got out the speed chain this weekend and tried it for the first time. I also saw about a 6MPH gain in average club head speed after using it for only one training session. This was measured while hitting balls with my Swing Speed Radar.
I do have some thoughts as to why it helps so quickly with swing speed. I've used heavy clubs, swing fans, mops, etc. in the past, but the feeling of the chain is quite different. The heavy club gives resistance only in the direction of gravity which is not a significant component of the golf swing. The swing fans and mops give the most resistance when the device is in a vertical position and very little when the club is in the horizontal position (top of BS and 6/100's).
The speed chain gives a ton of resistance immediately as you start the down swing (unlike the fan/mop.) It also seems to be consistently pulling back against the direction in which you are swinging until well after impact. This seems to offer a couple of major benefits over other devices.
- You have to use core muscles to get the chain moving back towards the target. You cannot accomplish this using your arms ... they just aren't strong enough. This teaches you to use a body centric swing instead of an arm swing. I could feel my stomach muscles tighten as I tried to move the chain. Emulating this feeling in the real swing added some speed.
- It forces a stretch between upper and lower body as you begin the DS. Bertholy called this the master move. Again, emulating this in my real swing really added some speed. For the first time it gave me the feeling of properly starting the DS with the lower body while leaving the arms/hands back in place. I could then try for maximum separation in the DS in a real swing. The more I could make this happen, the faster I got ... and the straighter the resulting drive.
I also noticed a big drop in the std. deviation between my swing speeds after using the device. I started with about a 20MPH deviation which dropped to about a 10MPH deviation.