To arctos and mm718: My current setup has been the Viscacha tail bag with a custom frame bag similar in size to the tangle and the DIY harness I made to carry a multitude of drybags depending on the needed gear. I recently got a Cannondale CAADX that I plan on buying the large Tangle for. The Sweetroll is nice, but my DIY solution is versatile enough, I don't see a need to spend the dough. The bag has been one of my top 5 gear purchases of all time. The thing is amazing. On the smallest setting, I could fit my clothes, size 12 shoes and a few extras. I commuted like this all summer 25 miles each way.

For sure you will have less overall carrying capacity with this type of setup. It might take a bit of a shift in your personal "touring" philosophy. On this forum in particular, there seems to be a big, fat solid line between "self supported" and "credit card" touring. Mostly, it comes up with CC touring holding an extremely negative connotation because all the cool kids carry 7 days of supplies and take a day to go 30 miles up a mountain in 22/32 gearing (I am of course, exaggerating). In the bikepacking world, self supported basically means no follow car or having your wife/buddy fly out to part of the trail with some supplies to help you out. Mailing stuff to post offices in advance of the race, buying parts from shops along the way and food/lodging along the way is totally fair game. Most people camp where they can, though.

All that gibberish to simply say: You aren't going to be able to carry as much food and water with a rackless approach. And really, you don't need to. I personally see zero reason to have 5 days of food when I'm going to be maybe 100-200 miles max between well stocked towns full of food. I've done the several days of food on my back thing with backpacking, I don't need to ride past a grocery store with multiple days of food already hanging from my bike to prove anything to myself. Again, I'm exaggerating here.

However, there will occasionally be really long stretches where you might need to carry a bit more. For this, lots of folks, myself included, will carry a light drawstring style backpack. Sea to Summit also makes a really nice packable backpack that has more comfortable straps. These are good for quick resupplies in town where you don't have a lot of space left on the bike. As you eat the food over the next bit of miles, you repack the bike the next morning and usually can put the temporary backpack away for the next few days.

The biggest limitation for space/weight in any touring setup will be your sleep/shelter system. This is also, unfortunately, the most expensive part. It's easy to spend 500-1000 bucks just to get a properly light/small setup. But there are budget deals to be found.

In short: the bags are great, but certainly have their limitations. Again, I would recommend people check out bikepacking.net for more extensive info. It's certainly not for everybody, and to each their own. I ragged on fully loaded touring quite a bit earlier, but I certainly understand that some people enjoy it immensely for reasons that I would hate it. Different strokes, right?