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Old 12-24-2011, 02:19 PM
5-7HEAVEN 5-7HEAVEN is offline
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Join Date: Aug 2008
Posts: 1,912
Default Re: very new to this motorbike thing with a few questions

Originally Posted by bro-die View Post
It running right and I ride it almost everyday. I also ride at night. I just want a little bit more speed and conquer that hill because if I do ill make it my dialy ride to work. hehe save some money on gas.

With a shift kit, you will conquer most hills. This depends on your overall gear ratio.

With a 36-tooth rear sprocket, your ratio is 14.76:1. Not too good for climbing hills.

With SBP shift kit and the lowest gears possible, you might want to use all 8 speeds.

The engine has 4.1 built-in gear reduction and 10t gear. Connected to a 17t jackshaft (4.1 x 1.7 = 6.97:1).

The second jackshaft sprocket can be 9t or 10t. Connected to a 44t chainring sprocket, that gives you 37.173 or 33.456:1.

Using a 30t chainring sprocket and a 32t first gear on your cassette gives you 39.65:1 or 35.69:1. That's equivalent to a 97-tooth rear sprocket or a 87-tooth rear sprocket.

The lowest gear ratio I can calculate would be with (4.1 x 1.7) x (48/9) =
37.173:1. Then using SBP's smallest 24t chainring and the largest (most) available 11t/34t rear cassette, you'd get

37.173 x (34/24) = 52.66:1, which is equivalent to a 128t rear sprocket.

The 8th gear in this combo is 17:1, equivalent to a highway 42t gear.

With a 10t/48t chainring, it'd be 33.456 x (34/24) = 47.4:1, equivalent to a 116t rear sprocket.
The 8th gear in this combo would be 15.33:1, equivalent to a 37t rear sprocket.

A good all-around combination would be using a 30t bicycle chainring, that'd give you a 42.13:1, like a 103-toothed rear sprocket for first gear.
The 8th gear in this combo would be 13.63:1, equivalent to a 33t rear sprocket.

BTW, the first gear on my Tanaka engine/shift kit is 46.36:1, like a 113t rear sprocket.

My 8th gear is 15:1, equivalent to a 37tooth rear sprocket. Since my Tanaka 47R engine can pull higher rpms than a Happy Time engine, 15:1 in 8th gear is not an issue. In fact, in cruising speed, I am in 7th gear @ 17.73:1, like a 43t rear sprocket.

In first gear, my motorized bicycle climbs hills like a dirt bike.

Just food for thought at low end and high speed.

Last edited by 5-7HEAVEN; 12-24-2011 at 02:22 PM.
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