Originally Posted by
megalowmatt
I have the Topeak and use it only on my mountain bike for carrying light stuff in the bag. My experience has been that under five pounds or so they are fine. Over that and the thing tends to swing a bit. Some will say they have had no issues with those racks at all. I may be too picky but it never seemed to be lined up with the rear tire in a straight line. I know it sounds crazy but it just bugged me.
Another thing to mention is that even though it h as a "quick release" lever, it has to be cinched down so hard that it hurts my hands just to get it on and off.
Yep, exactly my thoughts and experience. On top of that, it takes away some adjustment from your seat if you need your post down low. Another bad thing is the ease of getting it stolen.
OP you mention it is for your racing bike. Is the reason for the post rack is because of mounting issue? Or perhaps to be able to remove it for weekend ride without the rack? If it is not, then avoid wasting your money on the seat post rack.