Approximately one year ago I herniated a disk in my spine. It's been a long roller coaster, but I am finally starting to be able to do normal-people-things beyond sitting and laying down. Now that I feel like my back is more or less stable and isn't going to change preference any time soon, I decided it is time to get a "real" chair to work in - as I spend almost my entire work day sitting in front of a computer.
I have heard many great things about Herman Miller Aeron Chairs, as well as their Mirra Chair, so I had to try them out. I thought about getting one via Craigslist, as it is pretty easy to get 50% or mroe off the sticker price, but I came to the conclusion that was not the right solution for me. I didn't want to try out one of these chairs for the first time in someone's house, sitting in it for 30 minutes to make sure I like it, while trying to make awkward small talk with the seller as they eagerly wait for me to give them money and leave. Also, these chairs come with a 12 year manufacturer warranty, and I figure it is worth paying more for that - that's a REAL warranty.
I set off to the local Design Within Reach store to try them out. It took two trips for me to decide weather I wanted one, and which one to get. Here are my initial impressions in the store:
The Mirra Chair really looks cool to me, based purely on color. It also feels pretty good too. I find the lumbar adjustments on it to be superior to the Aeron's, but I only tried the Aeron's optional "Lumbar", not the "PostureFit". That said, the chair does have its flaws.
First of all the hard-plastic back, and the mesh seat, feel terrible if you are wearing anything that has a wrinkle, a fold, a seam, or in the case of my girlfriend - a bra strap. It pushes these things into you because it is a hard flat surface. I began to wonder if I would constantly be trying to pull out the slack in my sweatshirt so it wouldn't create annoying wrinkle bends pressing into my back.
Secondly, when you lean forward and hit the end of the range of travel, it really just stops with a clank. I need to reach onto my desk to play with circuits and this and that, and I would find this very annoying. I think there is an option for forward tilt that this floor model didn't have - not sure here.
That said, the backrest does have some benefits. As I mentioned before, the lumbar adjustment is nice, but I found myself constantly adjusting it. That may or may not be a problem. Also, I found it kind of nice to bounce back and forth in the chair (with my shoulders, more or less). However, it put me in a very upright position when sitting still, and I like to always be leaned back a medium amount on my shoulders. Being too upright will usually cause me to hunch forward. This might be possible to adjust out, I am not sure.
It is definitely worth trying. With some adjustment it could be right for you. I personally didn't rule it out until I pulled it up to a desk with a keyboard and started typing, at which point the high sitting angle just didn't feel right and that kind of led me to the Aeron.
The Aeron Chair is the old classic, instantly recognizable, everyone drools over chair. I am not one for cliche, so I had my doubts. I will say that it is a very good chair. The most interesting thing about it is how it moves back and forth when you lean your weight around. You can unlock the front and rear tilt, and it feels like you are riding almost like on one of those kid's rocking horses that are suspended on 4 trampoline. The seat platform and back rest both move in a fluid motion.
When I first sat in it, it was horribly rigid. As I said before, I like to lean back. I way 140 ish pounds, so I really had to loosen up the back rest - and on this chair it takes approximately 20 turns to really get a lot of progress on that. But once I did, the position and tension of the chair felt GOOD.
The one reason I don't like it is the lumbar support only feels good to me when it is pushed all the way to the lowest location. You can slide it to several places up and down, and you can flip it over to get two different "depth" settings. Generally speaking I found that if I move it out of the lowest position it feels like I am leaning against a baseball. This has me very weary. I might try out a "Posturefit" instead of the older "Lumbar" support. Generally speaking I think the lumbar adjustment is junky. However that one position I did find - all the way down - feels pretty good and supportive. I hope I will always be fine with that setting.
The seat pan is very similar to the Mirra Chair in construction. This one also has a little bit of that "hard" feeling, where you can feel every seam of your underwear. I am a particularly bony guy, so it might be different for you. The back rest, though, is a lot better in terms of softness.
Last, I found the position of the adjustable arm-rests on the Aeron to be superior. I like to have my elbows in. I twist the armrest to be pointing inward at my knees as far as possible, and rests my elbow areas on the armrests while typing. The Mirra wasn't bad, but the Aeron definitely felt better for my personal tastes.
Everybody is different, so I recommend you actually try the chairs out. Sit in them for 30 minutes. Be sure to really play with the adjustments - these chairs feel terrible if they aren't adjusted to you.
Both chairs are good. It took a lot of time for me to decide - two trips to the store, over an hour long each.
If I had to tell you which to buy and you couldn't try first, I would go with the Aeron. There seems to be a lot of resounding agreement that it is a good chair. I myself agree.
I purchased the Aeron, and I am waiting for it in the mail. I will probably make a followup to this after I have sat in it for a few days, but that will just be on the Aeron - which you can read about anywhere. I really wanted to write something focusing on the differences between the two chairs, and this is as far as I can go.