My CityBug project.

Joined
Mar 5, 2022
Messages
252
Location
Aptos, CA
Hello all, I'm working on something cool. I've found a CityBug scooter, by Sharper Image (hello 2007). I've actually been working on this for a few months now and am at the point where I've become confident that this scooter will become useful to make runs to and from the corner market.

Although the frame was in good shape, I found this scooter in a poor state. It was missing....

- Right handle bar, that originally had the throttle

- The seatpost was attached, but no seat

- Batteries, of course. Originally ran on 2x12v SLAs

- Missing kickstand, the bracket is still there though

What I've done so far..

- Added handlebars from a bike that my kid has outgrown

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- Added a seat from an old 80s metal office chair. I used the seatpost from my kids old bike. It fit right inside the seatpost that was found with the scooter. A seatpost within a seatpost.

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- I've placed a new controller, a YK31C 24v 500w

- Added a thumb throttle, from my ebike

- Added Hailong 36v 20ah (10s6p). Overvolting the rated 24v 300w brushed motor and controller. This may be an issue later

- Installed a coulometer to monitor my battery usage

- Cleaned up the wiring

- Cut up the fiberglass shell to accommodate the new battery

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- New tires and tubes

Here it is now.

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The next things I am looking to do is...

- Changing out the brake cable and lever. That is original.

- Fashioning some type of deck. Perhaps from wood, for now. With a deck, I'd have more area to stand on. The existing fiberglass shell wont last much longer. It's slowly breaking apart.

- A voltmeter with key, switch, and throttle. It's an all in one unit.

- Lastly, changing out the motor for an 8" rear hub with band brake

- A proper 36v controller. So I can wire a charging port and get off overvolting the 24v controller. Better LVC too. I should get this sooner, but I feel I should change the motor at the same time. I just don't want to buy a 36v brushed controller and then get a brushless motor, and again have to replace the controller. I guess I could go with a new brushed motor, but I'd rather go to the brushless motor.

The current motor is rated at 24v 300w, according to the manual. It gets hot at 36v. My meter shows that it peaks at 31 amps, when going up steep hills. I weight 150lbs and the scooter is about 40-50lbs. I assisted after a short bit. After reaching the top of the hill, I checked the motor temp. It was very hot too the touch and measured (with a BBQ thermal gun) 212f. I think that's too hot for a brushed motor. I'm pretty sure it was a bit hotter inside and that the thermometer only measures surface temp. I rode it around for almost 4 miles and still had 80 percent battery (16A measured by my coulometer). This scooter will definitely get me to work and back now. That's an 8 mile round trip. It's really fun to ride.

Here is my motor

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I've decided to go with a 8" hub motor, with a band brake for ease of install. I have no idea how I could attach brackets to mount brake calipers for disc brakes. I'm not looking to go really fast. 20mph is plenty fast on a scooter. I just need the power to go up hills. Anyhow, I'm not capable of working with metal. I have no tools for that scale of work. So the band brake fits my needs.

I'm pretty stoked on getting this working. I've been learning a lot from this project.

I'm open to any input. How does this look? Am I overlooking something important?
 
I’ll probably get this kit from

US $66.95 29% Off | kunray 24V 36V 48V 350W 8 inch Hub Motor For Electric Scooter Bicycle Brushless Motor Controller Electric Bike Conversion Kit
https://a.aliexpress.com/_msPJ3UY

The axle is the right length. The controller is rated for 350w and 15a. I’m pretty sure I can’t go by the watt rating, given the amperage of the controller. The amp rating, I don’t know if that’s the limit or the “rated” current. The torque is listed as 22nm, so perhaps the 15a rating is continuous.
 
I’m changing up my original plan a bit. I’m now looking at this kit from CSC

https://a.aliexpress.com/_mq1y9Le

I have the same kit, just with the LCD8H, for my ebike and I love it. The other kits I’ve been looking at, for this scooter, all seem to have a 20ah limit on the max current setting of the display.

Example, https://a.aliexpress.com/_mLNMlWk

I’d like to have a bit more and I know this KT kit will be able to deliver 25 amps.

The motor will stay the same. I’m still looking at the kunray, but it appears that there are many suppliers for that same motor. They are all the same size and weight. I’ll probably go for the cheapest price for that. I’m still planning on starting with one motor, and then (maybe one motor will be enough?), move on to a second motor. I’d get the same 25ah controller from CSC. With 2 motors, I’ll set my controllers for 15ah max. 36v x 30ah = 1080w. That should be plenty to get up hills. I’ll wire these to one throttle and use one display. I’ve seen other similar dual motor controller kits and the wiring for the display seems the same. Hopefully it’ll also work for KT controllers. I’m still looking up about that.
 
So the motor I got is about an inch and a half short of fitting in the frame. I dont want to cut my frame to fit the motor. It probably wont be very safe if I was able to fit it in that way. Im trying to NOT half ass this. I looked at extending the axle and am finding out that that isnt a safe method for a rear hub motor axle. I cant really bend the rear fork inward enough to fit the motor, even if I could, the length that exits the frame wont be enough to thread the nut back on the axle. I see why no one has replied here. This is a dead end project.

Unless, maybe, I can replace the front fork with one that would fit the motor. Hmmm
 
If you look at various threads discussing torque arms and torque plates, such as the Torque Arm Picture Thread, methods are shown that use torque plates that bolt to the frame or original dropouts to extend the dropouts either beyond the frame for motors too wide to fit, or as in your case, extend them inwards for motors too narrow to fit.

It doesn't take a lot of precision or much in the way of tools to create such plates; a hacksaw, angle grinder with metal cutoff wheels, files, drill with bits hard enough to drill thru the chosen metal for your plates, and the metal itself thick enough to take up the excess space (half on each side of the frame to keep the wheel centered), then bolts, nuts, washers to secure it all together. If you don't have metal thick enough, you can bolt together several thicknesses to make them.
 
Thanks for the direction. I did start looking at torque arms after I posted here. I was thinking, like you mentioned, that I could attach the torque arms to the frame, then I’d be able to attach those to the rear hub motor. I’ll dig through that thread and do more research. This is trying my patience, so I worked on other parts. I added a MTB handlebar and was able to attach that to the original stem. Now I have more height and is more comfortable to ride. I also added a much lighter seat. It is a wide ass seat that I got on Black Friday deal and it hurt my butt on my bike. A sit down scooter is much better for that seat.
 
Wow, just gone through half of the torque arm picture thread and see a few who have NOT installed axle bolts. I may be able to follow that lead. After all, this isn’t a beast scooter. I don’t plan on running this at more than 1000 watts. Lots of good info there.
 
I’ve been thinking about this all night. I decided to reverse the axle nuts outward. The scooter already has a 10mm “slot” for the flat part of the axle to rest on. The axle slides right in and it feels very secure. I just have tie wraps for now, but I’m going to get some steel hose clamps to apply the “biting” pressure onto the axle.
 

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Was able to squeeze in torque washers. Much better fit now. I’ll still be putting a steel hose clamp at the end of the dropouts. I’m think that maybe a torque arm kit. Like this, https://a.co/d/8xu0PXT maybe it’s better than torque washers?

Ended up using some gift cards and ordered these.

Vbestlife 36/48V 450W Electric Bicycle Brushless Motor Controller Kit, E-Bike Dual Drive Brushless Motor Controller with 866 LCD Display Panel for Electric Bicycle Scooter Accessory https://a.co/d/bIOjf0J

Should be here Thursday and I’m on vacation. I’ll have plenty of time to install this right when I receive it. :)
 

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Just realized that I need to attach a set screw to the drum brake, somehow. I’ll see if I might be able to use the old plate that the old drum brake attached to. But maybe the electronic brake will be enough stopping power. I’ve never had them and have seen other people like them and don’t need/want physical brakes. I’ll try the motor at 350 watts, at first, then bump it up to 500. I’m full expecting this to run fine at 500 watts per motor……if I’ve done my homework right.
 
I think you're probably going to need torque arms, good ones like the Grin Tech ones (not the clones, the real deal from ebikes.ca) to keep the very small amount of axle flat that intersects the single dropout flat you have on each side (since half of each dropout is just hollow tubing walls, not actual flats) from just chewing thru the hollow aluminum that was not designed to resist axle torque.

Otherwise your motor axle can spinout and rip out the wiring, or damage it such that it shorts phases to each other and/or the hall wiring, which usually blows up the controller and can blow the halls in the motor too.


The drum brake should also have a torque arm for it's own applied torque during braking. If it didn't come with one, or is poorly designed so it uses the axle for this instead, then you need the torque arm even more for this than for the motor acceleration (and because it is going to rock the axle back and forth.


FWIW, the zipties will do absolutely nothing to hold those axle flats together. Hose clamps probably won't either. If you want hardware that will do that, with those hollow dropout tubes, you're going to need something that properly distributes the load across the surface of the tubes, as close to to the axle as you can get it.

You might be able to use the recently-discussed-in-another-thread for a moped,
https://endless-sphere.com/forums/viewtopic.php?f=6&t=118017
thru-bolts with cable clamp hardware.

But it still wont' stop the thin hollow aluminum frame from deforming as the axle rocks back and forth in it.

See the pics here
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1737527#p1737527
for what happens even with good solid steel dropouts that fit very tightly, and tight axle nuts, when the axle is harder than the dropouts...
 
Thanks for the input. I was thinking that this frame was aluminum too. I’ll look at maybe putting a plate along both sides, or something more stable. I don’t have faith in the tie wraps, that was just an example of how the hose clamps would be installed. Perhaps a vertical bolt would be better. I can drill down l, through the frame, and have washers at both ends. Or, like the U bolt, I can use that to clamp down. But yes, the axle doesn’t go all the through the thickness of the frame, so I’d feel better reinforcing the frame with some type of plate. I could bolt it to the frame. I can get one side of the axle to go all the way through the dropouts, but the other side won’t even touch. Having plates at both sides and having them clamp down on the axle seems to be the best fit for this frame. I’ll take that path. Should be able to get the drum brake set screw to attach to that plate as well.
 
Lol. I just found a complete scooter frame kit.

https://a.aliexpress.com/_mOESjJo

I didn’t even know these existed. This one says it’s “aluminum alloy”. I think that means it’s aluminum with another metal. Maybe this will be more cost effective for me. I’ll have to buy an angle grinder and other items to make a torque plate/arm thingy.
 
Don't think you need a new frame. Just need torque plates between the motor and frame. The frame is riding on the ends of your axels. Build tq plates and bolt them to the frame.
 
I found a large piece of steel. Not sure what kind, but it’s so heavy. It’s 12”x 24” and about 1/4” thick. I think a buddy of mine has an angle grinder. I think I can put something together with this.
 
From my point of view, looks like there is plenty of room. 1/4" is not very thick, maybe double it. would still have it clamp the axel so you do not need outside nuts. I'm not there to see all you need to deal with. 12 x 24 should be plenty of metal for what you need. some work to get it shaped right.
 
Ok. I’ll look to double the thickness, then bolt those to the frame. My angle grinder comes tomorrow. I’ve been thinking about getting one for a while and this is a good excuse. Also, it was on sale! I will resume this on the weekend, after my other packages arrive. I’m still reviewing the many pictures associated with “torque arm/plate”, to finalize my aim. Having two 1/4” plates will not allow me to bolt them down, to bite on the axle. If I have one 1/2” thick plate, maybe I could bolt it at the end.

This is what I had in mind. Note the bolt behind the axle.
 

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Quickly finding out that I have no space to work with an angle grinder. Since I also need a way to mount the drum brake, I’m going to order a part. Sendcutsend seems to offer a service I need. I’ll need a torque plate on the brake side, with a drum brake mount. And another plate on the “drive?” side. Any other recommendations to order custom plates? I’ll need to measure everything, both sides, and create templates, remake them to be sure, then send it for order. Perhaps I can also use them to order a deck. I’ll leave the metal work to a pro. I know my limits. :)
 
Looks like this would work well.

It’s 48mmx68mm. The slot is 10mmx35mm. The holes are 6mm. They can be 9.5mm thick. With the wide slot, I should be able to slide the axle to line up the set screw for the drum brake to one of the other holes. I don’t know how to crate a CAD for my own design, so I’m using premade stuff on sendcutsend.

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Id drill through the frame, or have a bracket on the other side, to secure these with, at least, 4 M6 bolts. Also, with this thickness, I’ll be able to put nuts on the axle. Id have to remove the upper half dropout bits to make room for the nuts.
 
I ordered 4 of these. Two will be 9.75mm thick and on the inner frame. The axle will bolt through these. Two 6.35mm thick outer ones will be the anchor to the inner plates. Four 6mm bolts will hold them together in each side of the axle. I’ll work on the controller and other electronics, while I wait. Then, once the motor is mounted, I’ll have to see how I can anchor the drum brake.
 
Torque plates are in place. Went with 3 bolts, instead. Some of the holes, I can’t get nuts on the inner part due to the axle nut being too close to some holes. Also have torque washers closest to the motor, facing outward into the torque plates. It’s not pretty, but it’s solid. Thanks Sendcutsend!

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Also ran a brake cable. I CAN STOP NOW!! I ran the brake cable under the deck.

The handlebar arrangement isn’t the best. I think I got it to stop slipping around.

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With the torque plates on now, I may have to ditch the red shell. Or I might cut it up to fit back on the frame. It’s tomorrow and I should probably go to sleep. Working with the electronics and wiring next. I have everything temporary for now.
 
Awesome. Thank you. Yes, feels great to finally get this together. It was very late and I’ll probably look at adding a 4th bolt to each side today, or next weekend. Just riding in my garage, it feels very solid. Since I have a solid tire on the motor, maybe I’ll need extra support to account for the lack of suspension. I imagine that the bumps can get quite jarring without suspension and aired tubes.
 
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