# Mamil eater eBMX bike



## voyager (13 Sep 2015)

Hi folks 

The latest addition to the fold , a BMX with suspension front forks , flatter bars and a longer stem , 
behind the rear rack and panniers hide a 24v Currie motor running on 36v .

Enough to bring a grin on anyone's face !










how to take a screen shot

regards emma


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## clid61 (14 Sep 2015)

Love it !


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## Bodhbh (14 Sep 2015)

Must be hilarious scalping roadies on that thing !


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## voyager (14 Sep 2015)

*The scenario *

A up hill stretch of road a 100 yds or so above my house - along comes a mamil and laughs as he sees me on a BMX waiting by the gate. so I wait 20 seconds for him to get past the next junction . ,

40 seconds later after he laughed , I pass him on the hill like he is walking .
Ridden off by a old blonde bird ( OAP ) on a single speed BMX bike -  with panniers 

Well it makes a change .....

They are usually ridden off by the same blonde old bird on an electric assist trike !!
and her almost OAP other half on another !!!!!.....

On Sunday morning the local kids had a go (yesterday ) and now they all want one .

The maths behind the motor combination is 15mph x 20% increase in original wheel size ( from 16" wheel into a 20" bmx rim ) x 37/24 battery increase gives in theory 27mph in unrestricted mode and 40% more torque with the battery increase 

When we get bored I will restrict it and sell it or dismantle and use the bits for another more sensible project . 
The actual value of the parts makes the conversion a bit of an expensive white elephant ( about £250 ) 
With the tye about a mile away I am sure it will get a bit of use off road if the sun ever shines long enough before we get bored ..



Since the photo we have tidied up the electrics and applied a little matt black paint to the cranks and rack , Plugged the ends of the handle bars and added another couple of cable ties .

The bike is still in the pink colour but looks a lot tidier since I fitted the battery box end caps we made .

Only things left to do is make a sliding battery mount to allow the removal of the battery rather than the battery straps fitted ..
The battery is a 36v LifePO4 10ah battery that should be good for 15 or more miles with throttle only use - the addition of a pedal sensor would extend the range . The seat stem need a little cranked addition to the length to give a better riding position with a higher seat .

Initial tests were done with a 37v 5ah lipo batter carried in a triangular pack behind the seat but I estimate it would have only had 8 miles range 
and the addition of the rack and panniers helps to hide the motor and battery from "view "

The weight is about 54lbs and the majority of that is on the back wheel 18lb /36lb front /rear distribution . with 50 psi in the standard road tyres 
gearing is 44-16 and you run out of pedal power quite quickly but if you get carried away it is easy to pedal back with a flat battery as the motor has a sprag clutch and the motor disengages when not in use.

regards emma


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## Dogtrousers (14 Sep 2015)

voyager said:


> the motor has a _*sprag *_clutch and the motor disengages when not in use


A new word to me. I've just looked it up. You learn something every day.


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## voyager (14 Sep 2015)

Dogtrousers said:


> A new word to me. I've just looked it up. You learn something every day.



The sprag clutch is a simple piece of engineering that uses a ramp to wedge the roller bearing in one direction , its uses are in electric hub motors and are also in in model aero engines starters . The Xiongda hub motor uses 2 sets of these in the 2 speed hub motor - one set in either direction as the motor spins in reverse to achieve the lower gearing .Simple and efficient. more drive force applied locks the rollers to the shaft tighter.

regards emma


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## voyager (27 Oct 2015)

Six weeks later and we have lost count of the scalps , its still a fun machine but TBH I haven't the need for the e-bmx now having served its purpose ,

Its up for offer if anyone wants an interesting project to use and perhaps tidy up a bit further . , It is complete with 10 ah lifepo4 battery and charger etc

I have still a couple of full build projects that I need to complete and a quad recumbent to complete before winter sets in .






regards emma


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