Touring - knapsacks as panniers

It is "Back to School" time AND I am considering buying panniers.

As I passed by a wall of kids school backpacks at the store, I wondered, "Why can't you just add a clip to the insid of these to snap to the carrier and then use two knapsacks for panniers?"

Am I missing something? The geometry seems to be OK. ie won't interfere with my feet when pedaling.

If you did this, you could have two removable backpacks complete for probably around $15.00 total and these are pretty good looking packs.

Has anybody tried this? Any suggestions?

I thought about it. Many backpacks stick farther out in back then panniers and, if not full, could flop back into the wheels. I have this problem with the Nashbar MTB bags I got and I need a stretch cord around the bags to prevent accidents.

I thought about it. Many backpacks stick farther out in back then panniers and, if not full, could flop back into the wheels. I have this problem with the Nashbar MTB bags I got and I need a stretch cord around the bags to prevent accidents.

I heard that panniers need to have some kind of rigid backing to prevent them from floating into the spokes. I had intended to use some kind of foam insert.

How do you use the stretch cord?

You must use a support frame for the backpack. It's actually very simple to make one cheaply. Just use 1/2" PVC plumbing pipe. First thing to do is purchase the backpack you plan on using. Carefully measure the pack and fabricate a frame from plumbing pipe to fit it. Strap the backpack to the pipe frame using plastic zip ties and add small hooks or carabiners to the pipe frame for attaching it to your bicycles rack. I found one backpack provided plenty of room. If your going to use two for huge amounts of storage just make a double frame that would drop over the rack with pipes that would cross over the top of the rack. Here are pictures.
http://i143.photobucket.com/albums/r154/n4zou/touring.jpg

http://i143.photobucket.com/albums/r154/n4zou/rearview.jpg

There are a few problems with using backpacks as panniers.

1) Backpacks are not designed to be strapped to a bike rack.
2) A stray strap that goes into the wheel could cause, how shall we say, minor issues. ;) Hopefully very minor, but if the strap gets tangled it could cause a crash.
3) All the panniers I've used so far have a stiff plate (usually plastic) that faces the wheel. A backpack of that design would be very uncomfortable; and as others mentioned, a pannier without it could hit the spokes.
4) Neither backpacks nor panniers are such rare and/or outlandishly expensive commodities that too many people feel compelled to combine their functions.

Although at least one company has figured out a way to actually combine said functions:

http://www.rei.com/product/47849023.htm

By the way, I'd have rather limited trust in an $8 backpack on a bike.

How about these?

http://www.arkel-od.com/panniers/backpack/overview.asp?fl=1&site=

2) A stray strap that goes into the wheel could cause, how shall we say, minor issues. ;) Hopefully very minor, but if the strap gets tangled it could cause a crash.
Just use a zip tie to hold the extra strap material to the backpack or frame.

3) All the panniers I've used so far have a stiff plate (usually plastic) that faces the wheel. A backpack of that design would be very uncomfortable; and as others mentioned, a pannier without it could hit the spokes.
All backpacks have a semi-ridged back to prevent sweat from penetrating the bag. It's good enough on store bought backpacks to prevent the pack from protruding through the pipe frame and into the spokes.

4) Neither backpacks nor panniers are such rare and/or outlandishly expensive commodities that too many people feel compelled to combine their functions.
I'm fine using your standard X-mart cheap backpack as a pannier. I'm retired and have nothing better to do most days than get out and ride my bicycle. Consequently, I end up putting many hard miles on my bicycles. I purchased a pannier set which wore out in just a few months. Using standard cheap backpacks from X-mart stores allows me to replace them when required and there much cheaper and last longer than most bicycle panniers.

By the way, I'd have rather limited trust in an $8 backpack on a bike.
My current backpack was purchased for $5.98 and has over 1,000 heavily loaded miles with no problems encountered. I also use military surplus bags as well. Checkout the gas mask bags made into panniers as shown on a tour I made in the fall of 2006. they cost me $2 and I spent another $3 on buckles and straps for them.
http://i143.photobucket.com/albums/r154/n4zou/loaded.jpg

No reason why not. With some modifications two backpacks sized to fit your rack and bike would make a super pannier outfit.

I plan on searching for some backpacks after all the kids go back to school. One word...Sales. Another idea is to use the dry bags Wal Mart sells. Waterproof PVC bags with roll down tops.

Do you want to leave the shoulder straps? If so you need a way to cover them to keep from becoming entangled in the wheel. A thin piece of plastic sheet (or 1/8" plywood) stiffener to fit the back could be bolted onto the backpack at the 4 corners, covering the straps. You could install grommets or just burn thru the fabric with a hot nail. 1/4" stove bolts with fender washers on the fabric side and use washers and wing nuts on the plastic or vice versa. Attach hanging hooks (1/8 " aluminum strapping.) to this plastic. With the removal of the 4 bolts you're converted to a backpack again.

If you cut the backpack straps off you still need the plastic stiffener on the back. It's a dedicated pannier then.

n4zou,
Those bags are way cool.