Please consider and discuss, hybrid motorised bikes, its not as silly as it sounds

libranskeptic

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Jan 13, 2016
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1/ legal issues affect many of us re petrol bikes. Laws are often largely honored in the breach, but why push your luck?

2/ low torque petrol power is a pain to start and for stop go work (as are chain drives)

3/ electric range issues ~go away with a regen capable motor and controller

4/ adding a front hub motor is simple and cheapish (NB, i really think the premium for a 2 speed one is worth it)

SO:

A front motor with regen and fast charge storage could charge the bike when under petrol power or braking. A; big, heavy, expensive battery is not mandatory. Just a; light, fast charge/discharge, ~5ah 36v one should do (36o watts of power for half an hour or 720watts for 15 minutes, even 1000 watts on a 3c max discharge battery like mainstream lifepo4 chemistry units).

Getting rolling on electric and dropping the clutch = electric start convenience

Use electric when cops are a risk, motor on back roads and hill climbs where the extra power is really appreciated. Once altitude is gained, a puny electric alone is fine. A QUIET petrol motor seems a must for similar reasons. Why push your luck.

Much of life is factoring risk. Get this one wrong, and once the local cop has warned you once, your petrol bike may as well be scrapped. They dont like their rulings, no matter how silly, being ignored.

Technically, it's only illegal if the petrol motor is powering it on a public road, maybe even if the motor is warm? "I only use that motor on private land officer" should work sort of.

A simple example is a farm kid rides to the edge of town on petrol, and switches to electric around town. If he is sensible, the town cop may well turn a blind eye, even if he spots him on rural roads.

Aside from the above, electric when it suffices, is so much more pleasant.

Much as I love my mid drive ebike, the chain and cogs have been the most troublesome bit of an otherwise very maintenance free, joyous workhorse.

For many, the extra traction of an AWD bike may have big appeal - mud/snow etc.

I have to say, its kind of cool that such cutting edge prius like automotive technology, is so readily accessible to DIY folk in the bike world. I predict that for EV autos to work, they have to be lighter and simpler. The minimalist Nissan Leaf, is 1600 kilos for gods sake. Its just too big an ask for batteries to propel such mass very far for a long time to come. 150 kilos should be easily doable for a four passenger tuk tuk/mini moke type vehicle made from bike framing and bits.
 
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wheelbender6

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I understand the logic.
When road conditions are unsafe (Or illegal for a gas motor), the e-hub motor can be used to propel you on the sidewalk or multi-use path without offending the joggers and walkers. A good 24v hub motor with Lipo batteries starts at over $600 around here.
 

sbest

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Nov 1, 2015
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I am planning on doing just that.
50cc Grubee engine for the open road and back trails, charging a very small Lipo 24v batterypack and a 500w motor for around town.

I have a lot to learn before I get there. I have several electric bikes, all SLA powered, and HT powered bikes.
I carry the electrics in my van and ride them around towns and cities, I use the HT powered rigs for long trips and experimenting.

My end goal is to put the two together in a simple bike of under 40kg. Because pedaling and fuel are options, batteries don't need to be large. I am looking at a mid drive electric and maybe the gas motor too. I am a way from even starting to put it together.


 

libranskeptic

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Jan 13, 2016
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I understand the logic.
When road conditions are unsafe (Or illegal for a gas motor), the e-hub motor can be used to propel you on the sidewalk or multi-use path without offending the joggers and walkers. A good 24v hub motor with Lipo batteries starts at over $600 around here.
 

libranskeptic

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Jan 13, 2016
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You do get it. Good. I am not alone.

A great deal of the utility I get from my ebike relies on my ability to morph between being an honorary pedestrian and a road user. Screw parking hundreds of meters away. I park on the observable (and therefore secure even unlocked) doorstep or even inside of each of my errands premises. Relaxed and fast.

Round Sydney Oz, it's a compulsory $1k P.A. before you even start/maintain/insure a car. So relatively, a once only cost of $600 is a rational choice for many. If a farmer mom can pass on driving kids to school even sometimes, its a bargain for a family. Range anxiety for rural folk is a killer factor, which precludes ebikes as an option for their needs, yet their need is great. A pre driving age rural kid is very trapped/isolated at home, and families are slaves to chauffeur duty for them.

$600 sounds high. All i can say is based on firm quotes but hazy recall of FOB china prices maybe a year go received by me.

A geared hub & controller kit, ~$80US, 2 speed hub motor ~$130. A 20ah 24v lifepo4 pouch cell lifepo4 battery $290 ~3 weeks ago. In theory, a 5ah should be 25% of that, which of course it isn't -maybe $150?

Incidentally, I got a quote from a specialist re-spoker for A$100 ($70US~) locally. Given airfreight costs added by sourcing the bulky entire wheel in china, its tempting to just get the hub sent and scrounge a known quality rim locally.
 

libranskeptic

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sbest

good for you. I plan similar, ONE OF THESE DAYS :). Trouble is, its just for a giggle. It doesn't suit me here in the city.

As before, I love mid-drives, but I am a bit leery of having both motors power the same wheel. Sounds like a complex, stressed and awkward rear axle.

Intuitively I would prefer the simplicity and the traction benefits of a AWD bike with a front hub.
 

sbest

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Nov 1, 2015
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Hey, it has been done;:

I have a spare 500w electric motor and drive for my Schwinn/Currie Izip I picked up off Ebay for $60, and am thinking of using these for battery packs:
http://www.walmart.com/ip/The-Everstart-Multi-Funciton-Jump-Starter/46528407
Total weight about 15 lbs and low enough torque to not destroy the chain drive. Range will only be about 5-10 miles but so what? Top speed at present is about 15mph and I don't think gearing will help. The battery packs are only 2.5 lbs each and the motor will take up to 48v so extra speed comes at little weight cost.

My Izip is single speed (like a hub motor) and is useless off road and needs help on city hills. Gearing the electric to the pedals makes sense. The gas motor is for distance and charging, so direct drive to the wheel makes sense. Also considering connecting the throttles somehow. I would consider a hub motor. One of my bikes has one:

Again, not my bike but a picture of the same type, Schwinn 1020 Izip I gotta get a camera.
It is even more torque limited than the larger bike. Goes FOREVER on a charge, 20 miles but at only 10mph or so.

So, quiet electric in the city and thru areas where there are pedestrians. Power up the speed with the electric and kick in the gas at 10mph up to the legal limit or the present 60kph (37mph) I achieve with my present bike. A charging system may take some juice from this.


Cheezy low quality pict, sorry.

Steve
 

jaguar

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Nov 25, 2010
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the hub motor electric I had exhibited "rolling resistance" when the juice was not on, like a slight braking.
so you need to consider that in your design process.
 

sbest

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Most of the electric motors have some drag, so all work best with a freewheel of some kid.
My hub motor has that same slight drag Jaguar. Not a problem unless you are pedaling, and we all pedal some time.
Steve
 

bluegoatwoods

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Mar 23, 2008
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I like the idea. I've considered it myself.

Two different throttles could be a bit of a problem. Someone a few posts up alluded to this.

One other thing, too. I'm no expert. But I've gotten the impression that re-charging from rolling is a neat idea in theory, but difficult in practice. My understanding is that the the circuitry becomes a great deal more complex and expensive, with little actual gain. No personal experience with this. It's just what I've heard. But it sounds believable.

I wonder, though. Imagine two twelve volt bottle generators be mounted on the bike. Could their output be wired in series? Put a cheap automotive voltage regulator on each, then wire their outputs in series, giving 24 Volts.

If that's feasible, then that would seem like a good way to charge the electrical part of the bike. A 24 Volt system, anyway.
 
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