Anyone have any suggestions on a cheap, fairly dense material that could be used to add weight to something like 30-80 lbs (increasing as I get used to it, naturally) to a backpack? I was thinking 10 lb bags of rice could work, and I could probably get 5-8 in a backpack, depending on size, but i'd have to be very careful in bagging it to make sure it doesn't rip and spill. Anyone have any other suggestions for something that would be fairly cheap?

Very curious here .... why??

Just use iron weights from walmart. They are far more compact than bags of rice. If thats too expensive, Basspro is running their Spring sale, get a few cheap anchors.

I looked at walmart's website, the cheapest they had was still like 20$ for a 20lb weight, not to mention Idoubt it would be very easy to pack very many into a bag without a ton of clanging around.

What is this for?

If you plan on putting the weight on while you ride a bike, I would suggest spending money and doing it right. The backpack will make you more hot and sweat more.

I would buy a iron belt (weight belt) and strap that to the bike.

Water isn't that bad... Cheap!

It's most likely not going to be worn while cycling. As far as water goes, i'm not sure that would be heavy enough, and if it is, I don't really have any old bottles sitting around I could fill up, what would I use?

Go to your local lawn and garden store ( Lowes/Home Depot) and get an 80# bag of pea gravel for ~$5.00.

Gravel! Of course, rocks! I think we have a winner, thanks.

play sand?

Sand and ziplocks gives customizable weight system. I usually wrap the bags in towels to keep the weights from shifting as well as evenly distributing the weight. If you start doing a lot of weight I would go to a second hand store and get a old down vest that is quilted. If you make a slit at the top of the quilts you can pull the down or fill out and add the baggies of sand, just tape up the holes. I did this to get into shape for a firefighters exam in which you had to wear a 50lbs vest while you completed the course.

Bagged beans are good too. Get a 50 lb sack and some Ziplock bags. I made a new friend on a Centruy ride. He had a complete set of full touring bags. When I complimented him he looked furtively around and admitted that they were stuffed with newpaper to make him look good.

B.B. shot heavier than sand.

That idea for a jacket isn't bad...there's a place that sells brand new winter coats around here for 8 bucks each, Could easily do that, plus if I need any help my grandmother was a seamstress, and my mother has done a lot of sewing hobbies (stuff animals, clothing, etc), so I could just ask them.

Sand would work well, I could easily make ziplocs full of sand to weigh down a backpack, and a coat... probably not at the same time, but still. BB Shot seems like it would be very expensive, at about 15$ per pound by a quick check, although I could be very far off.

I agree. I use 2 Liter bottles filled with water. Plus the more you ride the more you need to hidrate, and hey you already have the water with you. But make sure the bag can handle the weight. If you can find one, I would use a ruk sack from the military. They can handle alot of weight. I'm talking almost 120#.

Be sure your bike can handle the additional weight. You don't want to add 50 pounds to beef up your sprints or downhill skills and end up collapsing a wheel.

Water all the way

Water is kind of bulky at only 8 lbs per gallon.

Yeah, but you can drink it if you need to--it can be a self correcting load if you do drink it. Heavy going out, no so much coming back. Can't do that with dried beans, rocks, gravel, anchors, bb shot or iron weights.

And you can get bottles of all different sizes and shapes to mount/hang/carry all over your bike.

The "weight" thing is a stupid idea. Either reproduce the load you want to train for or don't.

The only way to simulate the load is to use items that will reproduce the same center of gravity and density as a real set of gear. Just carting around excessive dead weight is not likely to be of greater benefit.

Again, it's not going to be worn while riding.

All right ... what are you trying to accomplish? What is your goal?

Are you "training" for a backpacking adventure? Is this your way to do squats?

I'm just asking because you have to be so careful with you back ... carrying around extra weight in a backpack can lead to all sorts of back issues, which can lead to all sorts of pain. Ask any student.

I'd agree. Sand would work well. Easy to maintain and you can be as accurate with it as you want.

People replying to this post can be more helpful if you tell us what you have in mind with the weight.

Go to a dive shop and check out the diving weights 1,2,6 lbs each