I second what Tony had to say, about making sure they are high enough so
the risers clear the sides. I drilled first, without really measuring,
and now there's about 1/8" of clearance. Phwew! Just drilled the holes
like I would in wood, worked fine.

I put mine as far back as possible, just fore of the raised part on the
way back. I spaced them so that a basket would fit in between the bars.
Its not bad lifting with just the rack and basket, with a bike it gets a
little hard, with a bike and a spare tire its real hard.

Doug - the photo is the only one I had, no rack on but you can see the
mounts. Let me know if you need a better one.

Cheers,
 Jeff