Cheap Brompton Conversion Kit?

[shemozzle999]

I still prefer the push/pull crossing method as I want to obtain the maximum life and reliablity out of the build - which is not cheap when you add all the costs up!

 

[shemozzle999]

I finally managed to find the time to replace the old motor with the new Bafang SWXB.

The wheel build went ok - thanks to catsnapper for supplying the spokes - calculated out at 109mm but could be slightly shorter by 1 to 2mm.

New Chinese rim was good - I have had a few test rides top speed 15.5mph unassisted on the flat - everything feels solid and true.

I would recommend this motor as it is cheap, fits well into the forks with plenty of clearance, solidly built and most spares are available.

https://www.youtube.com/watch?v=BMHZlJAdlUg

Now I can move on to the second build using the SWXU motor but I am still sorting out the wiring assembly as I will be trying to build a pedelec version. I have found a suitable control wiring harness from Outrider but all other parts have been sourced from MW Motors.











I have just received an order from them for the cable connector boxes and they kindly sent me a sample of their 5:1 control cable system.

electric bicycle kits connector box,View Electric bicycle kit connector box, Product Details from Outride Technology Co., Ltd. on Alibaba.com

5-in-1 mouse water-proof connector cable,View water-proof connector cable,OutRider Product Details from Outride Technology Co., Ltd. on Alibaba.com

It has 4 handlebar outlets:

2 x 2 wires (brake) - white (signal) / black (0v) - both commoned together through the junction point

1 x 3 wires (throttle) - grey (signal), violet (signal) and black (0v) commoned through the junction point

1 x 5 wires (display) - blue (signal), green (signal), yellow (battery +ve), red (5v) and black (0v) - commoned together through the junction point

The main cable to the controller has 8 wires - all wires being 7 strands of 0.2mm dia tin plated copper wire rated 5A and I believe PTFE sleeved. The socket end could be soldered directly to the controller pcb.

All cables have moulded gold plated plugs/sockets color coded and polarized.

The moulded junction has 2 slotted round lugs which can be compressed to pass through a round hole then snap out to retain the junction block onto a mounting plate.

I think I have found a suitable method of attaching it to the bike using a special terry clip after attacking it with some needle files to get it to fit.

https://www.youtube.com/watch?v=MYopX0LtF_E

 

[jerrysimon]

Nice job and the vids show everything really clearly. That is going to be one nice neat looking conversion.

Thanks for posting the detail.

Regards

Jerry

 

[shemozzle999]

Thanks Jerry, the terry clip is available here:

Tool Storage super Clip Wall Mounted Backplate Spring Steel 38mm 1.5" TERRY x 2 | eBay

 

[shemozzle999]

Now I have to spread another set of forks to fit the SWXU motors they will be slightly narrower that the SWXB.

After using the bar method to spread to 80mm, I am using a turnbuckle and jack screws to take them out to their final size.

 

[shemozzle999]

I add more nuts to the outside of the screw jack (on the inside of the forks) as the spreading stages progress to keep the inside threads located well within the body of the turnbuckle and don't forget to keep the threads oiled.

 

[shemozzle999]

Job done - next thing to do - file out drop outs from 8mm to 10mm.

You need to expand them to approximately 130mm for them to spring back to just over 100mm.

 

[jerrysimon]

Great posts shemozzle999 showing others how to spread Brompton forks.

I think spreading steel forks is not really that big a deal (they only cost £50) as I have done a few now, but when I had to spread my £250 Ti ones (even only to accommodate a 83mm wide motor) I was sweating

Again filing out steel dropouts is not to0 hard either, unlike the Ti ones that took me quite a long time to remove Titanium material!

Jerry

 

[shemozzle999]

No worries Jerry if anything goes wrong you can always fix it!

https://www.youtube.com/watch?v=4q7LmVSgIPk

what about even more expensive ones:

https://www.youtube.com/watch?v=p92Stnnigjs

 

[jerrysimon]

Ha ha

The first video was interesting. I meant though if the dropouts failed on the welds cracked

PS I have just seen these kits on ebay for small dropout widths/wheeled bikes ?

Electric bike kit for Dahon Brompton folding bike 36v 250w, without battery | eBay

I wonder what motor it is ?

Not a bad deal if you don't want to import etc and ready built into, I hope, a 349/16" rim.

Oh and radial my favorite

PPS and looks like a 28h hub!

OMG they are Tongxin Nanos I think!

Snap them up you wannabe E Brompton builders

Regards

Jerry

 

[Jeremy]

Yes, they are the new Outrider motors, that use the Tongxin roller drive system. My understanding is that the Tongxin motor was a university project and the idea has now been licensed to two Chinese manufacturers, Outrider being a spin off (with the same staff) of the original Tongxin manufacturing team.

The Nano was just a marketing name (together with an absolutely ludicrous price mark up) that was used by a UK dealer in Marlborough. I tried to buy a Tongxin from him several years ago, but his customer service was close to non existent. After waiting weeks for a reply from the chap in Marlborough (just 20 miles up the road from me) I bought a Tongxin motor from Justin (in Vancouver, 6000 miles away), for around 1/3rd the price(inc delivery) and delivered inside a week.

 

[jerrysimon]

Yes you are again correct Jeremy. I had forgot Nano was a rebrand/UK name and that company was plagued by poor customer service fueled by over demand.

I guess I just got use to referring to them by that name. The mark up for these Brompton kits has been common by many of the resellers as you say.

Last time I spoke to Outrider they said that their new light weight Goldant motors would eventually replace these Tongxin "Nanos".


Regards

Jerry

 

[Johan van der Spoel]

I think spreading steel forks is not really that big a deal (they only cost £50) as I have done a few now, but when I had to spread my £250 Ti ones (even only to accommodate a 83mm wide motor) I was sweating

Jerry

Do you have any experience on widening aluminum forks? Will this be a sweaty job as well? For me this would be the case when converting my Dahon Mu.

Regards,
Johan van der Spoel,
NLD

 

[shemozzle999]

Hi Johan,

It will need you to closely examine the dimensions of proposed motor you intend to use to ensure the side walls will have sufficient clearance after widening the forks, if not, then it may mean finding some replacement forks or alternatively you might consider fitting a rear motor conversion like this:

The BionX Electric Folding Bike

 

[Deleted member 4366]

Do you have any experience on widening aluminum forks? Will this be a sweaty job as well? For me this would be the case when converting my Dahon Mu.

Regards,
Johan van der Spoel,
NLD

Once you push aluminium beyond it's elastic limit, it work-hardens as it moves, which resists further movement. If you then try and move it further, it snaps. To be safe, you need lots of heat; Bend a bit (use jack-screws); re-heat to stress relieve, then bend a bit more; repeat until you get to where you want. I've never used this technique on forks before, but it works on normal aluminium tube.

 

[shemozzle999]

Update.

I have been delayed in completing the SWXU build because of a incompatibility problem with the Wuxing brake levers. They have an open clevis arrangement and require the older style Brompton wide barrel ended inner cables which are now obsolete ( QBRCABFA-M/P and QBRCABRA-M/P ).

I hope I have found a supplier who appears to be selling them off cheap - I will report back here if they are the right ones for the job:

Bikefix - the bike shop on your desktop

They also appear to have stock of the obsolete yellow walled tyres @ £5 each:

Bikefix - the bike shop on your desktop

And finally they also have a passenger chair for the Brompton:

Bikefix - the bike shop on your desktop

review here:

http://documentally.com/2011/08/20/a-child-seat-for-a-brompton-folding-bike-review/

 

[Johan van der Spoel]

Hi Johan,

. . or alternatively you might consider fitting a rear motor conversion like this:

The BionX Electric Folding Bike

My rear hub is a Nuvinci N360 . .
Reading all courtesey on these topics my arrows are aimed now on the G209 or the Goldant hub for a front wheel conversion.
Both hubs are available at suppliers here in NLD (unfortunately not at Chinese picing).

 

[shemozzle999]

Hi Johan,

Even with the small Goldant motor I think you would have to set a secondary bend in the forks to accommodate the parallel walls of the motor to give you a clearance.

This would mean you would have to initially use the expander bar method Jerry detailed to give the desired drop out width then use another spreader further up the forks to bring them parallel, while still holding the drop outs in position with the expander bar.

I did look into this for my conversions and I found this device which may be suitable but I didn't buy one so I am unsure whether it could do the job:

Lisle Exhaust Manifold Spreader #13000 | eBay

 

[shemozzle999]

Just found this link to and alternative 20" fork with 100mm dropout width from an old post on bikeforums.net although the shipping charges may be restrictive:



Downtube Aluminum Fork



Link to forum post:

http://www.bikeforums.net/archive/index.php/t-148767.html

 

[Johan van der Spoel]

Shemozzle,

Thank you for the help and great advise. I will defenitely look things up.
Planning to convert the bike this spring, so I'll have some more time.

Regards,
Johan