Originally Posted by
AdamDZ
I'd try mount it to the seatpost with a clamp or to the seatpost collar. It may result in the rack tilting forward a bit, but that's not a huge deal.
Something like
this might help:
I second AdamDZ's suggestion - it's what I use on one of my bikes:
Due to the geometry of your frame your seatpost clamp is lower in relation to the rack than mine is, but since those attachment struts are already bent, flipping them over should line them up with the clamp.