So you have nice wheels drilled for schrader valves but you want to put in presta tubes. Maybe like me, you tried to put it into schrader hole and ruined 2 perfectly good tubes.

You cut out a small piece of aluminum or any hard material that will fit on the internal bottom of the rim. As thick as possible for safety.

You drill presta size hole into it and put it over the valve hole and some electrical tape over it to hold it in place.

I know it seems like a finicky way to do it, but it has worked for me for over a year.