Hi everyone, long-time-reader-first-time-poster.

 

I can't find any examples of people using the Cute Q70 motor for a Brompton conversion - I'm amazed and confused! Am I missing something obvious? It seems to have been available a while and fits the front forks without having to spread them.

 

Assuming there's no reason it won't work, I'd appreciate some advice on the parts I'd need for a conversion - BMS don't offer a complete conversion kit. How does the below look?

1. Q70 motor, 328 rpm (https://bmsbattery.com/motor/868-16985-q70-36v250w-front-driving-v-brake-hub-motor.html#/214-rpm-328)

2. Bottle battery/ built in controller (https://bmsbattery.com/ebike-battery/932-17760-36v10ah116ah14ah-new-bottle-battery-pack.html#/138-color-silver/323-controller-s06s_hall_sensor_sine_wave/380-display-lcd3/514-cells_capacity-samsung_35ah_14ah) with these selections:

- Display: LCD 3

- Controller: S06S Hall sensor sine wave

- Cells/capacity: Samsung 3.5AH / 14AH

3. S-V12 pedel sensor (https://bmsbattery.com/parts/705-dual-hall-sensor-12-signals-easy-assembling-pas-ebike-kit.html)

4. Thumb throttle (https://bmsbattery.com/parts/904-thumb-level-throttle-with-waterproof-plug.html)

 

Total cost incl. shipping = £390

 

Are all of these parts compatible? Are they easy to fit? I have no electrical know-how ( can't solder, don't have a volt meter, wouldn't know what to do with one if I did) but I'm a competent home mechanic. My plan is to mount the battery unit on the Brompton main frame, in front of the seat pillar.

 

Any and all advice would be greatly appreciated.

 

- Tom

Hi Tom, hard to be categorical from the details available but going back to basics- I'd be concerned about the physical fit (esp the bottle mounted on frame) and also would want include brake cut-offs in your design.

I'm trying to pull together info on conversion kits for my Brompton too which I'll post up before long, but I've found nothing so far less than 550gbp! I would be interested if you dig out any examples of folk using the q70.

The Q70 is new. That's why you can't find any info on it. Q85 was the previous best motor for the Brompton, which involved spreading the forks by 10mm to fit (no problem). Now I guess that the Q70 would be better. The KT Sinewave controllers work very well with all the other Q series motor accept the sensorless ones, so should be fine with the Q70.

 

That bottle battery is too big for a Brompton. It would look ugly wherever you mounted it.

 

I've converted a Brompton and learned a bit along the way. If I did it again, I'd mount the controller in a box above the forks. That would mean that you'd have to shorten most of the wires on the various parts, but it would make it much easier to fold.

 

This is the battery that I'd use. It fits in a springy bottle-holder that you can mount wherever you want - probably on the frame in front of the seat tube where it won't interfere with the fold. Buy two if you need to go further than 20 miles. There are new versions now, but I haven't tried them.

https://www.aliexpress.com/item/32820640934.html?spm=a2g0s.9042311.0.0.47494c4d0wnXul

 

You need a Sun CR 18 16"rim to go with the motor. Chinese 16" is too small. That means you have to lace the wheel yourself or get someone to do it for you.

 

The Brompton I converted had non-standard sized handlebars (not 22mm), so I had to dremmel out the throttle clamp.

 

I'd use the KT-LCD4 and controller from Topbikekit, but it might not fit if your handlebars are bigger than the standard 22mm. I wold go for the 12 amp version of the controller.

 

These little motors give immense torque in 16" wheels, like double what you'd get in a 26" wheel, to get you up any hill, but you'll be climbing at 4 mph instead of 8 mph.

If you’re happy to wait until next March (or maybe longer) the new Swytch kit looks good. I have the previous version which is very good with only a few niggles. The reduced price offer is supposedly only available for a few more days if you are interested. If your Brompton is less than 3 years old (when they changed the bottom bracket) everything fits well.

 

https://www.indiegogo.com/projects/swytch-the-world-s-smallest-lightest-ebike-kit#/

I am also wanting to convert a brompton that is capable of 19-20mph for off road use. Interested to hear how you get on.

 

I did see below on Ebay. Would the 16" version fit a brompton easily I wonder?

 

https://www.ebay.co.uk/itm/Electric-EBike-Conversion-Kit-Front-Wheel-Motor-Hub-36V-350-500W-16-29in-700c/392384822144?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Db61056fbe7e845bc833f4a18e44a3d25%26pid%3D100675%26rk%3D4%26rkt%3D15%26sd%3D113932039634%26itm%3D392384822144%26pmt%3D1%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aeab2d3da-fe44-11e9-9e6f-74dbd1801ea2%7Cparentrq%3A31a2628316e0a9c98cd174d3fff5e758%7Ciid%3A1

I am also wanting to convert a brompton that is capable of 19-20mph for off road use. Interested to hear how you get on.

 

I did see below on Ebay. Would the 16" version fit a brompton easily I wonder?

 

https://www.ebay.co.uk/itm/Electric-EBike-Conversion-Kit-Front-Wheel-Motor-Hub-36V-350-500W-16-29in-700c/392384822144?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Db61056fbe7e845bc833f4a18e44a3d25%26pid%3D100675%26rk%3D4%26rkt%3D15%26sd%3D113932039634%26itm%3D392384822144%26pmt%3D1%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aeab2d3da-fe44-11e9-9e6f-74dbd1801ea2%7Cparentrq%3A31a2628316e0a9c98cd174d3fff5e758%7Ciid%3A1

That kit will have the wrong size wheel. As I said, Chinese 16" is smaller. Also, the motor will have a 100mm axle, which will mean substantial stretching of the Brompton forks to get it in and awkward folding thereafter.

 

If you want 20 mph, you have to go up to 48v, which will mean some sort of custom battery installation. A pack in the bag on the front would work, but will be heavier. A conversion with anything more than a 26 cell battery pack will make the bike too heavy to fold and carry. That's why I recommend a detatchable bottle battery.

Thin king of how and where to mount the battery, I found a few adapters available for bottle mounts using the front luggage bracket - or in this case completely replacing it. E.g. ...

 

https://dinokiddo.me/shop/mudguards-stays-and-fittings/custom-black-cnc-water-bottle-cage-adaptor/

 

Or this one:

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=322070832686&category=62132&pm=1&ds=0&t=1506844718000&ver=0

 

Not cheap but these would allow for a range of battery types to be mounted without interfering with folding the bike. vfr400 's point is still valid re. looks but then beauty is in the eye of the beholder..

 

Tom - going back to your original post about compatibility, From what I can see these look compatible. One thing to check though is that the connectors all match up. If not then you may need to buy a soldering iron and get onto youtube!

If you’re happy to wait until next March (or maybe longer) the new Swytch kit looks good. I have the previous version which is very good with only a few niggles. The reduced price offer is supposedly only available for a few more days if you are interested. If your Brompton is less than 3 years old (when they changed the bottom bracket) everything fits well.

 

https://www.indiegogo.com/projects/swytch-the-world-s-smallest-lightest-ebike-kit#/

Hi Jonah - I meant to get back to you on this. How did you get on with the Swytch? I had a look and at the discounted prices they are very good value for money. It's a lot of risk to take on though, if they don't come good.

I am going down the DIY rout.. I'm incurable!

The Swytch kit is basically a normal Chinese electrical system with the controller and battery in a bag that can be removed thanks to a fancy connector. There were problems with that connector. The lighter weight of the new battery would probably improve that, though by now, they must have revised the connector. maybe that's why they've invented the smaller version. You can easily do the same yourself, but without that connector as a weak point. There are plenty of handlebar mounted bags on Ebay for you to put in whatever battery or controller you want.

https://www.ebay.co.uk/itm/Bike-Bicycle-Front-Basket-Large-Capacity-Canvas-Waterproof-Handlebar-Bag-G/323771761698?hash=item4b624d0422:m:mRQ58P0Y-O0AqSi0bB-6Xkw

 

I tried the Swytch kit, but the weight on the handlebars was immediately apparent, and it gave weird handling. You'd probably get used to it.

Hi Jonah - I meant to get back to you on this. How did you get on with the Swytch? I had a look and at the discounted prices they are very good value for money. It's a lot of risk to take on though, if they don't come good.

I am going down the DIY rout.. I'm incurable!

I did a DIY conversion on my Thorn but thought I’d try the Swytch out, replacing a powerful but heavy conversion on my Brompton. It was a few months late on delivery but the kit itself was good and easy to fit. I couldn’t fit the PAS ring on the crank so I use throttle only to control. The newer Bromptons do have space for the PAS to fit. Other than this it works really well and it’s very easy to remove and replace the battery when needed. The new version fits directly on the luggage bracket so would be better still (in my opinion). I think Swytch have learnt a lot over the last 18 months and appear to be better organised and resourced now. Their communication and support has also improved.

Thanks guys - yes I'd seen a few comments about the comms

[mention=4809]vfr400[/mention] , going back to the question about compatibility, this all looks fine to me, based on the power demands of the system but how can you check compatibility for components like the LCD monitor ? Is it a question of checking the connectors (easier said than done given they often don't get shown in pics). I asusme there more to it than that. Any thoughts?

Hi guys

 

If you search Swytch review you will find my review here.

 

The motor what Swytch is using on Brompton is the same as Q70 (basically both from Aikema).

 

I have moved the battery to the luggage block and the handing is much better after. No major issue after 1500 miles run.

 

Hope that helps. Feel free to ask any questions.

 

Pat

Here are the photos. I have tried out the new powerpack too and it is very lightweight

[mention=4809]vfr400[/mention] , going back to the question about compatibility, this all looks fine to me, based on the power demands of the system but how can you check compatibility for components like the LCD monitor ? Is it a question of checking the connectors (easier said than done given they often don't get shown in pics). I asusme there more to it than that. Any thoughts?

You buy the LCD with the controller as a pair.

You buy the LCD with the controller as a pair.

Fair enough

Fair enough

How do you know the bottle battery from aliexpress works with the KTLCD4? It looks great in principle but I don't see it as s package and would love to know how to be sure they're compatible. What'syour thoughts? I'm thinking I'll put this package together

Pat- apologies, just saw your post. Thank you. The swytch looks really good. It'd be really interesting to see how you get on withit.

All normal batteries are compatible. It's only OEM batteries for bikes with Bosch, Yamaha, Raleigh, Shimano, etc systems that aren't.

 

The only requirements for the battery is that it can give you the power (amps) that your controller takes from it and has enough range for what you need.

What is the summary of this thread then?

 

Is it possible to build your own custom Brompton kit and what would the parts list be? Can anyone reccomend what I would need to buy from BMSbattery including a 48v battery and controller etc?

 

Would this front wheel fit? Which controller and battery and pedal sensor would i need?

 

https://bmsbattery.com/ebike/600-16249-q85-24v250w-front-driving-v-brake-e-bike-motor-wheel-ebike-kit.html#/214-rpm-328

Edited November 8, 20196 yr by Collis123

@vfr - yup. Gotcha. I thought the bottle battery included the controller. It doesn't so that makes things easier.

[mention=23760]Collis123[/mention] - you'll at least need to spread the forks out to fit the q85. It doesn't mention wheel diameter so who knows but going on previous comments it doesn't look promising

So let's look at a recipe for about 10km range :

Q70 - MOTOR (thanks Tom)

KT sinewave controller with brake cutoffs and PAS - CONTROLLER

KT LCD4 Screen - small and neat - SCREEN (Thanks [mention=4809]vfr400[/mention] )

Small 36v 5.8 Ah bottle battery - BATTERY (ditto!)

Bag for the battery - BAG

Spokes Calculator

Rim

This post has got me interested & I'm thinking of putting this together - maybe with a bigger battery but I think this would give a pretty and useable set up.

Thoughts?

So let's look at a recipe for about 10km range :

Q70 - MOTOR (thanks Tom)

KT sinewave controller with brake cutoffs and PAS - CONTROLLER

KT LCD4 Screen - small and neat - SCREEN (Thanks [mention=4809]vfr400[/mention] )

Small 36v 5.8 Ah bottle battery - BATTERY (ditto!)

Bag for the battery - BAG

Spokes Calculator

Rim

This post has got me interested & I'm thinking of putting this together - maybe with a bigger battery but I think this would give a pretty and useable set up.

Thoughts?

 

How straight forward do you think it will be to add the motor to the rim and spokes?

 

And having used a Swytch kit that is limited at 15mph, I recommend a bigger battery to give you a bit more juice on the flats. Just put the battery in a front bag because it will probably be too heavy to mount on the handlebars.

You don't need a bag for the battery. It's fully waterproof. Just fit a bottle holder on the handlebars or wherever you want it. If you're going to use a bag, a bare cell-pack with BMS will be a lot cheaper.

Hi [mention=23760]Collis123[/mention] , got be honest, haven't done it for years. I used to find wheel building tough but satisfying.. I'd only do it now if i couldn't buy what i need ready made. In this instance I think I'll do it to use the q70 - and to be sure of a good quality front wheel. In this case the kits on ebay are just too much of an unknown quantity for me. I know there will be much swearing ahead if I get started....

[mention=4809]vfr400[/mention] - yup, good point. bag not needed but i think is looks pretty& is also convenient option for carrying the battery about off the bike. That said I am looking at alternative batteries. I share concern about range, so I'm still lookin at that. The rest of it looks okay to me. Im tempted to start hitting the "sod it" buttons and start ordering soon.

That said I just found a thread on this forum of interest. Same idea using a fatter motor:

https://www.pedelecs.co.uk/forum/threads/wheel-building-tongxin-in-brompton-wheel.5090/page-2#post-65911

Edited November 10, 20196 yr by Paradad