Dutch Style Electric Bike Conversion

Homebuilt Dutch style pedelec

I recently bought my better Womble a Pendelton pedelec, which she hopes to ride around on, particularly when I am out at work.

I figure it might be good to get out on a bike with her maybe at the weekends. I do have a "Marin Pine" Mountain bike that I could use to do this. However the riding stance of that is more aggressive than the Pendleton. I did toy with the idea of electric conversion for it but eventually decided to buy a very cheap Dutch style bike and convert it.

It all seems very easy on the surface of it. Get a 26 inch wheel hub, motor controller, battery, peddle sensor, speed controller and away you go.

There are many kits out there that say they have all you need, but choosing one that is UK road legal is just one of the hurdles. Staying legal is the first tough choice, but as fun as a 1000W motor conversion maybe, I do need my driving licence for work.

I found a UK supplier that seemed to have good reviews and researched the options available from them. I elected for a rear wheel hub witch enough torque for a cargo bike, coupled to the largest available rack 48V mount battery pack they offered. This is where the problems started. I already knew I was going to have to spread the rear stays to accommodate the wider hub motor. The motor I had chosen was not in stock, but they had some with a little less torque that would be better powered from a 36V battery pack.

The supplied ready built wheel was only available for cassette gear sprockets, my bike has a freewheel. The cassette would be better as a 8-speed but my bikes twist grip gear selector is for 6-speed. I could change the shifter or install spacers and just limit the derailleur to not change to one of the gears. This rear wheel hub had about the same torque as the front hub wheel. So the decision was made for a front hub conversion. The bonus to a simpler front wheel conversion is that the forks do not often need spreading.

At this point I chose to have a split ring magnet and a down the seat tube hall effect pedal sensor. The helpful chap selling the kit wanted some pictures of the bike at this point which was still boxed. I provided the pictures but did not get any feedback but these were supplied.

I had chosen to purchase inline brake sensors rather then replace the brake levers and a thumb throttle. At the point of ordering I was informed the thumb throttle was not in stock. I said "okay, I will not fit the thumb throttle". He went on to tell me the inline brake sensors were not in stock but that if I am not fitting the thumb throttle then I do not really need the break sensors. Presumably, then it is natural to always stop peddling when you apply a a break. Hopefully that is true, because my better Womble is likely to encounter stopping issues if not.

The optional Bluetooth link to the controller was also out of stock, apparently it does not really do much that the handlebar mounted power selector does not do anyway.

So the kit was ordered, cost were 3 to 4 times what the Chinese import kits seem to fetch, but this was quality kit all be it rather less powerful and rather less full featured then originally envisaged.

A couple of day go paste and the first of the boxes arrive, the rack battery but the one supplied was wrong. I contacted the store and arrange for the correct battery to be supplied. A few more days and it arrived and I placed it on charge and eagerly awaited the rest of the order.

The supplied 26" wheel was offered to the bike, which was when the real issue began. Apart from looking a bit odd with its black inner rim, the wheel was about an inch smaller then the break hangers! The tyre profile would need to be one more akin to the average mountain bike! Now, I had supplied photos and explained to the supplier who has a good reputation, what type of bike I was converting, yet this was not picked up on. When I contacted them to see if they had any other rim options they had none. I seemed my options were a wheel build using the existing motor or ride the bike with no front break!

At this point I was starting to get a bit disheartened. However my better Womble , sensing the gravity of the situation quietly did what she does so well. My better Womble has a nickname "Google". Before long she had found me a couple of spoke size calculators of one of them seemed simple enough for a Orinoco like me to follow. Grin Technologies! Awesome and even some guides on YouTube to show me how to do the job with limited tools at home!

Sedley the spokes they recommended they could not ship! These same spokes were available from 2 eBay sources, but neither recommended them for e-bikes! Good for a Canadian downhill, but too weak for UK pot holes! I ignored this advice and ordered up some spokes! I later discovered I ordered too few, tried to order more and they were out of stock so seller refunded me! No word as to when of if they would restock them. As luck the same seller listed them again and this time when I placed the order the items were sent!

Ordering too few was actually the second mistake I made. The first was in my reluctance to disassemble the wheel supplied with the bike I tried to measure the spoke length with the hub in place. This resulted in a small error that just made the wheel build a little bit harder. The spoke I ordered could have been 1mm or 2mm longer, but they were still long enough to work fortunately.

I laced the wheel and used the forks and some cable ties to help guide me in truing the wheel. It is a tiny bit egg shaped, but is better laterally then the banana the factory supplied on the rear wheel!

When I placed the wheel in the forks the hub motor was faintly rubbing on the forks. To cure this I would need a couple of spacer washers on the axel between the motor and the forks. I do have some wahsers but the axel diameter is larger then a non motorised axel, so these washers would need drilling out. Instead for now I just moved the 2 washers supplied for the wheel nuts to the inner side of the fork. The nuts holding the wheel then tighten directly onto the forks paintwork. I might get around to drilling out the washers at some point.

The supplied battery rack did not come with the mounting hardware, a quick trip to Wickes at least allowed me to use some washers and correct gauge screws to hold it in place until the correct hardware was obtained from Amazon.

I was glad I bought the split ring magnet disk, it saved having to purchase tools to remove the bottom bracket pedals. I simply spent some time centring them to the inside of the chain ring. There is only a small clearance between the magnets and the frame so every now and then the magnetic force attracted the ring off of the chain ring. I did get it centred well enough and marked its position. For now I have used epoxy to help keep it in place. If I find it gets free over time I will drill a couple of holes into the chain ring, tap them and use machine thread screws to hold the magnet in place.

The down the tube pedal sensor was another good choice, although the supplied mounting bracket was not any use for me. The cable was just long enough for me to position it on the bottom bracket. I could 3d print some kind of custom clip to hold it in place. This would take time and a bit of trial and error. Instead I used epoxy to secure it to the metal work. I then added Sugru, which is moldable silicon glue. This is heat resistant, water resistant and somewhat flexible.

The final issue was the supplied cable from the controller to the display was way too short, fortunately I had spotted this early on and ordered one from a UK seller that was not actually a UK seller as it shipped from China!

Bike built I needed to remove the basket to adjust the handle bars, the supplied screws stripped so this was a long process and now the screw are replaced with silver ones but a sharpy hides that enough.

I added some green slime to the inner tubes so hopefully will be puncture free for some time.

I have only taken out for a short while but on flat grass the acceleration and speed is fun. I a not sure it the motor will haul me up a steep hill, but its got to be easier then pedal power alone.

One thing that strikes me right away though is how after a small delay in pealing the motor sharply engages, particularly on the high assistance setting. This seems like it could be a bit dangerous. I think a throttle that can be feathered in would be safer then to stop go action of the peddles! If only they were legal!