New commuter

[BethG]

If I have to, I go with a pack over a messenger bag - just feels more secure to me. But as others have mentioned, it can affect your posture and cause back pain. I can also make you sweat like a pig. I commute into Boston, MA (5 miles each way), and even in cooler weather my day hike pack, which has ventilation channels built into the back panel, can soak my back.

You can find some pretty inexpensive bike panniers on ebay. Add them to a cheaper rack or other support, and it may just run you less than a decent commuter bag or backpack.

[rebeccaC]

For just a change of clothes, a ziplock bag of items to clean up with and a lunch a handlebar bag with a shoulder strap might work well.

[lph]

I commute with a backpack every day, but it's very small and most important, it's very narrow, so it sits nicely between my shoulders. It will not take a full change of clothes, but maybe it would take summer clothing minus shoes. (Maybe you can keep shoes at work?) I usually just carry lunch, keys and wallet, but I end up doing some grocery shopping on the way home and having a bulging pack for the final half mile :-) And yes, it gets hot.

Conversely I hate carrying anything but a very light load on my back, but I'm not too happy about panniers either. I'm fussy about bike handling :-) Panniers are probably great if you need the space, but you could try to get away with a small pack and judicious packing first. I will typically keep several changes of clothes at work and bring home one garment at a time to wash. They need washing very seldom since I shower as soon as I get there, and have a quiet office job.

[Msquared2]

I commute (33 mile round trip) with a backpack. Since I am changing clothes when I arrive at work anyway, I don't mind if my back gets a little sweaty. I have an Osprey Talon 22 and it's the prefect commuting backpack! It will fit everything I need (and then some!) I don't like riding with racks and stuff hanging off my bike, but lots of people prefer that.