E-bike project - General E Lee

[Metallover]

Well, I got the inspiration to start another E-bike project. This time it's on a 20" DK General Lee frame. I am running a 250kv hobbycity outrunner and I want a 30mph top speed on 36v. I figured I need a 16:1 gearing reduction. Looking at what I have, I can make a reduction close to 16:1 with a 11/66 and a 15/40 reduction. If my math is right, that's a 6:1(2.6:1)=16:1. Do those numbers and ratios look right?

The hard part will be attaching a freewheel (15t) and my 66t spur (from scooter) to a 3/4" shaft running where the crank used to be. That will be the mian hub. The pinion on the motor will run to a spur on that hub then a spur on the other side of the hub will run to a pinion on the wheel.

The bike needs a 20" rear wheel to get it going. I'll get more pics when I buy wheel.

I expect the motor to be turning at 9000rpm, do you think a small electric scooter chain will be too loud? Should I use a belt instead?

Edit- forgot pics

Edit- pics blurry... thumbs for now.

[BL_RV0]

IMO with a 250kv outrunner you should go for a 24v setup. 9k rpm on a 25-30lb bike with a 150? lb rider will be a but much for the motor. What batteries will you run? I'd think that anything except lipo or a123 won't keep up with the amp spikes on the motor. Your reduction sounds right to me, but I've also been trying to figure out how to add gear ratios. Are you going to mount the motor on the downtube or on a bike rack on the rear?

[johnrobholmes]

Looks about right to me. I like the idea of using a hub for the jackshaft. Motor to big ring, freewheel to rear hub. I am getting some ISO disc mount to chainring adapters made right now, it could allow you to use a bolt on front hub for the rear with a few washers.


Keep in mind if you use a freewheel to drive the rear, it will need to be left side drive when the freewheel is a normally right side. It goes from being normally driven to being a driver of power.

[Metallover]

Originally Posted by johnrobholmes

Looks about right to me. I like the idea of using a hub for the jackshaft. Motor to big ring, freewheel to rear hub. I am getting some ISO disc mount to chainring adapters made right now, it could allow you to use a bolt on front hub for the rear with a few washers.


Keep in mind if you use a freewheel to drive the rear, it will need to be left side drive when the freewheel is a normally right side. It goes from being normally driven to being a driver of power.

I'll carefully think the freewheel through. I'll probably weld it all. I remember now that you have been in the E-bike business for awhile? Do you have a website or any tips/tricks for me?

And Ian, on the voltage. The 16:1 ratio gives me about 23mph on 24v and 30mph on 36v. On 36V I expect to make 1200-1600w, maybe even more. iirc I saw a youtube vid of a 1000w motor pushing 30mph. I plan to run 2 12v SLA batteries to start with for 24v, then I'll look into a third sla or a 9s lipo system. My controller is only good to 7-8 cells (It's the $30 supersimple one) so I won't run much more then 24v on this one.

If all goes as planned on this one, I'll go back to my beefy mongoose and try to run the big 130kv motor on 48v on 12s lipo. Then I'll have two e-bikes! I have a nice eastern battery bmx bike I ride too and maybe I'll try a gas bike after one or two e-bikes...

edit - Just registered foir endless sphere. I saw you on the Johnrobholmes... You a mod/admin?

[zeropointbug]

Use A123 for this, don't use Lipo. If A123 cell were designed for something, this would be it, IMO. Small light weight electric vehicles such as e-bikes, motorcycles, and scooters are best powered by A123's, or Headway cells, which are LiFePO4 cells as well, just not "nano-cells", thus not as powerful. But they are cheap cheap, and last 2000+ cycles like A123's.

[BL_RV0]

That sounds good Riley.
ZPB- Can you give me a link to the headway cells? (where to buy them)
Thanks!

[BL_RV0]

Nevermind ZPB, the cells are very cheap as you said, Hmmmm....
For all of you- http://www.evcomponents.com/SearchResults.asp?Cat=41

[Metallover]

Those arent too cheap... Looking at the 36v 10ah pack it's 275 bucks. A 9s2p 33.3v 10ah 20c turnigy pack is 180 bucks. (6 3s 5ah packs) A 10s2p 37v 10ah 20c turnigy pack is $200. (4 5s 5ah packs) You could figure $20 for every 10ah of cell.

[johnrobholmes]

Yeah, I am an admin over there. search yahoo for my username and my site comes up, I don't want to plug it since I am just a participant on this forum- in respect to Mike.

If you weld the freewheel be sure that you have a pretty good margin for controller voltage over your battery voltage. Going down hills on throttle can cause over run that will pop caps (or other parts) if you don't have some headroom there.



Headway cells are good for LiFe chemistry and low discharge rates. I run the Turnigy and Zippy 5ah packs on my bikes right now, along with a123. Gotta say the hobby city stuff is great for the price, but we shall see how many cycles they last.

[Metallover]

I guess that's true about the hobbycity packs... I guess I'll find out how long they last myself. When I said weld the freewheel, I still plan to have the "Freewheel action" but just weld the inside threads to the shaft, which has to b 3/4".

Now on runtime, can I expect about 8-10 miles from 5ah? Can someone give me a rundown of how many miles I can expect to go on 24 and 36v at normal speeds? Thinking ~15-20mph on 24v and 25-30mph on 36v. Thought I'd need 10ah to go any distance at all but seems like I won't need that much...

[zeropointbug]

Yes, you guys are not thinking about cycle life! Headway cells are $17/cell and are 10Ah, are good for 10C discharge. $204 for a 12s headway pack @ 10Ah... and easy to assemble as they are large cells. Or go for the 12x A123 cells on eBay (although quality and genuineness has to be verified) for $240.

Lutach also mentioned to me that you can get the Headway cells for $10/cell.

[BL_RV0]

Originally Posted by zeropointbug

Lutach also mentioned to me that you can get the Headway cells for $10/cell.

Where?

[zeropointbug]

Don't actually know, he just told me. At $10/cell that is roughly equal to lead acid as far as $/Wh.

[sikeston34m]

Yeah, where zpb? LOL

[BL_RV0]

Hope it's not one of his classified things...