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one for mr harley davidson.

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leolion
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Joined: 14 Feb 2019
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PostPosted: 15:48 - 21 Jun 2019    Post subject: one for mr harley davidson. Reply with quote

Would it be possible to attach a 50cc lump to a 'front hub' ebike, sort of like hybrid motorcycle?

The idea ive had (which may be crap!) is to have it as a pedal assist (up to 15.5mph) ebike then when you get past 15mph (a'la 70s pedal and pop style moped) the 50cc lump kicks in for higher speed.

Could you have the ebike bit on the front hub then the moped bit operating from the back wheel, (i have no idea what happens to the pedals on a pedal and pop moped,do they go round really quick?)

Anyway is it conceivable?
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kgm
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Joined: 04 Jun 2015
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PostPosted: 18:39 - 21 Jun 2019    Post subject: Reply with quote

Why, when there are already electric motors for ebikes than can achieve higher speeds? There wouldn't be any licensing/insurance benefits either so the way I see it is that you'd be better with either an ebike (legal or otherwise) or a moped. It's not like current mopeds are lacking in fuel economy either so I don't see the benefit.

Electric scooters/commuter bikes are one application where I think electric is a good idea, current costs aside but I don't see the value in a hybrid. Sorry
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G
The Voice of Reason



Joined: 02 Feb 2002
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PostPosted: 00:35 - 22 Jun 2019    Post subject: Re: one for mr harley davidson. Reply with quote

leolion wrote:


Could you have the ebike bit on the front hub then the moped bit operating from the back wheel,

Yes. You can buy kits with really poor quality engines for not much.
But it's going to make it really obvious you've got what I presume isn't a road legal vehicle.
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HardlyDavidso...
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Joined: 08 Mar 2019
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PostPosted: 13:13 - 22 Jun 2019    Post subject: Reply with quote

Brace yourself! Tef level reply incoming...

I've had a similar moment of madness. Things to consider...

Ebike motors

You can have any size motor you like on the back or for mid-drive but on the front you'd want the very lightest possible so 250/350W internally geared motors. So a bit lacklustre TBH but it will get a "normal" bike to 15mph however what we're talking about here is a MUCH heavier bike so 250W is just a little boost. (Your own legs can put out ~700W.)

For any ebike you need a controller, battery, pedal sensor and/or throttle... maybe a display. (Mid-drives tend to have the controller built into the motor case.) All that stuff has to go somewhere on the frame, more on that later...

50cc el cheapo chinesium motors

Assuming you have a standard "trapezoid" frame you'll need a fairly large one. I normally ride 17 to 19" MTB frames but the petrol motor only just fitted within a 21" frame in the end. Luckily my inside leg is relatively long (wayhay!) for my size so it was still rideable. (BTW, hardtail only frames.)

Okay, so you've just consumed all the space "inside the triangle" so where are you going to place the ebike battery? Hmm... maybe a pannier rack one? Maybe not...

The petrol tank is a PITA and was my ultimate defeat for getting the conversion bike through the MSVA. It's neck sticks up too much and about the only way round it, as far as I could see, was to mount it on a pannier rack at the back to avoid any "knackers caught on filler cap in a crash" type issues.

Also consider the petrol motor needs a motorbike sized throttle & kill switch and a locking clutch lever. Your rear brake lever needs to go somewhere or you could go for a double cable right lever, eeek! The handlebars are going to get pretty cluttered with all the controls.

Out of the box petrol motors have you clamp the rear sprocket directly to the back wheel spokes around the hub using some old off-cuts of car tyres. Yes, old car tyres! However, this does sorta work a teeny-weeny bit like a cush drive. There's no freewheeling function in any of this; callback to the locking clutch lever.

The way I looked at it the bike then only had two gears: me pedalling = low gear, release clutch and use motor = gear 2. Or in our case ebike motor + pedalling = gear 1/2 and petrol motor maybe gear 3. It's a lot to juggle! Pedal + conventional gears, ebike pedal sensor? or maybe a thumb throttle, petrol motor throttle + clutch, brakes... however you go about that!

As an aside there are aftermarket kits that reroute the petrol drive output through the right-hand side gear train so you could use your derailleur or IGH but consider that the chainset is not build for the ~1.6kW of a petrol motor. My boss has a mid-drive 1.5kW BBSHD and has being through 3 chains and two rear cassettes in the last year.

Are we even getting into the electrics you'd need if you wanted to get this through the MSVA. No? Good Wink

And you would need to get it through the MSVA as, unlike the "sleeper" nature of any conventional overpowered ebike, the distinctive 2-stroke (which, with the supplied exhaust, is borderline on the decibel limits) offers zero plausible deniability.

tl;dr

Sounds like an exciting project! Best of luck Smile
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Keeway Superlight 125, 50cc turd scooter, 50cc 2-stroke bicycle conversion, 1500W ebike, hand-made fixie
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