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: will this rack fit properly on an elliptical seat post?
Document: i love the rack, but hate the fat mounting plate. this does not fit properly on a bike seat post. you can try all you want to put rubber or gasket material between the seat post and mount, but no mater how tight you make it, it still crimps and wiggles free. i feel like this rack could carry anything i could fit on it... if i could just securely mount it to the post. if anyone could get me a perfect fitting spacer for this i would easily give it 5 stars.
I got this because it looked easy to instal, in contrast to lots of other racks which required bending of the metal to fit my bike (according to the reviewers). It is easy to instal, but just isn't stable enough. There is minimal up and down movement if the bolt is tightened enough, but I cannot eliminate the lateral movements. The clamp itself is stationary on the seat post, but there is too much flex in the arm. Any amount of side to side movement on the bike (for example when putting in extra effort going up hills, or moving off from stationary) is exaggerated by the rack, sapping your energy.
While great for potholes, cobblestones, curbs and posteriors; having one precludes any ability to mount a more classic style bike rack with supports attaching to the real wheel hub.These single-post units by Ibera solve the problem perfectly by mounting only to the seat post frame (or to the seat post downtube itself).Originally I purchased the IB-RA6, as it was somewhat less expensive and since I had bikes of two different sizes to mount racks on, I wanted to see fit/finish on the smaller bike first.
It only took one tool and a few minutes to get the rack installed. It does come with some rubber pieces to put between the rack mount and your seat post so that it doesn't scratch or mar the seat post. I figured the rubber would also act as a bit of a non-slip type of material, so I used the thin one.Installation is really easy, and the way it's designed would allow for the rack to fit a variety of seat post sizes.Once I got it installed, I realized it was crooked...so I took it off and adjusted it.
This rack came with two sizes of rubber shims for the inside of the rack clamp which easily fastens on with an screw that tightens with an allen wrench, to fit a variety of seat post sizes. His larger diameter MB seat post required using the thinner rubber shim. I moved his under seat reflector to the end of the rack, which has space to accommodate a rear light, as well.I liked the idea of being able to buy the commuter bag that fits it, tho we likely won't. I watched a YouTube demo/review of the bag and rack in use, to check it out.
Do you have a bicycle standard hex wrench? Bully for you. you can get the clasp open. Do you ride a clowncycle with a  2 foot clearance on the comically high seat post? Then you should be good. Pedal on in your floppy shoes, honking your clown horn, storing whatever weird things clowns store in your commuter bag. I don't want to know. Clowns creep me out.. If you however ride a normal bike...and have purchased the ibera commuter bag that clips on, it will not fit under your seat in the default position this rack ships in.Hey why not just loosen that bolt and slide it out, you already got that alan wrench at the ready?
Nice rack. Relatively easy to mount and dismount. Light and sturdy. Looks good. Several spacer to make sure rack fits snugly to the seat post.
If you are looking for a rear bike rack that does not require attachment to the axle then this one is for you. It is well made, light weight, easily attached to the seat post, sturdy and works perfectly with the same brand bag that is connected by just a one-click attachment.
Anyway, the rack installs very easily with a swing arm type clamp system and a hex bolt. It also comes with rubber shims to go around the seat post to help if you need it. If you get it tight enough it does not swing from side to side. Solid construction and light.
This proved to be a good move as while the IB-RA6 was a perfect fit on my Wife's 24" Mongoose, it proved to be just a bit small on the larger frame of my 26" model. For those that have bikes in the 26-28" size range the additional frame length and adjustable rack placement of this model (IB-RA1) will likely make for a more pleasant install experience and justifies the higher expense.Mounting the unit on my bicycle proved to be a slight challenge as clamping the rack to the Bike's Seat Downtube didn't provide enough clearance between the rack's horizontal rack tube and the travel of the independently-suspended rear-wheel.
Answer: yes