how often do you commute with only one pannier attached to your rear rack. The reason I ask is I am considering the Arkel briefcase so I can carry my laptop when necessary.

I have two bags but rarely need both....just a pain in the butt to take them on and off so I leave them both on.

I mostly use the one, an Arkel Utility Basket. Occasionally I'd use a Nashbar Townie Basket to the other side, I ended up zip-tying the Townie on and keeping it folded all the time as a "just in case" solution.

I'm using the waterproof Axiom rear panniers right now cause our crazy weather mean I never know how much clothing to pack, Light raingear heavy raingear windbreaker vs. Waterproof breathable. When we get into our drier season (soon I hope) I will switch to the Nashbar day trekker panniers. I hate to leave without being sure to have what I deem is enough stuff. I"m a packrat so there ya go.

I only use two when I can't fit everything in one. And that usually means I just use one.

I choose other because I have a topeak bag. It has two built in but I rarely ever have both dropped. So I guess that it is only one. I will tell you that on the occasions that I have used to two it has been from work carrying stuff home and not at the house in the morning. I am glad that I have had the built in so that even when I do leave the house with only one side dropped I am technically always carrying two.

Generally, one is all I need, but I am strongly considering putting a Wald folding basket on the other side for those times I might need to carry an extra miscellaneous item or trips to the farmers' market.

1 bag most of the time. 2 if I expect to stop for groceries.

I always have two even though I could get away with one. Extra storage space comes in handy if I need to stop at the store on the way home.

This is what I have (though my folding basket is not made by Wald). If I remember to take clothes ahead of time, I don't usually need the basket. Otherwise I usually end up using both.

I ride with two panniers but only because I carry that much stuff back and forth the work. Previously I rode with only one bag when my commute was shorter, I had no shower, and I could leave stuff where my bike was stored. Now I have to go to a shower building next to my office building, and we're not strictly allowed to leave anything there so I have to carry in every morning and carry a full-sized towel.

Strictly speaking I only need one pannier for my work items; however, I have a handlebar bag that I use for carrying my jacket home on the days when I need it in the morning but not the afternoon, and for change of gloves warm vs cool. In the summer, I actually need more space, for trousers & shoes to change into since I wear shorts & road shoes in the warm weather vs. regular trousers & mtb shoes in the cooler weather. So I just got a pair of small (intended as front) panniers, one of which I will use for the needed extra space.
And of course I always have my trunk bag for tire repair items, lights, and a lock.

Thanks for all the replies but now I have another question for those of you using only 1 bag, does it make the bike feel off balance with only 1 bag loaded.

I used to commute several years with just one pannier. I wasn't bothered by the balance issue, I could only feel it if I topped the pannier up with heavy groceries on my way home. Groceries and errands were the reason I moved into using two panniers. Most of the time I could fit everything in just one, but the extra space came in handy often enough.

Currently I have a Carradice saddle bag. I can fit my commuting stuff in there, with room for a couple of items from the grocery store. I now do majority of my grocery shopping during weekends.

--J

Not a big deal unless the weight is huge. We automatically correct for an out-of-balance load by slightly angling the bike beneath us. The degree of angle depends on the weight, the height of the load, and its lateral distance from the central plane of the bike. I've found that a dramatically asymmetrical load makes it a bit harder to ride hands-free.

You could rig a simulation of the computer's weight to one side of your bike to investigate.

No. Don't worry. Ride.

I used to run with on pannier. It doesn't affect balance at all. Now I carry more and use two. If I'm carrying extra, or need to go to the store, I'll put two more panniers on my front rack for a total of four. I've only done this a few times while commuting.

I run with only one pannier, it is all I need. I have two, and sometimes I am tempted, but I have yet to absolutely need both. I have been strongly considering installing a folding basket on the other side.

It never affects my balance. It does make it a little harder to guide or carry the bike when I am not in the saddle.

One if by land. Two if by sea (rainy days when I need to take the laptop)

Me too. Carradice saddlebag is usually all I need; I'll attach one pannier if I need to carry more.

This is my big problem. I use one of those TransIt garment bag panniers (it looks just like a mini-garment bag, and drapes over the rack.) I kind of like the pockets for organizing and such, but it's heavy (when loaded with my clothes, lunch, shower materials, and the usual bike-emergency stuff, it's about 13 pounds), it's not waterproof, and attaching the bungee hooks is a minor pain in the neck. It also somewhat obscures my rear taillight. I have a very nice set of Ortlieb panniers, each of which is *much* lighter than the garment bag, attaches and de-taches with zero effort, and is waterproof. (I think the "big bag" approach might bug me for commuting, though.)

I only need one pannier to hold my commuting stuff, but I've tried it, just tooling around the neighborhood, and I hated the way the bike felt. Maybe I just need to give it more of a chance and I'd get used to it. Or maybe I'd end up with a giant left quad and a puny right quad.

I'm cycling to work. Not going on a tour. So one bag is enough for me.
I store my dress shoes at my office and lately been experimenting with bringing in office clothes ahead of time. Who knows, I may end up being like of of them roadies that ride in with full race gear without a rear rack! Ha!

One bag doesn't create any load issue for me.

I almost never use the 2nd Pannier. All my work clothes fit in one just fine. If i have to include my boots, it's right at the limit, but it still fits.

I commute always with only one pannier. However saying I only need one is not completely true. I am still saving up for the second one...
I believe I can feel it a little bit if I really load it up and ride free-handed.