Re: [CR]Wheelbuilding Questions - valve stem holes

(Example: Framebuilders:Dario Pegoretti)

Date: Wed, 03 Dec 2008 19:44:20 -0800
From: "Steve Maas" <bikestuff@nonlintec.com>
To: classicrendezvous@bikelist.org
Subject: Re: [CR]Wheelbuilding Questions - valve stem holes
References: <8CB22D27AEDB6F8-1224-127D@webmail-de07.sysops.aol.com> <249DDD9704676C49AE6169AE3D2D9F4ECDB6EC@Exchange-SVR> <3.0.6.32.20081203115013.0173f198@mailhost.oxford.net>
In-Reply-To: <3.0.6.32.20081203115013.0173f198@mailhost.oxford.net>


Just a quick FYI: those rubber grommets you get for $1.50 at the bike store, for converting a schrader hole to presta, are just common 3/8" electrical grommets, which you can get for about two cents at any decent electronics parts store. ('Course, you might have to spend a couple bucks and buy a 250-year supply.) The bushings are a bit more special, but easy to make if you have access to a lathe.

If you do drill out a presta hole, be sure to deburr it carefully. In fact, in any new rim, check the valve hole to be sure it's smooth and not burred or sharp. These days, I see badly finished valve holes more often than not. I'm amazed people don't have more trouble with them.

Steve Maas Long Beach, California

John Betmanis wrote:
> At 10:27 AM 03/12/2008 -0600, John Hurley wrote:
>
>> One interesting thought
>> regarding valve stem holes was that you can always turn a Schrader rim
>> into a Presta rim by simply drilling a second hole. I'm not convinced,
>> however, that a Presta valve would mind using an oversized hole instead
>> of the usual 6mm.
>
> Wasn't the original question whether a Presta hole cam be drilled out fot a
> Schrader valve? Of course it can, if you're careful. Best done in a drill
> press. You don't want the drill to grab or end up with a 5-sided hole. My
> question would be, why would you want to use a Schrader valve tube? Most
> on-topic good quality vintage bikes used Presta valves. To this day,
> Schrader valves are only found on mountain bikes, children's bikes and
> department store bikes.
>
> As for using a Presta valve in a Schrader hole, I too doubt if it would be
> a problem in the real world, although it wouldn't look "right". There are
> bushings and grommets available to take up the gap. I certainly wouldn't
> drill a second hole. Personally, I'd make a couple of aluminum bushings
> with a thin flange on the inside of the rim. I don't usually use them, but
> a nut on the outside would hide any evidence of the bushing.
>
> John Betmanis
> Woodstock, Ontario
> Canada