Dual mid drive hub drive prototype

[Needmorespeed]

Good luck with that
Let us know the outcome

 

[Needmorespeed]

Crystalyte came the other day and I've managed to put it on
Need to sort some new chain ring as I'm getting lots of problems. But the new hub runs perfectly and helps the gng to run much smoother. Can climb hills at 40 mph
Pics coming soon

 

[Needmorespeed]

Pics of the bike with the crystalyte installed. Laced to a 24" rim with with a 3" tyre.
Went for a spin on it today. Pouring down with rain,still managed 50 mph
New downhill 46 chainring added. Runs so smooth,don't even notice the extra weight on the back.

 

[lantice13]

here is mine. just finished building it tonight. tested it on the hills. it'a amazing. it's not a speed demon at 2kw combined going 24mph up hill without pedaling. around 30 mph initial test in a short flat road. ran out of flat road since my testing area tonight is all hilly terrain. more testing coming up in a couple of days. single throttle is wonky. one motor cuts out at WOT so I went with the dual throttle solution like everyone did. much better control.

 

[Needmorespeed]

Good to see other peoples take on the idea!
I got mine running at 96v now just to see what it's like.... Went like a motorbike for a few minutes and then sheared off the drive shaft!!! Ouch!!
Out of action with the gng. But at least I've got the hubby to get about still. Lovely backup when things break !

 

[lantice13]

more photo.

 

[lantice13]

peaked at 46 amps with a 51v 20ah battery. it's no crotch rocket but it climbs long hills really good. the beauty of this setup is having the ability to only use one motor to conserve juice for long rides. Weight penalty is lower too, compared to a 2nd magic pie direct drive in the front wheel. and the best of all, if one motor beaks down... you are not stranded since you got a backup motor on board.

 

[iovaykind]

Looks like you could do well with bigger front brakes.. thing must be pretty heavy.

 

[lantice13]

It's not too much heavier than when it was a single motor. my front brakes I think is the largest already AT 200mm. the wheel is 29" so they appear small. :wink:

 

[Needmorespeed]

Needmorespeed doesn't need any more speed !!!!
After fixing the driveshaft with a new bit of silver steel I managed to get out this morning and hit a new top speed.
Now it's proved that the two motors run perfectly together I will be making up a new frame with welded battery box and some decent brakes!!
Dh comp or big hit what do you think?
Think 60mph is enough for my first prototype. Need to have a safer bike now

 

[Needmorespeed]

Been scouring EBay and have just recieved the new frame
It's a tomac magnum. Super strong frame apparently. Think it lends itself to being an ebike
Any info on this bike greatly appreciated as I've not heard of one before.
Going to take my time on this project so won't be many posts in the near future. Got to think about where to cut the frame to place the battery box.

 

[Needmorespeed]

Just about finished my new dual drive ,got some chain issues to fix but it's nearly they're.here's a pic for, anyone's that's interested I've got a few more pics of some of the mods I've had to do ,

 

[spinningmagnets]

Looks awesome! I like the battery box too. Well done.

 

[Needmorespeed]

Thanks!
Been very frustrating getting here. Never seem to have time to do it and there's always another problem to solve. But that's just ebiking for you I s'pose ! I'll get some pictures of the other side now the gng is direct drive.

 

[John Bozi]

subbed as I was looking into this but was put off by the someone ripping a sidecover off, see you ripped one off too.

Please can you post a picture of the ripped off side cover, I want to see where the stress happened,,,

How much power were you running through it when it ripped off....? etc. what were you doing? changing gears? jumping? Would it be possible to get a custom cnc sidecover and drill more holes into the hub? etc

Surprised nobody else is asking questions about this as it is the most important reason you would not run more than human power onto the ebike rear cassettes.

Also it seems the main comment of excitement is going faster with double the power. I don't care about going faster (the hub can do that alone) I am interested in how you can hammer steep mountains at low speeds for long periods in a granny gear with hub to help it.

Since having all those sprockets at back seem pointless to me because from zero to 30 in seconds with a hub anyway, I reckon if it were possible to just mount one big ass pitbike sprocket bit like LMX runs and a straight line with no deiralleurs this thing will get real interesting.


how many extra kg are you carrying in total as a result of having gng on there = motor wiring controller throttle.....?
My other problem I have is dirt and dust even on just my normal riding its caked and starts shifting real bad on even one ride that gng looks like it will get bad with nothing covering it... any ideas....?

love it -build on

 

[ddk]

 

[lantice13]

I like my throttles separated so that individual hand can control it better depending on the riding condition. I guess I'm Ambidextrous now with throttles! But yep, my middrive hub drive 29er cruiser at medium power is a year old now and have ample miles on them. planning on upgrading the stock controller of the gng gen 2 middrive to a kelly so that I can control the torque ramp up better and makes the system much more smoother in power delivery. This should lessen the stress to the bicycle drive train that the motor hammers at maximum torque at stall.

 

[John Bozi]

You guys that running the mid drive through a freewheel on the hub,

Have you tried removing the freewheel?

At some time you will need to either change the freewheel or open the hub for either bearings or something else, i'm just concerned that unhuman amounts of power applied will make it impossible to remove.

This is now my greatest concern to going down this route.

thanks.

 

[John Bozi]

you guys dont like answering questions much on this thread huh?

This is my favorite thread awaiting answers from the limited few who have gone down this route...

I have my mid drive now, but would like some discussion here.

apart from my previous questions I have more:

At what point is efficiency?

For example Ive got a bafang bb02 750w

Now my hub has to push 5kg more but I have a motor which has all the granny gears. Compare that with what else you could do 5kg such as carrying 5 kg more of battery and thiings are starting to look a bit a pair shaped.

Personally I think it comes down to the way you ride. I basically have added a lot more thermal capable mass of both copper and casing that a single motor couldn't achieve. That's the reason for going the dual motor route for me I am trying to elimenate ever having to stop because of heat.

However, not every ride is up the mountains and at this point I know I am losing out because I never overheat on road, bitumen means I can go fast enough for my vented 20" tyre to stay under 100 degrees celcius.

What do you guys reckon? Eventually I will get a watt metre installed but it will be a lot of quasi science without it for a long time.

 

[lantice13]

I never removed my free wheel yet for servicing for my bike with this setup. So I cannot really exactly answer your question regarding that matter. But this issue should also be present with the middrive only bikes since they are putting a lot more force on those threads since they dont have the hub motor to cushion the initial tourque from the middirve part of this setup. But I do have some experience removing a freewheel from another bike with a single motor 1kw peak middrive. The free wheel came out using a long wench and a hammer. I think those guys that run high power setups on their single motor middrives can answer your concerns better. :wink:

 

[lantice13]

I think this setup would work better if both motors are close enough to each others peak watts rating so that they can share the load more evenly. The middrive could be a little weaker since you have the bike gear advantage. the 750w motor will only be capable of taking away 750w from the other motor 1:1. It's really a balancing act finding the sweet spot for both motors in a hill climb. The definitive way to find out is to attach 2 sets of watt meter monitoring both side of the drive systems in their performance while you cycle on all of your gears. Since you have the bbs02 middrive already, why not experiment with it! I really didn't had the time to fully do a detailed test like this when I first built the thing... shame...

 

[John Bozi]

thanks for the reply lantice13,

But this issue should also be present with the middrive only bikes since they are putting a lot more force on those threads

they aren't using thread on freewheels with rear sprockets are they? Aren't they usually modern free hubs with splines as found on bicycles these days?

I think this setup would work better if both motors are close enough to each others peak watts rating so that they can share the load more evenly. The middrive could be a little weaker since you have the bike gear advantage. the 750w motor will only be capable of taking away 750w from the other motor 1:1. It's really a balancing act finding the sweet spot for both motors in a hill climb.

Personally with my limited knowledge, I believe that the hub since you have one will be much more reliable to take 5000 watts peak than anything running through a drive train, and do that with less heat as mine is vented. There's no way I can carry that much more battery to run the second motor even near that watt peak.

The mid drive second motor I hope will be almost totally used in granny gear. I am just doing rough guesses that 5000watts @ 10 kmh on a hub = 1000 watts @ 10 kmh in granny gear mid drive.

As for testing properly, its just a pain. To be done properly, I need to record tests

1, with the bike as is
2. with only the mid
3 with both

and then probably trial 12s2p hub vs 12s2p mid.
making sure only to use the same number of cells.

Looks like we've got a week of rain ahead of us, was waiting for all parts but since I cant ride my bike anyway, I am going to start building tomorrow, but unfortunately I am waiting on batteries and adaptors and then the holidays means this will probably not be complete till January... Not my kind of holiday....

 

[lantice13]

You still can't take the possibility that someone might had been using an old school freewheel on their bikes as well so not gonna hurt to ask, specially the ones that runs those cheap 2 stroke and 4 stroke petrol engines in another gas motorized bicycle forum Some of them are really really old school. the guys that are modding the cheap izip trailz bikes also uses a single speed freewheel on the left side of the bike which the motor drives. Might want to ask there as well.

on a nearly even peaking motors ,you can still use 5kw total like your single motor at peak but this time it's split on both motors nearly like 40%,60% if they are really closely matched in their peak rating and depending how much heat the other motor can handle. So you really don't need a larger battery. if your pack can feed enough amps to run your single motor bike at 5kw peak, it's just a matter of doing the balancing act manually or programming the controllers and set some amp limiters so that both system wont exceed 5kw total combined motor power. 3 speed switch is also a good idea setting the limit of the motors on the fly depending on the condition. Now you probably can still use a weaker helper motor but you'll need to climb a bit slower using that 1kw peak bbs02 on the right gear. you need to ramp down the amps on your much more powerful rear motor so that the less powerful mid drive motor can actually contribute in sharing the load with the other motor.

 

[John Bozi]

HOws the dual club going?

thought Id update here.

30t x 48t single speed bafang bbs02
crystalyte 4065 in 19" bicycle rim

both running off one battery = 12s 3p

charging ease is still what's keeping from upping the volts.

[youtube]A2z1tCqbw6g[/youtube]

 

[Tommy L]

Interesting Thread! Subscribed!

I'm moving from a flat area to a steep graded area. If I'm going to continue ebiking, then this is great info.