FIRST Step in Building an eBike is....

[coolrunning]

picking a battery brand and size.

Is that a fair statement?

This will mostly determine where and how far I can go between charges.

Any input is appreciated, this is my first post here, thanks.

 

[buzzfirst]

There are a lot of folks here with more experience than me but my vote goes for determining what your needs are for the bike, if you only go 2 miles to the grocery you will have a different bike than 30 mile commuter. YMMV

 

[dogman dan]

Determining your needs can lead to a motor choice, which then determines your battery need, which may then determine that you start over with a different evaluation of your needs since you can't afford that , which leads to another motor choice that determines your battery need, which can deternine that you start over by saying this is how much I can afford, and what is the cheapest stuff I can possibly find.

Seriously this time, look at what you need, vs what you want, if funds are not unlimited. Then look at which motors can do that, and which batteries can supply that motor for the distance you want. Depending on your needs it may be real simple, If you need 20 mph for 20 miles, a great deal of the hubmotor kits can do that speed and a Ping 20 ah battery can supply that motor fine. Once you start wanting real range, like 50 miles, or real speed, like above 30 mph, the decision gets a lot more complicated, but you really do have to start by asking what do you need, how far, and how fast.

 

[Wile E. Coyote]

"determining what your needs are"

I agree, I think the first thing is to decide is how much pedaling you want to do, this effects your DONOR BIKE, BATTERY and MOTOR/CONTROLLER choices. Other important considerations:

Hill Climbing - What's the steepest hill you want to climb and at what pedaling effort level?
Top Speed - How fast do you want (or need) to go?
Stealth - How important is it to pass off as a regular bike to the casual observer (or cop)?
Weight - Will you need to pick up the bike and carry up/down stairs?
Comfort - How long can your behind tolerate a bike seat?
Terrain - Urban / Sub-urban / rural / off-road?
Budget - How much can you spend before your wife freaks :lol:
(I'm sure there's more I'm forgetting)

It took me 4 builds and way too much money to finally build a bike that meets all my needs. I like to learn the hard way!
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=7548

 

[coolrunning]

Budget - How much can you spend before your wife freaks

haha, I don't have a wife to contend with...and I ride lots so I can justify spending the $$$

 

[TylerDurden]

People can look here:
http://www.endless-sphere.com/forums/viewtopic.php?f=16&t=1763

Then here:
http://www.endless-sphere.com/forums/viewtopic.php?f=16&t=1499

 

[coolrunning]

Okay, suppose I want a top speed around 40 mph with ~100 mile range.

My donor bike will be a 25 lb. mountain bike...

The amount of pedaling I will do will just depend on my mood.

Initially, I only want to spend around $600 on battery but I suppose I could up that to $1000 or more.

 

[pwbset]

Okay, suppose I want a top speed around 40 mph with ~100 mile range.

Yikes. That's completely impractical for a mountain bike in my (humble) opinion. More realistic would be top speed 30mph max range 20mi. Anything over about 20mi and battery weight becomes prohibitive. Anything above about 22-25mph on my Jamis and I feel the looming shadow of the grim reaper closing in.

Having said that... some people are doing 40mph+ on MTBs... for how long we'll just have to wait and see. :?

 

[Wile E. Coyote]

40mph speed and 100 mile range is a bit much for an e-bike. That puts you more in the electric motorcycle category.

WANT or NEED?

 

[TylerDurden]

Okay, suppose I want a top speed around 40 mph with ~100 mile range.

Yikes. That's completely impractical for a mountain bike in my (humble) opinion.

The bike and rider might need 1000W to travel 40mph.
That's >2.5kWh for 100mi range
$.60/wh for lifepo4 = $1500.00


Close, but no cigar.

 

[Zoot Katz]

First, decide on your budget.
The second step is to double that.

 

[philf]

I have to agree with pwbset - 40 km/h (25mph) is a useful speed, but going much faster on a regular bike begins to feel a little uncomfortable. If your front wheel gets loose, it's not pleasant. Actually, I think the thing that consistently happens to me has less to do with feeling safe at speed than it does with motorists. My bike is reasonably "stealth" in the sense that it isn't immediately obvious that it's motorized. While just minding my own business and riding along, it frequently happens that a car will pull up to a stop sign that crosses my route. They look left, see a cyclist (me), then look right - see no cars - and just start pulling out. They're not expecting a guy on a comfort bike to cover the kind of distance that you do with the motor, and I've nearly become a hood ornament at least half a dozen times this season when going at my fastest speed.

There are a few speed demons on this forum, but if you look at the way they've set up their rigs, seeing the bike (even from a distance) will make you double-take.

The other thing about going fast is that a rider and a mountain bike aren't all that aerodynamic. Going faster is less efficient. On top of that, for me, the smallest cog I have on my freewheel has 11 teeth. If I got much faster than 45km/h, I'm less able to "help" the motor by pedaling, because the cadence I have to keep to add any meaningful torque (to bring down those amps) is beyond what I can comfortably maintain.

None of this is intended to be discouraging - once you get out there and try it, you'll find the real sensation of speed different than you might expect

As for range - I take only as much battery as I think I need. This does mean I wind up deep-cycling my batteries more than I would if I just carried one large pack, but it also means that I run as light as possible. Of course, I'm not afraid of pedaling if I short-change myself

 

[dogman dan]

My joke about picking out some stuff, finding the price, picking some more, and finding the price, was more on the mark than I thought. 40 mph mountain bike is possible, for sure, check the build threads in the picture section and you will see some, that got really expensive. I don't say it isn't worth it, but if your battery budget is $600, you will be going 20-25 mph for about 25 miles. Deal with it by refining your desires or your wallet. 100 mile range is pretty much for going 10 mph or less on dead flat ground in the ebike world unless you are riding some kind of cargo bike or towing a trailer to carry huge battery capacity. With two Ping 48v 20 ah packs parallel connected, around $1600, and a crystalite 5304 you could go quite some distance at 30 mph for around $2200- $2500. If it was cheap to go 40 mph for 100 miles we'd all have been doing it years ago. Bear in mind that when you see range and speed claims for EV's the range is how far at 5mph. To go really fast, like 40 mph, you need a lot better bike than something under $300.

But since you actually describe wanting an electric motorcycle maybe you should refine your strategy from bicycle to small ICE motorcyle and start working on the parts to eventually convert it to a nice E motorcycle. Start with a decent 150 cc bike and you could be doing faster speeds or longer ranges since the bike can carry more battery weight.

 

[Kurt]

40mph or over 60kmh will take some voltage on most ebikes .I know my own setup 5304 would need 72v to do this speed and the wind drag at this speed is huge.I wouldn't be suprized if it took 2000w to sustain that speed perhaps even 3000w. Like others have siad this speed is ok to do a couple of times just to show of to your friends and get a quick thrill. It isn't a practical or safe speed for most ebikes unless they are bordering on a motorbike style frame, suspention and braking and even then. Is a motorbike helmet and other motorbike style protection your kinda thing?

40kmh is a nice top speed and 36v will get you there on most e bikes.I am not sure what others think but I think motor torque is a very important factor over speed.If you ride a non powerd bike on flat smooth ground it is very comfortable to sustain a nice speed with next to no efort. Once you start to introduce even a slight incline things start to get tough and thats where a ebike starts to shine.

I gess what i am getting at is most people start of wanting there ebike to go fast but soon after start chasing torque by going with smaller wheel size, more amps, and so on.

Range is somthing I have two views on.One is that you will start to take your bike longer distanses once you see how practical it is.Two is that you all though your bike might be capable of traveling 60km range after about 30 or 40km you have prob had enough unles your riding a recumbent ar very well setup comfortable bike.
Kurt.

 

[Icewrench]

First, decide on your budget.
The second step is to double that.

Then double that again

 

[kazbluesky]

I'm very new to ebikes. I got up and running about 3 weeks ago so maybe my viewpoint will be a little closer to where you are (if you see what I mean). I'm a very big chap (about 120kg) and I went for a 500w 36v ampedbikes kit. I have a 36v 10ah LIFEPO4 battery. On the flat even with my weight this bike will do about 36kmph. That feels very fast especially along the path. I usually ride a big motorbike, 1450cc, so I'm used to speed but believe me 36kmph on a bike is waaay fast enough , feels free and clean too. Monday I did my first fairly long run which was exactly 32.8 kms. It was through the city (Tokyo) with constant stop starts. By car it usually takes me an hour and 10 mins or so, on my ebike it took me 55mins one way (16.4km)!!!! There are a lot of hills and inclines , I pedaled all the time but used the throttle every start and all inclines - it was a very very easy ride, one that I could NEVER have attempted with just an ordinary bike. When I got home, though the throttle said half full still it was beginning to struggle on the hills. Cost for everything I guess would come to about 750 - 800 dollars.

Get yourself a bike which can be fitted with disk brakes, my bike needs new brake pads and ive only done about 150 km on it.

I'm very happy with my bike and it's performance but once my warranty is up i'll probably go up to 48 volts - just for the hills.

forget 40mph , you'll kill yourself (or get a motorcycle). As long as you can recharge every night at home or at work during the day 30-40 kms is the distance that is practicable.

I love this new way of travelling - it feels really good . Good luck in your choice.

 

[dogman dan]

No kidding about double the budget, I call all the stuff that fried, never worked, or was just unsuitable to my needs entertainment budget. Even so, with allmost 2000 miles of commuting done this year, I still need about another thousand miles to say the bike paid for itself and I'm getting to work for a 10 cent charge. And I already jones for an upgrade. But looking at the money equation from another angle, I broke even months ago, since no weekends lost to repairing the ICE vehicle for an entire summer is priceless. It doesn't break down if I don't drive it.