However, since this is a drilled hole (probably slightly smaller than the Schrader / Dunlop hole should be according to spec.) I'm thinking that such grommet may cause more harm than good.
To be honest, this is what I've done so far. I simply put a Presta tube inside the drilled rim and screwed the (one!) Presta nut pretty tight.
What's the long time expectancy on this approach, would you guys think?
I could need some confidence here!
It probably depends more on how well the hole was drilled than what kind of grommet you use in there.
I've been running presta valves in Schrader holes for 5 years on my commute bike - no grommets, no stem nuts, zero problems.
