I have to keep this unofficial at the moment but there is a ‘possibility’ that there will be a home made electric bike race at an event in August. I reckon either a 30 minute or an hour endurance race on reasonable easy terrain ought to do it.

Anyone here reckon they can beat my creation (yet to be created)?

No technical rules decided on yet but double diffusers WILL be allowed.

Please give me some ideas of how to build one as it sounds fun. I reckon a couple of car batteries either side of the rear pannier rack with a washing machine motor or similar straped in the front triangle, some zip ties and gaffer tape should do it.

If I were you (especially with your reputation!) I’d use non conducting pedals, grips & saddle. I’d also put a rack on it with a fire extinguisher strapped to it 😉

I was going to get my Chaffeur to ride the thing, it would probably be deadly.

If this race does go ahead it will be physically seperate from the lake jump.

The lighter the better I guess….

Anyone got clever ideas on how to do the transmission bit?

Do I need to have some kind of throttle to gradually increase power or have some kind of clutch so the motor switched on and then the spinnyness is gradually pushed to the wheel?

hmmmmmmmmmmmm,

does it have to be a bike? are trikes/quads allowed (i’m thinking light wheels and heavy motors/batteries might be a recipie for diaster on singletrack), if so at what point does a quad become a golf buggy?

Trikes yes, quads no.

No reason behind this judgement, I am using the F1 method of rule creation 😉

No clutch needed and at the sort of power output you are likely to get an on / off switch should enough I think. Throttles are hard to do due to the current you are running. If you run multiple batteries you could probably do something with progressively adding more batteries in.

Car starter motor would be a good motor to use – 12 V DC. Washing machine motors are 240 V AC and a car battery produces 12 V DC 🙂 Complex electricery needed for that.

Want more power? Truck starter motor and 24V DC

The motor will need to be geared right down

Mount a motor on the rack, with drivechain to (SS) sprockets as normal – then you can freewheel…you wouldn’t need a clutch then, but you would need a throttle.

Hmm – 24V DC sounds fun.

If we did go ahead with the race, would any of you lot take part if it meant building a bike?

It would be a fun event rather than overly serious.

I’m not going to be there (my birthday, wedding anniversay, kid’s birthday & Mrs Feet’s birthday that weekend) but if I was, I’d just take a quad bike and stick a Ferrari badge on it – that way it would conform to the regulations, despite having too many wheels, etc

LOL @ cheeseyfeet

I built one once many moons ago in CDT at school; had a very very cool PWM controller with some monstrous power transistors that I rember getting quite warm., a motor/gearbox from a C5 and about 30kg of battery and mounting.

Completely mucked up the gear calculations and hence could only do 3 mph. You could use it to tow cars though with the amount of torque it had.

Car starter motors sound good, but they’re only rated for a few minutes constant use. Windscreeen wiper motors have a good output and are rated for several years.

If I were to rebuild it, I’d stick a tray of batteries in a trailer and get the drive to run through the l/h crank.

sounds like a good idea – care to build one?

I was going to get my Chaffeur to ride the thing, it would probably be deadly.

You mean Juan then? Yes, that would be deadly alright…..

You mean Juan then?

French Fries anyone?

Mirth, this could be cool, so YES, I’m up for it!

Can we outlaw being funded by Qinetiq as they always cheat spend 10 times what anyone sensible would and then win?

The judging will be based on effort, novelty, personal attire and anything else I think of.

Prizes (yet to be confirmed)will be good. There will also be a demo fleet (probably).

Electric bikes isn’t something I had thought of before I just need to work out if we will get enough interest if we let this sponsor come along.

nae I’ll survive, if I can drive the most soopidest car on earth back to safety I can drive or ride anything…
Even an ostrich

easy, stick a motor on a panier, with a chain running down to a cog on the cassette of a normal bike.
you wont be able to shift past it, but other than that the bike remains unchanged.
batteries on the pannier i guess, eqally spread front and rear to balance it a bit.
a big “dimmer switch” for a throttle.
and with the freewheel still attatched, you turn the motor OFF alltogether for anything vaguely downhill, to reduce your power consumption.

when can i sign up?

Here – http://www.bigbikebash.co.uk/tickets.php
and Now

Unless your chosen motor has a gearbox on it ( windscreen wiper motor??) you will need to gear down A LOT – electric motors turn at many thousands of RPM, rear wheels at what 100 rpm or so at ten mph – so you will need at a very rough guess / back of a fag packet calculation a 20:1 reduction between motor and wheel. – unless you use roller drive on the tyre.

You are only going to get a bhp or less – so I don’t think a throttle will be crucial for bodgeups

roller drive above the rear wheel? and a ‘clutch’ where the harder you pull on the lever the more it pulls the drive onto the wheel (would be quite involved though.

Theres a trike on the estate (more council and country unfortunaltely) ridden by some scrote, with a SA 3 speed hub mid way betweent he pedals and rear axel (like pre-unit motorbikes).

how much torq a SA 3 speed can cope with? i.m thinking, drive to the pedals via 22-44 gearing, then 22-44 to the hub, then 44-22 to the wheels.

are we allowed KERS?

roller drives are ok for road applications but you get a lot of slippage in mud. Mine tended to mill big flats (or occasionally damned great holes) in the tyres too.

Chain drive is most efficient and if you can get it to use the bike’s transmission, most versatile too.

SA 3-speed hubs are seemingly hewn from solid lumps of tungsten and will happily take a few hundred watts of power so long as they’re kept topped up with oil.

Err.. what size motor? Running a speed controller for a big motor might be a good idea. Lecky motors develop max torque at zero RPM, you can’t just switch it on if its got any go at all, it will just shred everything and batteries are going to be very heavy. Look at battle robot building sites for some inspiration. In the spirit of creative rule interpretation I’d be tempted to bungee the smallest motor you can find with one AA battery and pedal like mad. Good luck!

found rusting in me M&D’s garage…

Weighs nearly twice as much as the bike frame itself!