Converting Presta hole in rim to Schrader - drilling

[Roopak Suri]

Here's the deal..
I got a nice Rocky Mountain bike from UK. Pics here
http://picasaweb.google.com/roopak.suri/MyNewBike
I'm very pissed with the Presta valve - have broken two valves so far
in a week of riding - after filling the air with a small giyo piston
(taking all precautions i can possibly take), as soon as i take out
the piston, sometimes the inner valve (small piece at top) breaks and
comes out with the piston - thereby destroying the tube as well.

I wanted to get tubes with Schrader valve - since i can't keep on
wasting the tubes and get stuck with broken valves in middle of road
-
However my bike has Alexrim DP17 rims with holes small only for Presta
- so i'll have to get the hole bigger by drilling.

My question is - is it safe for the rim? Will it affect the rim's
strength. The hole only has to be marginally made bigger to
accommodate schrader valve to pass through.
Please suggest.

[rushi]

Do it. Just make sure you drill straight through and not at an angle.
Use a good quality drill bit, I don't quite remember anymore, but
certain alloys need certain type of metal drills. There are look-up
tables for that. Also use a file to round off the edges after.

Or just change the pump; lock nuts shouldn't rip like that. Although
the whole stem will rip at the base, if you're brutal with the hand
pump.

Or don't open up the lock nut *all* the way if that's what you've been
doing.

On Mar 14, 8:17 pm, Roopak Suri <roopak.s...@gmail.com> wrote:
> Here's the deal..

> I got a nice Rocky Mountain bike from UK. Pics herehttp://picasaweb.google.com/roopak.suri/MyNewBike

[Rajat Agrawal]

If its only a marginal increase in the hole circumference then instead of drilling it might be wiser to use a small circular file (diamond encrusted depending on the rim material)

However, I am guessing your warranty on the wheels will become void. Better give the other options a try first before going postal on the rim :)

-Rajat

[Vasu]

Are you very sure you are not doing anything wrong/out of the way while filling air?? Also, are you sure your pump is ok? does it have a tendency to bite the valve?? I guess you should think of filling/drilling ONLY after you have made sure you are not doing anything out of the way. Doesnt hurt to have a review/re-check.

Thanks,

~vasu

--
Tour of Nilgiris
http://www.tourofnilgiris.com

[Roopak Suri]

What do you mean 'do not open the lock nut all the way'!
Aren't we supposed to do that? Is there a partial setting?
I'm pretty sure i'm filling air through the portable pump the wrong
way...This problem doesn't come when i'm filling thru the big giyo
pump (probably coz its not as hard on the valve as the portable pump).
Generally while filling the air, i place the bike on the ground and
with tyre flat on ground and push the air with pump vertically - and i
make sure that the pump is not bending the valve...
But this lock nut thing appears to be prob i guess - what if i change
the inner black/green thing in the pump with my bigger giyo pump and
see if it happens again....

[Rohan Kini]

Dont do it .. there is a reason why you have prestas on your bike ...
Presta valves require smaller holes in the rims and hence it allows manufacturers to have thinner rims and hence make the bike lighter. You would compromise the strength of the rim by drilling a bigger hole, plus there is a good chance you will screw it up. However easy it looks, drilling machines require practice.

Solve the actual problem.

Get the rim tape - that should solve the puncture problem - hence you wont have to fill in air with the giro mini pump on rides. The bigger pumps wont give you the issue

even if you have to - follow Rishis suggestion. Open the lock nut a little so that air can be forced in. If you open it too much it can get bent and break !

you can also try and get an presta - schrader adapter and use that on top of the presta valve !

anything but drill a hole in that rim.

~ ROhan
@ http://blog.bumsonthesaddle.com
awesome cycling group: http://bangalorebikersclub.com

[srini]

hey
i think its because ur holding the pump wrong while filling air....
if ur holding the cylinder in one hand n pumping with the other...
then ur wrong... thts when the valve twists to an angle n snaps!!!
wht u need to do is hold the pump at the nozzle firmly with ur middle
n ring finger & hold the spokes on either sides of the valve with ur
index n little finger making sure tht the pump is firmly in place,only
then start pumping!!!
drilling the hole needs precision... like rushi said u need to use the
right bit n file off the edges... it might also void ur warranty like
rajat said...
ppl have been using Presta for ages now...
its jus tht u need to DO IT RIGHT!!!

ridesafe
-srini

[Roopak Suri]

Thanks for the expert advice.
I was holding the nozzle and spokes with one hand while pumping the
air. I think i'm opening the locknut all the way which might be
bending the valve.
@Rohan - the liners are on their way - will take 3-4 days.
Cheers
Roopak

[rushi]

> anything but drill a hole in that rim.

Chicken!
:P

BTW Rohan, when is the Savanadurga road ride happening?

[Rohan Kini]

puck .. puck .. puck .. pukaaak  .. :) heh ..
Dude .. I have drilled .. I have steady hands .. the hole, well lets just say it was not perfect ;) I would hate to see a oblong hole on my rim

Road ride - shhhhhhh ... we need to raise some shackles here .. lets announce it soon ;)
wannna do the honors ? does the coming Sunday look good ?

[sriram.bmsce]

i think rohan here has hit the NAIL rite inside the HOLE..;-)

actual problem is frequent punctures..use a rim liner inside,punctures stop..only use the big pump then onwards..we roadbikers only have prestas and dont face problems of breaking valves when we use the big pump..yep i have broken valves when i used the small pump...