Commuter Booster - <1kg Friction Drive

[adrian_sm]

Final option is, I do have a few smaller Commuter Booster kits. These have a shorter swing arm by 7mm, and only suit a 50mm diameter motor. This gives ~12mm more clearance compared to the 63mm template you have tried. But looking at the photo I am still not sure that it would fit. It would be very tight, and I don't really want the motor crashing into those nice carbon seatstays.

The 50mm diameter motors also have much less testing behind them, so I have not really pushed this as an available option. They will not be able to sustain as much torque/power as the larger motor. So probably only ~500w max.

Here is a hastily updated installation template for the 50mm Commuter Booster.

CB-install_template_50mm_v1.pdf

(21.23 KiB) Downloaded 136 times

- Adrian

[spinningmagnets]

Beautiful work Adrian, very professional-looking.

When you started the design process, I think the 200-kV was the lowest 63mm motor with a skirt bearing. I am hearing good things about the 170-kV @ 6S...

[adrian_sm]

Thanks.

The SK3-6364-190kv motors I have been using have been great so far. In fact I am just about to send a demo kit to an ES member to have a play with that uses this motor.

Looks a lot like this:




And on the bike, resembles something like this.
Note: this has the older swing arm design that looks a little more bulky, the new design shaves some of the profile size, and therefore weight off.

[Masure]

Thanks for your help with the new template adrian. I'll give it a try but I think I'll change my bike one day to use the basic 63mm motor. As you mentioned, the bigger, the better, for reliability and other concerns, I'd like to stick with your first design.

Here is the faulty cruiser I love so much


Hope to come back with a new bike that will fit !

edit : notice the topeak underseat bag, I had it before I knew about your commuter booster .

[Chalo]

Yeah. Smaller wheels will give you more clearance to install the drive, but then (as kevo alluded to) rim brakes will now not match the rim size.

There are lots of different length caliper brakes available. Those look like short reach, which is 49mm maximum. Next is 57mm, then 73mm, then big ol' brakes for BMX bikes, then much bigger ones for cruisers with 3" tires.

Using 57mm "standard reach" brakes would allow the pictured road bike to accept ISO 590 (26 x 1-3/8") wheels, probably. Using 73mm "long reach" brakes would definitely allow the use of ISO 571 (650C) wheels.

The pictured bike could probably be fitted with a drum brake or Roller Brake rear wheel, too.

Chalo

[Zapro]

Hi folks. Looking into making my own CB just for the hell of it

I like to reuse parts, and avoid buying new parts. I have all the parts needed, but the only motor that i have that's suitable, is mounted on my Kick scooter at the moment.

I have a Scorpion HP-5020-450KV in spare. It needs a rewind since the windings are cooked at the moment.

Am I wasting my time to rewind this motor for - say, 200 KV for testing out the Friction drive system ?

The motor doesn't have any skirt bearing, but the bell is pretty short, so it should be doable... ?

Regards,

// Per.

[adrian_sm]

I wouldn't bother, since a new 50mm motor is so cheap. They are probably only good for 250w continuos, maybe 500w peak. If you have the room on your bike go for a bigger motor.

Also 200kv is good for 63mm diameter motors on 5 or 6s LiPo, but will be a but slow on a 50mm motor. You may have to up the voltage to compensate which will mean a more expensive controller.

Good luck with the build.

- Adrian

[Zapro]

Thanks Adrian.

If I were to rewind it, how many KV would you recommend ? I'm mounting it on a 26" mountain bike, and there's plenty room to spare, so just for testing out, i think i would like to try. I can get magnet wire for free, so it's essentially free for me to rewind it, and i get the practice on bigger motors.

I have 5S and 6S LiPo packs i can drive this on.

Regards,

// Per.

[full-throttle]

If I were to rewind it, how many KV would you recommend ? I'm mounting it on a 26" mountain bike

The beauty of FD is the wheel size doesn't matter
Pick Kv dep on how fast you'd like to travel

[Zapro]

The beauty of FD is the wheel size doesn't matter
Pick Kv dep on how fast you'd like to travel

Ah, yeah, that's right, the wheel size doesn't matter.

I reckon 40 Km/h is just fine, so what KV range should i try to match for that?

Rewinding the motor is gonna be fun

// Per.

[adrian_sm]

You can calculate the no-load speed of the motor using this formula

Volts = Battery Voltage
kV motor revolutions per minute / volt
60 is to convert per minute to per hour
Diam = motor diameter in millimeters

kph = Volts * kV * 60 * Pi * Diam / 1,000,000

So you want the no load speed to be 20-25% higher than the speed you want assist at.

I typically have 5s LiPo ~20v, 200kv, Diam 63

kph = 20 * 200 * 60 * Pi * 63 / 1,000,000 = 47.5 kph

This will typically get me about 40kph on the flat. But the top assist speed will vary as the battery voltage drops with use.

for a 50mm motor this would need about 250kv to be the same road speed.

Hope that helps.

- Adrian

[vni]

Hello,
ist the Commuter Boster to go with a MTB ?

[adrian_sm]

Yes, Just don't use knobbly tires.

[NoneToBe]

Hi,

I'm trying to decide between the commuter booster and the GNG mid-drive. I would predominately using this to provide additional power to get up steep hills or long flat runs up inclines. Would the commuter booster have enough torque to get up steep hills or would the GNG, despite its heavier weight be a better option ?

[adrian_sm]

For long steep stuff I would go for the mid drive. Plus it is available. At the moment I am sold out of Commuter Boosters.

[vvougiatzis]

Hello,
ist the Commuter Boster to go with a MTB ?

No knobbly tyres and probably no rear suspension allowed

[voicecoils]

Thanks for bringing your Commuter Booster drive to show off & have a chat at Ausbike. Really nicely made and an elegant design, I want one!

[adrian_sm]

No worries. Was great to shoot the breeze.

I'll send you guys a sample to play with when I get one spare.

[turbo1889]

@ adrian_sm

I've been watching your work with admiration from a distance for quite a while now. Primarily because you have taken a course that I have long since advocated namely using remote control hobby motors and controllers to power an e-bike and also because your set-ups (at least so far) have been lower voltage compatible, specifically compatible with 12V battery power which has the advantage of being able to directly power large powerful bright LED lights designed for full size automobile applications in parallel with the e-drive system directly off the same battery pack without having to use an expensive and potential point of failure DC to DC voltage reducer. For a daily commuter which is often riding at night and in fowl weather being able to use a big bright automobile type LED taillight can be a literal life saver. My primary interest is in mid-drive/crank-drive set-ups that power an e-bike through the existing chain drive allowing use of the bikes gears or at least the rear gears. Not just because of having the gears available to you for better hill climbing ability but also for all weather capabilities that unfortionatly friction drive set-ups have issues with. Winter riding on snowy icy roads with studded snow tires and friction drives do not mix.

Based purely off of the motor diameter of the out-runner motors you are using combined with common wheel sizes it appears that the gear down ratio your system creates in the friction drive is between 10:1 and 15:1 between the RPMs of the motor and the RPMs of the rear wheel of the bike depending on the exact motor used and wheel size and tire used. That gear down ratio is well within the capabilities of a simple single step gear, belt, or chain gearing reducer attached to the motors output shaft and transferring geared down output power to a threaded output shaft that a standard single speed bicycle freewheel could be screwed onto to transfer the power to a bicycles chain as a mid-drive rather then a friction drive.

Long story short, my question is, considering you have already developed all of the necessary components and technology to use RC hobby technology to power e-bikes if someone else were to build such a gear box that used the same class of motors you are using for your set-up would you sell the rest of your kit to them for use with such a mid-drive gearbox?

[adrian_sm]

Hey turbo,

Thanks for the kind words.

Regarding lights, I prefer to use the high power LED bike lights, like the magichsines. These run fine off of the 5v BEC voltage that the ESC puts out. And are already designed for bikes, with all the required mounting etc, quite power efficient, and deliver more than enough light.

As for selling my electronics for other drive systems, no not likely. The electronics are too specific to my drive. If you want something more universal, you would be better off getting a new cycle analyst, and marrying it up to the ESC and throttle of your choice.

Yeah the mid drive concept is really attractive in principal. Definitely good for long steep rides, and will handle the wet and dirt a truck load better than a friction drive. I can understand why it will suit your needs. All the best with it.

- Adrian

[liteCycles]

OK, is this product dead?

Actually looks pretty good on paper but all I see is alpha (or beta) is closed/sold out. Appears nothing is going on.

1. For those that have this setup - How bad is the additional tire wear?
2. Did this throw a wet towel on development? http://endless-sphere.com/forums/viewtopic.php?f=4&t=37964&start=45#p553760

So what if you have to pedal the bike up to speed before you lay on the throttle. I don't want to start thinking about a light geared hub motor, but what are the options?

An ultra-light setup has unique benefits. This propulsion mechanism is an exercise in minimalism. Extremes are good.

And I don't necessarily want to do it myself but if this doesn't move forward someone will pick up the torch. For a certain wattage range it appears this could end up being one of the most budget friendly and simplest setups going.

[adrian_sm]

Still alive and kicking.

We are currently in the process of completing a huge robustness testing program, which is helping resOlve the final pieces of the system which will then be offered as the next Commuter Booster.
This offering will be a complete kit with nothing else to buy. I may also offer it with battery of charger I have not decided yet.

Sorry for not offering these for sale in the mean time but I really wanted to lock things down to a single robust and proven design.

To answer your questions:

1) Tire wear - Is a non issue when running the system in the dry. The system has more than enough traction between the tire and the bare shell of the motor. If you are looking for an all weather setup I would advise going for a hub motor. If you are really keen on the friction drive in the wet you could glue belt sander material on the outside of the motor, but it is still dies not provide perfect traction and will increase tire wear

2) CA v3
No the CA v3 is great for those wanting to build there own drive, but my electronics are a very different offering. Also my brain box will no longer be a stand alone item, all it's features will now be rolled in to a custom controller and only sold with the Commuter Booster as part of a kit.

- Adrian

[mr.electric]

Sounds like a nice upgrade. Looking forward to laying eyes on the newest commuter booster.

[41south]

Any update on availability, I'm looking for a complete kit with electronics as soon as it's available.

[adrian_sm]

Still resolving the electronics side of things, to make sure it is reliable even when people do stupid things. I ended up spending a huge amount of time with the last release supporting the kits. This time I want it robust and as complete as possible to make it easier for everyone.

Adrian