Ok, traces tangle, it happens and we have to deal with it.
First-off, lets look at why traces tangle:
- Turbulent water washes everything around
- The current makes the bait spin
- Bait spins when casting (helicopter effect)
The most general solution is to use thicker line, use a shorter sinker line or to streamline your bait, so that it "swims" through the water instead of spinning.
Check your swivels after every cast to make sure there is no binding or weeds stuck on them.
These solutions work, but sometimes we want to use thinner diameters, so let's have a look at the dynamics of a sliding trace in the current.
When your bait starts spinning, it not only spins on its own axis, but also has a toy plane effect as such:

When this happens, it can cause the bait to spin onto your sinker line, or in some cases even onto your main line. The following examples are some ideas to keep your hook snoot and sinker line as far apart to prevent this effect.

Here we have a current running straight in away from the angler. By casting straight in, the the current pulls the bait in line with the sinker. If it spins, it will probably wind onto your sinker line:

By casting slightly to the side, your sinker line will hopefully stay a bit to one side (right in this case) while the current pulls your bait straight in and away from your sinker trace:


With a current running parallel to shore, you should try to cast as straight as possible. In such a case, your sinker will be anchored straight in while the current pulls your bait to the side:

If your sinker gets washed down-current, the same thing will happen as in the first example - the bait will be washed in-line with the sinker trace and a tangle will probably occur:

This is just some general observations and is not going to completely prevent tangles. As I said, if you cast into the wash or your bait spins in the air, there is little you can do, apart from the first two ideas as also discussed here:
http://www.ultimateangling.co.za/index.php?topic=12914.0Now, for the bead:


See how the one without have the two swivels folding in on each other? With the bead, your swivel's eye goes over the top of the bead and it ends up sticking almost 90 degrees sideways, giving you that little bit of leeway to prevent tangles.
There you, hope it helps.