800W Q128c commuter build

motomech said:

The torque arm and the axle nut are too far out on the axle.
The TA should be clamped against the bottom of the chain stay and the nut should be inboard of the wire exit slot.
Do you have the fat washer/spacer in there? I think you need to replace it with a reg. flat washer.
Remember, when it's right, the wire should exit downward with a loop to prevent water ingress.
Then you should be able to fit the plastic end cap.

Click to expand...

I see what you mean about the torque arms - not a lot of meat around the nuts. I did use the fat washer provided since it aligned them well with the dropout. I'll try switching to a thinner washer and mount the torque arms further up the chainstays.

motomech said:

The BMSbattery order was perfect except they sent me a left handed thumb throttle; turns out, this arrangement fits the handlebars better anyway.

Click to expand...

I don't think BMS B. sells a left-hand thumb throttle. I just flip the reg. thumb around when I mount it on the left and I suspect that is what you have done.
If you like the thumb on the left, you would have really liked the LH half twist i recommended you get.

Click to expand...

When I flipped it around on the right side, the throttle wires were pointed away from the gooseneck and needed to be bent 180 to run down the frame. I don't mind it on the left, but I'll have another look, as I was tired and could have overlooked the obvious.

motomech said:

Do you think the motor would have fouled the original brake disc/caliper?

Click to expand...

I tried mounting the motor with the caliper in the original position with the 160 rotor and it impacted the motor. I had the extra parts on hand just in case (my measurements indicated it would impact by 5 mm), and went from a 160 to a 180mm to fit the motor. I'll post a clearer pic to illustrate the clearance with the new 180 rotor later tonight.

motomech said:

Looking forward to the performance report.

Click to expand...

I had to scrub my morning test run as I ran into an "03 info" error, which according to the LCD-3 manual, indicates a hall sensor fault. I didn't have time to troubleshoot this morning before work, but I'll test the motor hall sensors with and without the motor cable, then check the connections to the controller - it should be fairly easy to sort out what's wrong.

motomech said:

It doesn't work that way. Even a Q100 on a road bike is too parasitic to ride with the power off. One wouldn't think that 10 pounds and a free wheeling motor wouldn't have such an effect, but it does.

Click to expand...

chas58 said:

I don't know about that. I have a couple of q100 builds (road and mountain), and riding them with a dead battery is just fine. The bikes weigh about 30lbs each with motor and battery, so maybe that is the difference. In the 10-15mph range, I'm quite happy riding without the motor.

Click to expand...

I regularly ride my 500w CST with the power off. Rolling on DH bike paths in rush hour I have been side by side with many bikes, and have noticed not drag, but that I roll faster than everyone else with my smooth wide tyres on. Everyone else. In thousands of miles, nobody has rolled away from me, though I'm over making comparisons to every other bike now. I know my wheel won't go on forever when span by hand, but the drag loss is overcome by the gain from wider tyres. If I spin the wheel by hand, with the kind of effort just moving your wrist creates, it will do a dozen or more turns easily.

As far as these lightweight hub builds are concerned, I have no practical issues pedaling power off.

By the seat of my pants, it “feels” as if the added system (battery, motor, controller) weight introduces more resistance than anything to do with properly functioning, lubricated and broken-in hub freewheel.

Hall sensor error? You know about these links, right: http://www.ebikes.ca/learn/troubleshooting.html

Very curious about performance report too!

friendly1uk said:

[
I regularly ride my 500w CST with the power off. Rolling on DH bike paths in rush hour I have been side by side with many bikes, and have noticed not drag, but that I roll faster than everyone else with my smooth wide tyres on. Everyone else. In thousands of miles, nobody has rolled away from me, though I'm over making comparisons to every other bike now. I know my wheel won't go on forever when span by hand, but the drag loss is overcome by the gain from wider tyres. If I spin the wheel by hand, with the kind of effort just moving your wrist creates, it will do a dozen or more turns easily.

Click to expand...

Ykick said:

As far as these lightweight hub builds are concerned, I have no practical issues pedalling power off.

By the seat of my pants, it “feels” as if the added system (battery, motor, controller) weight introduces more resistance than anything to do with properly functioning, lubricated and broken-in hub freewheel.

Click to expand...

Needing a bike, I grabbed the Kona with Q128c and no battery for my morning commute and am happy to report that it handles almost like it did without the motor. I can detect no difference in rolling resistance - if anything, the momentum of the spinning hub helps as stored energy, which is dissipated by increasing the distance I roll to a stop. It seems slightly harder to pedal up to speed, but again, it is the inertia of getting the heavy hub up to speed. The momentum is conserved, and I see no net loss in energy overall. Happy to say, my 14 km 2 way commute was no harder this morning than usual. I'm used to carting 20-30 lb of gear in my saddlebags, so I wouldn't notice the extra 5 or so pounds of hub, controller etc.

Ykick said:

Hall sensor error? You know about these links, right: http://www.ebikes.ca/learn/troubleshooting.html

Click to expand...

That's a great resource and simplifies the testing enormously. It wouldn't surprise me if the hall sensor wires were connected to the controller plug all backwards - we'll see...

motomech said:

Do you think the motor would have fouled the original brake disc/caliper?
Looking forward to the performance report.

Click to expand...

Here's the caliper clearance from the top. This gap is just over 5mm: (edited to get rid of photobucket crap and provide uploaded image)


And the side:

I tested the hall sensors. From black(ground) to green, black to blue, black to yellow, I get a constant 4.5V on all three regardless of spinning the wheel (backward since it freewheels forward).

There's definitely a short, either in the motor or the controller; testing continuity may reveal the location of the short.

Now the fun begins...

The Black(- voltmeter) stays on the black and you rotate the red(+Voltameter)between the remaining three colors(grn., yel., blue).
It would be most unusual for all 3 Halls to be defective.

So here's the hall sensor cable"


The white wire is probably the speed sensor line

After careful re-measurement, I'm getting:
+4.45 volts between red and black (-black probe on black)
+4.95 volts between black and the halls (green, blue, yellow) (-black probe on black, +red on halls)
+0.5 volts between red and halls (green, blue, yellow) (-black on halls, +red probe on red)
0 volts between halls (green, blue, yellow) and white (speed sensor)

Moving the wheel does not change the voltage between any of the combinations tested.

motomech said:

The Black(- voltmeter) stays on the black and you rotate the red(+Voltameter)between the remaining three colors(grn., yel., blue).
It would be most unusual for all 3 Halls to be defective.

Click to expand...

I agree, and I don't think the halls are defective. I'm at a loss to explain the observation, except that all three lines could be shorted with a 5V power source in the controller. The black should be 0 volts and the red should be 5V. Maybe they swapped the red and black lines in the motor connector from the controller? It's hard to tell without making my own wire harness, as the motor cable and connections are quite cryptic.

I know my way around a multimeter and have it set properly at the 20V DC setting. Getting at the wires on the controller side of the plug is ridiculously easy as the metal is easily accessible in the plastic housing. I examined the plug and I don't think it's shorted.

Did you disconnect the controller and do a continuity check between each of the power wires (Red Positive, Black Ground) and their three cousins (green, blue, yellow)?
It should go without saying but ... you should NOT get any continuity.

I was checking continuity, but after reading a few other threads, It seems that you will often get readings like these controller side if the power connection isn't making it to the halls.

I took the motor-cable to motor connection and reefed on it with all my strength and to my surprise, it went in deeper

It lives!

I'm going to go over a few more things like readjusting the torque arms and installing smaller washers; maiden voyage scheduled for this Monday...

Can you help me out by measuring the total axle width? Is it 205mm or greater?

[EDIT] YKick has already advised they are about 205mm. ta!

Welcome to give us your thoughts on whether its worth buying a q128c or whether I'd be better off with something else. Proposed use - commuting, pavements/bike paths approx 350 - 400km per week.

My goal was to come up with an ebike which would function and feel much like a normal bike while providing extra assistance when needed. I also wanted it to be powerful enough and have the battery capacity to provide major assistance on those off days.


The motor itself was easy to install. I couldn't believe that after putting on a 9 speed cassette and two inner washers, it just slipped into my dropouts with no fuss.

On my test ride to and from work, the bike with battery, motor and controller weighed in at 22 kg (48 lb); my saddle bags weighed 8 kg and with my 78 kg, the total load that poor motor had to lug was 108 kg or 238 lb. The morning was cool and sunny (~8C), and the afternoon was sunny and around 14C. The battery was stored indoors prior to both morning and afternoon rides.

I pedalled the entire trip and fed the motor with the thumb throttle when I needed extra speed or acceleration that I couldn't provide with my legs. I started the first morning with the 11.6 Ah battery at 54.6 V. Arriving at work, I tested the remaining voltage with a multimeter at 51.8 V. Upon returning home after 27.2 km of travel between charges, the voltage remaining was 49.8 V. The trip home (13.6 km or 8.5 mi slightly uphill) took just under 35 minutes. The next day's commute was completed in a similar time with 50.6 V remaining, though there was less headwind.

Reading about how soft the gears are, I tried to keep power to less than 500 W for steep hills and maintained a speed of at least 15 kph, providing substantial pedalling effort in low gear for the steepest hills. On the slight downhill sections, pedal power was enough to maintain >30 kph, and for the most part, these speeds were attainable on slight uphill grades with a 200-250W contribution to my pedalling.

After arriving home, the motor was cool to the touch and the controller (contained in a vented canvas bag) was ever so slightly warm.

I'm quite enjoying the thumb throttle on the left side, as it frees up my right hand for the cassette gears, allowing me to operate it as a normal bike while choosing the amount of assistance with the left hand. After a couple minutes, it was intuitive.

I haven't set up the PAS yet. I have to admit I stripped the crank arm threads with my extractor tool and nothing short of a hack saw will get it off now. I might try PAS in the future, but the throttle is ideal for my current needs, as it allows me complete control of when I get motor assistance and how much.

The motor is very quiet quiet but not completely silent; rather, it had a slight but audible hum that increased in pitch along with speed. This hum is reminiscent of textured or slightly treaded tires on asphalt and could easily be mistaken for that. The sine wave controller does seem quieter and smoother than the square wave controllers I have used in the past, though I'm comparing different motors. The charger that came with the battery is very noisy by comparison - so much for charging at work.

All in all, I think these Q series motors are great for those that want to keep the bike element in the equation. In these terms, the build has greatly exceeded my expectations and it is totally ridable without power. For those that want to travel primarily by motor power, I think they will be better off with a dd hub or a stronger geared motor. It seems like this build will do exactly what I need it to. Having a 9 spd cassette is awesome, and the shifting is incredibly smooth. It's stealthy enough that even my neighbours, wife and kids haven't yet noticed it's an ebike.

Just coming up to two weeks daily riding on the Kona light commuter. Weather's been mostly great here, mostly sunny with day time highs from 18C to 26C - and one day it reached a whopping 32C; the upcoming week should bring much the same.

On the hottest day, the controller, which is in a vented canvas bag, was hot to the touch but not scorching burn off your skin hot. On cooler days, it was quite warm. Mind you I'm only putting 100-200W through the controller on average with brief peaks of 400W and if I were interested in higher output, I'm quite sure I'd smoke that poor controller. All the same, I plan on opening the zipper to give the controller lots of air on days hotter than 25C or if I plan on higher power runs.

One interesting thing I've noticed is that with zero throttle, there is absolutely no motor resistance. As soon as I give it a little throttle, the console still reads 0 watts but I can feel motor resistance slowing me down. If I'm going quickly, I have to provide a great deal of throttle before getting a positive watt reading and overcoming the feeling of motor resistance; as long as I'm getting a reading of at least 10-20 watts, I no longer feel the motor dragging.

Cool beans, mr molybdenum.

Warning: Careful with those wires exiting the motor though!

One warning. I was riding my bike last year, doing a very slow tight turn, when the power threw my balance off and I dropped the bike. No harm, no fowl I thought.

Wrong. With the wires exiting the motor like you have them, I bent/tore 3 of the wires, and the motor no longer worked. It was repairable, but that is a HUGE weakness. Lay the bike down or scratch anything on the hub, and those little wires will be gone, rendering the wheel/motor useless. I took one of those 3mm wide nuts from the inside and screwed it on the hub, forcing the motor wires to exit the motor through the slot inboard of the nut. That way, if the axel hits anything, it won’t tear my wires apart.

Anyone else have a different solution for this?

I like your build!

I just finished V2.0 of my road bike build. Q100 on a drop bar bike, push button throttle, 29lbs, 25mph cruising speed. It’s a nice way to get to work. And yes, I spend a fair amount of time riding without the motor (at speeds less than 20mph), and it does fine with no motor. I get what motomech is saying. A 50-60lb mountain bike is a lot of work to pedal under the best of circumstances. A 30lb road bike with efficient tires is amazingly easy to pedal with the motor off.

chas58 said:

Cool beans, mr molybdenum.

Warning: Careful with those wires exiting the motor though!

One warning. I was riding my bike last year, doing a very slow tight turn, when the power threw my balance off and I dropped the bike. No harm, no fowl I thought.

Wrong. With the wires exiting the motor like you have them, I bent/tore 3 of the wires, and the motor no longer worked. It was repairable, but that is a HUGE weakness. Lay the bike down or scratch anything on the hub, and those little wires will be gone, rendering the wheel/motor useless. I took one of those 3mm wide nuts from the inside and screwed it on the hub, forcing the motor wires to exit the motor through the slot inboard of the nut. That way, if the axel hits anything, it won’t tear my wires apart.

Anyone else have a different solution for this?

Click to expand...

Very good point. I've done that too, though my lovely Xiongda motor couldn't be repaired.

The black plastic cap that you get with the Q100 is sufficient to protect the wire. It should be fitted!

I have replaced the wires a couple times on the Q100.
I use a new 9-pin cable (good to order extras of these) and since the half-axle unbolts on the Cute, it's pretty easy to do.
I pull the cable down firmly when installing and yes, the plastic caps offer suprisingly good protection.

I get what motomech is saying. A 50-60lb mountain bike is a lot of work to pedal under the best of circumstances. A 30lb road bike with efficient tires is amazingly easy to pedal with the motor off.

Click to expand...

Yes, my Rocky Mountain is quite a pig, lot's of bob among other things.
Not being a bicycle guy, I suppose I underestimated what a road bike can do.

Still, Moly seem to be intimating that some throttle jockying is required when going from un-powered to powered.

I still have to wonder, if the LCD-s is used, why not leave the system on all the time, ride in PAS #1 and bump it up for the hills?

Having put 280 km on the odometer, I can say I'm very pleased with the outcome.

d8veh said:

chas58 said:

Cool beans, mr molybdenum.

Warning: Careful with those wires exiting the motor though!

One warning. I was riding my bike last year, doing a very slow tight turn, when the power threw my balance off and I dropped the bike. No harm, no fowl I thought.

Wrong. With the wires exiting the motor like you have them, I bent/tore 3 of the wires, and the motor no longer worked. It was repairable, but that is a HUGE weakness. Lay the bike down or scratch anything on the hub, and those little wires will be gone, rendering the wheel/motor useless. I took one of those 3mm wide nuts from the inside and screwed it on the hub, forcing the motor wires to exit the motor through the slot inboard of the nut. That way, if the axel hits anything, it won’t tear my wires apart.

Anyone else have a different solution for this?

Click to expand...

Very good point. I've done that too, though my lovely Xiongda motor couldn't be repaired.

The black plastic cap that you get with the Q100 is sufficient to protect the wire. It should be fitted!

Click to expand...

I've installed the little black cap and it does a remarkably good job at channelling the wires exiting the motor. I usually travel with two overfull saddlebags for my commute which provide additional protection. I'm kicking myself for not ordering an extra 9 pin wire from bmsb; well next time...

motomech said:

I get what motomech is saying. A 50-60lb mountain bike is a lot of work to pedal under the best of circumstances. A 30lb road bike with efficient tires is amazingly easy to pedal with the motor off.

Click to expand...

Yes, my Rocky Mountain is quite a pig, lot's of bob among other things.
Not being a bicycle guy, I suppose I underestimated what a road bike can do.

Still, Moly seem to be intimating that some throttle jockying is required when going from un-powered to powered.

I still have to wonder, if the LCD-s is used, why not leave the system on all the time, ride in PAS #1 and bump it up for the hills?

Click to expand...

I post this because it may also be possible that the throttle, while seemingly off, could in some cases (depending on the throttle) still provide a little power to the motor causing resistance; with the LCD3 registering 0W all the time, one would just assume the motor resists without power - but it shouldn't.

Needing to jockey the throttle between un-powered and powered is a minor inconvenience since I tend to ride un-powered on flat sections and downhill, powering up to 200-300W for the uphill. Still, I won't discount PAS until I try it - and I might find it just the thing I need. I stripped the threads on my crank arm with the extractor tool so I never got around to installing PAS. I'm going to take my gear puller to the crank arm and try to install the PAS next week and will report back. While I'm at it, I'll install a matching Marathon Plus on the front to replace my ageing continental.

My colleagues, wife and kids still haven't figured out it's electric :lol:


View attachment 1

Yeah, where is the motor? LOL.

It certainly doesn't look like an electric bike. Very nice build!

Now, I'm wondering if I have those plastic caps anywhewre. I don't remember ever seeing them with my motors. I'll have to dig through the parts bin.

Here is what I do to protect my wires.

molybdenum said:

so I never got around to installing PAS. I'm going to take my gear puller to the crank arm and try to install the PAS next week and will report back.

Click to expand...

You'll love the PAS. It's so much easier.

chas58 said:

Yeah, where is the motor? LOL.

It certainly doesn't look like an electric bike. Very nice build!

Now, I'm wondering if I have those plastic caps anywhewre. I don't remember ever seeing them with my motors. I'll have to dig through the parts bin.

Here is what I do to protect my wires.

Click to expand...

Your work with the Cute Q100 lightweight builds https://endless-sphere.com/forums/viewtopic.php?f=3&t=49691 provided inspiration and the certainty that I could achieve my build objectives. It's nice to see these types of builds on the sphere.

d8veh said:

molybdenum said:

so I never got around to installing PAS. I'm going to take my gear puller to the crank arm and try to install the PAS next week and will report back.

Click to expand...

You'll love the PAS. It's so much easier.

Click to expand...

This weekend the crank arm will come off one way or another! I think you're right about the PAS.

Get the PAS working before you assemble it to the bike. There's 4 combinations of direction and magnet disc orientation. Connect it up and twizzle the magnet disc around against the sensor to make it work. On some, only one of the four combinations works, two on others. Test it again before tightening up the crank. That will save you a lot of work.

No love with the gear puller to remove the crank arm and install the PAS; I'd need to file off the rounded bottoms of the puller claws to allow purchase under the crank arm. Now a hacksaw and the spare crank arm I found seem to be my best options

I've been waiting to install the PAS because I need to get the brake lever motor cut-off worked out for safety and legality reasons. With hydraulic disc brakes - and not wanting to pay hundreds of dollars for a Magura solution, I searched the sphere and seen what others have done to improvise:

"Using Reed Switches For E-Brakes" rkosiorek https://endless-sphere.com/forums/viewtopic.php?f=16&t=11760
"How and where to mount magnetic reed switch for regen brake?" electrobent http://endless-sphere.com/forums/viewtopic.php?f=2&t=16722
"Reed Switch buggered" Kingfish http://endless-sphere.com/forums/viewtopic.php?f=2&t=18944
"Normally Open Reed Switch as ebrake" Sunder https://endless-sphere.com/forums/viewtopic.php?f=3&t=47423


I've ordered:

- 20 x Normally open magnetic reed switches with 7 mm length.

- 20 x Neodymium Magnets (4x4x4mm)


and here is the planned mod:


The magnets are 4 mm and will just fit into the gap in the lever arm. The 7 mm reed switch should fit nicely behind the lever, and I will drill a hole to pass the two wires from the reed switch through the lever body and to the controller. Everything will be hot-glued into place; when the brakes are applied, the magnet approaches the reed switch closing the circuit and cutting off the motor. The parts were cheap ($6.00 US for everything inc. shipping), and with 20 spares, I should be good for another 10 foreseeable future builds The mod should be nearly invisible, save the two small wires running from the brake levers to the controller.

I will wait to install the PAS for when I have a reliable brake lever motor cut-off installed, but now I wait for the slow boat...

You don't really need the brake cut-offs with these modern controllers. The response time to starting and stopping pedalling is very quick.

d8veh said:

You don't really need the brake cut-offs with these modern controllers. The response time to starting and stopping pedalling is very quick.

Click to expand...

It's good to know how responsive these controllers and I look forward to seeing first hand the responsiveness of PAS and the how the controller simulates a torque sensor.

I plan to install the magnetic reed cut-offs to comply with local regulations that stipulate the motor must stop when the brake is applied; Also, I don't really trust myself not to start pedalling on PAS5 and go lurching into traffic

That being said, you present a good argument for setting up the PAS in advance of receiving the parts - and I can always unplug it.

d8veh said:

Get the PAS working before you assemble it to the bike. There's 4 combinations of direction and magnet disc orientation. Connect it up and twizzle the magnet disc around against the sensor to make it work. On some, only one of the four combinations works, two on others. Test it again before tightening up the crank. That will save you a lot of work.

Click to expand...

Does this prevent backward pedalling from activating the system?