Originally Posted by
Mendel
I am trying to make my racing bike work for all my riding without going to two bikes - something I can't fit into the budget right now. My commute is 16.5 miles each way, all on roads. The seatpost rack is attractive because I can take it off for group rides which I like to do when I can. (These can go up to ~60miles.)
In that case, then yes. Use a post rack. Just be a little careful if your seat post is carbon. After the rack is tight to the post, you may have to tighten your seat post to the bike frame tighter than usual to keep the rack from twisting your seat. It happen often when I swing my leg over the rack and hitting the rack in the process. You most likely will need to use some sticky tape wrap around the post to keep the rack from turning. I usually apply one or two layer of electrical friction tape.
In your list, I like the Topeak rack. They come with several offset height on the clamp which is nice. Also the majority of bag selection is nice.
I also have another bag that has the mounting hardware tighten around the post like a screw clamp. The bag then clip on that mount making it removeable and yet sturdy where it won't twist. Don't have the model off the top of my head at the moment, but it was bought at REI.
Edit: It is a
Detours Hightail Seat Post Bag.