Q:

How do I tie a sleeping bag to my backpack?

I recently upgraded to a modern backpack and I'm stumped as to how to tie accessories down to it.  My previous backpack had tie-down points on the bottom of the pack that I could attach long straps to, which allowed me to tie down my sleeping back, tent, and a small sleeping pad.
My new pack lacks these generic tie-down anchors, and instead has two (smallish) straps on the bottom.  They're perhaps large enough for my tent, but certainly not large enough for my sleeping bag.
There's a waterproof "top lid" that can bind down, it's not impossible to stuff the sleeping bag between the pack and the top lid and cinch it down, but this is sort of awkward and top-heavy.
What's the proper strategy here?  Any tips for attaching my sleeping bag and tent to my pack?
Edit:  I'm not totally opposed to putting my tent and sleeping bag in the pack, especially for short and light trips, but on a multi-week outing, I may end up with the lion's share of the gear and food to haul, depending on the company.  If there's a clever way to have stuff outside my pack, it would be nice to have the option.

A:

Looking at the picture of your new pack, those 'smallish straps' appear to be compression straps to pull in your backpack once you've packed to stop the weight inside from shifting. I'd say they're definitely not for packing external gear.
I would avoid hanging anything below my bag - it alters the weight balance, and can strain your back.
After one particularly sodden hike in the north of England along time ago, I learnt that you really don't want to carry anything that absorbs water outside of your backpack - sleeping bags, especially.
All of my overnight hiking packs have had a bottom compartment, in which I stored my sleeping bag and warm change of clothes (both wrapped up in 'rubble sacks' for extra waterproofing). Tent canvas would be packed inside the main compartment, right at the top, for quick access - tent poles were strapped to the side of the bag.

A:

If your sleeping bag, or its compression bag, doesn't have straps around the outside, you'll need at least four pieces of twine to strap your bag down. Two to loop around the sleeping bag, and two more to link the loops on your bag to the loops on your backpack.
Make sure the pieces intended for linking the sleeping bag to the backpack are tied down by the pieces looping the sleeping bag.
It gets trickier if you want your bag and your tent to hang off those straps. The bag and the tent will have to be either lashed together or containerized, first. But then the same idea applies.

A:

This gets into the realm of "personal preference" but I would suggest only tie those things on the outside of your pack that you don't want at the end of the day.
Anything on the outside will tend to get chewed up by brush, be-thorned by cactus, ground into rocks and dirt every time you set your pack down, get soaked when you slip on that stream crossing, and... yes... fall off.
Your sleeping bag is a great item to pack FIRST inside the back to provide some padding in that lower lumbar region which will be rubbing against your body.

