wheel size and speed?

[eDJ]

Cabinfever,

If you look in the DIY Homebuilt Motorized Bicycles, Stickies, Gear Caluclator thread of
Fairracing's there are three links. The first two work and should be checked out by those attempting what you are wanting to do.

You may have seen it but for those who haven't it is quite handy for calculating engine rpm and sprocket teeth# with tire diameters and sprocket teeth# into MPH. I've used this alot.


http://motorbicycling.com/f36/gear-calculator-4820.html

 

[Cabinfever1977]

thanx i will use it,im thinking of switching wheels on my bike.
now i will know what sprocket to use on back wheel according to what size wheels i use.
i have a 26" mountain bike with warped back wheel. im thinking of using a 18" heavy duty wheel in the front and a 16" heavy duty wheel that has a hub mounted sprocket already,for the rear (its not the right chain size but i can mount my sprocket to that sprocket).my peddal cranks are short and will clear the ground no problem.my bike will sit lower to the ground. i have a heavy duty front suspension fork that goes with the 18" wheel.i only use the front brake so i dont need the rear brake to work. i would like the bike to be able to do around 20mph or so. with my 26" s my max speed is 32mph.but my kickstand will be too long.

 

[eDJ]

I've played with that software a bunch now. Just start plugging numbers in and teeth
numbers for counter shaft & rear sprocket and you'll be amazed at what you can calculate
in minutes. I'd also keep a piece of paper to write down info on that you want to save
and don't have to rack your brains recalculating. USE THE BICYCLE ANALYZER Carl_Baron123
posted a link to in his post in Fair's sticky thread.

Once I had the idle and top rpm of my Briggs Stratton I started calculating for my motorized
camping trailer with the jack shaft drive and within an hour had the answers I needed to give
me a speed that would allow me to nearly start off from a stop and run up to 24 mph. I'm going
to be hunting for that 80 tooth sprocket on a junk yard for some time, but I found new ones
available on line...not for cheap though. But looking thru the online catelog gave me spec's on
centrifugal clutches with sprockets from 9 to 13 teeth to design from.

I used a one to one ratio from the jack shaft to the axle and an 80 tooth on the jackshaft to 11 on
on the engine so the top rpm would be around 2000. (the motor tops at 3200) The three
images show the trailer frame with motor, jackshaft and gears in the first. Second is a side
view showing the enclosed motor, and last is the view of the finished trailer with tent opening
and interior. The bike wouldn't be motorized in any way with this trailer.

Just using the trailer project by means of explaining how handy that software is.