On my Randonee, the seat will not tighten up and it rocks back and forth. I took the seat and seatpost off my old trek and have been using it. How much of the seat post should be in the frame? I have been using an old Avocet Touring 1 model seat, and its comfortable to me. It is basically a piece of leather that covers what I assume is a piece of plastic. so no padding. I am looking at a brooks saddle, but just dont know if popping down some serious money would be worth it.

Seat posts come in many sizes sounds like your post doesn't fit your seat tube? Or is it the seat rocking in the clamp? Often the max extentionis marked on a post. A good interface is 3 times the diameter.

I like my B17. Pick it up off Nashbar for low bucks when they go on sale. Worth whatever they cost. Another option might be the velo orange seat if it is in stock.

According to Saint Sheldon you should have about a hand width of seat post exposed from the frame. "About" being the opperative but if you have 1" of seat post or 12" of seat post showing then you might have a look at your frame size. This is based on conventional frame geometry and not frames with slanting top tubes. As far as your seat rocking, take your bike to someone with the proper measuring tools to measure the inside diamiter of your seat tube, OD of your seat post and aslo the seat rails and clamps to determin whish one needs to be changed out to get the proper fit.

I am taking it by REI tomorrow and going to have them take care of the issue.