Climbing multi pitch routes with bolted anchors? You might want to leave the cordelette and anchor slings at home. All you really need is the rope you’re attached to and two carabiners to connect to the anchor. (These knots are also perfect for fixing a rope for big wall climbs, and top rope soloing.)
Many more experienced climbers like this approach, because it's simple, clean, and requires less gear.
Because the leader is directly tied to the anchor, this generally works best of each partner is swinging leads every pitch. (If one person is doing all the leading, then typically climbers will swap the ends of the rope at every belay. The easiest way to do this is to connect to the rope with a figure 8 on a bight knot and two stout locking biners, rather than the standard rewoven figure 8 knot.)
Rescue geeks, I can hear you now: “But how are you going to escape the belay if you need to rescue your partner?” The answer is, yes, it’ll be a little more difficult, but you can do it. But, here’s a question to ponder - have you, or anyone you personally know, ever had to actually do this in real life? Climbers who use this method generally feel the simplicity, weight savings and lower cluster factor of tying in directly with the rope outweigh highly unlikely rescue scenarios.
Here’s two different knots you can use to tie directly to a two piece anchor.
1 - Bowline on a bight
This is my preferred technique. This is essentially a bowline knot with two loops rather than one. The knot is easy to learn, fast to tie, and easy to visually inspect to see if you did it right. You can adjust the size of each ear to equalize the anchor. John Long tried to popularize this in one of his rock anchor books about 15 years ago, but it never really seem to catch on. Too bad, it's a great knot. Maybe it was the cheesy name I think he gave it, the “atomic clip”. Just call it a bowline on a bight; that’s the common name and describes it perfectly.
Here’s a video showing how to tie a bowline on a bight.
2 - “Bunny ears” Figure 8 (aka Super 8)
This one is probably the top choice for most people, and a close second place for me. I find that I often get an extra twist in the knot when I'm tying it, and it looks a little wonky, so it's not my top pick. (I probably just need more practice.)
This knot has a cool feature of being able to slide the “ears” to two different lengths, to accommodate one bolt that may be a little higher than the other. This is actually sort of magical, you just need to play with it to see how it works.
Here’s a video showing how to tie a bunny ears figure 8, by expert climber Beth Rodden.