4 wheeled downhill Mt . bike electric conversion

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nofear43   100 µW

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4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jun 29 2014 10:06pm

Looking at the possibilities of making my 4 wheeled downhill mountain bike electric.

Ive seen mountain bikes that are electric using mini hub motors. http://www.electricbike.com/mini-hub-motors/ One on each rear wheel

Id like to use some thing small like those but still powerfull enough to pull me around, im about 165...and be able to get pull itself up a medium sized hill. I am not familiar with anything in the electric bike community and would like some advice and recommendations on motors and everything to make it work.
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sigimem   100 W

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by sigimem » Jun 30 2014 3:43am

i know that ebikes.ca sells motors mounted on one side only. But I think that were Crystalyte HS3540 motors so far away from mini (7kg)?

Do you have a source for a these special hub motors?

Speaking of power etc. you should clearify what you want so people can give recommandations easier.
It would be good to know:

How fast do you want to go?

What range would you like to achieve?

Will you go up steep hills a lot?


whats your budget?


It would also help to look at the ebkikes.ca simulator to give you a general impression of what power you need.

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by Drunkskunk » Jun 30 2014 10:07am

Awesome project.

Unfortunatly, those mini geared hubs aren't suitable for turning into a single sided axle. the internal parts just won't handle being supported that way.

Single sided direct drive hubs exist, and normal DD hubs can be converted if you have access to a machine shop. but they will be heavy and the torque for hill climbing will be lower.

I think your best option is for a chain drive to the rear wheels. a sprocket could be mounted where the brake disks are, and a motor could then be mounted on the swing arm, one each side. Doesn't look easy with that setup, but doesn't look imposable either.

The front could probably be done in a similar way, though the motors would have to be mounted on the steering hub, or some extension that bolted to it, making that more complex.
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nofear43   100 µW

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jun 30 2014 10:35am

I was thinking something like a mini hub on each rear wheel...something light and simple, no chain or axles.

Id like to be able to get about 2 hours of time out of the batteries. And id use it for jumping little tabletops and hitting some bike trails for fun as well as cruising around the pits of motocross races. Im paralyzed now and getting around would be easier in this than wheeling my wheelchair for miles in gravel and mud. Plus it would be pretty cool.

This is a gravity only bike and I live in kansas...not much for hills and definitely no mountains, so just trying to make this into something that can be used, have some fun on from time to time and make getting around rough terrain feasible.

Thanks

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 01 2014 9:47am

Any recommendations? Ive read about a guy building electric bike using mini hubs but they were 250w motors which people didnt think was enough. Ive seen another company use 350w motors on a down hill bike and it didnt mention if it was underpowered or not. Although I'll be using 2 of them im pushing twice the weight.

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 01 2014 9:51am

Ive read the US law is 750w for am electric bike...I've seen these and they go about 50mph. I dont need to go 50 mph....15mph would be more than enough. Id need quite a bit of torque to get up a medium slope....roughly 30° incline and about 20ft tall, without burning the motor up. Again im new to all of this.

Any information would be appreciated

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by sigimem » Jul 01 2014 10:04am

30° (degree!!!) is really steep thats 50 percent gradient. I would guess you have never seen a road with a sign that says 50 percent gradient?

You should go with Drunkskunks advice and put motors on the swingarm of that bike that way your bike can climb anything when geared to 15mph (25km/h)

What size are your rear wheels? We could calculate your torque for going uphill at a certain degree.

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by Tench » Jul 01 2014 11:49am

Funny this topic should come up when I have just made some axles to single side mount mini geared hub motors for use on a similar vehicle, some pics;

The axles, showing top and bottom of old and new.

Image
Image

The motor as I was rewiring the cable.

Image

I would imagine this could be done with most motors.
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nofear43   100 µW

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 01 2014 12:43pm

Mounting a motor to the swing arm...I dont think theres enough room to mount one on there and then run a chain back to a sprocket on the wheel...that sounds like alot.

What about those small electric hubs on each rear wheel...so you really wouldnt even notice much, and a battery pack of some sort under the seat?

30° I might be off road with this so yes, 60° isnt unheard of, ive hit many jumps on dirt bikes where you could barely walk up the face of the jump. I just wanna take it easy on this. ..im not trying to get hurt.

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 01 2014 12:45pm

I believe the wheels are 26in on the back

nofear43   100 µW

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 02 2014 9:57am

Tench wrote:Funny this topic should come up when I have just made some axles to single side mount mini geared hub motors for use on a similar vehicle, some pics;

The axles, showing top and bottom of old and new.

Image
Image

The motor as I was rewiring the cable.

Image

I would imagine this could be done with most motors.

Nice job.

So id need a mini hub motor, lace it up to my wheel, and a single sided axle like this to make a complete electric wheel for each side. Then I'd need some sort of ECU and battery, correct? What kind are you using or planning to use?

Thanks

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by ecycler » Jul 02 2014 10:26am

That thing looks really cool! The route I would probably look into would be to see if you could get Tench's new single side mount axles to work with these new 2 speed gear driven hub motors. Then the big question is how well they would lace into your existing wheels and setup. I would think 2 of these should be able to pull you up some steep hills and easily hit 15mph. They seem to be a great deal, although no one has really put them through their paces yet, but with by running two, at least you don't have to worry as much if one burns up!

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by Tench » Jul 02 2014 3:14pm

The problem with the 2 speed motors could be getting them to change direction (gear) at the same time!

I certainly think the axles could be made for any motor to single side mount them, all I would need is the details of the axle fitting on your suspension uprights.

I don't know how these motors I have converted are going to be powered, I was sent the motors and returned them after making and fitting the axles. There were 4 of them for a 4 wheel drive buggy. The clutches will be welded up so they can reverse too.
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by ecycler » Jul 02 2014 3:50pm

You can use a switch button to manually change between high and low and forget about the auto feature.

It hurt my brain a bit the first time I was exposed to this concept, but provided you have the traction, it could actually be advantageous to have them switch at different times! I remember reading a while back about the mosler twinstar where this was a fundamental part of the design... the geared each engine/axle differently. As long as they are independent, it provides for smoother acceleration. See the third paragraph of this article:

http://www.caranddriver.com/reviews/mos ... ialty-file
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by r3volved » Jul 02 2014 4:36pm

But if the same throttle is powering both motors and one motor switches out of sync with the other, you'd have one wheel trying to spin twice as fast (faster anyway) as the other. If either wheel slips, the stock controller would attempt to switch gears on it.
With a switch, you could set it up to momentarily cut power through two aftermarket controllers with reverse function (acting more like a regular shift).

Would two of these motors work off one controller?

Just my thoughts...
bikemore wrote:You can use a switch button to manually change between high and low and forget about the auto feature.

It hurt my brain a bit the first time I was exposed to this concept, but provided you have the traction, it could actually be advantageous to have them switch at different times! I remember reading a while back about the mosler twinstar where this was a fundamental part of the design... the geared each engine/axle differently. As long as they are independent, it provides for smoother acceleration. See the third paragraph of this article:

http://www.caranddriver.com/reviews/mos ... ialty-file

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by teklektik » Jul 02 2014 4:52pm

I believe you will want reverse, so the two speed motors would be out.

You could lock up the freewheel in any regular geared hub (weld or epoxy) and it will run in reverse adequately with the proper controller (eg the old analog Crystalytes).

I agree with Drunkskunk on this one - at slow crawling speeds hub motors are in a very bad efficiency place. Replacing the rear swingarms with custom units with an arm-mounted motor chain-driving the wheel would get the rpm up and give you some good torque. With replacement arms, you could easily revert the buggy to stock if that became desirable.

It looks like you could pack the battery and controllers onto or behind the seat back.

Hmmm - on the other hand, eliminating the freewheel to enabling reverse would slow the downhill WooHoo! aspect, so maybe reverse is a no-go anyhow.....
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by nofear43 » Jul 03 2014 10:43am

Tench wrote:The problem with the 2 speed motors could be getting them to change direction (gear) at the same time!

I certainly think the axles could be made for any motor to single side mount them, all I would need is the details of the axle fitting on your suspension uprights.

I don't know how these motors I have converted are going to be powered, I was sent the motors and returned them after making and fitting the axles. There were 4 of them for a 4 wheel drive buggy. The clutches will be welded up so they can reverse too.
Ok. I was thinking the battery/electronics would fit under the front part of the seat...more easily seen in the first 2 pictures.

Wouldnt both motors be wired to 1 control until? So when I give it throttle power goes to both motors equally? I can see how this might make tight turning a lil difficult...like having a sokid axle or a locked rear end...but of im in loose dirt and have to id hope I could just spin the back end around.

Yes, Im unsure of what motors would lace up to my rear wheels.

Reverse would be nice, but I dont want any more drag than possible from the motors as im freewheeling downhill....although ill probly be on the throttle downhill anyways.

I think 2 350w mini hub motors....one on each side using ine of your axles amd some sort of ECU and battery pack is all I need? Besides the throttle and wires themselves.

Anybody familiar with mini hub motors and which ones I should be looking at.....as well as an ECU and battery?


Thanks guys

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by r3volved » Jul 03 2014 10:51am

Teklektic is right... You will likely *need* a reverse, unless you are able to manage reverse direction now, without a motor...I can't tell.
Being as how you won't be able to jump or shift the bike sideways with your legs, you will more than likely run into spots where reverse is necessary to maneuver around something (more like 4wheeling).

This is a sweet project and I'm excited to see what you end up doing!

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by teklektik » Jul 03 2014 12:05pm

nofear43 wrote: Wouldnt both motors be wired to 1 control until? So when I give it throttle power goes to both motors equally?
No - one controller per motor (the motor clocking and rotation actually control the application of phase power so since the motors rotate differently - two controllers). Share the throttle with both controllers. This works particularly well if you drive the controller throttle input from a Cycle Analyst which has an independent 5v supply. I think you will want a CA anyway so you can accurately monitor your battery situation - certain driving behaviors will chew up surprising amount of Ah and the last thing you want is to be caught unexpectedly juice-challenged out on the trail...
nofear43 wrote:I can see how this might make tight turning a lil difficult...like having a sokid axle or a locked rear end...but of im in loose dirt and have to id hope I could just spin the back end around.
Although the same voltage will tend to make the motors turn at the same speed, there are no electronics that are actually forcing a specific speed so it's more like a not-too-limited slip differential than a solid axle. As long as you are just turning instead of pirouetting in place, all should be fine. If you want an emergency one-wheel drive capability for getting out of sticky jam-ups, it's trivial to hook a thumb switch to kill the throttle to one or the other motor.
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by AussieJester » Jul 03 2014 9:46pm

Chain drive all the way listen to drunkskunk, at the best of times hub motors aren't good for hard off road use...add the complexity of the freewheeling two speed and its setting yourself up for failure imho... I realize it sounds like a great and simple idea, you will burn them up...you can't pedal our push whilst on the throttle either relying exclusively on motor power, you can't use direct drive Motors as you need the freewheeling ability, you get cogging with direct drive motors... Not to mention how much the heavy hubs will mess with that trick suspension...

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by Samd » Jul 03 2014 10:04pm

I am diggin that four wheeler platform.

I think Kim is right about a chain drive on that platform. Those stub axles on that quad wheeler are solid so might be best left alone.

How much torque do you want? Kim will give me a hard time for not recommending an outrunner based RC drive :mrgreen: , but whilst the rest of the forum fusses around with the wet fish that is the new Bafang MidDrive, this new rickshaw motor discovery seems destined to be the new hotness.
I think it comes in at about 34 rpm per volt - tidy for an inrunner motor.
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by AussieJester » Jul 04 2014 1:24am

Haha. Nah, what ever is going to work best, the gng motors like Adam is using work well, two of the little ones on each swing arm would be the go...

I looked into getting one of these four wheelers few years ago, price was extraordinary as was the 6 month wait time back then...

Being a wheel chair user of over 20 years now I would also be very cautious into recommending any single sided axle that uses threads and nuts to connect to the chairs frame, all the high end wheelie stuff are hollow titanium quick release axles, touch wood I'm yet to bend one and I give my chair Hell, the threaded axles I once used, regularly snapped at the thread, much much weaker than the hollow quick release versions..

If money's little object, pm es member Recumpence see if he can hook you up with mounts and drives..otherwise the gng motor is likely your next best option...

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by sigimem » Jul 04 2014 4:43am

Maybe its possible to clamp the motors on the existing swing arms. Then run a chain to a sprocket on the disc mount. Disc brake could be mounted on the motor axle as well so you brake and accelerate by putting a force on the chain. The chain won´t take the abuse too long I guess...

You could also hook up two throttles (need 2 controllers anyway) it seems like you are able to handle that 4 brakes!!! I guess it should be quiet interesting to actually support turning with the use of the motors once you are used to it.

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Re: 4 wheeled downhill Mt . bike electric conversion

Post by ecycler » Jul 31 2014 5:11pm

Any progress on this project? My vote is still for 2 of the cheap 2 speed motors and some axles from tench. (provided you don't care about reverse)

It will get you around up to a reasonable speed, will go up hills, will take minimal fabrication, has less stuff to break, and should be quite cost efficient to get started.

How are your welding/fabrication skills?
If you want to go super cheap, then buy a couple of the brushed motors for the currie ezips and some controllers from alibaba. Just be sure to get everything aligned properly and really solid or you will be throwing chains like crazy! :-)
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Re: 4 wheeled downhill Mt . bike electric conversion

Post by docnjoj » Jul 31 2014 5:26pm

If you check the Xiongda site they have single sided motors for trikes. Might work for your project and they are reasonable in prices.
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