I'm a noob and I want to go 25-30mph (friction drive)

[spinningmagnets]

20-MPH is the legal limit for selling street E-bikes to the public, and I was investigating possible interest from the local college students.

If you want to go faster, you can use a higher Kv of motor, use a roller with a larger diameter, raise the volts, or some combination of those three.

You've stated that the only hill on your commute is short, but it's very steep. 37V climbs much easier than 22V, smaller roller climbs better than a bigger one.

 

[BeaversSuck]

20-MPH is the legal limit for selling street E-bikes to the public, and I was investigating possible interest from the local college students.

If you want to go faster, you can use a higher Kv of motor, use a roller with a larger diameter, raise the volts, or some combination of those three.

You've stated that the only hill on your commute is short, but it's very steep. 37V climbs much easier than 22V, smaller roller climbs better than a bigger one.

Ah okay, are you looking to start a business ? where I'm at I'm surprised e-bikes aren't more popular, during the summer there's so many bikes it's ridiculous!

Yeah, again I'm not worried about that hill, I'm not gonna go through any extra trouble or expenses to climb a hill that'll take me a minute or two to push the bike up, plus it's good for my butt muscles since I won't be using them for pedaling .

I will make a list of components and run it by you before ordering anything (I'm hoping ordering in bunches will help with shipping costs since with amazon it does but this is gonna be hobbyking and other stores so we'll see).

Thanks for your help!

 

[spinningmagnets]

Are you looking to use the shell of the motor, or have the motor drive a separate roller? I have the stuff to make rollers with one-way clutch bearings that are one-inch, 1-1/4, and 1-1/2 inch in diameter.

Ever since cell_man began selling very affordable kits, and college students (the biggest potential customer base for me here) did not want to use LiPo batteries, I decided to not make any for sale. I have two complete drives, and the stuff to make a few more. I could sell you one complete drive at the parts cost, or tell you how to make your own. All you need is a vice, hacksaw, and drill (with an assortment of bits).

I don't know if I mentioned "sync loss" yet. I tried a variety of ESCs to see what the most affordable one would be to reach my goals. For flat land you can do fine with 6S (22V), but unless you get a Castle Creations ESC, you will occasionally get sync loss on hills. Sync loss is where the ESC loses track of the rotor position is, with a sudden loss of power. RC planes are light and accelerate fairly quick, E-bikes are heavy and accelerate slowly. The Castle ESCs have a more sophisticated electronic sensing circuitry. The ESC will be more expensive, but you won't regret it. The batteries and charger will be less expensive at 6S.

If you go with 10S (37V) or 12S (44V), the drive won't bog down as much with the extra power of the higher voltage, and you can use a more affordable mid-grade Hobbywing ESC. The battery and charger will be more expensive at a higher voltage.

EVTodd designed the drive, and posted that anyone who wanted to make them was welcome to do so. Feel free to make a copy of your own.

 

[BeaversSuck]

Are you looking to use the shell of the motor, or have the motor drive a separate roller? I have the stuff to make rollers with one-way clutch bearings that are one-inch, 1-1/4, and 1-1/2 inch in diameter.

Separate roller just makes more sense at this point.

Ever since cell_man began selling very affordable kits, and college students (the biggest potential customer base for me here) did not want to use LiPo batteries, I decided to not make any for sale. I have two complete drives, and the stuff to make a few more. I could sell you one complete drive at the parts cost, or tell you how to make your own. All you need is a vice, hacksaw, and drill (with an assortment of bits).

How much will it run ? I might end up doing both, I definitely want to learn how to build this but I might need one for a friend

I don't know if I mentioned "sync loss" yet. I tried a variety of ESCs to see what the most affordable one would be to reach my goals. For flat land you can do fine with 6S (22V), but unless you get a Castle Creations ESC, you will occasionally get sync loss on hills. Sync loss is where the ESC loses track of the rotor position is, with a sudden loss of power. RC planes are light and accelerate fairly quick, E-bikes are heavy and accelerate slowly. The Castle ESCs have a more sophisticated electronic sensing circuitry. The ESC will be more expensive, but you won't regret it. The batteries and charger will be less expensive at 6S.

Yes you have in other posts and so have other people so that's why I was wanting to get a higher end higher amp ESC, plus you never know when I decide I want more power haha.

EVTodd designed the drive, and posted that anyone who wanted to make them was welcome to do so. Feel free to make a copy of your own.

Good man

 

[spinningmagnets]

The first drive I made was just to personally see the limits if the design, and evaluate if there was a market for them, The second one was functionally identical, but slightly different to make it more professional-looking (all fasteners are metric, used steel rivnuts instead of tapping threads into aluminum, shifted position of the motor one inch to ease access to mounting-plate connectors, etc). Since I have firmly decided to not make these for sale, the first drive is collecting dust and I would be willing to sell it for the cost of parts (It was fun to make, I'm throwing in my work for free).

If you follow the build-thread, you would be getting the drive on page 5, you can compare to the one I'm keeping which is on page 6. I'll figure out what the price would be (no obligation to buy). It sounds like you would be best served by a 6S/22V system, the remaining question is what Kv of motor and diameter of roller would you like? I only have one 295-Kv motor, and a 250-Kv that have shafts cut to fit the slotted roller-tip. If you want to buy a motor with a different Kv, I can sell you a slotted shaft you can swap-in.

My interest right now is the MAC axle-to-driven-shaft conversion that crossbreak is doing. I believe it is an important development, and it can be used as a left-side-drive, or a BB-drive similar to the GNG (but capable of much higher wattage).

edit:
$35 stem and seat-post tubing shim
$90 Castle Creations Phoenix ICE 75A ESC, plus two extra 50V capacitors
$10 servo tester + servo wire (used as a throttle)
$80 Exceed 63mm 295-Kv motor with notched shaft tip
$85 Copy of EVTodd drive with 1.5-inch roller
_____
$300

Does not include battery or charger, I could sell you this LiPo charging set for $80 ($40 25A power supply, and $40 10A 6S charger). There are better/faster charging systems, but I consider this set the minimum I would recommend.
http://endless-sphere.com/forums/viewtopic.php?f=16&t=23465#p341300

beaversSuck has first dibs on this kit at this price, but if he passes on it, anyone can buy it. Be aware if you want to upgrade to a higher voltage than 6S, you will need a different ESC and charger. I got 20-MPH using 24V and a 1.25-inch roller, 22V with a 1.5-inch roller might get you 23-MPH.

If you want to get a higher speed than 23-MPH with 1.5-inch roller at 6S, you will need a higher Kv motor. The smaller 50mm motors have higher Kvs, but less leverage, and less copper mass to absorb/dissipate heat. EVTodd was happy with the 50mm motors on fairly level ground, but he was using 37V.

This drive system works great using a 63mm motor at 36V-44V, but when you add the extra costs of the higher voltage battery/charger/ESC, a GNG or cell_man geared-hub looks pretty good. The one big benefit of this drive is that you can lift off the seat and carry the drive indoors/upstairs while the bike stays down at the bike rack.

 

[BeaversSuck]

I will have to pass since I really want to build this, nothing really beats the satisfaction of creating something that works, and I can't afford both. Unless my friend sees my setup and wants one but by then yours will be long sold probably lol.

Thanks for the offer though.

I'm super busy right now but I will get started some time in January after I get back from vacation and will definitely need your expertise on this project.

 

[spinningmagnets]

No problem. I agree, building something is more fun than just buying it. Best of luck.

 

[lbz5mc12]

Well here's a thought. Get a hub motor set-up to start with. If you don't like it then you could always convert the hub motor into a friction drive. The hub motor is as wide as a regular bike hub. All you'd have to do is flip the hub motor over so that it runs in reverse to spin the wheel forward. You'd just have to devise a mount for your motor to run it on the wheel. You'd have to get one of the smaller geared hub motors to get the right amount of torque. Also a hub motor as a friction drive would still be about as quiet as a regular hub motor set-up. Just a thought.