Advisability of reaming a valve hole

[Werehatrack]

Okay, so I'm slowly crawling up out of the ooze of crappy second-hand obsolete bikes; this is
probably a no-brainer for some, but I'd rather ask before I jump either way, than make an assumption
and then later find out that I should have gone the other way, or that it didn't really matter...

I just picked up a wheel that has a Mavic X221 rim on it, which (obviously) has a Presta valve hole.
This is a pretty narrow rim, skinnier than any of the otehr mtb rims I have, and double-walled.
Since it's terra somewhat incognito, I'm a little dubious about reaming that hole out to take a
Schrader valve's stem. On the other hand, I'd prefer to have just one kind of tube in the stable if
possible, but it's not critically essential. Can anyone vouch for having done this wthout trouble?
Or should I just get the tube that fits (and a spare) and be done with it?

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[S. Anderson]

"Werehatrack" <[email protected]> wrote in message
news:[email protected]...
> Okay, so I'm slowly crawling up out of the ooze of crappy second-hand

<<snip..>>

> possible, but it's not critically essential. Can anyone vouch for having done this wthout trouble?
> Or should I just get the tube that fits (and a spare) and be done with it?
>

Drill away..done it countless times with no problems. I personally like presta tubes better and work
it the other way, but all my rims are drilled for schrader since you mostly see those more and you
never know when you'll have to borrow a spare!

Cheers,

Scott...

 

[E & V Willson]

How do you "work it the other way" and make the valve hole smaller? Is there an adapter ?

Thanks, Ernie

"S. Anderson" wrote:

> "Werehatrack" <[email protected]> wrote in message
> news:[email protected]...
> > Okay, so I'm slowly crawling up out of the ooze of crappy second-hand
>
> <<snip..>>
>
> > possible, but it's not critically essential. Can anyone vouch for having done this wthout
> > trouble? Or should I just get the tube that fits (and a spare) and be done with it?
> >
>
> Drill away..done it countless times with no problems. I personally like presta tubes better and
> work it the other way, but all my rims are drilled for schrader since you mostly see those more
> and you never know when you'll have to borrow a spare!
>
> Cheers,
>
> Scott...

 

[Werehatrack]

On Mon, 29 Sep 2003 22:40:54 -0400, E & V Willson <[email protected]> may have said:

>How do you "work it the other way" and make the valve hole smaller? Is there an adapter ?

Yup.

http://www.loosescrews.com/index.cgi?d=single&c=Tire/Tube&sc=Rim%20Grommet&tc=&item_id=CU-87685

Probably available at your lbs as well. (I've also seen them in brass once or twice.)

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[S. Anderson]

"Werehatrack" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 29 Sep 2003 22:40:54 -0400, E & V Willson <[email protected]> may have said:
>
> >How do you "work it the other way" and make the valve hole smaller? Is there an adapter ?
>
> Yup.
>
>
http://www.loosescrews.com/index.cgi?d=single&c=Tire/Tube&sc=Rim%20Grommet&t c=&item_id=CU-87685
>
> Probably available at your lbs as well. (I've also seen them in brass once or twice.)
>

I actually don't use the adapter. What I meant was I drill for Schrader on my MTB rims so that I
have the most common tube (for MTB) as an option in the event I need to borrow a spare. I run presta
on both the road and MTB bikes. The OP I think wants to run all Schrader and drill as such, I run
all presta but drill for Schrader so I have more options. I think the adapter is probably more
warranted on the road setup as opposed to MTB because of the higher pressures. I've never had a
problem with the MTB setup with presta in Schrader holes at my usual 50 psi or so. I've always left
my road rims as presta. Actually, the whole presta-only thing for me came about because I'm too much
of a lazy-ass to change the chuck in my pump every so often! How sad is that?!?!

Cheers,

Scott..

 

[Pete Geurds]

>Okay, so I'm slowly crawling up out of the ooze of crappy second-hand obsolete bikes..........
...............I'd prefer to have just one kind of tube in the stable if
>possible, but it's not critically essential.

Make the break now. You don't want to go on forever drilling rims right? As stated in previous posts
you can get the adapter to use Presta in shraeder holes so at least you can run presta tubes on the
same bike. (assuming new wheel going on a bike where the other wheel is drilled for shraeder valve)
I've used rubber grommets in lieu of proper adapters.

Pete Geurds Douglassville, PA

 

[Werehatrack]

On Mon, 29 Sep 2003 23:43:36 -0400, "S. Anderson" <[email protected]> may have said:

> Actually, the whole presta-only thing for me came about because I'm too much of a lazy-ass to
> change the chuck in my pump every so often! How sad is that?!?!

Makes perfect sense to me!

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[Mark]

Reaming out the valve hole to take a Schrader valve won't hurt anything, but don't leave any burrs
or sharp edges to give you flat tires...

Keep in mind that a Presta valve will hold air pressure better than a Schrader valve. As for
borrowing tubes when you get a flat, carry a patch kit and a tube or two, and ytou can be the one
helping people out.
--
mark

 

[Carl Fogel]

Werehatrack <[email protected]> wrote in message
news:<[email protected]>...
>>
>> (obviously) has a Presta valve hole. This is a pretty narrow rim, skinnier than any of the otehr
>> mtb rims I have, and double-walled. Since it's terra somewhat incognito, I'm a little dubious
>> about reaming that hole out to take a Schrader valve's stem. On the other hand, I'd prefer to
>> have just one kind of tube in the stable if possible, but it's not critically essential. Can
>> anyone vouch for having done this wthout trouble? Or should I just get the tube that fits (and a
>> spare) and be done with it?

A search for rim + drill + presta + "jobst brandt" will find this comment, which suggests that a
bigger hole in a narrow rim is a bad idea--the narrowness of the presta valve was one reason for its
use in bicycle rims. Further searching along the same lines will produce more extended comments.

from a posting by Jobst Brandt:
>
>I hope you realize that the hole for a Schrader valve is larger than one for a Presta valve stem
>and that the rim is a compression structure. As the hole you drill in the rim gets larger there is
>less cross section to support the spoke tension that puts the rim under about 1000 lbs compression.
>Spoke holes are large on the bed of the rim and small at the back side. The Schrader hole, on the
>average removes as much wall from the rim as a spoke hole, the Presta does not. The larger hole in
>the back side of the rim weakens it locally.

 

[Jobst Brandt]

Mark Felber writes:

> Reaming out the valve hole to take a Schrader valve won't hurt anything, but don't leave any burrs
> or sharp edges to give you flat tires...

Not so. For narrow rims, the stem hole is a major weak point and it alone limits tension of spokes,
tension defining the load carrying capacity of the wheel. Spoke tension put the rim in compression
and that is limited by the smallest cross section of the rim. That occurs at the stem hole.

> Keep in mind that a Presta valve will hold air pressure better than a Schrader valve. As for
> borrowing tubes when you get a flat, carry a patch kit and a tube or two, and ytou can be the one
> helping people out.

Both valve types are leak proof as far as bicycling goes. Presta valves seal as well as Schrader
valves. If there is any evidence that there is a difference I would like to see it. That light
weight tubes have Presta valves and that light weight tubes hold air more poorly than heavier ones
does not mean that their valves leak.

Jobst Brandt [email protected]

 

[Chalo]

"mark" <[email protected]> wrote:

> Keep in mind that a Presta valve will hold air pressure better than a Schrader valve.

How do you reckon this? If there were a difference in this regard, it seems very much like the
advantage would go to the valve with positive spring closing (that is, Schrader).

The seal is Buna-N against brass in either case.

Chalo Colina

 

[x]

RE/
> On the other hand, I'd prefer to have just one kind of tube in the stable if possible, but it's
> not critically essential. Can anyone vouch for having done this wthout trouble? Or should I just
> get the tube that fits (and a spare) and be done with it?

I'd switch to all Presta tubes. The convenience factor is high and for two bucks you can get a
little brass thingy that'll allow a Schraeder-only pump to fill the Presta tubes.

I've read a number of posts to the effect that Presta valve stems are happy in Schraeder holes - and
for the truly-careful, there are little rubber grommets that can be put in the hole.

-----------------------
PeteCresswell

 

[Werehatrack]

On Tue, 30 Sep 2003 23:06:25 GMT, "(Pete Cresswell)" <[email protected]> may have said:

>RE/
>> On the other hand, I'd prefer to have just one kind of tube in the stable if possible, but it's
>> not critically essential. Can anyone vouch for having done this wthout trouble? Or should I just
>> get the tube that fits (and a spare) and be done with it?
>
>I'd switch to all Presta tubes. The convenience factor is high and for two bucks you can get a
>little brass thingy that'll allow a Schraeder-only pump to fill the Presta tubes.
>
>I've read a number of posts to the effect that Presta valve stems are happy in Schraeder holes -
>and for the truly-careful, there are little rubber grommets that can be put in the hole.

I may go this way, slowly. I still have three spare tubes in stock for the mtb tires, but the
presta/schrader adapters are cheap by the dozen, and there's this presta-only hand pump I've had
sitting here doing nothing for quite a while...

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