded lock collar:

http://www.biketiresdirect.com/product/continental-tour-mtb-26-tube

http://www.biketiresdirect.com/productimages/images450/cot262-2.jpg

biciclero
04-08-2011, 12:08 PM
The last few presta tubes I've bought have all been threadless (no locking collar to keep them from sliding into the rim-hole). The only saving grace is that the stems are longer than Schraders, so they hit the inside of the tire before disappearing below the rim. Unless you have deep rims. The other saving grace is that smooth stems are easier to push a pump onto.

If you want threaded valve stems, be sure to check before you buy.