Det virker ikke helt klart fra sram sine sider, men her er fra mtbr:
"The standard Motion Control is available with both an internal and external Floodgate, and the basic damper works the same between the two. However, there are two real difference which affect performance:
1. The BB Motion Control damper has what Rock Shox calls a speed stack, which is a shim in serial with the low speed and high speed compression circuits. It's debatable whether this is a good thing or bad thing, and a lot of people are removing and reporting their fork is plusher with less high speed spiking.
2. The BB Motion Control damper has a shimmed rebound damper, which Rock Shox calls Dual Flow Rebound, opposed to the standard Motion Control's port orifice damper. This is a definite performance advantage as it keeps the fork from packing down over fast, successive hits."
og:
"Here's why it's better. In short, the damping in your forks works by moving oil through a piston. In an orifice damper, there are simply small holes in the piston for the oil to flow through. Since the holes aren't that big relative to the size of the piston, oil can only flow through them so quickly. Thus the motion of the fork is damped. A shimmed damper works on the same principle, but goes about it in a little more sophisticated way. Instead of just having some small holes in the piston, the holes are larger, but are covered by a stack of thin steel discs (shims). When the piston tries to move through the oil, the shims flex and partially uncover the holes, allowing some oil to flow through. The faster you try to push the piston through the oil, the more the shims will flex, and the more oil will flow through.
This is better because it allows the damper to better handle a range of shaft speeds. Think of it like a door that you're trying to control traffic through. You don't want people to run through, but you don't want them waiting to be able to go through either. If the door is of fixed size, you'll run into one of two problems. If the door is big, if not so many people want to go through, they'll have room to run, and will be inclined to do so. If the door is smaller, and a lot of people want to get through, a traffic jam will ensue. This is like an orifice damper. It'll work fine under some circumstances, but will have a hard time being just right for big and small impacts. If you have a door that you can control the size of, you can set it so that there isn't enough room for people to run, but there's enough room for them to get through quickly. This is like a shimmed damper. In the case of rebound, this lets it return quickly from big hits, and not pack down, while not feeling bouncy and underdamped over small bumps.
As for how much better the Blackbox MoCo really is, I haven't ridden two otherwise comparable forks back to back, so I can't really say."
http://forums.mtbr.com/showthread.php?t=505837http://forums.mtbr.com/showthread.php?t=596566http://forums.mtbr.com/showthread.php?t=136225http://forums.mtbr.com/showthread.php?t=538905http://forums.mtbr.com/showthread.php?t=521898
