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Advisability of reaming a valve hole



 
 
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  #1  
Old September 30th 03, 02:46 AM
Werehatrack
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Default Advisability of reaming a valve hole

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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  #2  
Old September 30th 03, 02:55 AM
S. Anderson
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Default Advisability of reaming a valve hole

"Werehatrack" wrote in message
...
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...


  #3  
Old September 30th 03, 03:40 AM
E & V Willson
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Default Advisability of reaming a valve hole

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

Thanks,
Ernie

"S. Anderson" wrote:

"Werehatrack" wrote in message
...
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...


  #4  
Old September 30th 03, 03:55 AM
Werehatrack
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Default Advisability of reaming a valve hole

On Mon, 29 Sep 2003 22:40:54 -0400, E & V Willson
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...em_id=CU-87685

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

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  #5  
Old September 30th 03, 04:43 AM
S. Anderson
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Default Advisability of reaming a valve hole

"Werehatrack" wrote in message
...
On Mon, 29 Sep 2003 22:40:54 -0400, E & V Willson
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...im%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..


  #6  
Old September 30th 03, 11:22 AM
Pete Geurds
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Default Advisability of reaming a valve hole

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
  #7  
Old September 30th 03, 12:43 PM
Werehatrack
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Default Advisability of reaming a valve hole

On Mon, 29 Sep 2003 23:43:36 -0400, "S. Anderson"
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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  #8  
Old September 30th 03, 02:53 PM
mark
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Default Advisability of reaming a valve hole

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


  #9  
Old September 30th 03, 07:22 PM
Carl Fogel
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Default Advisability of reaming a valve hole

Werehatrack wrote in message . ..

(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.

  #10  
Old September 30th 03, 07:56 PM
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Default Advisability of reaming a valve hole

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

 




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