Yet another clueless newbie with 2 Townies and . . .

[eddywanderer]

. . . some slightly geekish DIY electromechanical engineering questions for you wrench-and-voltmeter-wielding risk takers out there:

Old(er) age, a fixed income and the need of exercise having reduced me from midlife-crisis crotch rockets to sedate e-cruiser bikes, I have one definite project and one under consideration.

A first-generation (I think) high-bar Townie Electra, 36V / "250W" (RMS or peak?) planetary gear hub motor, cheapo 7-speed pedal drive train, mechanical disk brakes, in super-good condition, freshly re-rubbered with lower-rolling-resistance Maxxis road tires. Acquired late last year, so only got a little riding time in, enough to see that I love it despite being a bit feeble on top speed for longer rides.

Where in blazes is the pulse generator on this thing? Web searching yields a huge assortment of pretty much the same deal everywhere - usually a magnet clamped to a spoke and a corresponding inductive pickup coil attached to some stationary frame location. Examined every centimeter of the bike until blue in face, found zippity-squat. Nor any indication of the pieces having already been removed. Do some of these hub-drive bikes have the speed sensor built into the hub? Or could it be that a class 1 bike simply doesn't have enough power to warrant it? But if that's the case, how would it get information necessary for pedal assist synchronization?

There is one mysterious little 2 or 3-conductor wire that goes up inside the bottom bracket from what appears to be something electronic integrated with the battery holder. Could this model of bike be getting its rotational reference from the crank instead of the rear wheel like everyone says is the usual case?

Additionally, how do you folks feel about doing a high-powered direct-drive / higher-wattage upgrade on this kind of machine, what with its robust frame that seems ideal for such tinkering? Or would I be better off doing a front-drive conversion from scratch (lacking the spendy funds for a mid-drive) on my other Townie, a somewhat more nicely appointed 9-speed with the weird "roller" brakes..?

Advance thanks to any and all for input on this stuff.

 

[tomjasz]

I've done a few Townie front drives and am pleased. They are not hill climbers but there are hub motor versions that COULD be billy goats by throwing some upgrades at the build. Were it my build I'd look at the hub motor kit California eBike sells. A VERY reliable MXUS motor with easy-to-find parts and support KT controller and display. OR if the budget allows, a Grin ebikes.ca RTR kit.

Leave the Amazon and eBay kits to the tightwads that can't understand the value of sustainability. Low ball kits are just that, low ball. Support and issues can be daunting. A few more dollars can mean an easier path forward. INMSHO

 

[indianajo]

Where in blazes is the pulse generator on this thing? Web searching yields a huge assortment of pretty much the same deal everywhere - usually a magnet clamped to a spoke and a corresponding inductive pickup coil attached to some stationary frame location. . . . Do some of these hub-drive bikes have the speed sensor built into the hub? m what appears to be something electronic integrated with the battery holder. Could this model of bike be getting its rotational reference from the crank instead of the rear wheel like everyone says is the usual case?

Shows what videos are worth.
All hub motors have 3 hall effect sensors built into the motor. The 3 phases could not act in proper sequence if the controller didn't know where the 3 windings were. BTW, winding position /3*frequency gets the controller rotation speed. Wheel size is a parameter stored in the controller at the importer or factory.
Most low end hub motor bikes have a crank sensor that picks up a magnet wheel on the crank. Usually 6 magnets on a plastic disk, and a hall effect sensor tied to the frame. If your bike starts power after the crank is turned 1/2 or 1 turn, in PAS1 or above, that system is working. Some high end hub motor bikes have a torque sensor built into the crank housing to pick up force from your feet. I don't imagine Townie is high end.
"750" watt hub motors are still legal in the 3 class states. I previously had 1300 w and 1000 w geared hub motors, but the legislatures have decided that carrying 60 lb of groceries or ag supplies uphill at 6 mph on road is hidously dangerous. Who am I to argue with the industry association that made up this stupid rule? Supply of 1000 w 12t (slow, torquey) geared hub motors has totally dried up, but you can still buy 2000 w DD motors for "off road use". Those DD motors can't climb a 15% hill with groceries without a 20 mph head start.

 

[harryS]

Whatcha looking for and why? Does the bike have a display that shows speed? Then it has a speed sensor and those are often built into the wheel.
.
With a direct drive hub motor, the controller already knows the notor rpm since it is using the positions of the three hall senors to spin the motor, and it can calculate speed knowing the wheel size. A geared motor needs a speedsensor, which can be inside the hub or mounted external. Then knowing the wheel size, the controller can deduce speed.
.
A few controllers, looking at you old ebikeling junkboxes, will use the motor rpm and gear ratio, and wheel diameter to calculate speed, but when the bike coasts, the rpm drops to zero and there is no speed. Some controllers, for some reason do it this way and swotch to to the speed sensor when the motor coasts.
.

 

[harryS]

How do I feel about a big motor on the front of a Townie? You'll get to exercise your mechanical engineering skills on making sure your front forks can withstand the twist of both the motor and the disk brakes. If you have a nice cassette in the rear, you get to keep it.
.
I did a cruiser frame with a 500W geared front motor. I've torqued the axles nuts to 24 ft-pounds, and use torque arms. I only ride this bike on paved bike paths. Not a good fit fro gravel. It's also more than fast enough with a 22 mph top on throttle, On pedal assist I prefer to sat around12 mph, The motor itself is around 8 pounds. Doubt I;d want the 10-12 pounds of a 1000-1500W direct drive,
.

 

[tomjasz]

My very first build was a Trek Pure 3-speed coaster brake. Without due care, I ordered a BBS01 36V 350W motor. Only to learn it wouldn't work with a BBSxx and coaster brakes.

I bought a 1000W MXUS DD front motor and a 48V EM3ev Dolphin case battery.
It's been my tractor pulling a loaded trailer and many lbs of groceries since August of 2014. Thousands of miles with only one issue. The CA2 display went wonky. I still run the original Lyen controller. I can crank it up to 25MPH but never do these days. I'm adding hydraulic rim brakes this season, but only as a curiosity. The front motor regen braking is quite amazing.

 

[eddywanderer]

Whatcha looking for and why? Does the bike have a display that shows speed? Then it has a speed sensor and those are often built into the wheel.
.
With a direct drive hub motor, the controller already knows the notor rpm since it is using the positions of the three hall senors to spin the motor, and it can calculate speed knowing the wheel size. A geared motor needs a speedsensor, which can be inside the hub or mounted external. Then knowing the wheel size, the controller can deduce speed.
.
A few controllers, looking at you old ebikeling junkboxes, will use the motor rpm and gear ratio, and wheel diameter to calculate speed, but when the bike coasts, the rpm drops to zero and there is no speed. Some controllers, for some reason do it this way and swotch to to the speed sensor when the motor coasts.
.

I was starting to suspect that the pulse generator is situated within the hub, which would seem to involve a ridiculous amount of engineering to relocate. In which case an aftermarket kit may be the only option, since I find speed control by pedal force much more useful than a manual throttle, even though I've been a motorcycle person for most of my life.
But come to think of it, there is no speedometer. I thought the speed sensor was for determining how much torque to apply with a given amount of pedal force.

 

[eddywanderer]

My very first build was a Trek Pure 3-speed coaster brake. Without due care, I ordered a BBS01 36V 350W motor. Only to learn it wouldn't work with a BBSxx and coaster brakes.

I bought a 1000W MXUS DD front motor and a 48V EM3ev Dolphin case battery.
It's been my tractor pulling a loaded trailer and many lbs of groceries since August of 2014. Thousands of miles with only one issue. The CA2 display went wonky. I still run the original Lyen controller. I can crank it up to 25MPH but never do these days. I'm adding hydraulic rim brakes this season, but only as a curiosity. The front motor regen braking is quite amazing.

Danke. I'll give that a look.

 

[eddywanderer]

How do I feel about a big motor on the front of a Townie? You'll get to exercise your mechanical engineering skills on making sure your front forks can withstand the twist of both the motor and the disk brakes. If you have a nice cassette in the rear, you get to keep it.
.
I did a cruiser frame with a 500W geared front motor. I've torqued the axles nuts to 24 ft-pounds, and use torque arms. I'd only ride this bike on paved bike paths. Not a good fit fro gravel. It's also more than fast enough with a 22 mph top on throttle, On pedal assist I prefer to sat around12 mph, The motor itself is around 8 pounds. Doubt I;d want the 10-12 pounds of a 1000-1500W direct drive,
.












.

I can do the dropout/fork reinforcements no prob, and may even prefer to fabricate them from scratch with some nice aluminum alloy bits from my scrap heap. I have always wondered, though, what all that constant pulling force might eventually do to the headset bearings. Also the extra unsprung mass at the steered end. But it can't be any worse than the Goldwing Interstate I rode in younger days, right?

 

[eddywanderer]

I've done a few Townie front drives and am pleased. They are not hill climbers but there are hub motor versions that COULD be billy goats by throwing some upgrades at the build. Were it my build I'd look at the hub motor kit California eBike sells. A VERY reliable MXUS motor with easy-to-find parts and support KT controller and display. OR if the budget allows, a Grin ebikes.ca RTR kit.

Leave the Amazon and eBay kits to the tightwads that can't understand the value of sustainability. Low ball kits are just that, low ball. Support and issues can be daunting. A few more dollars can mean an easier path forward. INMSHO

I've had a few mixed experiences with cheapo funny-name Amazon entrepreneurs. Fairly happy with my cheesy little triode tube phono preamp now, but it required some easy mods (mounting inside a heavy Faraday cage) to make it quiet enough for my purposes. That is a nice-looking kit you referenced, BTW. Thanx kindly for the link. I may just go that route when funding permits.

 

[indianajo]

I have always wondered, though, what all that constant pulling force might eventually do to the headset bearings.

I have passed 10000 miles with a geared hub motor on my front fork. No headset looseness yet.

 

[eddywanderer]

Shows what videos are worth.
All hub motors have 3 hall effect sensors built into the motor. The 3 phases could not act in proper sequence if the controller didn't know where the 3 windings were. BTW, winding position /3*frequency gets the controller rotation speed. Wheel size is a parameter stored in the controller at the importer or factory.
Most low end hub motor bikes have a crank sensor that picks up a magnet wheel on the crank. Usually 6 magnets on a plastic disk, and a hall effect sensor tied to the frame. If your bike starts power after the crank is turned 1/2 or 1 turn, in PAS1 or above, that system is working. Some high end hub motor bikes have a torque sensor built into the crank housing to pick up force from your feet. I don't imagine Townie is high end.
"750" watt hub motors are still legal in the 3 class states. I previously had 1300 w and 1000 w geared hub motors, but the legislatures have decided that carrying 60 lb of groceries or ag supplies uphill at 6 mph on road is hidously dangerous. Who am I to argue with the industry association that made up this stupid rule? Supply of 1000 w 12t (slow, torquey) geared hub motors has totally dried up, but you can still buy 2000 w DD motors for "off road use". Those DD motors can't climb a 15% hill with groceries without a 20 mph head start.

I figured DD motors would be all about top speed on level ground with Twiggy aboard. My e-Townie has a planetary hub, and the biggest concern is that they're plastic gears. Which I suppose may or may not be a bad thing, depending on whether it's plain old nylon or some exotic variation of Delrin.

I have passed 10000 miles with a geared hub motor on my front fork. No headset looseness yet.

That's reassuring.

 

[indianajo]

Plastic gears is all they come with. I wore out the gears on the first hub motor @ ~4500 miles. Pedaled home fine with the bad gears. The second motor wore out the clutch at ~2500 miles, but the clutch was slipping 10% when I received it. It was the last Mac12t 48v 1000w USA, I kept it because it was the best for grocery hauling on hills. Now outlawed 36 states.
Hub motors are pretty cheap, ~$400 for new ones & I've been buying used ones from the Jump fleet for $36. I keep spares in wheels in the garage, am only without power a coupla days when I wear one out. Connectors change by the year; I have to buy adapter harnesses.