Which electric bike conversion kit should I buy?
 

Hi folks,

For 50 Dollars, I got a new an electric bike battery with a rack.

Not a bad deal but I got a tricycle not a bicycle. My tricycle has definitely 20 inch wheels/tires. I assume I can get rid of the rack and install the battery in the basket.

However, my real problem is that I one ordered one of the conversion kits but my fork was too small of it. So, in other words, the kit had wider fork than that of my tricycle.

I am not a technician of any kind and a neighbor (no specialist) convinced me that I should give it back as adjusting a fork on a bike would be really difficult.

I addressed Workman as my tricycle is from them but they didn't help at all just tried to sell me one of their extensive new electric tricycles.

What should I do now? Did I buy the battery for nothing?

Any advice is appreciated.

Thread moved from General Cycling Discussion to Electric Bikes.

In general, most front forks for bikes are 100mm wide. Some smaller folders are only 80mm. Many fatbikes are 135 mm wide. You're the only person who can tell us tell us how wide your fork is, Measure it and also use a magnet to find out if it's steel or alloy.

What kind of battery did you get for 50 bucks? What voltage is it? Does it have an Ah rating?

What kind of conversion motor did you buy? Yeah sure, why keep it if it's not going to fit. Most front motors will fit a 100mm wide fork, unless you bought a fat bike motor or a rear motor.

Hi Doc Wiu,

Thanks so much for your reply.

I measured my fork at the widest point from edge to edge and it is almost 5 inch wide. It is alloy.

The battery that I got is a 36V 14AH Lithium Battery Rear Rack Li-ion For Electric Bicycle E bike Motor Kit + Charger

The kit that I had to return (upon advice of a neighbor, no technician) was a 36V 750W 20" Front Tire Electric Bicycle e-Bike Conversion Kit Cycling Hub as the fork of the kit was too wide to fit my bike, despite that my tires are indeed 20".

I saw that the fork was too wide too but he said there would be no way to fix it. But I read online that washer could solve the problem, but again what washers?

Can you please help and advice me?

You need to remove the front wheel and measure both the inside and outside, edge to edge. Now 5 inches is 125 mm, So my guess is you have 100-110 mm wide forks. If you have 100mm, everything fits.

At 110mm and higher, it gets dicey. Sure, you can turn the washers around and put the wide ones on the inside. You can also add a few extra washers, but you're stuck if the the axle of the motor isn't long enough to for the axle nuts to fit.

For example, I'm looking at a print of a Bafang SWXK front motor. Axle width is 140 mm, which is 5.5 inches. Might be too narrow. There are other motors. Some show 150 mm for axle length. Others are less than 140mm. If you still have your motor, maybe you can check it for the fit of the nuts.

If your fork is steel, it's no problem to skip the spacers and squeeze it 10mm. I recall using a scissors jack to spread a steel frame about 1/2 inch to fit a motor, Meanwhile, the front fork had gotten squashed in the shipping box and was about a half inch too narrow for the wheel, But that was steel too. I just bent it back.
If the fork or frame is alloy, you cannot bend it it. If it doesn't break right there, it will break later. Anyway, I wouldn't do it.

Hi Doc Wu,

The magnet sticks to my fork.

I measured the space inside of my fork. It is only 70mm. However, I did not remove the wheel to measure. Most certainly not bigger than 80mm.

Should I buy the 36V 750W 20" Front Wheel Electric Bicycle EBike Conversion Kit for 20"x1.95"-2.5" tire with the larger fork but some additional washers to make it fit?

What would you suggest?

If the motor on the kit you returned was designed for a bigger fork, then I don't understand how washers would male it fit on a bike like the one below.

Let's see a link to that kit you mentioned to see if the dropout requirements are mentioned/ .

And while you're at it, what Workman trike is it?. Is it one of these? A 2.3 inch tire on the motor kit probably has a fairly wide rim. The bike below shows caliper brakes, and you might have to hunt up wider brake calipers to go around a 2.3 inch tire.
https://cimg9.ibsrv.net/gimg/bikefor...7c5ac30175.jpg

https://www.worksmancycles.com/pt2f.html

Hi Doc Wu,
Thanks for your response.

I have a Trifecta Adult Single Speed Workman bike.

Bike Forums doesn't allow me to post the link to the picture.

Still clueless what kit should fit.

Thanks for your help and advice.

Doesn't Workman sell kits for their three-wheelers?

That Trifecta doesn't seem to be sold by Worksman these days, I suppose it looks like this. Caliper brake up front? Does your fold?
https://cimg5.ibsrv.net/gimg/bikefor...ecfced03c4.jpg
If you measured a 100mm front axle, here's two possibilities on ebay. I think the first one may have a rim that is overly wide. Fitted with 2.5" tires, it may be too wide for your rim brakes. Maybe the 1.95" will work. Is this the similar to the one you sent back? At $169, it's my kind of deal.

You should also install torque arms on a front wheel ebike. These are attachments that fit over the axle and clamp to the fork to keep the axle from spinning loose, Cost $10-20 per side. I use torque arms. DOn't want the wheel forces breaking the fork and dropping me on my chin..


https://cimg0.ibsrv.net/gimg/bikefor...c5ecd0f031.jpg
EBay direct drive kit $169

Another selection on ebay is this one from CSC in China. This one is $100 more than the first one after shipping, and you have to eat it if you buy it. It would cost you $100 to return it. However, for sure you will get a narrower rim.

https://cimg3.ibsrv.net/gimg/bikefor...d784b3d3c1.jpg

Ebay Geared Motor kit $269

The two motors are different. The firs one is a direct drive motor. No internal moving parts. The motor boasts 750W, which means you could easily feed 20-22A @ 36V into it, but it's not strong on torque and will be a little slow starting off or climbing steeper hills. If you live in flat country, that won't be a big problem. The second one has internal gears. The 350W version will climb as well as the direct drive motor and be a better fit for your battery, Also comes with a slightly better LED display and also a pedal sensor that you won't use. as it will not fit in your pedals.

A direct drive doesn't coast as well as a geared motor. Has more drag if you ever run out of battery. Plenty of folks though are putting these direct drive motors on their bikes and are happy. I've never owned direct drive though. Always went for geared motors. I have several bikes with 20' wheels. One has a geared motor up front. The other has a geared motor on the rear. I value the lighter weight and small size of a geared motor. Den458 can tell you about his CSC kit in this thread.
https://www.bikeforums.net/electric-...it-issues.html


The most important thing is that you know your brakes will fit. It seems that users are putting the first kit into BMX bikes, per ebay reviews, but those are disk brakes.

Dear Doc Wui,

Yes, this is exactly my trike. Even the color. It folds and caliper in the front.

And yes, this is the kit that I mailed back. I liked the price but there was the fork problem.

The wheel for the tire seemed also broader than the wheel that I have on my Trifecta. So you would not recommend that I order the same kit again and try to use additional equipment (if available) to make it fit?

As I can't post a link, could you kindly refer me to a link for a torque arms as I also don't want to fall on my nose.

I have small hills to ride, nothing major.

I wish you would live in my town and own a bike conversion shop. I would be your customer for sure.

There are very expensive at Workman. I wasn't happy about their customer service either. And I have already a battery for an electric bike. I just need a conversion kit.

P.S. Doc Wu, a handyman told me know that one measures the fork by measuring the diameter of the screw that holds the wheel. Not sure if he is right. The screw that secures the wheel is just one (1) cm on my Trifecta. I measured the fork at its widest opening from its inside edge to the other inside edge.

I think your handyman is thinking of something else. You need both length and thread to define a screw.

The diameter of the axle on a regular bike is 10 mm. Most ebike axles are usually 12mm. but what they do is square off two sides so it's 10mm and slides into the slot. The thread on the axle is 12mm x1.25, so if you ever lose the nuts that come with the motor, you're going to have an awful time finding them in the USA. Not carried at Ace or Sears Hardware stores, Lowes, or Home Depot. I haven't lost any, but I ordered some extras off amazon.

https://cimg0.ibsrv.net/gimg/bikefor...d1403ee29e.jpg

If the nuts get loose, all that keeps the axle from spinning is the square edges of the slot. So we put torque arms that fit over the axles and clamp to some convenient point on the frame. Sometimes they use hose clamps. This guy on amazon has a good price. Here's the torque arms on both sides of my front drive 20" motor. One is home made. The other is store bought. I have never seen a torque arm on a commercial ebike as they will design the forks specifically for holding a motor. You can also see from these pictures that I got so much hardware on the axle, I almost ran out of threads to hold the nuts.

https://cimg3.ibsrv.net/gimg/bikefor...10b84f8c98.jpg https://cimg5.ibsrv.net/gimg/bikefor...f7180a1c49.jpg

Back to your issue. is it possible they sent you a rear motor wheel instead of a front motor wheel? That would have been an inch too wide. They do claim the front is a 100mm axle width so there should be no problem fitting a standard drop out.

If they included a cluster of gears that would have been been the clincher.

For fun, here's pictures where people used wrenches for a torque arms.

https://cimg9.ibsrv.net/gimg/bikefor...48dab657f8.jpg https://cimg0.ibsrv.net/gimg/bikefor...42ba42d5b7.jpg

Thanks so much, Doc Wiu for your advice and the pictures. Yes, the torque arms are making sense.

It said front wheel frame kit on the package when I got it. I should have taken a picture. A guy I knew was there when I unpacked it. We didn't completely unpack the wheel. Still in plastic, we held it against the frame of my tricycle, and we both noticed that the fork of my trike is approx. 2 inches too narrow on both sides. And the rim of the wheel (where the tire needs to go) was also probably an inch of even more wider. So, I sent it back but read briefly after that things can be bent to fix or that washers could be used.

Amazon sells this product: AW 16.5" Electric Bicycle Front Wheel Frame Kit for 20" 36V 750W 1.95"-2.5" Tire E-Bike. I am thinking of ordering it (Amazon takes products back and pays the return postage and ebay not always) and looking for a new handyman around here to assist me to give it another go. I am no mechanic at all, unfortunately. Usually, I go to YouTube and look for a how to do video to learn. Some people show how they converted their bikes into e-bikes but no one with the kit that I mentioned above. Too bad.

Thanks for all your advice, Doc Wiu. It is really refreshing finding a soul who is giving sound advice.

The amazon kit is pretty much the same as the ebay one. I read the reviews. You always should, with amazon. Also, amazon has a tricky return policy with third party vendors. If you ever bought a bike on amazon where the shipping is like $75 to return, the sellers try like heck to have you keep it. The shady ones will dicker you until the return period expires. Anyway, some happy customers. Some sad ones. Really, you need to have access to some bike/motor knowledge to make a $200 kit work. They do seem to have installed it on all of kinds of bikes, including trikes, so it ought to fit your trike.

Did you get a charger with your $50 36V battery? Do you know what kind of internal cells. Most take 42V chargers, but some take 37V and you need to get the right type. Chargers are not expensive either.

I better check with the 3rd party vendor about the return policy before I order from Amazon.

Exactly, Doc Wui, there are numerous people who say that the AW 16.5" Electric Bicycle Front Wheel Frame Kit for 20" 36V 750W 1.95"-2.5" Tire E-Bike should fit a tricycle like mine.

I need mine to do my shopping 3 miles away in a rural town when I don't have a car, which is often. I did it with the mechanical tricycle but 2 bags of 20 pounds potatoes in the basket isn't that easy without a motor. Moreover, I am getting lots of hungry guests lately who want to be fed, etc. For me, having an electric tricycle wouldn't just be for fun.

The backside of the coin living quietly in the country is that skilled work is hard to find. Not many people here.

Yes, a charger came with the battery. I charged the battery once and it worked just fine.

The first seller probably sent you a fat bike kit by mistake. Rim would be 2-3/4 inch wide, which fits your description, and motor would be over 5 inches wide at the axles.

Amazon will back you with third party if the guy did something like the above, sent the wrong goods, or sent damaged goods. Otherwise, he shouldn't have to take it back if you changed your mind or ordered the wrong thing,

If you buy it, don't put the electronics in the bag they give you. It will just cook the controller in summertime and kill it. Mount it on the frame somewhere so it runs cool. Cover the connectors so they don't get wet

You might be right and it was a packaging error. I read now something about a mid drive as a method to convert a bicycle or a tricycle. What do you think of a mid drive, Doc Wui?

A mid drive kit is more expensive than the hub motor, at $400-600, Since you want to use your 36V battery, that will probably limit you to the less powerful kits. I think the biggest obstacle is that you have a single speed trike, and that's going to be hard on the mid motor. You want gears on small mid drive, like we used to want stick shifts on small car motors, until automatic transmissions improved. If you had a derailleur model, a mid drive could work,

I get it, Doc Wui, thank you again for all your advice. I know a lot more than before. It is really kind of you assisting me.

Have a great day.