# Planning scratch built reverse trike



## Woodsmith (Jun 5, 2008)

Almost the same spec and starting point as me.
Only real difference is I want to get to 70mph as my journies are almost always on the motorway given I live by a junction.

Have you looked at the Enertrac hub motor?
It might be the sort of thing that keeps things light and compact.

The only things with the MSVA and new registration, from what I gather, is that you have to have all new parts with a paper trail of invoices and only one reconditioned part. If you can keep to that then you will be doing well.
I can't as I am using a lot of old parts and scrap so I will have a Q plate.

My lightweight, skinny wheel, design was scuppered when I came across a rather nice 11" motor. It then became a hot rod build.

I think you will be best with lithium.
Andrew Kirk used lead in his trike and was disapointed with it.


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## Salty9 (Jul 13, 2009)

Have you checked the Locost Forums? 

http://www.locostbuilders.co.uk/

and: http://www.locostusa.com/forums/index.php

They are mainly for 4 wheels but the build process should be similar to your requirements.


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## MalcolmB (Jun 10, 2008)

Hi Blip

I've been thinking about doing something very similar for a long time (maybe next project...). Your performance goals are pretty modest, so that makes things a lot easier. If you're looking for readily available bits that don't cost too much I would look at a mini or metro front end. OK, I'm biased and it's old tech, but there are loads of good second-hand parts and nice aftermarket performance parts if you want to make it lighter/faster. 

Complete motorcycle rear ends often come up on ebay for next to nothing, so all you need to fabricate is the chassis to join them and your fibreglass skin. The simplest drive arrangement would be something like a 7" series wound motor mounted as close as possible to the rear wheel and driving it through a single chain reduction. Front wheel drive would be a bit less skittish (and less fun), but could easily be done with a chain drive diff. Finding the right motor can be difficult, but if you're prepared to scour the local scrapyards for old fork lift motors you can probably find something useful, and there's plenty of advice here on what to look for.

I used top quality lead acid batteries on the first version of my motorbike, but they didn't survive for long. They just don't like rapid discharge, especially if you want the smallest pack possible to keep weight down. There have been a few batches of barely used lithium cells come up on ebay uk and the forums recently. I'd suggest designing your machine with plenty of space for the batteries and just keep an eye out for what comes up.

For a lightweight aerodynamic trike, 5kWh of lithium cells should easily give you 30 mile range at the speed you want.


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## Woodsmith (Jun 5, 2008)

If you wanted front wheel drive you could fit a diff from an IRS axle between the drive shafts and then add a motor tot he nose of the diff. That would save having a chain drive at the front.

The motor could be ahead of the diff helping to keep weight over the front axle for that 1/3 overall weight per wheel.


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## blip (Oct 17, 2011)

Thanks for all the replies.




Woodsmith said:


> Almost the same spec and starting point as me.
> Only real difference is I want to get to 70mph as my journies are almost always on the motorway given I live by a junction.
> 
> Have you looked at the Enertrac hub motor?
> ...


Thanks for the link, lithium definitely sounds awesome. If I can budget for lithiums then that's what I'll go for.

You're right about msva, I'll see if I can go for a new plate but if not i'd be quite happy with a Q (that's what my kit car got)



Salty9 said:


> Have you checked the Locost Forums?
> 
> http://www.locostbuilders.co.uk/
> 
> ...


Hi Salty, i've been on locostbuilders since 2004, very useful forum!  The chassis/suspension/bodywork area of the build is something I have an idea of what to do and I'll be posting on locostbuilders about it no doubt at some point, it's the electric side of things that I need most help with.




MalcolmB said:


> Hi Blip
> 
> I've been thinking about doing something very similar for a long time (maybe next project...). Your performance goals are pretty modest, so that makes things a lot easier. If you're looking for readily available bits that don't cost too much I would look at a mini or metro front end. OK, I'm biased and it's old tech, but there are loads of good second-hand parts and nice aftermarket performance parts if you want to make it lighter/faster.
> 
> ...


Thanks for the info, malcolm! I think i'd like to stick to rwd, the chain reduction idea sounds good. I guess I can experiment with changing sprocket sizes too. I like the idea of using a bike rear end, would save a lot of fabrication. I might make my own front end, but i'll look into using subframes from other vehicles too. It would be ideal if I could make the vehicle 130cm wide or narrower so that I can have a single headlight (I'm planning to make it as small as I can) so maybe using an ATV or big quad bike suspension/wishbone parts could work...


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## MalcolmB (Jun 10, 2008)

If you plan to tour the scrapyards for a motor you should ideally look for a DC series-wound motor with a diameter of around 7 inches. These generally have four terminals. Try to find a traction (drive) motor rather than a pump motor, as they're designed for continuous rather than intermittent use. If you find a motor it's a good idea to take photos (including one of the commutator and brushes if you can get access) and post them up here for some advice.

The Enertrac hub motor that Woody mentioned makes for a very neat and simple installation, but it's not cheap. Another option would be a brushed permanent magnet motor such as an Etek or Agni, which are very light, but you would be pushing these to their limit with an all-up weight that's likely to be over 400 kg.

Good luck!


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## Woodsmith (Jun 5, 2008)

This place might be worth your while looking at.
Fork Truck Breakers near Chesterfield. A small warehouse full of motors at around £300 each.

You can get cheaper pulling it out from a forklift yourself but they have them on the shelf to play with.


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## GREENHORNET (Dec 25, 2012)

Hey Blip,

I was originally going to do the same as you. I got as far as buying the little diesel motor and then I realized why diesel I only drive 20miles a day for 99% of the year. So long story short I came to the same conclusion as you Electric Reverse Trike  

So I am currently in the on going design process but I have purchased the chassis as well as the rear swingarm, Electrically adjustable monoshock, disc break, Rear wheel and tire. 

I am currently cleaning up the chassis and applying rust proofing. Once complete I will attach the aluminum single sided rear swingarm and suspension. Most likely before the end of next month I will have the rolling chassis completed. 

Then on to the drivetrain hurdle!

My goal is to have a fully enclosed 2 passenger side by side electric reverse trike by the end of summer to tear up the streets with  

Good luck Blip good to see another Electric Reverse Trike (ERT)! 

Take Care,

GreenHornet


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## blip (Oct 17, 2011)

Hi Greenhornet, that sounds like a good plan  I didn't realise I'd made this thread so long ago. I've not given up, just had to put the project on hold but will be doing more on it this year. I look forward to seeing any progress you make!


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## vmrod (Jul 2, 2010)

You may get some good ideas from RIley's XR3. 

I built the chassis so far, and have driven it for 100 miles around the neighborhood. It is front wheel drive, but the original plans have previsions for rear wheel drive (with electric motor back there).

http://m.youtube.com/watch?v=Ctl3FjS9-BI

Constructing the chassis is not for the squeamish, but the final product is awesome. I documented the build here;

http://xr3.proboards.com/index.cgi?board=diary&action=display&thread=19

Before I resume construction on the body, I am completing my electric Opel.

It is LOTS of fun to drive!


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