Using 3-speed hub, how to make auto-shift?

[Urban Fatbiker]

Yep. Buzzbike is already pushing the line with the 'engine lockout disengagement hand lever', no its not a clutch, officer, yeah I know sure sounded like one...

So yeah, if they hear 'VROOooom, Vrooooooom, vroooom...I want to show an auto shift.

Beatings, tasings, and a local jail riot, and the police officer drug down Broadway by a rampage of dirt bikes and ATV's, adds motivation to keep it legal.

 

[JerboaJohn]

if servo driven, then no arduino needed? thinking if you use 1 variable resistor for a 2 speed with a dynamo front hub. the servo will activate at a certain voltage (speed reached) 3+ gears is a bit more complex

 

[Urban Fatbiker]

if servo driven, then no arduino needed? thinking if you use 1 variable resistor for a 2 speed with a dynamo front hub. the servo will activate at a certain voltage (speed reached) 3+ gears is a bit more complex

I'm thinking that if I hit a hill I want some logic to make setpoints for shift based on not only speed, but event, i.e. if I slow down, and downshift, I don't want it cycling between gears at the same point as a constant accel from a stop or a bigger slowdown. Or, holding a speed near a shiftpoint won't make it cycle back and forth. Might use a throttle position sensor for another input so it knows if I"m trying to giddyup, or just hold a speed.

The mechanics are new to me, some bicycle hardware has really advanced from the last time I played with it. On the other hand...I used to be the overload of robots, the guru, machine god (got called a lot of names...some were not as flattering).

Configuring a mini-PLC with two inputs and one output? Doing it already in my sleep. In that world, already added a daylight sensor to turn the lights on, and a motion sensor to honk at people in front of me

 

[JerboaJohn]

yeah, the hunting around between gears was the bad thing abt that autoshift 5 spd derailleur. it was a spring that relied on pedal pressure.
so 2 hall sensors, 1 for wheel speed 1 for engine rpm but it'd be vague without load sensing.
an ebike (cool would be belt driven!) might be easier bcs there's already pedal cadence and load sensing for the assist.

interesting project for sure!

 

[curtisfox]

This is Kool, reminds me of a old hit and miss engine govener, with the fly weights, simple........Curt

 

[LewieBike]

Not to be a spoilsport,

But, You should consider that these hubgears were made for human power levels and an auto shifter would bang through the gears if not engineered and programmed carefully.

Especially bad would be the 2nd to 3rd shift, you would need some sort of way to pause the engine power as it made the shift, otherwise the false neutral between 2nd and 3rd gears will allow the engine to build revs incrementally and it will start breaking internal bits. Better would be to keep it manual shifting, and be stealthy with it.

BTW my bona-fides: I'm a bicycle mechanic for about 35 years and I know a few things about internal gear hubs.

 

[curtisfox]

My thought would to use as a jack shaft, would be not the strain as in the hub...........Curt

 

[Urban Fatbiker]

That thought about banging thru the shifts did cross my mind. One thought this AM was to use throttle input and output, making it controllable by the Arduino. Then throttle could be retarded during the shift.

I will be using it in a jackshaft or roller, not in the wheel hub.

 

[Sidewinder Jerry]

When I first built my bike, I'd been riding for about a year before I ever got on any of the forums. In spite of this fact when I got onto the forums nearly everyone told me the auto shifter wouldn't work on a motorized bicycle; that it'd bang through the gears. They were so stuck in the belief it wouldn't work that they missed the fact I said I had been riding the bike for a year.

My bike has never banged through the gears. Yes there'll be tweaks you'll have to do before you finally get it right but I know you can do it

 

[LewieBike]

When I first built my bike, I'd been riding for about a year before I ever got on any of the forums. In spite of this fact when I got onto the forums nearly everyone told me the auto shifter wouldn't work on a motorized bicycle; that it'd bang through the gears. They were so stuck in the belief it wouldn't work that they missed the fact I said I had been riding the bike for a year.

My bike has never banged through the gears. Yes there'll be tweaks you'll have to do before you finally get it right but I know you can do it

The difference being that if it's a CG bike engine there's no slight buffer like an auto clutch and that your bike engine is about 32 cc and a four stroke.

And driving the power through using the hubgear as a jackshaft isn't going to make it any better, you're spinning it 5 times faster than it normally would turn, so the engagements will be at higher speeds. This also will fling the gear lube off the sun and planets. Expect to lube it more far often and it will leak all the oil you've added.

But you know, go ahead, you are the expert, right?