Instruction: Given a question and its related document, determine if the question is answerable by analyzing the information in the document. Output yes if the document addresses the question, or no otherwise.

Input:
Question: Does this work with the sort of rack that attaches only to the seatpost?
Document: The basket itself is OK, sturdy and folds up easily.The hardware is not acceptable--the clamps are flimsy and as other reviewers mentioned, the screws are way too short.Also, please note that if your rack doesn't have a bracket that attaches to the back wheel this basket will not work for you.
This basket is exactly what I needed. They fold up easily, and are very sturdy. Installation can be a little tricky, depending how your rack is set up, but it's doable. I don't really understand how the bottom bracket attaches to the down arms of the rack, but a ziptie can hold it in place. It may not be universal for all racks, but once installed, it works great.
great baskets, the hardware didn't fit my bike so I had to sort out the bracket, but SO convenient to have folding baskets
Just installed this and I am happy with the quality of the basket itself. The mounting hardware did not work well with my rear rack(Trek) ,so I used3 mini hose clamps($3.00) and was up and running in no time.
These baskets are great. I used to have a crate mounted on my rack and these are lighter weight, better weight distribution, look nicer, and can be folded in when not needed. I commute to work and bring a purse, gym bag and lunch. It all fits!
I had to buy some hose clamps to make it works, and it feels and looks a bit kludgey. But it does work. (And to be fair, the product description does state that this rack fits "almost" any rear rack. It's just the kind of thing I would assume would be universal.)
Probably the only reason I won't give this product 5 stars is that the hardware included in the package just won't work with some bike frames. Some inexpensive cable clamps and/or nylon zip-ties will probably do the trick, though. Otherwise, I have no complaints - the rack is exactly what I expected and what I wanted.
Pros:Easy to install.Definitely worth the price.Make my daily commute very easy.No need to use a backpack to carry my books, lunch bag, etc. anymore.No more sweaty back.Cons:It will not work without a rear rack (I had to get one).Baskets are sold separately (nos as a set), so you will need to buy 2.
This also took some ingenuity to install, and quite a bit of time. The clips provided for attaching it to the bike rack were not quite the right size and I ended up bending and twisting them to make them work. I finally got them installed. They fold up neatly, and can carry more groceries than you would think! I REALLY love my baskets, and love that they came in a pair.
These baskets are great. (I bought 2) While I would've wanted them to be a little larger (I have a generously sized rear-rack on my crank-forward  Electra Amsterdam, meaning a lot of space for cargo), they work great but take some finaglign to install. Out of the box, the included clamps and brackets did not fit the oversize tubing on my Electra rear rack.
Answer: yes