Mongoose and cheap brushed Currie motor setup

Here is my third ebike build. This one came about since http://www.allelectronics.com/ had some cheap surplus motors I could not turn down. At first I bought them for a go cart, but since they had the chains and sprockets and I had a spare bike. It was just too cheap not to do it. The motor is 600watts. I plan to set it up much like the Cyclone designs. I have the sprocket completed, CNC'ed on my mill. I will be working on the motor mounts next.

Nice. A build after my own heart. Does it have a freewheel crank setup? If not a low budget add on if you get it to fit- with a shimano FFS crank you will be able give the legs a rest whilst still powering. They typically go for $0 to $20 used off of late 70's and early 80's entry level bikes.

Yes, it's a Shimano freewheel. It's hard to see it. I'll take a close-up of the crank when I get it all together. The motor has a freewheel as well. It's a one way roller bearing. This should be an easy conversion once I CNC the motor mounts; I plan to use the water bottle screws as part of the anchor. The batteries will be A123's. I plan to keep the bike light and agile for the trails. Probably only 20cells in a 10S 2P, installed into the triangle of the frame.

Light and cheap.. dual freewheelin too! Nice one.

The part I like best other than it being cheap is the motor doesn't stick out like my 650w cyclone. I don't have to extend the cranks. I can later change it to an RC motor if I need more power or range.

Might be worth it to check out some racecar rollcage brackets. They aren't too expensive, another guy here used them. May save you some time if they will work. Looking forward to seeing the guts of that BB.

I don't mind doing the CNC part of it. It's actually one of the things I like to do and gives me a reason to use the CNC machine I built. I plan to mill out a custom battery bracket as well to keep the battery from moving about. Things sometimes move slow around here, only because I have so many other projects going at once.

Here is a close up of my freewheel main sprocket. The freewheel is sandwiched in-between the CNC’ed spacer/mount and the currie sprocket. I had to play around with different combinations to get both sprockets to fit. Mainly because the currie sprocket is so large.

Nice sandwich stackage. Good find on those cheap parts also, you can easily pay five times that on some other sites. I have a couple freewheel cranks similar in function to yours. I'm going to try em on a tandem cruiser ebike, but not as part of the E drive system. In our case the only purpose is to isolate the two pair of legs.

Update, haven't done much with this setup. Currently the ratio is 6 to 1 since the sprocket is 90 and the motor sprocket is 15. To get the speed to a 80-90 cadence I need to add a 5 to 1 second gear stage. I am tempted to just mount the motor on and see what it does, but something tells me it would be setup too high for speed. Has anyone tried something similar. I think the cranks will be revolving around 350-400rpms, so I really don't want to invest anytime in it just to have to redo it. In the workings is a planetary gear reduction of 4.8 to 1, I picked up from allelectronics. I will need to house the gears and figure out how to mount and work out the hardware. This will take some CNC and cad work to do so it won't happen till I finish my other ebikes. A very quick solution and a tempting one is to pick up one of Currie's geared reduction motor. Cost is less than $100. Allelectronics had them for $45, but since has sold out on them. Had I known at the time I needed this motor, I would of picked one up. This would of been a really cheap ebike with really good climbing performance.

Hi - Razor has a 350W 24V gear reduction motor with a 21 tooth #25 sprocket for $36 + $11 s/h. It's for the Dirt Quad. It's also available from other suppliers. At that price you could try it and if it's not strong enough the gear reduction unit might come off and bolt on to your 600W motor - jd

TNC Scooters seems to be out of stock for MY1018Z but they usually have 'em at about $50
otherDoc

Hey the razor looks interesting. Too bad they don't list the gear ratio or the dimensions. TNC motor looks good, have to wait till they stock up on them. Thanks for the info guys.

Be aware 1018's aren't the quietest of motors. Be sure to check out Tyler D's thread on ventilation if you do buy one. I run one 24v 1018 overvolted to 36v with TD's passive venting and it seems to work well.

Another neat thing you can do with the 1018 (if you setup a diy BB clamp mount).. take advantage of the offset drive shaft as a way to adjust chain tension by rotating the motor case in the clamp. I forgot who it was that did this, but it was pretty slick.

http://en.unitemotor.com/ProductView_40.html

I put the Razor motor on my front wheel drive bike. Some pix at http://endless-sphere.com/forums/viewtopic.php?f=6&t=12318 but I can take some more or give you some measurements if you want. Don't bother to write Razor - they replied to my questions regarding ratios, etc with "Although we are happy to assist you with info that will help you with purchasing a Razor product. We are not able to assist with making modifications to or building a product. Our goal is to make sure that your product is as safe as possible." Let me know how I can help - jd

Yeah, that would be great. I'm sure other who are interested in the motor would like some measurments of it as well. I'm interested in the total width, height and diameter. That way I can tell if it fits inside the frame of the bike without interfering with the pedals.

From your post
"I'm guessing the gearing on the motor is about 1:7" have you verified this a all?

OK here are some pix of the Razor motor, a Unite 1016Z3. According to the table of Unite motors above (Wed 8/26, from gogo), the no-load speed is 3850, rated rpm is 3000, ratio is 9.78:1. It runs in either direction, depending on wiring. I changed the 21 tooth #25 sprocket to a 9 tooth bicycle one - jd

Oops, that grid was for the Z.
Here are the specs for the Z3:http://www.cn-dcmotor.com/productShows.asp?ArticleID=189

Thanks for the measurment, it seems the motor is wider than I would like. I plan to put it in the triangle part of the bike. I think it would interfere with the pedals.

I'm back on the mongoose project now that spring is here and I wanted a ebike I can let friends borrow and ride along. Here is an update, I decided to go with the cheap currie motor I already have. To do this I needed a gear reduction stage. Here is what it looks like. It's adjustable so I can get the chain slack taken up. I will be using a #25 chain for the first and second stage. Will be interesting to see how this bike performs since it will be using the bike gears for its final stages. I still need to machine out a holder for the 80tooth sprocket. My concern currently is jackshaft spindle, it should have been thicker. I went this route so I could use the rollerblade bearings I had. You can’t see them, but they are press fit onto the other side of the plate. I’ll see how this initially works out and change it if needed.

Your idea is very similar to what I'm building right now. I did go with the 1018 motor, the 36v 450watt geared one. Running it with no load in my room - was unbearable, the noise, like nails on a chalkboard. TNC scooters said it won't be as bad with load on it. And so that is my only concern with this entire project of mine. On my first project bike I had a 24v 600w currie motor, no gear reduction, and that was blissfully quiet. Big problem is the lack of reduction.

But as far as mounting it, I just bought some aluminum 1.5" angle 1/8" thick at Lowes, will use that to attach the motor to the bottle cage mounts on the down tube and seat tube for a sturdy setup. (Last week I was using clamps and didn't have any vertical support so the motor had so much torque it yanked it out of alignment.

I'm going to take pics and start my own build thread today.

I finally had time to complete this build. I’ve been waiting on my new frame from my BMC that broke recently, due to the battery weight from the rear rack and too much space in the down tube. This was an easy build once I got around to it. I took a 10 cell A123 pack for the test run. I was able to hit 19 mph reliably on 2nd gear. Moving up a gear cause the controller to shut down after a short while. It’s not able to handle the current loads. The controller was one from TNC scooters. Rated at 36volts and 30 amps. Disappointed with the shut down feature, but it’s safer than a full short upon failure. I will need to get a beefier controller if I want more speed. Not sure if I plan to do this since the bike has no suspension and only rim brakes. 20mph is easy to achieve with pedaling so this bike pretty much performs as expected with the currie motor. It was supposed to be a spare bike originally, but I’ve moved on to better frames. It was a fun experiment; the end result is a solid setup for the power level expected. I ended up going with a bigger bearings and a 12mm shaft. I'm glad I did since it sheared the pin once on low gear in the grass already, so it has some torque to it. Lots of room for batteries in the triangle area. I might try a brushless motor next on it since it would be easy to mill out a plate that can be swapped with the currie mount so I can do some RC testing and get around to playing with Bertie's timing board.

I have too many ebikes now. If anyone is interested in buying this e-bike, let me know. Chromoly frame, 30 inch stand over height. It’s a small-medium frame. I’m 5’7” and it fits me well.