The pocket sling. No hand slings here. Rather than the riders locking hands to exchange into the race, the relief rider keeps both hands on the bars and drops down like normal. The rider in the race, meanwhile, draws up along side their partner, puts his left hand on the tops, but now pushes his partner in the lower back to get make the switch. A mere push is only the most rudimentary form, though. A true pocket sling requires, as its name alludes to, a pocket. And the shorts you wear are no normal riding shorts. They're made with a more static material around the waist, which comes a bit higher than normal, have padding around the hips (apparently predicting the worst) and a tall, narrow pocket sewn on the inside of the short, running vertically along the left hip.
The specialization doesn't end there, though. You also have what's called a "jamming tool." In my rather improvised case, it's a rolled up paper town, wrapped in duct tape until it's about 6 inches long, and 1.25 inches in diameter. This goes into the aforementioned pocket, and give your partner something to grab onto when throwing you in. At this point, it's clear to see that the pocket sling is considerably more than just a push. You grab this lump attached to your partner's hip, and thanks to the more static material, hurl them for all you're worth.
Here's the back view of the shorts. That wad on the left is my jamming tool. Garnett wasn't quite satisfied, so he may make one more to his specifications, seeing as it matters more for him than I. The white line shows where the inside pocket is, so that your partner knows what to aim for in the race.
After one night of practice, I'm still not entirely sold on the pocket sling, but am starting to see it's virtues. The relief rider never comes behind their partner, making the new wheel easier to follow for the other racers. It's also a lot simpler, technically speaking, to pull off than a hand sling. At slow speeds, and pocket sling can be as simple and just putting your hand on the back of your partner, matching their speed to that of the pack, and then slowing down yourself. When things aren't on the rivet, it's much more natural than a hand sling.
I still have my reservations, though. Namely, I don't like dropping into the race and getting thrown in with no control of how hard the throw is. If the line stacks up in front of you, you had better hope your partner notices and holds back, rather than hurling you into the wheel ahead of you. Maybe I'm a control freak, but I like being able to attenuate my throw if traffic is getting iffy up the track. The other thing I don't like as much is that you can't come in with as great of a speed differential when you're on relief. You need to pretty much match the speed on your own by virtue of the banking, and your partner can just provide and extra boost from there. All in all, it means you need to spend more energy on the act of entering the race, which no one really likes, especially when they're already in the box.
I still have some hand sling habits to get over by race time, like finishing my throw downtrack to put my partner into the lane. Garnett explained this to me (with remarkable composure) after I threw him in, pushing him downtrack to the point where our bars collided. We rode out of it just fine, but without that arm extending backwards, you don't have as much space. Lesson learned. I hope the learning curve isn't that steep when racing starts tomorrow night.