new guy needs help....

deacon

deacon

minor bike philosopher
Hi every body!!
I am new here and have been doing quite a bit of reading but have found nothing like this.
I want to make an electric full suspensioon mountan bike that is powerfull enough to spin the back wheel out like on a dirtbike.
Has anybody made something like this here? what motor would be suitable?
I was thinking about using a 48v 1000w motor from TNC scooters but Im not sure if it will have that type of torq.
Any suggestions are greatly appriciated!!
Thanks!
ps. I will also use this when commuting to schol 17mi one way! and the rest of the time just for fun with friends on field trails.
thank you!!

rtboa
Motorized Bicycle Newbie Join Date: Apr 2010
Location: Benicia
Posts: 3

Electric bicycle...in dirt??


I moved this from the introduction... See what you can come up with....
 
My first thought is range is the number one issue, even before power. A 17 mile commute is a hoss in my opinion. Definitely going to need to recharge at school. Thirty four miles is a long long way on a charge.

The other possibility is more than one battery pack. Charge one while the other takes you out to fool around. On a mountain bike to be used in the mountains weight and space will be an issue. So you are looking at advanced battery technology which is expensive to buy. I'm trying to build an advanced battery pack now, but I don't have the parts to test it just yet.

Resolve those issues, then think power but power will also determine how much battery you have to have. It's a lot more complicated than it sounds at first, I'm sorry to say, but also it is easy once you get a handle on it.
 
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Welcome Deacon.Check with Deacon,he has forgotten more about Ebikes than anyone on this sites knows.He is a pro.
 
okay I have decided to go with the 36v 1000w motor from TNC for (77.00). Im going to run it at 48v, with 4 batteries(100.00), 48v controller(35.00), twist throttle(10.00), 48v charger(40.00)

I know that I will need a way to connect it to the wheel and was thinking about either just connecting with a chain to the existing gears on the back wheel, or putting a jackshaft on the other side of the hub.(so that the wheel will spin when the motor does, but I can still pedal with out interfearing with motor) I think that is how I've seen it before.

Does anyone have any suggestions or ideas about gearing, also if you see any obvious problems with my plan...please by all means tell me

Thank you guys very much!
-Julien
 
Check out the thread almost an electric bike by grouchy. He isn't haveing much luck over powering that geared motor. The plain currie scooter motor is what I use for my friction drive. It is a different motor.

If your motor isn't geared, you might have a problem hooking it to your bike sprocket without a jack shaft and I'm no gear person so I can't help you probably some of the others can...

If your motor from tnc is geared one, it will use a bike chain instead of the #25 chain scooters use. If you go that way, yu could use one of the gasoline kit sprockets that attached to the off side of the rear wheel with bolts through rubber spacers.

Keep on thinking and asking questions.
 
I don't have any experience with that chain, but I expect you are going to need a jack shaft to use it. You could almost go with a hub motor it would be much simpler to install. or the currie motor and wheel kit. But it won't have the power you are looking for. Is this ebike going to be legal where you live. A lot of states have some pretty strict requirements.. As to watts and speed ect.
 
Welcome rtboa. I don't want to discourage you, but you might want to do the math before you go with 1000 watts and SLA batteries. Amps = watts divided by volts so your 1000 watt motor will be drawing about 21 amps at 48 volts. If your 4 batteries are 12 volt 12 ah SLAs, the maximum you will get is just over 1/2 hour of full power (12ah divided by 21 amps = .57 hour, about 34 minutes) If you run the batteries down that much you probably won't get much life out of them. A smaller motor draws less so will get you further if you can live with less power.

Having gone through 2 sets of SLAs, I am quickly moving toward being a Lithium battery advocate. LiFePO4 batteries from Elite Power Solutions or Ping or A123s are safe, reasonably priced lithium. Li poly or Li ion are even lighter and support larger current draw but can catch fire or explode if not handled carefully. I am testing some LiFePO4s from Elite and Deacon is working with NiMH so stay tuned as we report out our findings.

Friction drive is probably the simplest. Check out any of Deacon's "rhino" postings. I'm using a cobbed up system that allows the motor and/or pedals to drive through the 8-speed derailleur on a MTB. You can read about my system at Endless-sphere.com • View topic - Dual Freewheel Front Sprocket system. I used parts mostly from SickBikeParts. For complete kits, there are 2 different systems from Cyclone that do something similar. Also check out Elation (Australia) and Eclipse (GB). Of course, mounting a motor and driving the rear sprocket can be done more simply. Scour the forums and you will get lots of good ideas. The main tricks, as Deacon mentioned, are using the correct sprockets and chains and getting the ratios correct. Good luck - jd
 
@rtboa
Welcome!
As jdcburg said , you can't get the range and power with SLA's . LiFePO4 is the way to go. Also, you should research hub brush less motors (you'll over volt it , of course)with pig of a controller (at least 60 Amps) for your requirements. E vehicles are all about efficiency , so forget chain or friction drives. These kind of setups (performance bikes) aren't cheap and couldn't be approached in "easy and relaxed" way. There are many considerations about it: considerable speed and strain(therefore forks and suspension and tires must be up to a job - that is quite expensive), complicated electric system ( advanced battery chemistry requires BMS , controller has to be able to "know" how much Amps can be drawn from battery pack and how much is allowed into motor - in order to keep motor from melting and it is best if controller is programmable) and few gadgets (all sorts of "...meters").
Things you've chosen are OK , but you wont be even near performance you wanted. It would be just regular electric bike (+ problems with lack of room to put all the components). You should check Crystalyte 5304 or 5305 hub motors (they are for scooters) , over volt it up to 72 V and better to 96 V , Kelly controller and battery with BMS on it (not Ebay - if you want to "plug&play - custom ordered from manufacturer). We are talking about $1000 + and shipping not included. However , best of luck with your build.
 
Shoot I just ordered everything... sounds like down the road I will have to upgrade to some lithium iron phosphate batteries. I looked at a couple of those sites but didnt se prices for the battery packs. thanks jd
Iam not sure if it is leagal, but Iam not trying to excessivly speed anywhere, thats for sure. just want a lot of torq for when Iam tired of pedaling a few miles and then encounter a hill!...a big hill i suppose. haha
Thanks Deacon

wow thanks zabac... looks like Iam starting with something a lil different then my original plan...but thats ok, It will be great experiance for the future!
 
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if you learn from everything you build every build will be the foundation for the next build. It's a great hobby. In my case it's a never ending struggle to make chicken salad from chicken feces. fooled the censor again
 
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