2WD (Two-Wheel Drive) FAQ

[cycleops612]

PS.

My biggest fear w/ incurring the wrath of the local cops, is not having a plan B to make it kosher again once I have been warned once and noted. Simply removing/swapping the front wheel for road use I could live with.

To being precluded from the road seems a big/costly risk.

 

[d8veh]

You can use one throttle with more than one controller provided that you only use the 5v wire from one controller, i.e. don't parallel the 5v wires. If you're using more than one battery, you need to make sure that the grounds are linked to give one common ground. You don't need a buffer if you do it that way.

The problem that you need to avoid is that the 5v will not be the same on each controller, so you can get strange effects when you connect them, and the same thing if you don't have a common ground.

 

[motomech]

You are breaking the law, are you prepared for that?

I bet you'r fun at parties.

Just saying, my longyeah axial drive mid motor (24 powered gears) is only visible to the practiced eye (unlike the battery of course). I strongly suspect a second motor would pass notice.

What hasnt been mentioned afaik, is there are advantages to opting for powering each wheel optionally, vs sharing a controller, and it to some extent diminishes the need for full power to both from a single battery, tho I agree, more amps is better for when you do want both at full power(best avoided rangewise anyhoo). This is not the case when traction is the issue.

I also like regen on one (front ideally) but not both motors, due to the slight drag.

In theory, I think I would opt for a twist throttle, with an adjacent thumb throttle, and with practice, both controllable with one hand.

In theory, I think I would opt for a twist throttle, with an adjacent thumb throttle, and with practice, both controllable with one hand.

In theory????
On page 8 I show how I do it (w. pic.s) and explain that it works well.
Time for you to stop pretending you are charting unexplored territory and rather than rehashing our ideas, maybe you should build something and show us something new in your own build thread.

 

[teklektik]

.....
What hasnt been mentioned afaik, is there are advantages to opting for powering each wheel optionally, vs sharing a controller,
...
In theory, I think I would opt for a twist throttle, with an adjacent thumb throttle, and with practice, both controllable with one hand.

In theory????
On page 8 I show how I do it (w. pic.s) and explain that it works well.

Time for you to stop pretending you are charting unexplored territory and rather than rehashing our ideas, maybe you should build something and show us something new in your own build thread.

Seriously? You kept reading after 'shared controller'?

 

[Alan B]

just to be crystal clear, you cannot share BLDC controllers (unless the motors are locked together in the right phase relationship). BLDC's electronic commutation must respond independently to each motor's actual position.

You can share Brushed controllers (with brushed motors).

 

[cycleops612]

motomech, more laboriously than "in theory", i meant i have not done it, but that seemed best from past reading & considering the matter for myself.

Its a v old thread and yes i saw your? late posts belatedly - it happens - boo hoo - why so upset?

it seemed relevant to the posters query & you confirm that - its simply a repeat.

 

[Monkeypowah]

Battery mount needed some alteration...drill, to let battery fit in frame, it was like 3mm from letting the lock hold it in place.
rear wheel mounted, test ride with everything taped on, nice acceleration, can't complain about this kit for the money, it slotted in perfectly, disc lined up spot on.
Left off everything like pedal assist, brake cutouts, it has a 3 led indicator on the twist grip which is suitable for warning aircraft at night, thats getting ditched.

 

[Rassy]

it has a 3 led indicator on the twist grip which is suitable for warning aircraft at night, thats getting ditched.

Those 3 led indicators are set for a 36V sla battery so go super bright on 48 volts and don't give you any information except that the system is turned on. It's a good idea anyway to "cut" the wire that carries full voltage to the throttle which helps eliminate one potential source of a short. Of course I don't know which color that wire is. I think normally red, black, and blue/purple are the three wires needed for the throttle, but you would need to verify that.

 

[Monkeypowah]

Thanks, probably going to put a thumb throttle on, I'll have to work out the wires by taking it apart just to be sure.
Ordered one of these to be built into a 24 inch rim, have to seriously widen the stays out to 175mm, but 80nm of torque should help a lot.

https://www.ebay.co.uk/itm/36-48V-500W-8Fun-Bafang-Brushless-Geared-Threaded-Fat-Bike-Rear-Hub-Motor-175mm/192116668853?hash=item2cbb0bb9b5:g:4FsAAOSwCU1Ytmyb

 

[Monkeypowah]

I've instantly hit all the problems that the wise old owls on here warned me about, basically it works fine, I've got it just banging in the front hub, no problems, not enough torque to be an issue, things like the battery clanking away over rough ground are making the bike feeling like a tank.
Updates are, more securely, rubber mounted battery, 24 inch rims and a high torque fatbike hub in the rear, the battery is coping well.
Also bough a second hand downhill rear suspension frame, hopefully that will reduce the stress on the battery as well.
I'm not taking any pictures cos it looks like an electric scarecrow at the moment.

 

[markz]

I was being facetious ( not meant to be taken seriously or literally: a facetious remark. 2. amusing; humorous. 3. lacking serious intent; concerned with something nonessential, amusing, or frivolous: )

in a sense because some people take the term 250W literally and go to extraordinary lengths to follow some bs law to the T.

I say since a 500W motors diameter is the same as a 3000W motors diameter (but much wider) no one will know nothing anyways. Im not scared of power legislated or otherwise 8)

 

[tomjasz]

Finally ordered the rear 10T MAC for my 2wd build. Anyone use MAC? I've a wiring scheme from teslanv. Any suggestions? Two 12 FET IRFB4110 EM3ev Controller (Black Case). Not sure how clunky it'll look with two controllers and a bundle if wire to cover and hide away.

 

[linear]

PS.

My biggest fear w/ incurring the wrath of the local cops, is not having a plan B to make it kosher again once I have been warned once and noted.
To being precluded from the road seems a big/costly risk.

Yes, to incur the abuse of the LEO team, especially when they already have their focus on you is annoying to say the least. Most of my current project plans will no doubt cross the line in their minds.
Anyway, did order a pair of kits to experiment with 2WD, regen, and electric braking. Winter coming soon will really limit any use or testing.

 

[csc]

I found a trick to push the slave speed limit in 2wd mode ! More details here : https://endless-sphere.com/forums/viewtopic.php?f=30&t=87712&p=1338398#p1338398

 

[Monkeypowah]

Well it is moving along, though I bought thru axle front forks without thinking that through.
So how do I mount a front hub to them...possibly get some adaptors machined, I guess anything is possible.
Have to be caliper off to remove wheel.
Anyway..herrs the nearly finished bike in 1 wheel drive.

https://i.imgur.com/aHta9dlr.jpg

 

[Valopallo]

Hello. Building a 2wd here also. I have s06s with the rear DD motor and KT36ZWS with the front geared hub motor. Both have individual 36V 15A batteries and they will share throttle, PAS and brake signals and also the common ground of the batteries. I already have mounted the main power switch (of the LCD cable harness) for the rear motor/s06s to the bike and would like to use that same switch to power on/off both controllers/motors. I don't use LCD but have bluetooth for both of the controllers. Can I connect the red and blue wires of the controllers in parallel so I can use only one switch to power on/off or will this result burning the controllers?

 

[tomjasz]

New from Grin!

Precision 1mOhm Stand Alone Cycle Analyst Shunt prewired for dual controllers. A plug and play solution to let you easily run and control dual motor systems off of a single V3 Cycle Analyst. Battery cable input is split for 1 or 2 batteries in parallel, battery output is split for each controller power, and throttle signal from CA-DP plug is split into two 3-pin throttle plugs for the controllers.

 

[electricwheels.de]

Hi all,
I've been riding my AWD Surly Ice Cream Truck now for about 3 years. It basically has 2 12T MACs, each having a 40A Controller with one common shunt, one CA3, one thrigger (for motor speed, similar to a throttle) and one poti (for motor torque). 48 V and limited to 50A. Total weight is about 40kg.
Pros: Really good on Sand, super steerable - easy to do a donut/180 deg turn on dry fine deep white sand without putting a foot down. Easy to run through a foot deep water or snow. Excellent acceleration.
Cons: Heavy. Not good at jumping, or short, sharp turns on single tracks. Still managed 8th place in an amateur enduro event though .
My opinion: Good if you live where there are lots of sandy tracks, like some MTB tracks in the Netherlands (my favoured: Schoorlse Duinen MTB track).

 

[Matteo's Mobile Bicycle Repair]

I'm quite behind everyone in understanding what's being said here even after reading it...

but i believe my situation calls for two motors to help me. but not sure. I two approx 500lbs of bike trailer and bike and me, like to move at approx 25/30 km/h and when i hit a grade of 30% higher i find it hard to get up the hill. So i installed second motor to help me in those cases and to have back up in case of breakdowns. but this graph seems to say that my crystalyte would be doing nothing? because i need to balance it and graph doesnt do that...or is this saying its a bad idea??
nm i don't know how to post images gahh..

 

[MacgyverHK]

USING DIFFERENT VOLTAGE HUB MOTORS on Same Bike:

I am building a 72v bike with a 10kw 72v hub motor on the rear.

I am thinking about installing a front hub motor for low speed off-road trail riding.

Issue:
1- finding a low wattage 72v geared front hub motor has proven challenging. The smallest 135mm 72v hub motor I can find is 3kw and I do not wish to be that aggressive on the front.

Question(s):
1- Can I use a 52v or 60v 750w geared hub motor? - ( I realize it would require an independent controller);
2- Can I use a voltage reducer off of a line from the existing 72v battery to power the lower voltage 2nd controller?
3- If I use a geared hub motor, will this place drag on the bike as a system, other than the additional weight?

I Thank you learned bike builders for your responses.

Mac

 

[Chalo]

USING DIFFERENT VOLTAGE HUB MOTORS on Same Bike:

Hub motors don't really have a voltage. They do have an RPM per volt value, and if you're using two of the same size wheels, you probably will want two motors with similar or identical RPM/volt.

If you're using two different sized wheels, you will want to find motors that run at about the same road speed per volt. So you want the RPM per volt times the wheel diameter to be the same.

Personally, I don't think adding a front hub motor to a bike that already has 5X as much power in the rear wheel will help at all. Front motor alone is not great for off road riding, and if you run them together, the front motor will break traction whenever the rear one bites in.

 

[scianiac]

I mean if the front is used for low speed off road use only the motor speeds don't matter much assuming it's geared with a freewheel. I have considered a very small front wheel drive setup for off road use but I don't think it's as easy or useful as you think.

Even on my 2WD bike that has traction control that will limit the front wheel's power to stop it from spinning it acts strange at times when out of it's element. Without an active system to limit power it will either be unrideable as the front will have too much power and not enough grip often or the front will have so little power as to be not very useful and probably a detriment due to weight. This is due to the fact that the front's traction is highly variable and inversely connected to the incline. So the steeper the incline the more power you need but the less traction the front has. Meanwhile the rear is the opposite and on very steep nearly all of the weight is on the rear so it has all of the available traction.

Do you actually have traction problems on steep terrain now? At this point I've ridden up a wide range of seemingly impossibly steep hills and when I do fail a front motor probably wouldn't have helped as it's normally down to sharp edges or very very loose ground. A better tire setup is probably a better option.

 

[MacgyverHK]

Hub motors don't really have a voltage. They do have an RPM per volt value, and if you're using two of the same size wheels, you probably will want two motors with similar or identical RPM/volt.

If you're using two different sized wheels, you will want to find motors that run at about the same road speed per volt. So you want the RPM per volt times the wheel diameter to be the same.

Personally, I don't think adding a front hub motor to a bike that already has 5X as much power in the rear wheel will help at all. Front motor alone is not great for off road riding, and if you run them together, the front motor will break traction whenever the rear one bites in.

I will be running the front motor and rear motor on two different throttles.
I do like the extra torque the front motor can offer and hill climbing grip.
The rear motor is 10kw so plenty of speed but just OK torque.

 

[MacgyverHK]

I just found the Grin All-Axle hub motor, which can run 72v and can hit 100kph with a 135mm dropout and disc brakes. Wow. This is a game changer.
Impressive front wheel drive.
Now, I just need to know if I can run two different controllers off of one battery.

 

[Chalo]

I just found the Grin All-Axle hub motor, which can run 72v and can hit 100kph with a 135mm dropout and disc brakes. Wow. This is a game changer.

100 km/h with front wheel drive on a bike is not a practicable setup. The wheel will spin and skitter around at any speed that bikes are good at. Don't bother.

If you want better, like closer to 30 mph speed, use 2WD. That spreads out torque and heat, and increases power much more than torque top speed. If you want big, like 60 mph speed, only rear wheel drive will to do that reliably.

Bikes don't go much faster than 30 mph without misbehavior. You can work around that, but not without making handling qualities suffer at bicycle speeds.

(Edited to correct a mistaken detail.)