Front hub kit suggestions for Brompton clone with 20 inch wheel

[paulc1976]

Hi all,

I'm looking for a front hub kit for a 20 inch Brompton clone (Mint T9-20D). I don't have the bike yet as it's still shipping but wanted to get some ideas about possible kits.
20 inch wheels with mechanical disc brakes.
Front hub kit ideally 250w road legal but don't mind a bit more, 36v. Looking for a fairly light battery I can clip on a bag at the front. Ideal would be something that still allows the bike to be folded up pretty quickly and easily detach the battery when required. Smallish display and throttle if possible. Something with a bit of grunt for hills but not expecting too much.

Would prefer something already built into a wheel but will also consider motors without a wheel.

Does anyone have any good suggestions?

Here is the link:

Fashion Mint Folding Bicycle 20inch 9speed Disc Brake Foldable High Quality Molybdenum Steel Frame T9d-20d Tri-folding Bike - Buy Brompton Product on Alibaba.com

Fashion Mint Folding Bicycle 20inch 9speed Disc Brake Foldable High Quality Molybdenum Steel Frame T9d-20d Tri-folding Bike - Buy Brompton Product on Alibaba.com

www.alibaba.com

many thanks,

Paul

 

[matthewslack]

Search the forum for Brompton threads. Probably all you need to know is already there.

 

[sjpt]

Look at https://wooshbikes.co.uk/?hubkits#q70kit

 

[Nealh]

Woosh brompton kit.

 

[paulc1976]

Thanks all for the recommendations. The clone I've ordered has 20 inch wheels, I think Brompton's (apart from G-line) are 16 inch wheels. So I'm looking for something similar to the set up for the Woosh bike but 20 inch wheel instead. Also been looking at aliexpress, pswpower, etc but not sure if they would fit.

 

[guerney]

Doesn't say in the Alibaba listing if the front axle is 74mm, but if so, perhaps buy a 20" front hub motor conversion kit for Dahon?

 

[paulc1976]

I think it's 74 mm:

Opening

front 74mm,rear 120mm

Any recommendations on a suitable kit?

 

[guerney]

I stand corrected, it does say it's 74mm, I'll grab my hat and leave you to the hub motor dudes...

 

[guerney]

Are those wheels 406? I can't recommend any of these hub motor things, because I've never owned, installed, or riddden one, but websites such as Topbikekit do kits for 406 74mm. I don't know if their motors are marked "250W". KT controller - a fair few hub motorists here do like their KTs. I considered this kit for one of my Dahons, but was put off by the delivery charge and the mysteriousness of WTF PLC settings.

1.6kg TBK-74AD 36V250W 48V250W Front Motor with 20inch 406 Wheel Rim for Brompton/Cranston/Dohon Bike [TBK-74AD 36V/48V 250W Kit 20inch] - $154.00 : Zen Cart!, The Art of E-commerce

Zen Cart! 1.6kg TBK-74AD 36V250W 48V250W Front Motor with 20inch 406 Wheel Rim for Brompton/Cranston/Dohon Bike [TBK-74AD 36V/48V 250W Kit 20inch] - ★★★★★ Applicable to: Motor kit can fit Brompton,Cranston,Dohon Folding Bike or other forksize is 74mm Folding Bike with 20inch 406 Wheel Rim...

www.topbikekit.com

 

[paulc1976]

Yes 406, long write up on them here:

https://www.reddit.com/r/foldingbikes/comments/1idnn7g
https://www.reddit.com/r/foldingbikes/comments/1idnn7g
I could do with something similar to the Brompton kit where it clips on with a 20 inch wheel.

 

[guerney]

Do you mean with a clip on battery, like the Woosh kit? Perhaps get the motor laced into a 36H(?) 406 rim?

 

[paulc1976]

Yes either a clip on battery or a smallish Brompton clip on bag to house a small battery and controller with a detachable wire so it's easily removed. I'd prefer something lower down rather than the swytch-style handlebar mounted batteries. Something light but with a bit of grunt. I'm not expecting too much as I have BBSHD and BBS02 bikes but just something to help up hills.

 

[eas2lv]

> I'd prefer something lower down rather than the swytch-style handlebar mounted batteries

I know Swytch is universally hated here, but can't help point out they have "bro block" that mounts the battery lower down. Never used their kit on a folding bike, but know a few who seem satisfied.

 

[guerney]

Bung a bagged battery on a bracket on the front, like @StuartsProjects's eBrompton?

https://www.pedelecs.co.uk/forum/threads/ebrompton-build.45098/page-8#post-689055

 

[paulc1976]

Yes, something like that would be ideal with a 20 inch front hub.

 

[matthewslack]

The difference between a 16 and 20 inch hub motor is the nominal rpm. Most kits give a choice. I only know 700c number off the top of my head, which is 201rpm. You need about 7/5 x that, or about 280rpm. Have a look at what's out there.

 

[saneagle]

The difference between a 16 and 20 inch hub motor is the nominal rpm. Most kits give a choice. I only know 700c number off the top of my head, which is 201rpm. You need about 7/5 x that, or about 280rpm. Have a look at what's out there.

280 rpm is a bit low. Normal speed for a 20" wheel is 328 rpm. That will allow it to have good power at 15 mph. As a rule of thumb, for a 15 mph bike, you need a motor that will max out at 20 mph because the back emf will reduce the power as you approach maximum speed.

 

[StuartsProjects]

Yes, something like that would be ideal with a 20 inch front hub.

Well, I built it that way so that the battery\controller bag could stay in place when folded for rolling around shops etc. Also if you keep the bag small the bike does not really look like an electric.

Not sure I have seen a separate clip on clip off battery\controller bag, that you can buy, in the style used on the Brompton electrics, but if you find one do mention it.

 

[saneagle]

Hi all,

I'm looking for a front hub kit for a 20 inch Brompton clone (Mint T9-20D). I don't have the bike yet as it's still shipping but wanted to get some ideas about possible kits.
20 inch wheels with mechanical disc brakes.
Front hub kit ideally 250w road legal but don't mind a bit more, 36v. Looking for a fairly light battery I can clip on a bag at the front. Ideal would be something that still allows the bike to be folded up pretty quickly and easily detach the battery when required. Smallish display and throttle if possible. Something with a bit of grunt for hills but not expecting too much.

Would prefer something already built into a wheel but will also consider motors without a wheel.

Does anyone have any good suggestions?

Here is the link:

Fashion Mint Folding Bicycle 20inch 9speed Disc Brake Foldable High Quality Molybdenum Steel Frame T9d-20d Tri-folding Bike - Buy Brompton Product on Alibaba.com

Fashion Mint Folding Bicycle 20inch 9speed Disc Brake Foldable High Quality Molybdenum Steel Frame T9d-20d Tri-folding Bike - Buy Brompton Product on Alibaba.com

www.alibaba.com

many thanks,

Paul

That's not a good bike for conversion if you want an off-the-shelf kit. The forks are too narrow at both ends. A mid motor would fit, but then you'd need to sort out the gearing, which would be too low with standard parts.

Some of the Chinese resellers , like BMSbattery and Topbikekit offer the narrow AKM motor either on its own or built into a wheel. It's OK in a 16" wheel, but a bit gutless in a 20" one due to the lower torque. If you don't weigh much, it'll be OK, but if you're say 90+ kg, it might be better to get a 260 rpm one and run it at 48v to increase the torque a bit.

It's a lot easier to decide on a conversion first, then choose a suitable donor than it is to buy a random bike then try to figure out how to convert it.

In summary, it can be done, but a lot more messing about than buying a Woosh kit.

 

[guerney]

Well, I built it that way so that the battery\controller bag could stay in place when folded for rolling around shops etc. Also if you keep the bag small the bike does not really look like an electric.

Not sure I have seen a separate clip on clip off battery\controller bag, that you can buy, in the style used on the Brompton electrics, but if you find one do mention it.

If at all useful - spotted this 3D-printed hard shell clip on box, with print files which could be adapted:

https://friedhornet.com/blog/2022/06/17/brompton-diy-hard-shell-front-mounted-toolbox/