Gearing Calculations

[Motra]

I've been throwing some numbers together to get a better idea of gearing combinations. I'm interested in low geared off-road type bikes but I'd like to have a decent top speed too. It's good to see the numbers for comparisons. The DB-30 is a bike I have and this combination is fine for driving around on the streets but pathetic for climbing anything that even resembles a hill at 8500 ft. elevation; it has 40 ft. lbs. of torque at the rear wheel and 69 lbs. of wheel thrust. The early Tote-Gotes had about 200 ft. lbs. of torque at the wheel and 250 to 300 lbs. of wheel thrust, but they only went 14 MPH. Here are a few examples but I have some more I'll post tomorrow.

 

[Oldsalt]

The DB with approx. 7.5 to 1 final ratio [14 inch tire with jack shaft] is my kind of machine. 22 miles per hour is fast enough for most situations unless you are running from the law. I don't wish to fall off at any greater speed and the machine will handle reasonable hills. But the jack shaft sprocket can be changed to suit most any condition. The Boonie Bike II study sure shows the advantage of a vari drive.

 

[INJUNTOM]

Set it up for approx 8.5-1 to 9.0-1 and go climbing. I've done lots of experimenting and these ratios work quite well on a 6" wheeled bike.

 

[INJUNTOM]

BTW, it helps to have several bikes so you can have some set up low geared and some set up high geared.

 

[Motra]

Here are some more to bore you. The hands down winner is the Honda CT110 engine; you get huge gear reduction and 40 to 50 MPH top speed.