OK so now that everyone has X's and Y's confusing them
I need to review my college physics books one of these days
care to add more specific info as to the effects of a flatter or more curved profile as well as a heal/toe weight bias in actual application. ie the meat and potatoes of the above explanation, heal weight does this, toe weight does that kind of a thing.
I'll take a little stab at this. Please note there are many ways to get to the same end with clutching. As well your riding style comes into play. This is what I have found to work for me lately. However, it seems I'm always tuning and learning. Remember....baby steps.
Oh, and I especially want to thank AKsnowrider and Winter Brew for helping me out over the years.
I assume you are referring to something like the Heavy Hitter weights from Thunder Products or the MTX from SLP. The heavier weight in the pivot area will allow more belt squeeze at lower RPM. This has been said. What does this do really? It allows you to use the full gear ratio provided by your sheave faces. Standard (Polaris type)weights slip quite a bit at low rpm and actually require more rpm to positively engage the belt. So what most people do is go to a very steep initial angle on their secondary. Why? So the primary can shift through the secondary very quickly. This allows the clutch to move to a higher gear where it is less likely to slip and you are now into a ratio and rpm the clutch weight can perform at more efficiently. With a heavy pivot weight you have positive force on the belt so it can engage and pull smoothly at lower rpm as well pull less angle of helix. This gives you a nice low crawling gear without trenching.
Adjustable weights tend to also have a center hole and tip hole. As also stated earlier the tip hole will have the greatest effect on overall rpm. Now here comes a BUT. For most mountain applications we tend to like a very aggressive up shift. So if the heavier pivot weight already has things moving. Lets just add some to the center to control our up shift characteristics. Please note that I'm not taking into account weight angle. Now if you need more top speed you tend to move more weight to the tip. If you are running a few RPM shy you can take weight out of the tip.
I was on the phone with Lon from Thunder products today (Heavy Hitters)
He gave me a bit of a, OK a huge refresher course
. Now something I've always known, but sorta forgot is that the secondary isn't a clutch at all. It is a torque converter. It senses torque being applied to it from the primary during acceleration and from the track during deceleration. That may help a bit for some of you.
I hope I got all that right