Re: My name is Kenny and I am a MB addict
Welcome to the forum. Interesting build you have there. Does the wheel in front being smaller make much difference in how it handles? I ask because I'm fooling around with a 1980 AMF Roadmaster moped with 16" wheels, drum brakes and suspension fork. China girl fits fine, all is good except figuring out how to mount the driven sprocket in back. The drum hub is big, five inches in diameter and has no sprocket on the engine side since it was a friction drive setup when it was a moped. But looking at yours I can see that a 20" wheel would fit fight in there and I could do a rag joint with a smaller sprocket. So, I may try that. I'm looking for around 25 mph cruising with some hill climbing power... do you think a 36" sprocket would do it? Where do you find a 30T sprocket? And what kind of top end does that give you?
SB
I just noticed I said 18" front, it is actually a 16". I may change it to an 18", because this thing has almost no trail and its a bit scary at speed.
Not sure exactly what you are asking about the size. If you mean that the front is smaller than the back, i dont think this alone afects handling. Changing the sizes will change the rake and trail though, and this should be considered.
As for the gearing, circumference is proportional to diameter so it is easy to get a conversion factor.
ie
26/20=1.3 so
a 20" wheel with a 30 tooth sprocket will ride like a 26" with a 30x1.3=39 tooth sprocket
or
a 20" with a 36 tooth will ride like a 26" with a 36x1.3=46.8 tooth (I dont think a chain would like a 46.8 tooth sprocket but you get the idea)
I disected a mountain bike front sprocket to make my 30 tooth. At that time I did some gps speed testing, but I do not remember the #s. What I do remember is that I chickened out before the motor rapped out with the 30 tooth on a 27" road bike wheel.
Good luck and Happy Trails
Kenny