John Betmanis replied: <Wasn't the original question whether a Presta hole cam be drilled out fot a Schrader valve?>
Sorry to throw you a curve ball. This comes of having part of the conversation off-list. Yes, the original question was about converting a Presta rim to a Schrader. Someone wrote off-list that once you did this, you couldn't go back. Someone else wrote off-list that they had in the past converted a number of rims from Schrader to Presta by drilling a new hole. These were both just side-comments, without any mutual awareness by the writers, but my nimble mind immediately connected the two viewpoints, and I thought it worth sharing.
Several folks, myself among them, wondered why anyone would want to use a Schrader valve. The background story is that a potential ebay buyer asked me for a Schrader rim, and so I wondered why not just enlarge the hole from 6mm to 8mm. I did not bother myself too much with why he wanted Schrader, but since that question has been raised, I would say there were plenty of on-topic bikes of lesser stature sold in the USA in the bike-boom days of the 70's that were Schrader-equipped, and maybe that's just the look he wanted. And I suppose the reason so many bike tires in the USA had Schrader valves was because that was and is the standard for auto tires, and there was plenty of free compressed air available at every corner gas station. I could see how a person might want Schrader for his commuter bike.
Austin, Texas, USA