London self build - tips

[James4444]

Hi all,

First of all i am sure there is a thread similar to what i am going to post so apologies in advance if there is.

I work in London doing some pretty long hours and I'm on my feet all day. Using the tube with covid is something I really want to avoid for obvious reasons. I purchased a Ammaco Pakka 20" Wheel Folding Bike Black (cycleking.co.uk) second hand and would like to convert this bike to a pedal assist with the ability to not have to pedal at all. I am currently doing 5 miles each way so 10 miles in total. However, i can charge the battery at each end. Something light and cheap is my goal and quicker than 15mph.

Having looked into the types of kits avaliable i have been front, mid and rear. What option is best for price, power and ease of install.

Where is best to look? Do i buy a Amazon/ alibaba chinese kit? Or are there better options out there.

Thanks in advance for your help

J

 

[vfr400]

Probably best to look on Ebay, Aliexpress or Amazon. You should go for a rear motor and one with an LCD control panel. Most kits come with a throttle and pedal sensor, so you don't have to pedal if you don't want to.

Your brakes will be a real problem if you try to run at 20 mph. You have 4 times as much energy to dissipate when you're averaging 20 mph compared with 10 mph, so you'd need 4 sets of brakes like the ones that are on it at the moment to get the same braking. The pads will wear like crazy and become very inefficient in a short time. I converted a Dahon that could run at 20 mph, but gave up on it because of the brakes, which were higher spec than what's on your bike.

Regarding recommending a kit, there's the legality. If the motor has 250w or 500w marked on it instead of 250w, it's illegal and easy to see. As long as it has no label, it's virtually impossible to prove that it's not a 250w motor. The speed limit has to be set to no more than 27.5 km/h (17.2 mph) to be legal. That's pretty easy to check.. On a 20" folder, I doubt that anybody would check as long as you're not motoring along at 20mph without pedalling.

If you're not bothered about legality, this one would be pretty good with any 48v battery of your choice. I haven't tried one, so I can't say about the speed. They say it's 28km/hr (350w rear version), but it's 36v/48v. The motor will always run 30% faster at 48v compared with 36v, so I'd say that the top speed would be 36.4 km/hr, which is a nice speed (if you had brakes that work). Any faster would be dangerous on a 20" bike:

36/48V Electric Bicycle Hub Engine Motor Wheel LED Display E-bike Conversion Kit | eBay

Find many great new & used options and get the best deals for 36/48V Electric Bicycle Hub Engine Motor Wheel LED Display E-bike Conversion Kit at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

The important things are:
1. Freewheel rear motor. It must have the threaded boss for the gears not the wider spline.
2. LCD so that you can get at the settings
3. The motor maximum rpm. 328 RPM will just about reach 20 mph on a slight downhill, so you'd need around 400 rpm to cruise at 20 mph, which you can get by running any normal 36v 20" wheel motor at 48v.

 

[James4444]

Thanks for the reply.

What would be the reason to do a rear over front. Reason O ask is the install looks harder with having to change over the gears. Or is it more simple than it looks?

The legality is less of an issue for me. I really just need to be able to save time on my journey whilst not having to pedal too much. I know the legal speed limit is 15mph in the UK so 20mph would be sufficient.

How when searching can I identify the RPM as the link you posted has no mention of this.

In terms of a battery would something as simple as this ( High capacity 48v battery 48v 30Ah 1000w 13S3P Lithium ion Battery Pac – Grandado.com GBR ) in a bag mounted to the front be ok? Or would you recommend a specific battery like this ( 48V 20Ah 1000W 1500W Rear Rack Carrier Battery Lithium Electric Bicycle Bike UK | eBay )