Brompton Conversion Kit(s) + Plus other small wheel motors/controllers etc

Aug 27, 2009
3,277
32
48
Cambridge, UK
#1
Hi,

Now I am getting back into doing conversions I have quite a few spares that need to be cleared from my stock. If I cant sell this stuff here I will put it on ebay without the offers to help with conversions and lace up wheels. Hopefully give something back to the forum if Brompoton owners are looking for a little help adding a kit to their bike. Of course you could wait for the new Brompton solution ;)

1. First up I have all the parts new to convert your Brompton using the popular Tongxin narrow width motor. £200 + p&p. You will need to source a battery or see 4/5. below. Includes built up new Tongxin motor in new 16" Brompton rim, controller, throttle and hidden cutout brake sensor.

IMG_0417.jpg

Closeup of the 36v, 260RPM, 83mm wide, 28h motor which will give you around 15mph assistance.

IMG_0419.jpg

2. I do have a few unlaced narrow width Tongxin motors, (will convert most 16"-20" bikes with front hub conversion), and controllers. Looking for about £110 plus p&p for brand new motor. Could probably throw in a free "used" specific controller/throttle/cutout as well. You will need to build wheel/connect up controller, battery etc ( unless you want me to help see 4/5 below).


3. KeyDe kit. Full kit small 1.6Kg 36v, 28h, 260RPM front motor (new unused) with "used" controller for pedelec only function, new unused PAS and cutout brake. £150 + p&p. This will take a 16-20" wheel up to 17mph. You could also use a fully programable controller (I have one for £45) for throttle only if you want. I will lace it up for you as per 5 below.

IMG_0420.jpg

IMG_0421.jpg

4. I have some older small battery packs A123, 10s1p, 36v, 2.4Ah batteries and chargers which you can have free with any of the above. These are used but still have life in them and probably good if you need to test/do small journeys. I cannot post these, so collection only.

IMG_0422.jpg

5. If you live near me (Cambridge) now that I am retired, I am happy to maybe help you with your conversion. All the motors are for 16-20" wheels and again happy to build them onto either for about £40 including rim and spokes. Postage would be more than a bare motor obviously.

Here are some of my conversions for which there are complete build threads on this forum. I have a spare Brompton umbilical/wiring loom again which I can use to help you if you want my offer of help convert your Brompton.

https://www.flickr.com/photos/45051578@N05/albums/72157630015987898

https://www.flickr.com/photos/45051578@N05/albums/72157628035746854

https://www.flickr.com/photos/45051578@N05/albums/72157624967712412

https://www.flickr.com/photos/45051578@N05/albums/72157632417224342

email or pm me if you are interested. I will not post outside the UK as had my fingers burnt with this before :(

Jerry
 

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Apr 5, 2011
2,562
105
83
Brighton
#2
Hi there Jerry,

I just wondered if you can/would build the keyde or tongxin into a 700c road wheel ?
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#3
Hi there Jerry,

I just wondered if you can/would build the keyde or tongxin into a 700c road wheel ?
I/you could do that I even have a very lightly used black 36 hole one (I will post a picture) which I haven't listed. I have tried it in a 700c wheel but given these are 260RPM I had to programme the controller to slow the RPM right down/keep the current within spec. It then worked perfectly in the 700c rim but I only used it for a few weeks to test as I was going to do it for my daughters new bike.

I had relaced it into a 20" wheel as you will see it in the pic but its remained unused. I should still have the spokes for a 700c wheel but would need to buy a new rim.

Jerry
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#4
Here are the pics, as stated currently lace into a 20" rim. I have the controller that can be re-programmed which I could do for you or provide a programming lead for you to play around with it yourself.

IMG_0441.jpg

IMG_0442.jpg

Probably best continue via PM if you are interested.
 
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D

Deleted member 4366

Guest
#5
I don't want to crap on Jerry, but I wouldn't want you to be disappointed either, Kirstin. Personally, I don't think a Tongxin in a 700C wheel is a good idea. As Jerry said, you have to turn the power down, otherwise you end up with a cracked ring, which isn't easy to repair. That's if you can get the spares. Low power in a 700C wheel = wet blanket.
 
Apr 5, 2011
2,562
105
83
Brighton
#6
I don't want to crap on Jerry, but I wouldn't want you to be disappointed either, Kirstin. Personally, I don't think a Tongxin in a 700C wheel is a good idea. As Jerry said, you have to turn the power down, otherwise you end up with a cracked ring, which isn't easy to repair. That's if you can get the spares. Low power in a 700C wheel = wet blanket.
Thanks d8veh, what I was thinking was sticking it in my Ti road bike as a low weight, low power but high speed solution

Obviously I would need to be careful with power (not on start up or steep hills ) and provide decent leg input

I've a 36v 11a rated controller in stock which I thought might be ideal

Barking up wrong tree do you think then ?(both of you ?)
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#7
11 Amp might be a little high. If I recall I tend to set these around 6amps. I do have a controller that you can program lower. If you apply too many amps you can hear the roller bearing "slip"

It worked fine when I tested it in my daughters lady frame (Pendleton) bike. As you know Cambridge is flat so I can't comment on pulling power up a hill but then its a small motor and not meant for that.

Obviously the ideal would be a 201 RPM motor. All these smaller roller bearing motors have to be treated with a little respect i.e. no powering off from stationary. Even on my Brompton with its larger Tongxin I never apply power until I have started moving. That one has done me 10K miles and I only just changed it because it was getting rattly/noisey.

PS I do have a larger front 100mm Tongxin in a 36h, 36v, 201RPM but I was kinda keeping it as a backup should I want to try a front motor in a larger wheeled bike. One reason I love the Tongxins is they freewheel so well with the roller bearings over nylon gears.
 
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Aug 27, 2009
3,277
32
48
Cambridge, UK
#8
Talking myself out of a sale here, but thinking back whatever controller you use it must be capable of reducing the current. Mine has settings for different levels of assistance 1-3 and I had to set this to about 60% of the max 6A power to ensure it worked with this 260RPM wheel in a 700c rim.
 
D

Deleted member 4366

Guest
#9
How heavy are you, Kirstin?
 
Apr 5, 2011
2,562
105
83
Brighton
#11
11 Amp might be a little high. If I recall I tend to set these around 6amps. I do have a controller that you can program lower. If you apply too many amps you can hear the roller bearing "slip"

It worked fine when I tested it in my daughters lady frame (Pendleton) bike. As you know Cambridge is flat so I can't comment on pulling power up a hill but then its a small motor and not meant for that.

Obviously the ideal would be a 201 RPM motor. All these smaller roller bearing motors have to be treated with a little respect i.e. no powering off from stationary. Even on my Brompton with its larger Tongxin I never apply power until I have started moving. That one has done me 10K miles and I only just changed it because it was getting rattly/noisey.

PS I do have a larger front 100mm Tongxin in a 36h, 36v, 201RPM but I was kinda keeping it as a backup should I want to try a front motor in a larger wheeled bike. One reason I love the Tongxins is they freewheel so well with the roller bearings over nylon gears.
Thanks Jerry, it would need to be thin motor anyway to fit the forks

I've checked and I also have a 7a controller in stock
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#12
Well if you want it how about £60 + PP ?

It been in my box of parts for a year so I will test it, unlace it and pack it up for you. I will post a another pic as it has spacers on it I made because the wire comes out just above the shaft and depending on your forks frame thickness you may need them What's the fork spacing ?
 
D

Deleted member 4366

Guest
#13
Thanks Jerry, it would need to be thin motor anyway to fit the forks

I've checked and I also have a 7a controller in stock
Your 7A controller is most likely rated at 7A, which means 14A or 15A maximum. I think that the programmable controller would be the best option.

I've been trying my new Xiongda motor at 11 amps. I found that to be enough power. You're 10kg less, so that would mean that you get the same performance with 10 amps. If you could find a way of reducing the current until you're up to speed, you could run with that.

At only 70kg and with a light bike, it might be OK. The main thing is to help it get started where it makes most torque. Once it's up to speed, you could use much higher current to sustain speed. All the problems are related to high current at low speed.
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#14
Agree a programmable controller would be the best chance of you having success with this motor.

Jerry
 
Apr 5, 2011
2,562
105
83
Brighton
#15
Ok thanks both for your input and also your honesty!

Your price is very fair Jerry and as I'm up near bishops stortford for a week or so soon I am sorely tempted

However, on sober reflection this isn't really what ticks the boxes for me.

So I'm very grateful for help and sorry to have wasted your time
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#16
No problem.

My gut feeling is its not a perfect fit. It can stay in my box of bits for a little longer. It certainly would be suited to a 16"/20" wheel though. You could try and get one from KeyDe at the correct 201 RPM.
 
May 14, 2013
234
28
28
Peacehaven nr Brighton
#17
Hi Jerry
any screw on freewheel disc braked rear hubs / controllers suitable for a 20" rear wheel e-trike ?

I fear another build is in progress

regards emma
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#18
Only front motors and none with disc brake fittings.

I have just purchased a Q100 CST rear motor with cassette fitting. This will be my first rear build :)
 
May 14, 2013
234
28
28
Peacehaven nr Brighton
#19
We have been using Q100 motors for the past 3 years , quite impressed by them . We have 3 of them and one Xiongda 2 speed motor all seem good and reliable.
regards Emma
 
Aug 27, 2009
3,277
32
48
Cambridge, UK
#20
Well I have had a few nibbles but nothing definate. I thought the Brompton kit would go very quickly!

I will leave it another week and then put it all up on ebay.

I guess not everyone checks the classifieds. I am sure there would be a few new users who would have wanted me to help them fit a kit to their Brompton.
 

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