Commuting backpack?
 

Does anyone have any recommendations for bike commuting backpacks? I'll need a decent amount of space (work clothes, shoes, shower stuff, flat kit)>
Thanks!

The Jansport Boost is a nicely sized backpack. It's larger than your everyday school backpack, but not as large as one of those hiking daypacks. I have one myself and it's pretty good for my purposes, though a bit large for me at times since I'm a little slender in build.

I can take a size comparison photo my school backpack and the boost if you'd like to see it.

If you have a place at work to stash shoes, a shower kit, towel, etc. that will work better in the end. By the same token I'd put the flat kit in a seat wedge or some other place on the bike itself in case you get a flat and aren't carrying the backpack.

You'll still a need a backpack, panniers or something but the less you have to carry IMHO, the better.

If you need something waterproof the Banjo Bros. Commuter Backpack is fairly inexpensive (for a waterproof backpack) and it comes in two sizes.

If your commute is not too long (under 8 miles each way or so) & you already have a decent backpack, I'd use that to start until you settle into what you will need to bring. I use a Mountain Hardwear Scrambler myself & it's just about perfect for me (A little bit large, but it works great if I have to stop & pick up groceries or anything on the way home). I second TJ's recommendation for leaving stuff at work. If there is any way you can, leaving stuff there will make your life way easier. Shoes especially, they are the hardest thing (at least for me) to pack. Aside from that, toiletries & a towel would be great to leave at work, along with a spare outfit (I leave socks, underwear, shirt & Pants).

I currently use a backpack, however I am moving towards another option. That said, use a backpack made Deuter and really enjoy it. The one I use is about 6 years old, but they are much like the ones I linked to.

as was already said, if you can stash some things at work once a week life will be a lot easier.

Backpacks are going to be like shoes and saddles- you're just going to have to do some experimenting until you find something that works for you. That being said, you might want to take a look at this if you're on a budget or this if you're not.

Just use a regular backpack and put your crap in it.

Use a wald basket strapped to a rear or front rack to secure it and you're good to go.

I like my North Face Surge backpack. Has great shoulder straps and a chest and waist strap. Good for holding it secure

Backpack
 

I've had a North Face Borealis and I really love it. I rarely carry clothes in it since I keep a stock of clothes at work. Shoes are the worst to carry. The Borealis has a sternum strap and hip belt and 3 compartments, 2 bottle compartments, and an elastic external mesh for tying on loose stuff. I use it every day and have had it for about 4 years. The stash pouch zipper went bad about 3 years ago, but NF repaired it for free in about 10 days.

What he said for both the seat wedge and stashing stuff at work.

When I do use a backpack (road bike), I've been using an REI Novara pack. Works well enough. Not waterproof, but has a rain cover for when it gets wet. I've had bigger problems from a coffee thermos leaking than rain getting in - but I don't leave things that need to stay dry in the outer zippered pocket unless they're inside a heavy duty ziplok. Main compartment stays dry (except for that thermons).

Arkel pannier(s). It's a lot more comfortable to have the weight on the bike than on your back.

Can't say enough about MissionWorkshop packs.