Brompton M2L-X (Titanium) - Super Lightweight Pedelec Conversion

[jerrysimon]

Well its finally done. For details of this new lightweight motor (1.4kg, 100mm diameter) made by Tongxin and known as a Goldant motor, see this thread.

Brompton unfolded

Brompton parked

Quick reminder of how the two Tongxin motors the current Nano (2.1kg) and new Goldant motor compare side by side. Note this was an earlier install pic, before I fitted the anti turn/fall out washer into the dropout/frame hole.

Given the whole Jubilee thing I thought the new stickers would set it off nicely

I had actually thought about this a while back, being British made and that the white needed something to set it off.

The bike carry weight is down to the same as a stock steel Brompton M3L i.e. 11.5kg.

More posts and details to follow.

Regards

Jerry

 

[jerrysimon]

Fitted with bag ready to go.

Based on my umbilical connection from my current Brompton, using the Maplin sourced eight pole Bulgin plug and socket.

This inside the pocket.

The other end of the Bulgin plug in its parked position on the carrier block, which has a modified female Bulgin socket attached to it.

PS note the frame clip extension spacer piece to space the frame clip out to clear the end of the motor shaft/rubber nut cover and clip on the frame when folded. This is the second one I purchased from shemozzle999, a very cleverly designed and useful part!

 

[jerrysimon]

This is pedelec only NO throttle. To get the motor to operate correctly you have to fit the pedelec ring and sensor on the non-crank side. Fortunately this also allows you to fit it on top on the BB frame which is good, because fitted underneath the BB it fouls the fold. I had to modifying the pedelec ring fairly extensively, as well as taking some material off the crank face itself to allow everything to fit in the small clearance between frame and crank on the BB shaft.

Five min epoxy ensures nothing is going to move or fall off. The cable tie holds the sensor cable firmly to the frame and then follows the route of the other cables to the front of the bike. The loop/slack in the sensor cable is required to ensure it moves forward and backwards with the other cables when folded.

Finally I have a switch on the cutout brake circuit to switch the pedelec in and out as and when I need it and of course one cutout brake to kill the motor when braking. This still needs sorting as I want to try another switch and if possible adapt the stock Brompton brake, to turn it into a cutout brake. The generic cutout brakes are big, ugly and a little industrial.

Next I will provide some details of how it rides and how it compares to my existing Brompton with a throttle based Tongxin Nano kit.

Regards

Jerry

 

[benjy_a]

Finally I have a switch on the cutout brake circuit to switch the pedelec in and out as and when I need it and of course one cutout brake to kill the motor when braking. This still needs sorting as I want to try another switch and if possible adapt the stock Brompton brake, to turn it into a cutout brake. The generic cutout brakes are big, ugly and a little industrial.

Jerry

I'd really like to do this as well..I'm thinking magnetic reed switch somehow installed into the Brompton brake lever.

Are there any reed switches that anybody knows about which disconnect with the presence of a magnet?

I did have a look for some small normally closed push switches but failed to find any suitable which could be tapped into the body of the lever.

 

[jerrysimon]

Ben, someone else has done it with other brakes, I will search and find the link.

Update - Found it here. Was posted by a guy called Dave who left the forum after a falling out and seems to have deleted the pictures

Regards

Jerry

 

[cwah]

Crazy work Jerry. I love your new bike

Too sad you don't like torque or higher speed

 

[jerrysimon]

Thanks cwah. We are both at two ends of the spectrum for sure

Regards

Jerry

 

[benjy_a]

Ben, someone else has done it with other brakes, I will search and find the link.

Update - Found it here. Was posted by a guy called Dave who left the forum after a falling out and seems to have deleted the pictures

Regards

Jerry

Thanks Jerry but reading this it looks like he has installed the switches on the cables and calipers which I don't want to do. I'd like to keep everything installed into the brake lever itself to avoid any further (folding) cable runs.

Google reveals that sub miniature push to break (normally closed) switches do exist...I just can't find any to buy!

Ben

 

[dingrpdl]

Here is an Instructable on adding a switch to an existing lever. It does involve drilling and tapping. You can probably do something similar with good ol' epoxy.

Add a brake light switch to a bicycle brake lever


And here is another implementation I found on Endless-Sphere.

http://endless-sphere.com/forums/viewtopic.php?f=2&t=36728&p=532936

Richard

 

[dingrpdl]

Jerry,

Thanks for documenting your conversion projects. Your attention to detail and care to preserve the original, clean look of the Brompton was an inspiration for my first Brompton electric conversion and will be for my upcoming second build.

Richard

 

[benjy_a]

Here is an Instructable on adding a switch to an existing lever. It does involve drilling and tapping. You can probably do something similar with good ol' epoxy.

Add a brake light switch to a bicycle brake lever

Richard

Thanks...will give this a go.

 

[polyphasic]

I placed the order today for the Goldant motor (98SWXN36 V brake motor/80mm/36V/260rpm/28H (28 hole) and WZK36 external controller and speed sensor with magnetic disc). Sky Zhang said the delivery of the V motor, controller, sensor/ring to the U.S. "may need to be 15 days, right now our factory is a little busy". I ordered a 28 hole. Now I just need to figure out what else I need to order to complete the system. Thank you for posting all this helpful information. Looking forward to some intelligence in my motor. lol

 

[jerrysimon]

Google reveals that sub miniature push to break (normally closed) switches do exist...I just can't find any to buy!Ben

Just been out to have another look at my Brompton brake levers. The ones on this 2011 model are different to the one on my 2009 model. The 2011 versions look like they will take a subminiature switch. Looking at the existing cutout brakes I think I will be able to move the switch in that across to the Brompton brake with a little modification. Will post some pics later.

Many are happy not to fit them and on a throttle based system, would agree. Maybe it is just that I am not use to pedelec but I feel the system benefits from one. Slowing down cadence when approaching a corner or stopping but the motor tends to "run on" and the cutout brake I think deals well with that.

I would probably have fitted a throttle but this little motor seems much happier with the stock controller. Other controllers I tried seemed to make it run very rough and the acceleration curve of the throttle was not very linear. Clearly this controller has been designed specifically to get the optimum performance from the motor.

Regards

Jerry

 

[jerrysimon]

Thanks for documenting your conversion projects. Your attention to detail and care to preserve the original, clean look of the Brompton was an inspiration for my first Brompton electric conversion and will be for my upcoming second build

No problem. For me posting and sharing on the forum is part of the fun. Its good to see that you "get" my desire to preserve the look of the Brompton. The real challenge here has been both getting the pedelec sensor position correct so that it does not foul the fold and sorting out the controller with an umbilical plug so that it could be mounted off the bike/in the bag. I was at a point of giving up as no matter what I seemed to do, introducing a plug into the system effected the sensor causing it to cut in and out when first setting off.

I must of soldered up and de-soldered the connector half a dozen times before I tracked the problem to the second plug connector for the sensor. Removing it sorted the problem but then when I tried to use a smaller 9 pole connector it happened again. In the end I went back to using the same 8 pole Bulgin plug as on my other Brompton which seems to be the only way I could get it to work.

At one point when I was ready to give up and mount the controller on the bike, the only place it seems to fit without effecting the fold and keeping the wires up front is on the main steerer tube. Problem is it looks ugly with wires everywhere and must be positioned exactly right to maintain the fold. Being on the steerer it also moves and turns and is overall not very pratical.

Ugly!

I will do some more pictures to show the sensor cable run on the other side and some more pics of how I modified the sensor ring and left hand crank. Also when fitting the pedelec sensor itself you need to build up underneath it to raise it up slightly to get the correct gap away from the sensor ring edge.

Regards

Jerry

 

[jerrysimon]

Sky Zhang said the delivery of the V motor, controller, sensor/ring to the U.S. "may need to be 15 days, right now our factory is a little busy". I ordered a 28 hole. Now I just need to figure out what else I need to order to complete the system. Thank you for posting all this helpful information. Looking forward to some intelligence in my motor. lol

Yes my wife had great fun with that. Ordered the 28h one is a good move if you want it for the Brompton. That way you can use the stock 28h rims which I prefer (I have some drilled with 36h) rather than the Sun CR18 rims which although stronger and better built are very hard to get tyres off and on because of the shallow well. Also at the moment none are available!

Sky is very good and her good English and communication skills make the whole transaction less frustrating than some other Chinese contacts I have had to deal with.

You will need a Brompton rim, spokes (catsnapper is fast, efficient and very helpful), plus Bulgin plugs (linked to Maplin earlier) if you want to mount the controller off the bike. In addition wire, heatshrink, solder, epoxy glue etc. You will also need some washers/spacers to fit the motor into the forks to center it.

Probably most of all though you will need patience. Hopefully though I have ironed out some of the most frustrating issues for fitting it to the Brompton, in this first build.

What battery are you going to use ?

PS Oh and a spacer for the frame clip, shown earlier designed and provided by the forum member shemozzle999

Regards

Jerry

 

[jerrysimon]

Some pictures of the sensor wire routing to cope with the fold.

Close up of sensor wire loop to provide slack.

Folded/Parked position

Unfolded ready to go. Note how the wire moves forward and backward, hence why you need some slack!

Jerry

 

[jerrysimon]

The stock Brompton anti rotation/fallout washers modified (right) to fit the larger motor shaft.

You will need an extra one (I had a spare anyway). Not sure these are really needed given the low power of the motor but I preferred to err on the safe side. You could use the stock ones that come with the motor but they are quite thick and it gets tight length wise on the shaft (cable side) after you fit the spacer washers, mudguard stay loop, nut etc


Jerry

 

[jerrysimon]

Ok as I am on a roll I guess I should say something about the ride. A bit of a ramble but here goes. Firstly be aware I live in pretty flat Cambridge so not many hills to test it on. We do have one very steep hill on the outer edge of the city where I live, so I will go an test it out on that some time soon.

As explained previously I am a throttle jockey, so this whole pedelec thing is new to me.

This setup is very smooth once you get it working properly. I like the a cutout brake to kill the motor when having to stop quickly or when coming to a stop as the pedelec seems to run on after you stop pedaling. I do however fine myself slowing cadence down to slow down the motor when coming to a junction or an expected stop. The controller seems to shut the motor down/engages the freewheel with a "clunk", probably fine and I am told by Tongxin part of the design but slowing it down first prevents that.

From a standing start the motor kicks in after about one revolution of the crank. The system is very smooth and accelerates linearly. As I understand, common in most pedelec systems, it does however want to take you up to full speed quickly which is again why I like the cutout brake if I need to stop suddenly. I would say this Goldant model by Tongxin is probably a little bit louder than the Nano version when running buts its still almost silent. Just a slight wine as it gets up to speed.

Power wise its fine for the Brompton and my weight (13 stone). Its hard to compare with my existing Brompton given it is lighter. I would say power seems very slightly less than the Nano with throttle but it still zips along. With pedelec you have to keep cadence up to keep the motor working if you want to go up hills/inclines. The throttle option certainly makes for a more lazy ride though I want to pedal more hence why I have stuck with pedelec. This lighter Brompton is MUCH easier to ride unassisted even though my steel one rides well unassisted as well. Speed wise on the flat it seems about the same (I have yet to fit a trip computer). The freewheel is nice and again appears the same/similar to the Nano.

I am planning to use it on my daily commute because as of yet we do not know how reliable the setup will prove.

So overall I am pleased. Its definitely a light assist setup. No powering away from standing starts with your throttle (there isn't one anyway). I think if you have a nice light bike and want to add a little assistance this may be just the ticket. That is the object of my project here anyway.

The real challenge for me has been the pedelec setup/fitting which seems a little quirky, but probably fine if you fit the controller to the bike.

I have a few more mods to do re the switch and the cutout brake and will post details as and when I do them and update the thread if there are any motor or controller failures.


Regards

Jerry

 

[polyphasic]

Sky is very good and her good English and communication skills make the whole transaction less frustrating than some other Chinese contacts I have had to deal with.

Sky was more responsive than most American companies. Smooth transaction so far. Are you sure Sky is a woman? I knew a guy named Sky. It's one of those names that could be male or female.

What battery are you going to use ?

Not a clue, that's my next thing to research to death. From the little that I've read so far, it seems maybe I should look for something a few amps higher than 36Volts, like a 39Volt battery. I'd like it to be below 300 watt hours since that's the maximum size allowed on U.S. airlines.

... sorting out the controller with an umbilical plug so that it could be mounted off the bike/in the bag. ... the only place it seems to fit without effecting the fold and keeping the wires up front is on the main steerer tube.

Your controller on the handlebar stem is the same location that nycewheels has their controller.
[video=youtube_share;ChoVvbQ1_lo]http://youtu.be/ChoVvbQ1_lo[/video]
I don't know the weight of nycewheels controller, but when folding the bike the stem seems heavy. So much so that I questioned them whether the controller could be located in the bag. But it's also much larger and bulkier. I don't know how much the Goldant controller weighs, but it looks tiny in comparison. I toyed with the idea of getting the 98mm Goldant motor with built-in controller just so I wouldn't have to deal with it.

The throttle option certainly makes for a more lazy ride ...

Funny that you should say the Goldant keeps you from choosing to a lazy ride. When I test road the nycewheels bike, I could totally see myself throttling all the way to the coffee shop and back. Sounds more like a bicycle-like riding experience which I like a lot.

Speaking of comparing throttle Nano to pedal Goldant. Were you aware that electricwheel offers an option to turn the Nano into a pedelec? It claims in it's FAQ that for 50 pounds, they'll add a pedal sensor to make it "legal" in the European countries that require pedal sensors. I imagine these are laws that aren't enforced, but I guess I was surprised to see the Nano could be throttle and/or pedal sensing. Not sure if it works the same way as the Goldant.

I have a few more mods to do re the switch and the cutout brake and will post details as and when I do them

Looking forward to the cutout brake and switch, because I'm still not sure what that is but I need to keep reading. I assume this is to turn the motor off quicker for sudden stops. I recall you talking about adding a switch to turn the assistance on and off so that you could use the bike without assistance. I assume that's for convenience from having to just unplug the battery.

Would you be able to do estimation on battery consumption for your work/home commute in comparison to the Nano? I'm not sure if you've ever measured how much juice the nano used on average for the commute. Sorta like an estimation without a cycle analyst to figure out the Wh/km. It certainly seems very similar to the Nano in performance based on your review.

 

[John in DC]

Hey Jerry -

Do you know if the controller would fit inside of the main frame tube? Putting it inside probably not a good idea but curious to know nonetheless.

Rgds...

- John