Hello, Brads bike here ,

[Brads bike]

I`m expecting my Grubee gt5a 66cc motor kit tomorrow, its going on my old Ritchie mountain bike , I`m 250 lbs, I live in the mountains and the only real commute is 15 klks into town on the hwy, otherwise its errends and some trail riding. Any suggestions on sprocket size, I`m thinking a 48 tooth from what I`ve read, anyone deal with this issue yet, thanks?

 

[Venice Motor Bikes]

48 is a good place to start... Install it & see if you like it.
if not?, switch up to a bigger sprocket.

Also keep in mind that these little 2-stroke engines will work best when you keep the RPMs high! (Don't try to just casually cruise up a big hill). & pedaling to help the engine will also give you extra HP!

 

[Sidewinder Jerry]

What is the drive system on your mountian bike 3x7, 3x8 etc

 

[Brads bike]

What is the drive system on your mountian bike 3x7, 3x8 etc

 

[Brads bike]

Its an old 87 Ritchie, bought it new ,mountained biked for 20 some yrs ,moved to a house on a main hwy not found of hwy travel, we set it up for trailer pulling , old 3x 6 setup

 

[Sidewinder Jerry]

Here's how a 3x6 gets shifted.

1(1-4), 2(2-5), 3(4-6) for 11 sequential non redundant gear ratio ratios. Starting gears are 1(1) for starts going up hill and 2(2) for all other stops. If a gear is to easy or to hard to comfortably maintain a cadence (crank rpm) of 70-90 it means you're in the wrong gear.

By understanding how to use your bicycle gears in the correct way; it'll best serve you to be in the most efficient gear ratio to pedal assist up hills.