Gear ratio suggestions please

pulsar2121

pulsar2121

Member
As many of you may know. I have been talking about doing a trike build for a long time. Well, this time I've actually bought the stuff to do it. I've got a 26" Schwinn Meridian coming in the mail, I picked a 212cc Predator engine up from Harbor Freight the other day, and I'm going to use a 10 tooth centrifugal clutch that I bought off of eBay last year for another project.

You're probably thinking "What? A 212cc motor on an aluminum frame trike! Isn't that a bit overkill?" And the answer is: Yes. Yes, it is. I wanted something fun to ride around in the winter and a rear mounted engine on a trike seemed to be the best answer.

Anyways, once the trike is here I will need something to attach the chain from the clutch with the axle. I'm planning on running a jackshaft due to the lack of availability of large axle mounting sprockets. I'll need an input and output sprocket for the jackshaft and a final drive sprocket mounted to the rear axle. My question is what sprocket sizes should I get? I was looking through Sick Bike Parts' catalog and it looks like my options are 9, 10, 11, 17, and 21 tooth. Which combination should I use for a typical motorized bike top speed of 30 - 35MPH?
 
A 7.67:1 ratio is approximately 100rpm per mph, so if you leave your engine governed I think 8:1 or so would be OK. Also, stay away from aluminum frames- recommend you return it and buy a steel trike. Especially for the 212.
 
I run the shimano nexus 3-speed trike tranny with a 49CC scooter engine. My frame is mostly aluminum. I hit 43+mph with the stock engine and exhaust.

Ideally you can buy them in non-hit form.

http://www.niagaracycle.com/categories/torker-tri-star-3-speed-coaster-brake-hub

or

http://www.niagaracycle.com/categories/torker-tristar-sturmey-archer-3-speed-coaster-brake-hub


But you may need these parts the kit comes with.


http://www.niagaracycle.com/categor...-brake-hub-conversion-kit-for-adult-3-wheeler

Im upgrading my 3-speed to a 5 speed with this one.

http://www.niagaracycle.com/categor...-brake-hub-conversion-kit-for-adult-3-wheeler

With 49CC, a 5-to-1 pocket bike tranny, and the IGH, you should couple the rear axle with about a high twenty to mid thirty tooth count sprocket.

If you put a expansion pipe on a scooter motor and couple it with the IGH trike tranny, you'll have just about all the fun you are imagining with the 212 predator, minus the weight, and plus the cheaper price of replacement parts.
 
Fo' the record... I have a 20 tooth rear wheel sprocket with a 12.5 inch electric scooter rim. DO the math ratio for a 26 inch tire.

I dont think the IGH will handle the predator in a performance application. It seems that these will handle a stock 49CC motor forever... but as soon as you start adding the pipe and carb and porting, you have to monitor the hub adjustment and axle position often.
 
bowljoman said:
I run the shimano nexus 3-speed trike tranny with a 49CC scooter engine. My frame is mostly aluminum. I hit 43+mph with the stock engine and exhaust.

Ideally you can buy them in non-hit form.

http://www.niagaracycle.com/categories/torker-tri-star-3-speed-coaster-brake-hub

or

http://www.niagaracycle.com/categories/torker-tristar-sturmey-archer-3-speed-coaster-brake-hub


But you may need these parts the kit comes with.


http://www.niagaracycle.com/categor...-brake-hub-conversion-kit-for-adult-3-wheeler

Im upgrading my 3-speed to a 5 speed with this one.

http://www.niagaracycle.com/categor...-brake-hub-conversion-kit-for-adult-3-wheeler

With 49CC, a 5-to-1 pocket bike tranny, and the IGH, you should couple the rear axle with about a high twenty to mid thirty tooth count sprocket.

If you put a expansion pipe on a scooter motor and couple it with the IGH trike tranny, you'll have just about all the fun you are imagining with the 212 predator, minus the weight, and plus the cheaper price of replacement parts.
Click to expand...

I was looking at the hub kits that you had mentioned. Do those mount up in place of the intermediary axle that connects the chain from the pedals to the chain from the rear axle? If so I'd assume that there's a freewheel inside that hub so you don't get hit in the legs with the pedals when the engine is engaged

Perhaps you could include a close up photo of your trike's drivetrain. It would help me visualize where things are mounted on the trike and possibly see what I could use on mine.
 
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