Shift Kit & NuVinci for a Large Jolly Man on 66cc 2-Stroke

Kioshk

Kioshk

Active Member
OK, against my better judgement, I have found myself obsessively daydreaming about adding a shift-kit and NuVinci hub to my build. Besides the prohibitive costs, I was wondering if my weight was also prohibitive. My motorized bicycle with me and my stuff weighs about 370lbs; I'm concerned that if the NuVinci doesn't pop open like a smashed coo-coo clock under my load, that a standard bicycle chain will stretch and snap like a fried mozzarella stick. So, does anyone have experience with either or both configurations under heavy load? I'm pleased with my present config: 56T on a 29er. Cruising at 24MPH, and takes moderate hills without a problem. The steeper hills are a concern...going up, pedal-assist is fine, but the engine can heat up more than I'm comfortable with, and going downhill, when I hit about 30MPH, I worry about the engine over-revving. I'd be happy to hit 35MPH downhill with mid-range RPM, and to crawl up steep hills in the same range.
 
My understanding is the NuVinci is a tad fragile for engine power. No direct knowledge, just hearsay.
 
You'd be spending a lot of money for very little gain. It could be done if you can find an N171 and gear it correctly so it doesn't get overtorqued.
They're known to seep oil when they get hot and that oil is ~$100 a quart.

IMHO, a Sturmey-Archer hub like CS-RK3 or CS-RF3 and a Megarange cassette cluster would be cheaper and more reliable. You'd have a nice gear range, too.
 
Our experience is also that the Nuvinci is a bit fragile especially under heavy loads. Other internals can be fragile as well, Sturmey or Shimano. Really you can't go wrong with a good derailleur and chain.
 
I'm 6'2" and 250 lbs. This is what I run on my 5 speed autoshift bike. Robin Subaru EHO 35 engine (8000 max rpm), 18.75 gearbox, shiftkit and custom built 5 speed freewheel. GB-SK 18-44; SK-FW 34-(34, 28, 24, 20, 16). My level ground speed is 29 mph and I can go up any hill here in Tennessee at least 8 mph.

Look up Land Rider Jerry 5 Speed freewheel on how to build it or go to my profile and view the album about it. This equates out to reduction from engine to rear wheel (45.83-21.57):1.

Without knowing details about your engine rpm and reduction being used I can't tell you what sprocket to put on a jackshaft. However you can still put a 34 stainless steal chainring on the shiftkit to power the 5 speed freewheel. This setup will work very good for you and save you a bundle of money.

picture.php

picture.php
 
Last edited:
This is another setup you can use and will give you a wide range either use a 11-34 8 speed cassette or an 11-34, 8 speed DNP freewheel. Still use a 34 stainless steal chainring on the shiftkit to drive the rear wheel.

For uphill use gears 1, 2, 3.

For level ground use gears 4, 5, 6.

For downhill use gears 7,8.

This will work very good be simple to install and save you lots of money.
 
Very late to the party, but I can address Nuvini questions.
Don't bother with the N360 for powered apps. It was built to be lighter for human-powered bikes. A strong rider on a mountain bike in rough terrain can destroy one. It wasn't meant for this app.

The old 170's were overbuilt and can handle motor power, with caveats.
Torque is more limiting than power. You can definitley push smooth 5HP through it continuously; it's the torque spikes of an ICE that kill it.
For a gasbike, you'll need a cush drive if you want it to live long.
I've personally run 1kW motors on both N360 and N170 through them all day with no problem. That's only 1.5 hp, but it's a point of reference.
 
Last edited:
You must log in or register to reply here.
Back
Top