Join Date: Feb 2003
Location: Fort Wayne, Indiana
Bikes: 84 Trek 660 Suntour Superbe; 87 Giant Rincon Shimano XT; 07 Mercian Vincitore Campy Veloce
If your speaking of the older treaded quill stem type of stem, you could mount a light to one of those. You would have to use some cut strips of tube to act as a spacer, then mount the light which would mount sideways but still face forward, thus the light would still reach the road.
If you have a Problem is with threadless stems is that the stem is too wide to accept a light bracket. What you could do then is to mount the light onto a fork blade if you don't have room on the handlebar. I don't know what kind of light your getting, but I had a friend mount 2 lights-one to each fork blade; this worked very effectively for his purposes, and it was quite noticable at night.