New user looking for feedback

[Tri-Star]

I am interested in building an ebike. I am relative early in my research process but I thought I would post my goals and concerns here as I build my knowledge.

My goal is to strike the right balance of price, speed, and stealth (aka hub motor). My commute is 9.8mi round trip. Therefore range is not much of a concern. I live in Florida so high torque is not a necessity. I would like to make full use of the power capability of the motor I buy with an appropriate matching controller. I imagine my battery set up in two stages. The first stage I buy now should give me enough to fully power my motor whilst giving my enough juice for a minimum of 20mi. The second stage would be purchased later to add additional range. I have no strict requirement for speed but 55 kph is my goal.

My research thus far as lead me to the Crystalyte HS3540 is seems like a great power/price ratio. This leads me to my first concern: Sensored vs sensorless. I have read that you should go with censored because of compatibility reasons with controllers. Due to the fact I will likely go with a Crystalyte controller (that I assume would be designed to work with either type of motor) makes that argument rather moot. On the other hand I have herd to stay away from the censored due to it being a common failure point. I do not NEED my bike to start from a standstill. Are there any other benefits of a censored version that make up for the increased risk of failure? Due to my goal in speed I will need a higher voltage controller. I have heard that the censors on these motors are doomed at higher voltages.

I recently came across a website that looks to specialize in what I think I need: http://www.ebikedeal.com/
Crystalyte HS3540 - $300
Crystalyte 18 Mosfets 4110 - $170 (I think this is 72v 50A)
Lifepo4 40152S - $28 x (however many batteries I need)

Feedback on the products I have picked out meeting my needs would be greatly appreciated. Also any revenant articles or discussions would be wonderful. If the setup I listed is indeed on par to meet my goals is there a way I can calculate how many batteries I need?

 

[Drunkskunk]

Hello, and welcome to the forum.

Its good to have goals, and they will help steer you in the right direction.

55KPH is fast on a bike. about 3 times faster than most people peddle, and most bicycles were never designed to survive at those speeds. Take a look at a moped or scooter sometime. they are designed to do a maximum of 50kph, and weigh 50 to 70kg. The motor can be only 10kg of that weight, the rest of the weight on a moped is dedicated to surviving those speeds. Thick tires, thick rims, spokes, axles, full suspension, heavy frame, heavy duty brakes, ect. Its all is built that way for a reason.

In a car, 50kph seems like nothing, but it was designed for high speeds. try it on a bike, and it will feel like every pebble and road crack is conspiring to make you the next astronaut. Even small bumps bang through the bike like it was hit with a sledge hammer.

It can be done, but at 55kph you need a full suspension DH bike, and enough experience to know why thats a necessity. This is a goal for your 2nd or 3rd bike. Experience is the important part here.


40Kph is a reasonable goal for an ambitious first time builder. Its a lot faster than a standard ebike, and it can be done with a most bikes and a 9 Continents 9X7 (AKA 2807).

Hall sensors do fail for a few reasons. But most importantly, they RARELY fail on their own. most cases of failure are in relation to water entry or abuse.

Hall sensors allow the motor to run smother. You can get away with not having them at lower power levels, but on high powered bikes, they are needed.

You can run a sensored motor with a sensorless controller, but you can't do it the other way around. so with a sensored motor, you have more choice. you don't have to run the sensors if you don't want to, but you have the option.

As for vendors, there is a sticky here listing who is known to be good. But I trust:
http://www.ebikes.ca
http://www.e-bikekit.com/
http://www.emissions-free.com/
http://us.itselectric.ca/

 

[Sunder]

It depends on your road surface. I do 50km/h all the time on my non electric road bike on public roads, and I am a total amateur. I have friends who race who do 60km/h AVERAGE rides, with peak speeds of 80km/h.

That said, they race on roads that have been cleared for cycling, and you never know if a tree branch that causes no problems to cars is going to kill you as you hit it at 55km/h+

 

[dogman dan]

I want to be stealthy at 55 kph.

Hmmm. Well, stealth issues aside, you are looking at some wattage to go 34mph. About 1500 minimum. So forget the gearmotors pretty much, and go with your HS. Perhaps the HT will be better, if you have to stop a lot. But somehow, I just get the feeling your idea of stealthy riding will include blowing stop signs too.

18 RC lipo cells in series (18s lipo) should be enough voltage to get you going 35 mph. 20s is "72v". Just depends on what you want to do. 72v of A123 lifepo4 would also have the amps to power a big controller. Forget stuff like Pingbattery or similar ebay lifepo4 batteries. You need more amps that they can stand.
6, 6s 5000 mha RC lipo packs from Hobby King will make you up a 66v 10 ah pack. It should have close to 10 mile range. Bear in mind, 35-40 mph for more than 10 miles often melts motors down, since they were designed for half that wattage.

So when you want that range, you better be thinking in terms of sub 30 mph travel.

 

[Tri-Star]

There are only 2 stop signs on my commute.

 

[pelle242]

My fairly modest setup does 53km/h on flat ground no pedling, clocked with both bike computer and GPS.
It's a cellman mxus DD hub (9C clone, not sure what wind) in a 26" wheel, 12FET infineon controller and a 18S4P A123 M1 pack (not from cellman).
The wattsup meter says 48 amps max .
With 18S lipo and a bit higher voltage you'd probably hit 55..

I dont do that speed often so how reliable it would be at that speed I can really say.

 

[jasonf150]

I run the hs3540 with a cellman a123 lifepo4 @16s4p (9.2aH). My commute is 12 miles and I use about 7.5aH. I have one pretty easy hill. That's averaging ~27mph with a top speed in the low 30's. I run a 29" hard tail mountain bike. I like my setup bu would change to a HT3540 for more torque off the line. I'd gladly lower my top speed a few mph's for a faster start.

 

[dogman dan]

5 miles with only two stop signs sounds ideal. Go for it with any motor then, HS, or even the cheaper muxus 9c clone. You won't melt the motor in 5 miles, and might not get seen all that often either. Anything in the 66-90v range, depending on whether you want 35 mph or 45 mph.

I don't know your area of Florida, but have heard some stories of some towns cops not giving a damn, and other towns having ebike nazi's that pull over everything with a motor.