Help! Building eBike for my partner

[Moecycle]

Hi Folks,

I’m new here. I’m an engineer from Canada who recently moved to London with my Partner. We bought two electric bikes (second hand) last year. We live in the Docklands in London.

I’ve got a Carrera Vengance E, and my partner has a smaller 20” “white bear” e bike.

We both love the E bikes, but her ride struggles to keep speed when we’re making long journeys into central London. She’s now convinced about getting a larger Bike. Given its lockdown times and I would like to learn a new skill, I’m tempted to build her one.

I’ve done quite a bit of research, and have a few questions of anyone would be kind enough to provide some direction.

Goal:
- E bike for my partner who is 60kg
- Pedal assist with mid or rear drive (she doesn’t like fwd)
- City riding, up to legal max (15.5mph)
- Disc breaks
- Comfort frame
- Roughly same price as buying something from Halfords

How you can help:
- Where should I be looking for a used donor bike in east London? Shops/websites?
- best online shops to purchase conversion kit?
- Is this a fools errand? Shall I just buy a used/new e bike?

Thanks so much!

(Our last project was building a sauna in the yard. Transported all the lumber with my bike)

 

[Raboa]

Donor bike
Look into Gumtree, Freecycle, Shpock.
London transport lost property sales.
Police auction (https://www.bumblebeeauctions.co.uk/XcAPViewInCat.asp?ID=24

 

[Swizz]

Kudos for carrying those planks of wood!

Unless you particularly want a build project or there is a particular bike she would like electrified, I would be tempted to buy a new one & get out riding but best of luck with whichever route you take.

Isla x

 

[vfr400]

At 60kg, just about any kit should give you what you want. The easiest bikes to convert are the cheapo catalogue bikes with 7 speed gears on the back. Look for one with disc brakes. They're more than adequate to make a good ebike. You can upgrade the cranks and bottom bottom brackets to get the gearing you need, which doesn't cost much, and changing the bikes to hydraulic at about £50 is also a good upgrade.

When choosing a women's bike, think about where you're going to install the battery. rack batteries are an adequate solution, but frame mounted ones give better handling, though they're almost impossible to fit on a step-through.

 

[Moecycle]

Thanks for all the encouragement and advice.

Anything I should avoid specifically on the donor bike? Wheel size, gear ratios, etc?

We are thinking of a donor like this:

 

[Gringo]

Thanks for all the encouragement and advice.

Anything I should avoid specifically on the donor bike? Wheel size, gear ratios, etc?

We are thinking of a donor like this:

That bike, Really!
What with only a front rim brake and no gears or any easy way to fit them (because that bike has a single speed frame) you’ll be knee deep in problems before you get started.

 

[D C]

Anything I should avoid specifically on the donor bike

That bike!
Maybe you're just joking

 

[richtea99]

Thanks for all the encouragement and advice.

Anything I should avoid specifically on the donor bike? Wheel size, gear ratios, etc?

We are thinking of a donor like this:

Flying Pigeon?!

OldNewBikes

Tienda creada con PrestaShop

www.flying-pigeon.es

 

[Moecycle]

That bike!
Maybe you're just joking

Hey! Yep, didn't go in that direction.

So, in the end I decided to go half project, half off the shelf. I bought a used imported Japanses "Sanyo Eneloop" from someone nearby. The bike is in good shape, but the seller had no idea on the state of the electronics.

Took it home and opened up the battery. It looks like 21 18650's. Was only putting out 10.1V

So, my first mission is to try to charge this thing before I find the next problem. This will be fun.

Wish me luck.

 

[Nealh]

Replied to your other thread battery is scrap at 10.1v, if around 20v then it might be recoverable.