First DIY Ebike project

[CuriousMind]

Hello everyone,

I would like to start my first ebike project. I read some articles and watched some videos to get a better feel for the project. Since I attempt a technical college, with it's main emphases lying in electrical engineering, I have a basic understanding of electrical circuits. Nonetheless I'm not that familiar with bicycles and have even less of a clue about the wide range of products on the DIY ebike market. So I hope some of You give me a bit of advice.

I thought about a 52 V (14pXs) System using this bike:

https://www.greenbike-shop.de/Hollandrad/Herren/Greens-Westminster-Herren-Hollandrad.html#&gid=1&pid=1

I choose it because I like this type of frame (with upright seating position), it's large (I'm 6"4) and it seems durable, with it's double tube construction. The bike is 20,5 Kg (45 lbs) with me, it will be 95 Kg(210 lbs). It has a hub dynamo, in the front wheel, which I hope is not a problem. The drum brake and hub gears though likely have to be removed.

My budget is flexible but I would like to keep it under 1000€€, excluding the bike.
As You can imagine, I won't go running down mountains or participate in races. The bike should be able to hold a constant speed of about 32 kph (20 mph), although some faster bursts would be nice if I'm in a hurry. As I'm comfortable with pedalling to get it going I'd rather have more top speed then acceleration. The region I'm living in is mostly flat.
Since 1000W hub motors already integrated in 28 inch wheels, seem hard to find in Europe, I guess I have to buy the motor and pay a bike shop, to get it into the wheel.

I don't really know about the controller. I don't need a lot of features, perhaps cruise control but that's not a must have.
It would be great if the battery had high energy density because the weight of the bike is already high and I don't want to pack a huge box on to it. If it's much cheaper I think I'm able to build a battery myself but then the question arises how I get hold of a battery box; one that would be lockable desirably.

As the build should be reliable and long-lasting (for as a student you don't always have money), I'll presumably get one of those Luna chargers to charge to 80% or some kind of other charger that is more easy to get in Europe.

Thanks for your attention
Felix

P.S.: Forgive me my potential writing mistakes

 

[d8veh]

I can't agree with a single thing you wrote. Firstly, the donor bike is about the worst you could find. It has hub brakes, which mean that you can't fit a hub-motor at either end. Its hub gears prevent a rear motor too, and are probably not strong enough for a mid motor. The chainguard prevents a mid motor too. It looks like your only hope for electification is to use a big propeelor on the back to push you along.

If you found a suitable donor bike (think disc brakes, normal triangle frame and derailleur gears), for only 32km/h, you don't need or want a 1000w motor and 52v battery. A 250w geared hub-motor at 48v will be more than enough, and it'll give you a nice light bike that looks and handles like a bicycle.

 

[CuriousMind]

Well, can't I just remove the Hub brake and gears and add a V-brake in the back ?
Also I read that 1000 W 52 V systems do about 28 mph full throttle if not pedalling, or is there something wrong about that ?

Thanks

 

[wesnewell]

See need Advice in sig. if you're not worried about being legal, then certainly pay no attention about the watt limit. The bike does suck though. Consider a MTB. Rim brakes are just real large disc brakes. And rim V brakes work better than cheap small disc brakes.

 

[ScooterMan101]

A bike something like this will be much better for you.

https://www.cube.eu/en/2017/trekking/travel/cube-travel-pro-greynblack-2017/

or this

https://www.focus-bikes.com/us_en/allround/planet

Also
You do not need to have a 1000 watt hub motor to go 34 Kph.
A 500-600 watt motor , ( or less rated motor run at 14s will be good enough )

I can go 34 kph on the flat ground with a 36 volt , 350 watt rated motor when using a 52 volt pack. ( 58-59 volts hot off the charger ) on a mid weight 700c wheel road/gravel bike.

 

[dogman dan]

If the bike frame has brake mounts, you can easily put v brakes on it. If not, then its a welding job.

Plenty of very similar bikes out there, with v brakes, and if you want a rear hub, 7 speed rear gears.

In fact, for a big guy, one of the better choices out there for an e bike is a very inexpensive steel beach cruiser, with 7 speed rear gears. The frames are large, so at most you may need to get a longer seat post.

Up scale versions of the same general thing are out there too, the electra townie being one brand name example.

Your needs are very simple, and easily satisfied by nearly any decent hub motor kit out there.

 

[ScooterMan101]

Also,

Rear hubs are preferred by many , that way you can use many different front forks, with a front hub you , must use a very strong steel/cro-moly Fork, that is not too comfortable at speeds of 34 kph.

Many of the cassette versions of hub motors can accept a 8 / 9 speed cassettes.

I have even fitted a 10 speed cassette to the little Q100c CST motor I have.

 

[d8veh]

Well, can't I just remove the Hub brake and gears and add a V-brake in the back ?
Also I read that 1000 W 52 V systems do about 28 mph full throttle if not pedalling, or is there something wrong about that ?

Thanks

You said that you wanted 20 mph in your first post. A motor, like the Q128 is half the weight of those 1000w DD motors and it has plenty of torque for hill-climbing and can hold 25 mph with a 48v battery. It's rated at 500w for the cassette version and 800w for the freewheel one.

 

[heavymetalthunder]

IMO with a 1000w unit, I would recommend a full suspension mountain bike using road tires. At 30 MPH a rider can really feel the ruts and bumps on the road.