so as you may know i currently have a magnum project with mb5 swingarm, tomos a55 motor, mb5 rims and a bigport mk80 kit in the works. i had to have a custom sprocket made for the mb5 wheel and the smallest i could go was a 32. as you know tomos works with much smaller rear gears than that however tomos use 16 inch rims and i am using 18 inch rims so at least i have that going for me.
now the problem i am runnning in to is that (assume we are looking at the bike from behind) the rear gear is pretty far to the left even if i change the spacing and push the wheel to the right about an inch which is as far as it can safely go without brake arm issues. i was planning on using a 31tooth front sprocket as this would help give the bike more top speed. well as it turns out the 31 tooth only seems to be available in the "flat style" and not the "offset style" i would assume this is because on an a55 with a55 ignition you could not go up to a 31 without hitting the external pickup. i was planning on converting to a35 ignition to solve this.
I should also mention that the tomos motor is thinner at the mount than a puch motor. so i am also pushing the motor as far to the left as i can instead of evenly spacing it out. so after pushing the motor to the left and the wheel to the right, it still will not align with the rear gear. there is maybe an inch difference =(
with an offset sprocket it at least seems close enough to run but the only offset sprocket i have is a 26. that would be 26x32 gearing which would be too much torque.
so here is the math. stock tomos sprint 08 a55s come with 26 front and 28 rear which is kinda torqie for a tomos. 16 inch rims with 2.5 tires have a diameter of about 21 inches so
21 inches X 26t front sprocket = 546 / 28 rear sprocket = 19.5 GEAR INCHES
my setup is currently 26 front and 32 rear with 18 inch rims whoch give a final diameter of about 24 inches. so...
24 inches X 26t front sprocket = 624 / 32 rear sprocket = 19.5 GEAR INCHES
THAT MEANS AFTER ALL THAT FUCKING WORK AND MATH I AM STUCK AT STOCK GEARING!!!! ARGH!!!
you can understand why i am upset. i dont want a cannon that can only go 45mph. i need some creative options to either raise the front gear as i can not lower the rear.
So it is maybe possible to remove the rear sprocket studs and somehow (no clue) grind the rim down torwards the center evenly on all 3 spots that the sprocket mounts to effectively push the sprocket to the right which would allow me to run a 31 front. is there any way to do this safely? i assume even the slightest uneven surface will cause disaster for my chain.
The other option would be to somehow offset the flat front 31 tooth front sprocket? has anyone ever done this or thought about it? i havent even pulled a tomos front sprocket before so i am not sure exactly how they mount but i dont think this is something that can easily be done.
am i missing something? obviously i will go with the biggest rear tire i can but it wont make much of a difference.
damn thats alot of text.