Hi Jared,
In order for the ratios to be changed via the belt, the pulleys must be able to work with them. A lot of pulleys will only work with one belt style.
You are correct that both pulleys change ratios with different belts and if they are the same size the ratio would always stay the same. As an example if both pulleys were 2" and different style belts are used the ratio will always stay the same 1 X 1. If the pulleys are different in size then the ratios can be altered via belt design.
Belt engineering is in fact a real art and many don't understand the basic concept. It appears we are never too old to learn, and many of the original ideas were based on faulty concepts. Belts in fact don't ride in the pulleys as we originally thought, belt design varies widely, and belt companies take a liberal approach to the interchange guides. Some belts from different companies can vary as much as 1" in length, and as much as 1/8" in width. It is for this reason that EZM will have belts made in the near future so that we can control the size, price, & quality.
Our research & testing has taken us to a new level concerning "V" belts, power transfer rates, belt design, belt ratios, belt pitch angles, belt material, and most importantly durability.
The Q-Matic was designed to incorporate the latest inovations and with the help of the major belt, pulley, and clutch companies, we can supply the most up to date drive system available.
Although we can alter the ratios with a vast array of belts we narrowed the options to only 3 because of design & quality. The primary ratios can be ordered in 2.62 X 1, 2.76 X 1, and 2.935 X 1, and can easily be changed if needed.
I will site a few examples of the final ratios, the 2.62 X 1 primary and 56 tooth rear sprocket will lead to a final ratio of 14.68 X 1 or 40 MPH @ 7600 RPMs, the primary ratio of 2.76 X 1 translates into 15.48 X 1 and 38 MPH @ 7600 RPMs, and the primary ratio of 2.935 X 1 ends up with 16.43 X 1 and top speed of 36 MPH @ 7600 RPMs. As can be noted, each ratio change effects the top end by approx. 2 MPH. In addition the rear sprocket can also be changed to add even more ratio options. For instance if the rear sprocket had 60 teeth and the primary ratio of 2.935 X 1 were employed the final would be 17.61 X 1 [33 MPH @ 7600 RPMs] and should allow the bike to climb the side of a building, LOL. Bill in AZ is using a 72 tooth rear and primary ratio of 2.62 X 1 for a final of 18.8 X 1 [31 MPH @ 7600 RPMs] and easily pulls hills with a trailer [with 2 grandchildren]and still maintains great gas mileage.
Hope this helps answer your questions, if not please ask again.
Have fun,
