My Nashbar Flatbar E-Bike

I really like my Jeep Comanche "trekking" E-Bike ( http://endless-sphere.com/forums/viewtopic.php?f=6&t=34102 ) but I found I was using more battery power than I have on some past bikes over the same routes. That limits my assisted range. I didn't want to mess with a good thing so I decided to build yet another in a series of flatbar type E-Bikes. I wanted a steel frame so when I saw on craigslist someone was offering a full chromoly frame from a brand new Nashbar cyclocross bike they stripped for its parts, I had to have it.

http://www.nashbar.com/bikes/Product_10053_10052_577468_-1___204687

I've had the frame since last summer and built it up a few months ago. Since then I have been going back and forth between it and my Jeep bike riding both on the same routes and swapping motors and tires between them to find what makes a difference. And what does make a difference for an assist bike is exactly the same things which make a difference for pedal-only bikes, namely; skinny(er) tires, reduced weight, reduced aero profile, to name a few. What did not make a difference was the motor I used, and I tried 3; A fast MXUS (E-BikeKit) geared motor, a fast Bafang geared motor, and a slow Cute geared motor. The max controller amps also make little difference when significant power is from pedaling. Anyway the latest configuration is this one:



As shown above it is a fully legal (slow) E-bike running a 201 RPM Cute Q100 motor on a BMSBattery 36V/15Ah "high C-rate" Li-ion battery and a stock 36V KU63/15A controller. No-load speed is 21 mph on a freshly charged battery which translates into an 18 mph top speed. baseline weight for the bike with motor is 35 lbs. The weight with everything shown in the picture (except water bottles) is 48 lbs. This includes the battery, a couple pounds of tools, spare tube, etc. Someday I may build a true lightweight but his ain't it. The frameset alone weighs a hefty 8 lbs bare.

I took it for a ride today over a usual course and while it felt quite underpowered I still averaged, well a pretty average trip speed for me. All I did at about 5 miles into the ride was let the cruise control hold full throttle then pedal along. The low power makes for a rather mundane ride though. Where I really missed the speed was pedaling up this one 4-5% hill at 18 mph right behind a lycra boy. It's fun to mess with these guys but with little power on tap I couldn't close the gap on him. On the downside he then flew away from me. Too bad I love seeing their expressions as I come up alongside them and then pedal past.

My power consumption is lower with this bike, around 25% less than my Jeep bike.

Stats for today's ride:

Distance: 39.8 miles (64.2km)
Average speed: 17.6 mph (28.4 kmh)

Amp-Hours used: 7.282
Watt-Hours used: 279.6
Peak Watts: 605.1
Peak Amps: 15.76

WH/mile: 7.0
WH/km: 4.4

-R

Nice bike. The low power bikes, although less exciting, can be just as challenging as the kW bikes.

Thanks Modbikemax.

I have a faster wound Outrider geared motor on order which will be the next change to this bike. That'll give me a little more speed.

-R

Today the YOUE geared motor I ordered from Aliexpress arrived.

http://www.aliexpress.com/item/36V-48V-250W-High-Speed-Brushless-Gear-Hub-Motor-E-bike-Motor-Rear-Wheel-Drive-YOUE/1888938628.html

This case is about 11mm larger in diameter than an Outrider or MXUS geared motor. I doubt the actual motor inside is any larger than either of those or a Bafang for that matter but what caught my eye about this motor is that the side cover is attached with screws. Most small geared motors nowadays have screw-off side covers that require a special tool...which of course is not available (except for Bafang motors at GBK). Eventually bearings do need replacing so having easy access is a real plus.

I tossed the motor on the forks of the bike and taped on a magnet to check its speed. I got a higher than expected 8.0 RPM/V or 25% faster than the Cute Q100.



I ordered a couple of Mavic A119 rims from Cambriabike and spokes from GRIN so hopefully I'll have it laced up in a couple of weeks.

-R

Got the new motor laced up using 242mm Sapim butted 13/14g spokes from GRIN. They sent 14mm nipples but I used 12mm nipples I had on hand since that is what the spoke length was calculated for. This bike does not have disc brakes however since I swap parts a lot who knows where it will end up in a year. Therefore to provide maximum disc caliper clearance I laced the motor to the Mavic A119 rim with all spoke heads facing out. I prefer a 2X pattern with a small geared motor in a 700C rim but 1X works better with all of the heads facing out.



I mounted the 36V/15A KU63 controller on the downtube. I cut a few slits in the case for some cooling. I also cut off about 3.5 ft of cable from the motor lead and re-terminated it with Andersons. The controller is running sensorless.



The saddle was replaced with a Planet Bike A.R.S. Classic model for more comfort.



Rode the bike the first time today with the new motor. As expected the top speed was right about 21.0 mph with a fresh 36V/15Ah Li-ion battery. The motor is somewhat noisier than the Cute Q100 while cruising. Noise under load is similar. My speed up an 8% grade with this 8.0RPM/V motor was roughly 1.5-2 mph faster than the slow-wound 6.4RPM/V Cute.

Oh and while the YOUE name is new to me...

View attachment 1

It probably shouldn't be since the Golden Motor Mini motor I purchased back in 2009 that I've been calling a Bafang SWXH...



...was actually a YOUE.


-R

Nice one. Lacing the spokes that way gives it a nice clean look. I have never thought to do that, I might give it a go on my next wheel.
I don't like where you put the controller though, first puddle and it will get drowned, plus you have got all those phase and hall wire twisting all the time.
I like to mount my controller so there is minimum wires twisting by fixing the controller to the forks or bars. You only have 2 thick power wires twisting instead of 7 thin wires.
I do like the box the controller is in, is that a standard box for that controller or is it a generic box? Where did you get it?

Modbikemax said:

Nice one. Lacing the spokes that way gives it a nice clean look. I have never thought to do that, I might give it a go on my next wheel.
I don't like where you put the controller though, first puddle and it will get drowned, plus you have got all those phase and hall wire twisting all the time.
I like to mount my controller so there is minimum wires twisting by fixing the controller to the forks or bars. You only have 2 thick power wires twisting instead of 7 thin wires.
I do like the box the controller is in, is that a standard box for that controller or is it a generic box? Where did you get it?

Click to expand...

I don't know if the wheel is structurally as sound laced this way but it's necessary to provide clearance for many calipers with a 160mm rotor. I have a similar small motor that I laced in a conventional alternating 2X pattern and had to go all the way up to a 203mm rotor for the caliper to clear the spoke elbows.

The controller box is a standard item at most Chinese vendors. I mounted it there to keep the thin phase wires as short as possible and for aesthetic reasons. Most riding on the road entails little actual rotation of the handlebars so while the bend looks severe it isn't stressed much. The Andersons will simply pull apart if the cable is pulled too taut. This is a fair-weather bike and will likely never see rain so I'm not worried about it.

-R