Help critque a build please.

[Jim53066]

HI,
New member here, never had any electric propulsion vehicles, this is my first. I have been reading and reading, so much so, that I am pretty much completely confused. Please help me by critiquing my plans so far.

What I want to do is build solid, low cost electric cruiser type bikes for my wife and I to use while traveling in our RV. Both of us are in our mid 60’s, so the normal issues of SPEED, ENDURANCE, and HILL CLIMBING are not of concern. PLUS, we do not need fancy led controllers, hydraulic brakes, and fancy gearing to repair and maintain.

What I (think) I have decided to do so far:

1) Beach cruiser type bikes as I am pushing 300 lbs., plus the vast majority of our riding will be on black top roadways within and around the campgrounds or nearby stores.

2) Single speed rear wheel, (possibly an internal 3 speed rear end?)

3) Front hub drive.

4) SPEED is not all that important, 15 mph would be just fine.

5) 10 to 15 miles, 20 tops is all that would ever be needed for distance.

With that said, will I be better off getting a vintage bike, or just buy one of the new Chinese beach cruisers for a couple hundred bucks and convert it ?

I am also looking for info on front wheel kits? Any recommendations on Volts? Watts?

Batteries?

Controllers?

Complete conversion kit with battery?

What works, what does not?

Am I blowing smoke? Should I just bite the bullet and buy a kit already put together?

Thanks ahead of time for your consideration.
Jim
SE Wisconsin

 

[bakaneko]

I am no expert but I will contribute based on my experience (500, 1000, 3kW ebike + 49,66cc gas bike) and hopefully spur some conversation to point you in the right direction. Also, caveat as I don't know your budget so I will assume lowest budget.

1. I went from mountain to cruiser and it is fine though I don't think I will try any trail riding. Cruiser has a bigger frame meaning you can put a big battery inside or add batteries latter with a mount system. Cruisers usually dont have disc brakes which might be a problem with the total weight. Also, try to get steel if possible instead of aluminum composite.

2. Single speed is horrible. You will want to have gears to help the motor take off to reduce wear and load and heat. I don't think it is possible to go single gear unless you have a super powerful motor like all the 72V guys here

3. Front is okay but I prefer rear due to mechanical advantage. You probably said front since you wanted single rear but again. I would do rear 6-7 cassette kit

4. 15 is about 200-300W but for you maybe 300-400W and you need to help bike take off and get to speed

5. so 20 mile top + 5 just in case means you need 25 mile of total range without 0% the battery. Typically its 1-2 mile per aH for 48V but for your weight maybe closer to 1 so I go big battery 20aH+

6. Vintage is fine again I would say multiple gears and possible disc brakes atleast the front

7. 48V 1000W rear hubs are super cheap $140 (throttle only) - $170 (variable PAS) on eBay. I would recommend 1000W as you will need probably 300-450W to do 15mph and you dont want to max motor at cruising speed. I did the analysis on my YT channel already 48V 1000W is the most economical for any speed (<30 mph)

8. 48V or 52V 20aH = 1000 wH. you can probably due with chinese cells rather than branded since you want to only do 15-20. But, branded if you want to go 25-30. There are billions of domestic ebay sellers selling chinese battery packs (good for commuting; bad for high performance) and you can go to em3ev.com for the branded. Dont know your budget so there are choices.

9. The standard kit controller is fine for your speed. Kits come in two variations throttle only (max PAS = useless) or variable PAS LED display. The variable PAS with LED display is usually just 30-50 more but worth it.

10. I think the kits including the battery is usually a rip off versus just buying the motor kit and battery seperate.

11. Its easy to put together a kit. Just match color wires and test voltage with multimeter. Make sure all nuts and bolts are tight.

I am also in SE wisconsin and 1000W should be ideal.

 

[Jim53066]

Bakaneko,
Than you for the detailed reply. That is the type of information I was hoping to get.
I understand that the single speed is not optimum, what about the older style internal 3 speed rear ends?
Will that give us an edge on take off? I am trying to keep it simple for my wife. I love her dearly, but she is about as coordinated as a brick. I was hoping it would simplify the operation for her. Other than that, I have no issues with the multi speed, or the operation.

I admit that part of the lure is trying to do what the big guys do, for LESS cost.
I want to put together a solid reliable (without frills) e-bike for under $1,000. (used bike) If I can not accomplish that, it probably will not happen as we are both on SS and a very small pension.

I am mechanically inclined, I have built street rods, and classic cars for years, so I feel confident that I can handle an e-bike with the guidance of those that have been there, done that. I do not like to re-invent things, if it has been tried and failed I will learn from others. If it has been tried and it worked, I will copy it.

Thanks again,
Jim

 

[Drunkskunk]

Welcome to the forum.

1) beach cruisers are generally good solid platforms. Balloon tires make for a more comfortable ride and also give much better traction. That's something you'll need when adding a second power source to a bike, along with your own power. You will want a bike with front and rear brakes. A single coaster brake isn't sufficient to safely handle stopping a with the extra power and weight you'll have on it.

2) More gears is better, but a single speed is fine too. with a 500 watt motor, you won't need to pedal except on the steepest hills. but it's nice to have gears for those times you don't want to use the motor.

3) Rear would be better, but at the low speeds you'll be traveling, a front is fine too. There can be some traction issues with a front motor when riding on things like wet asphalt or beach sand covered boardwalks.

4) 15mph is very reasonable. Most kits will do that easily.

5) 15 miles usable range at 15mph is very easy to do. We used to say you needed 1 amp hour of battery for every mile range at 20mph. But that was a rating of battery capacity, not power needed. And that was also based on old battery tech like SLA, LiFePO4, and early Li-ion, which under performed and had a short life. it was based on the idea that a battery bought to that standard would still perform to that range 3 or 4 years later.
Times have changed. So have ebike batteries.

And since doubling speed uses 4 times more power, 15mph actually uses 1/3 less power than 20mph
Now with a modern battery that is built of quality cells, you should be able to get more than 20 miles on mostly flat ground, with no pedaling at 15mph on a 37v/10Ah battery. meaning your 15/15 goal is easy to make. Pedal a bit and the range goes up.

there are 2 types of hub motors. Geared and direct drive. geared are small, light, and efficient at stop-n-go riding. they also have a coaster gear for when you wish to pedal. they do make some noise, but are generally quiet. Direct drive are large, heavy, and darn near silent. while cheap controllers can make then growl a bit under load, you often can't hear them at all while riding. they aren't so efficient at stop-n-go riding, but are supper efficient at cruising. But they do weigh more than a small bag of bricks, and that's less pleasant on the front of a bike.

Likely what you will want is a 350w to 500w geared hub motor. While 350w will meet your goals well enough, it's a bit anemic. with your weight, you might enjoy 500w more. But for a front motor, I wouldn't go bigger. As for battery, quality matters more here than on the motor. cheap batteries abound but are often fire hazards, as members of this forum who have had house fires from them can attest. So a good vendor is a must. 37v10Ah is about the smallest size you should go for. too small, and they struggle to supply the power. a bigger battery will let you use the power a bit more frivolously, so a 12ah to 15ah battery might be worth it.

 

[bakaneko]

I would disagree with the 500W motor and 36V. It is like a moped; you are amuse with it for a month and then want to sell and buy a real bike. Don't worry about the sound of a gearless hub motor; it is nothing compared to an actual gas bike or moped. I did wind resistance and current eBay/retailer price analysis not too long ago and as mentioned a 1000W rear gearless hub motor with 48V battery is optimal. My thoughts are

- Get the 1000W gearless hub motor with LED and variable PAS
- Your wife can use a lower PAS and be safe at lower speeds
- You can use lower PAS as econ mode so to speak
- When you want the thrill for faster speed (than 15mph) and you will you can change PAS to a higher level or use the throttle
- So win win for both you an your wife
- I would get a 48V 15aH minimum battery you never know when you need that extra range than what you mentioned.
- No one wants to pedal inevitably but it is important to pedal at take off so your peak power is lowered
- Just get branded batteries and not have to worry about regret of a "chinese domestic" battery. i still think they are good for the lower 20s. This will be the most expensive (branded)

If you are mechanical this would be a breeze.