20:1 Ratio is what it is set at now, but I can lower or raise it for even slower speed and more torque.
There are two belts and one chain with the twin jack shaft system.
Recently since I had to replace the rear wheel sheave pulley with a clone type Whizzer steel part. It is 15 inch diameter instead of my last home made washing machine pulley of aluminum that cracked but was smaller a 10 inch diameter. That meant to keep the same ratio, then the connection with the short chain between top and bottom jack shafts had to use different sprocket arrangement.
As it turns out, I only adjust the ratio with sprockets between top and bottom jack shafts. It is not a speedy process, but it works. I have to make different length chain for the sprockets, unless I just swap top sprocket with the bottom, this is not a common occurrence I would think.
I have sprockets with teeth in sizes 10, 18, & 28. Right now oddly enough when I got the 1/3 bigger rear sheave it did something funny.
I kept the overall ratio of 20:1 by removing the 28 tooth and replaced it with the 18 tooth. Now 18 tooth connect to another 18 tooth sprocket and provide a neutral 1:1 ratio that when multiplied by the other two belts ratios brought it back to the same 20:1.
The performance would be best if the belt would not slip. As tight as I can make them safely and have the torque pull up the hills I do. I even got the AX belt that works best with small diameter pulleys for the rear wheel pulley to bottom jack shaft pulley. I however cannot get a AX belt that will fit my clutch to first driven pulley on the top jack shaft. My back idler pulley to set the tension is working its best with an A belt. As much slack as I can take up, a 1 inch AX belt is either too tight or too loose.
I though it strange that the same manufacturer Gates would not have the same exact outside length belt to go from v-belt A section to AX section. If 1/2 inch increments were available and there was not some minimum order of like $100 I might try getting the first reduction belt to grab better on the centrifugal clutch to fist driven pulley using an AX v-belt.
I am going to see what I did with an old mini bike clutch that I freed the rust from the shoes and the bell and them have two chains and 1 belt system. I switched long ago the connection between the jack shafts from belt to chain as a 1.7 inch diameter pulley is no place for 3hp and my bike weighing 110 lbs with me added to it going up hills with a short run up.
There is a point I found with underpowered engine for this sport, that being too much torque and less speed does not help hill climbing. Run up speed and the mass moving is also an asset. If I do find the clutch with the chain drive and switch it, I may go for lower ratio maybe and see what happens.
My GPS told me top speed 19 mph (over reving) on a dirt fire road and trail average speed 7 mph where it is not real steep or too windy or bumpy. 12 mph with this ratio is probably the 3500 rpm max for the engine. A short while at near 5000 rpm was probably what had it doing 19 mph.
The gravel size of oranges and a few rock mixed in the size of grapefruit have me with my feet off of the pegs and steadying at a crawl. The tires I'm sure don't like it either. I find trails that are smoother. The muddy ones and creek crossings surprisingly I can do enough to get a rive out of.
Belts when wet and rim V-brakes you have to know don't like being wet. They dry off, but it is best to take it slow after a rain and see where the puddles are.
When I cross through a stream I apply the brakes and dry them.
You do want to not have to be going so fast on a trail you are not familiar with.
If you go through a stream and have to get a lot of speed for momentum to get up a hill just after crossing the stream, this could be bad. Imagine a blind curve at the top and a drop off with a major delay of braking!
All the protective gear will not help in all cases.
MT