Shimano Nexus Auto D - auto shifting for motorbikes?



Hello All! I'm still trying to figure out what bike and motor to buy, but reading your posts has definitely given me some interesting ideas.

First my idea: You'd need to have a motor setup like the Whizzer where the pedals and engine turn the same front sprocket.

The Shimano Auto D internal gear hub (Check Out Tiny URL 2ruxmj) uses a speed sensor on the wheel to electronically change gears. Uness I'm mistaken, this combo of motor & rear hub would give you a fully automatic motor bike.

Any thoughts?

Question: I am 6'5", 350lbs. I've pretty much decided on using a Worksman steel frame with fat tires (because of my weight). I'm looking at either the Honda 49cc 4 stroke motor, or one of the 80cc Chinese models that so many of you have. Any opinions as to which motor, (or perhaps some other motor), might be strong enough to push my big keester around?

Any suggestions you have will be greatly appreciated.

A brief explanation of my circumstances: I fell off the roof of my house three years ago and I didn't walk again for more than a year. Shattered heels + left ankle + bone infection = messed up. I now weigh more than 100 pounds more than before the accident.

I plan to travel this summer and a with a motorized bicycle locked onto the back of my camper van I should be able to get around beautifully. It's really hard for me to walk and stand but I can ride a bike all day long.

Thanks for your help. I've already learned so much here.

Rocky LaLiberte


with the weight involved, vabeachnet, i'd try for a 4-stroker...the grubee kit looks pretty nice, i've been wondering if a briggs & stratton minibike engine could be fit to it.

i bet the auto-hub would freak out at a sustained 30mph, just something to consider.

welcome to MBc 8)


Active Member
Local time
6:05 AM
Nov 5, 2009
East Texas
How fast do you have to go? If you only need to go 20-25mph, you can make do with a motor bicycle, by using a heavy duty cruiser frame and a common Grubee kit. Just substitute the 44t cog with a 50tooth cog. It will go 20-25mph (instead of the 20-30 of the stock cog).

I suggest these wheels! They have VERY thick spokes and Downhill type rims (jumping bikes), with bolt on hubs.

I just have the rear one so far and its great.

V 35

Local time
8:05 AM
Aug 27, 2010
I built a Worksman, good tough bike. One problem with the design = The fender braces are drilled 90 degrees opposite conventional bikes. I built caliper bridges out of mild strapping, ditto for tank, motor, chainguard, tensioner. Bike is very good handling, have the ' real deal ' wheels with thornproof tubes, and kevlar tires The Combo Lever squeezes a pair of MT bike cheapo calipers, with the front set quite loose. The Shimano Coaster Brake is welcome for decending steep hills . Engine drive = Pirate Cycle 2 pc Hub, 48 tooth sprocket, tricycle chain. 3 speed handle bars, and a triple sprung Sunlite saddle round out the package.


Well-Known Member
Local time
12:05 AM
Sep 8, 2009
Australia - Melbourne
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