Swiss Army EBike Build - Converting a 1937 bicycle!

[RobinCh]

Hello,

I am a 33 yo frenchman living in Switzerland. I have converted a antique swiss military bike to electric propulsion.

Swiss military bikes were designed and first produced in 1905 until 1993! A registered number of more than 68000 of them have been issued to the swiss Armee. They are fairly affordable on the second hand market. This particular one is from 1937 and has the frame number 15754. I got it for 320chf (=320usd). My plan is to use it everyday to go to work instead of my current non electric powered bicycle.

I used the following parts:
36V 20 ah battery: https://www.aliexpress.com/item/Fre...2614449803.html?spm=2114.13010608.0.64.pybEW1
Eunorau (bafang) 36V250W front roller brake hub motor: https://www.aliexpress.com/item/DGW...2692480353.html?spm=2114.13010608.0.77.pybEW1
Eunorau (bafang) converter and display: https://www.aliexpress.com/item/Bic...2706430067.html?spm=2114.13010608.0.72.pybEW1

Before:

During the Build:

Old and new front hub:

I had to do a cold spacing on the front fork. I had to stretch the spacing of the front fork to 135mm in order to have a final spacing of 101mm. This is because the steel of the fork is elastic.

That's sexy me lacing the front wheel:

After:

I really like the Bafang LCD display. It display very useful information while integrating well with this old bicycle:

The PAS sensor was installed by gluing the magnets directly on the sprocket. It works perfectly and it is very discreet:

The 36V 20ah battery fits perfectly into the frame bag which was originally designed to carry ammunition!

Sadly it was short lived as my first ride either fried the motor or the controller. I am researching the topic right now to try to find the best possible solution to put it back to the road. I hope the community can help.
The seller wants me to send him back the motor and controller. I however would like to test each component independently.

Here is what happened: I went for a 15 mins ride where I let the bicycle carry me at max speed with no pedal power when it suddenly came to an halt. The display was indicating a current of 40A when riding. With a fully charged 36V battery reading at 40V+ that means 1600W into a 250W motor! The controller is supposed to limit the current to 15A but when I contacted the seller, he told me 40A was normal :? .
After trying everything I could, I came to the conclusion that either the controller or the motor is fried. My plan to solve this problem asap is to order a new controller and motor. Should I order a bigger bafang 48V500W BPM front hub motor because it should be more robust? My goal is to have high torque and max speed around 30kph. The bike is extremely heavy (33kg). I live in a steep area with many hill. I need something reliable and strong. I want to occasionally carry my child in a trailer.
I thought buying a assorted 36V 250W motor and controller would give me reliability. Now I discover that it is common for bafang motor to just fry. Do you know what would be the best reliable alternative (motor + controller) for this project? I'm really in love with the Bafang display and control and hope to retain it but if it proves to unreliable, I will have to choose something else.

Thanks for reading and I hope you can give me some answers!

 

[RobinCh]

UPDATE 1: the bike is now up and running. The original converter had a factory issue. Changing it solved the problem

UPDATE 2: the measured range is 145 kms (90 miles). I'm very happy with this number

 

[footloose]

Hi Robin, and welcome!

Nice bike, looks like a cousin of Raleigh DL-1, one of my favorite frames.
I converted a DL-1 to electric couple years ago, like it.

You have a heavy bike, steep hills, big wheels, full speed run, 1600W into small motor.
That reads like a recipe for Fried Motor :wink:
So your conclusion about reason bike stopped sounds right.

The current setup looks very stealth and vintage, but I'm not sure it can ever work out well.
If you are open to it, may I suggest you re-think the project design a bit?
Believe you could come out with a cool bike that meets your needs and still looks pretty vintage.
Here is what I’d consider.

First, brakes. You have heavy bike, possible child in trailer, steep hills, and e-bike speeds.
The original setup (drum brake rear, spoon brake front) clearly won’t cut it.
And I don’t see any other front brake connected in your current setup though I’m sure that is temporary.
My answer was to braze a set of brake bosses on front fork (not hard) and mount V-brakes on front.
Worked very well.
But equally… in a new setup, you could ditch the front motor and go with modern
roller brakes on both front and rear? Available: http://www.dutchbikebits.com/shimano-roller-brake

Then about the motor. I used a BBS02 on my DL-1 conversion, with a Shimano Nexus 8-speed IGH hub plus a Shimano roller-brake on rear. Nice combo in a hilly area. Bet you could find a 'period correct' used Sturmey-Archer 3-speed hub with drum brake locally... stopping power maybe not quite as good as modern roller brake though.

If I am reading the specs right on the Eunorau (Bafang) converter and display package you bought, it sounds like it is 100% BBSxx plug-compatible.
If that is true, you might be able to order just a BBS02 bare motor without display, wiring harness, etc and save a few bucks?
Probably available from multiple sources, but here is a link to example: http://lunacycle.com/motors-and-kits/mid-drive-kits/bafang-bbs02-750w-mid-drive-motor-and-controller-only/ That example is a 48V setup, but I believe the LVC can be reprogrammed to lower setting (31V?) thus enabling it to run well with your 36V battery. (I could be wrong about that re-programming possibility… if so hopefully somebody will correct.)
You aren’t sure whether you’ve fried your motor or controller, but the BBS02 contains both. So you’d be covering both possibilities.

Alternative solution would be to mount a honking big and powerful motor on the front but I don’t like heavy/powerful front drive.
And with your existing brake setup, I don’t think it would be very safe.

Good luck, have fun!

 

[RobinCh]

Hi footloose, thanks for taking the time to reply!

The idea behind this build is to retain its original condition as much as possible. This is generally the mindset when dealing with antiques especially pre-war antiques.
The original front brake is basically useless but the rear brakes work exceptionally well. They are a combination of coaster brake and drum brake which offer great modulation and power. Both are swiss made and of really high quality. In general this bike is as well engineered as a swiss mechanical watch.
The bottom bracket is not compatible with a modern mid drive engine. Even if it was I would not like to change cranks and sprocket. I also believe mid drive are great but I don’t think this architecture is well suited for this build.

I am happy with the front hub. With a 250w pedelec motor and by limiting the speed to 25kph, I comply 100% to the Swiss legislation. The bike is not build for speed. It is built to enable the experience of riding a fine antique bike without the sweat and for this goal, it delivers

 

[footloose]

Update: the bike is now up and running. The original converter had a factory issue. Changing it solved the problem

Hi Robin -- Delighted to hear problem was found and bike is up and running, without need for modifications that would completely change the nature of a vintage bike. Enjoy riding!

 

[Compoundbike]

Hi footloose, thanks for taking the time to reply!

I am happy with the front hub. With a 250w pedelec motor and by limiting the speed to 25kph, I comply 100% to the Swiss legislation. The bike is not build for speed. It is built to enable the experience of riding a fine antique bike without the sweat and for this goal, it delivers

Nice, but check your brakes.. those were terrible from my memorys in the swiss army.

 

[free-trade]

I really like this build, my grandpa still have two very old bikes in this garage.
I don't exactly know when they were build, I think 1920-40, because he told my one of them was his first bike when he was 16 but then had to join the army('43 or '44)

Very well integrated without destroying the style of the bike. If you don't ride too fast this breaks maybe will work.
I ride much faster, because I use my e-MTB to get fast through the traffic to work and this is often quiet dangerous and modern discs breaks are a must-have.

many greetings from bavaria

 

[beast775]

I really like this build,keeping the settings on low will keep your motor fairly happy and no one will even suspect you are electrified .

 

[RobinCh]

I really like this build,keeping the settings on low will keep your motor fairly happy and no one will even suspect you are electrified .

Thanks! Yes and it's very silent too

 

[RobinCh]

I don't exactly know when they were build

Thanks for the compliment! You might be able to check the seat post for an engraved date/serial number!

 

[Wolfeman]

Thanks for your post RobinCh, it's one of the most attractive conversions I've seen on ES. Very nice, discreet and a beautiful older bike to cruise around on. Great work.

 

[Bas332]

HI Robin,

The motor is not a Bafang but a:

http://www.syimotor.com/products_detail/&productId=81a09d70-96ba-49b5-8a34-48e76ac5020e.html

Very nice build! But as the others say why don't you make a roller brake look old?

I have made a Gazelle Tranza Carbon, electric with the same motor.

Will start a topic about the build today.

 

[RobinCh]

Thanks for your post RobinCh, it's one of the most attractive conversions I've seen on ES. Very nice, discreet and a beautiful older bike to cruise around on. Great work.

Thanks! It's nice to read such a nice compliment! I'm also very proud of it!

 

[RobinCh]

HI Robin,

The motor is not a Bafang but a:

http://www.syimotor.com/products_detail/&productId=81a09d70-96ba-49b5-8a34-48e76ac5020e.html

Very nice build! But as the others say why don't you make a roller brake look old?

I have made a Gazelle Tranza Carbon, electric with the same motor.

Will start a topic about the build today.

Thanks! The motor is obviously sold under different brand names. Just because you bought the same motor under a different brand name does not mean that it is not a Bafang :wink:.

Good luck with your build! It looks like a very fun bike to start with

 

[RobinCh]

Hello everybody,

I have just cleaned up and serviced my bike and after using it for 2 years, I thought I would post an update.
Here is the bike today:

As you can see, I have almost 3000 kms (1864 miles) on it:

Overall I am still very much in love with this bike. It's always extremely fun to ride. I use it for everything from commuting to riding the kids in the trailer.
Being a singlespeed, the bike is fairly slow by ES standard as I cruise between 25 and 30kph (15 to 18mph) but that is very acceptable. My hi end wife ebike with a yamaha middle motor is actually slower :lol:

I have also issue with the motor whose nylon gears break down every year or so. I had to replace the motor twice. Fortunately I can just exchange the internal motor without having the rebuild the wheel so it's not as bad as it sounds.

 

[armandd]

What a nice antique e-bike you have!

 

[fechter]

Thanks for posting. We don't always get long term test reports. Still a really nice looking bike.

One thing to possibly consider would be dual motors, both front and rear. This would reduce the load on each motor quite a bit but top speed would be about the same. The gears would last longer and you would be able to climb hills better.

 

[wturber]

Nice bike. Somehow that black front hub looks like it belongs. I also love the irony of the front headlight dynamo. I'm torn between whether you should have put an LED in there or not.

 

[wturber]

I guess folks over here value those a bit more than they do in Switzerland.

https://tucson.craigslist.org/bik/d/1937-swiss-army-bike/6634620929.html