Recently I was left with a presta tube for a schrader rim. I decided to have a go with the nut on the inside of the rim to protect the tube from the extra space there.

I know I can get a little adapter to put in the hole for this exact reason and I plan on getting some today. At the time it was either what I did or nothing.

I just wonder if anyone else has ever done that. How bad is it? Should I change it right away when I get home with the adapter tonight, or will it be fine as is?

Interesting question. As long as you only have a nut on the inside and not on the outside too I think it might be ok. The nut will protect the rubber around the base of the stem from the edge of the wider hole. Just an opinion but I think it might be fine. In the name of science leave it that way and carry an extra tube and the adapter and see if you get a flat from it.

Good enough! In the name of science I will leave it and see how it holds up!

I will report back here - but this is on one of my bikes that doesn't get a lot of riding time.....

~20 miles this weekend and all is well.