Bonanza "Bulldozer" Dual PhaseRunner AWD

I received a question about what my goals are for this upgrade, so I thought I'd summarize the journey and consider that more carefully.

I originally built this ebike (in this thread), my first, with a 9C 9x7 as recommended by ES for commuting to work. Learned a lot about gear clusters, shifting, torque arms, controllers, etc. I was going to use Headways, bought a bunch, but the bulk, weight and mounting problems caused me to try Lipo. I started with 12S 44V 5AH Turnigy for testing. Torque was marginal, with good pedaling it did the hills sort of okay. So I ordered a 9C 6x10 and upped the Lipo to 18S 66V 10AH to improve it.

Torque was possibly better with essentially the same controller and the higher voltage. Not a lot, but we understand that a lot better now with more motor knowledge. It probably wasn't a great change to make, and cost quite a bit for a debatable improvement.

I considered adding front wheel drive then, even before my first commute.

I put the other 9C 9x7 on a steel mountain bike for my son, he has used it a lot with a 10S 20AH lipo I built for it. He rides WOT so I'm glad it doesn't go too crazy fast at 10S. That has been a good solid commuter and he uses it quite a bit.

Then I went on the ES group ride to Marin, up steep hills and dirt roads. I fell a couple of times due to insufficient traction and torque and rough terrain and minimal skill and just about melted the motor. The bike worked okay for commuting, with hard pedaling on the steep hills. The ride was a bit rough at commute speeds on poor pavement.

I bought one of the new HT motors for a rear DD upgrade on the mountain bike for better climbing, then saw the Cromotor and decided a whole new bike was prudent, so I sold the HT unused.

When I built the CroBorg, the commute became a lot easier, and the mountain bike was ignored.

I wanted to try AWD on the mountain bike early on, but complications with the alloy suspension front forks and the lure of other projects tore me away from that and I never got back to it. Till now, 4 years later.

So now I have this 9C 6x10 mountain bike sitting there with lots of pedal gears but not enough torque or traction for steep hills. I have a bunch of dirt roads around here that I can't take the Croborg on that I might be able to take the mountain bike on if it had more torque. Though they may not allow electric bikes on some of them so it might not end up being a great use-case. It needs to be somewhat electrically subtle. If it looks like a regular mountain bike there are also some bike trails around the bay that may be accessible. For that it would not need the front motor, just needs to be fully pedalable. I could even swap out the front wheel if it isn't too hard.

I've been considering a fat-tire bike since before they were popular (Surly Pugsley), but that is a whole new project, and they aren't all that fun to pedal motorless so would not be good for some of the uses. Still interesting, but what to do with this existing bike, to avoid throwing away a really excellent rear wheel build. Could get a mid-drive, but that would toss the nice motor wheel, and mid-drives tend to be noisy and wear the gear train quickly. Perhaps not the most subtle setup either.

So upgrading the front wheel has again become interesting to consider. I don't want to put a heavy DD motor in the front, a light gearmotor seems like a much better choice. Balancing the power between rear and front is an interesting challenge. And one that might have value beyond my own ride. But not too hard to do.

If I repackage the battery and cover things up I can make the bike look less electric. The rear hub hides behind the cogs and brake disc, the front smaller hub will also mostly hide behind the brake disc.

But I probably will have to get new front fork. The present inexpensive suspension front fork is not good material for a gearmotor. I see good a steel fork is not too expensive, but it will make the ride more harsh. The Schwalbe Big Apples and Thudbuster will have to handle the rest.

So, at the end of the day, it doesn't need to be a commuter (I'm retiring in a few weeks), it doesn't need to be a long haul machine, I have the recumbent for that. It has a sturdy rack, and I might get a trailer for it that would make it a good grocery getter. It would be good to take camping, though a folder would be easier to manage (another ebike on my todo list, but that's a separate story). The front motor's already ordered, so we're on a trajectory.

So what is this AWD Mountain Ebike for, in no particular order?

• Better traction and torque for steep paved and dirt rides
• A medium hauler with sturdy rack and good towing capability (I don't have a cargo bike, another on my list...)
• An interesting experiment to test some AWD control ideas on
• A project to keep the old ebike from gathering dust

I did talk with one ES member who has done a lot of 2WD ebiking, and he said there was no problem with wheel spinouts in his experience.

I have had 4WD on several trucks and SUVs, and both 2 and 4WD on a couple of ATVs, and I have to say that spinning the tires is mostly a 2WD phenomenon, not present on the 4WD vehicles I've experienced. What seems to happen is that the vehicle just accelerates quickly, even uphill in the rain around a corner with full power. The torque that would try to spin the tires is just used up accelerating the vehicle, and the resistance from the nonpowered wheels that would hold the vehicle back so it could spin is just not there. The vehicle just rockets off.

So I suspect that the same is true with the ebike. The tendency to spin is reduced. Even the tendency to lift the front end is reduced, since only half the torque is applied at the rear there is only half the lift to the front. Front wheel ebikes do have a slight tendency to spin the front wheel, so the power in the front may need to be limited somewhat. But if 1500 watts to the front wheel causes a spin, 750 watts to each wheel should produce great acceleration without spinning either wheel.

This will make for interesting experiments when we get to that point. Perhaps 60% rear 40% front will be the right split. That's what some AWD vehicles use, if I recall correctly.

So far the times I've had spinouts were simply from road conditions where there was insufficient traction, and that's been things like rain (wet and or oily surfaces), sand on otherwise smooth asphalt, crumbly asphalt over old surfaces, mud patches, etc., wet steel plates covering construction holes, wet steel manhole covers, etc., all on normal streets, typically in turns but sometimes in other straight-line trajectories.

Otherwise, it's been pretty good. I haven't done mountain trail riding with anything I have, but on dirt and gravel and whatnot canal paths / etc., it does usually just "go" rather than spinning out, even if I hit full throttle on both wheels at teh same time. But there are moments when different conditions exist at each wheel on such paths, and then it helps to be able to control both separately--or to have some other form of traction control, like the automation you've talked about here.

Many interesting things to try once the basic platform is built. The hardest part is testing, the automotive folks travel to frozen test tracks and flood parking lots to generate the conditions. We'll have to come up with something a little easier and nearer to home.

Probably the next issue on the project is selecting new steel front forks. These alloy suspension forks are not likely up to the torque of FWD at 1500W.

Perhaps Surly 1x1:

http://www.jensonusa.com/Surly-1X1-26-Is-Disc-Fork

http://surlybikes.com/parts/forks/1x1_fork

Did you see my CrazyBike2's cheap suntour front alloy forks, with the 9C 2810 (or 2806, I forget which, brain melted), just using the wrenches for torque arms? I should have at least 1500W on that wheel, cant' remember how much exactly (previous generation Grin 12FET, unmodified, whatever that can do on a 14s 20Ah EIG NMC pack), and I hit it up for max power at every startup, along with the rear wheel motor.

If you make up a good torque arm / plate I don't think you have any worries for your forks, but I guess it depends on the actual torque your motor produces (I don't know how much mine does, except I wish it was more :lol.


Also, for test tracks, perhaps see if you can get a friend at an ice hockey or ice skating rink?

The rear motor is a 9C 2810, the front a BMC V4TT.

Not many ice rinks here, don't know that I know anyone at one. Interesting idea though. I can probably find some sand to test in.

Existing Front Fork

Does this alloy fork look like a good front fork for for AWD?

To handle the torque a 1500W peak BMC gearmotor can make on rocky rutted roads?

Alan B said:

Does this alloy fork look like a good front fork for for AWD?

Click to expand...

I never heard of that brand...but the style looks like typical walbike stuff I've had. Does it do any good as a suspension for what you're wanting to do, in tests?

If not, you probably wanna first get a fork that does the suspension you need, and then make torque arms for that fork.

If it does the suspension job, then it ought to work with the hubmotor, as long as the motor fits within the dropouts without spreading them, and you can make a torque arm that will handle all the axle staying power needed, so the dropouts don't have to. And use C-washers to fill the lawyer lips so the nuts/washers on the axle don't press on anything but the flat area inside the lips.




The Suntour fork I have is something like 100mm travel, and I think it's just a spring/polymer type, not air or hydraulic or anything. It does well enough on average streets but I wouldnt' expect it to have any suspension effect on bad roads or offroad.

It does some good on the larger bumps. I put my finger on it the other day and it didn't move with the small road noise, it moved slightly on the larger ones.

Putting effective torque arms on this fork is tricky, and the dropouts will still be fragile alloy.

I would like to have a suspension fork work with a front motor, but I don't think this fork is going to be the one to do that, and in any case it will be a development project to anchor a motor safely to suspension forks.

A non-suspension steel fork would make the job trivial.

If you don't need the suspension, no reason to use a suspension fork (especially a poor one). So then might as well go with a good steel one.

Get a steel fork. The torque from the back motor will make a motor-wheel in a front suspension fork skip and bounce, which gives the drop-outs a very hard time. I have a lot of experience of mounting front motors in aluminium forks. I used properly anchored double torque arms on my powerful 2WD and bust the drop-outs in less than 10 miles.

Are you sure that fork isn't steel? The construction looks like steel to me.

I did a little poking around and couldn't find the thread about the bike, d8veh; which one is it?

I'm just curious, because you don't specify what "powerful" means.

My CrazyBike2 is 40A 12FET controllers front and rear, "48V" battery, for at least 1500W-2000W each wheel (I don't know the Nm torque values), and it's also really heavy (around 340-350lbs with me on it) so it pulls hard on the fork during acceleration (and pushes hard on it during braking) whether I'm using 2WD or just FWD, and I don't see the skipping you've had, either. I pretty much always use full throttle, instant start controllers, so full current from zero to 20MPH which is the AZ speed limit.

Even just using box wrenches for torque arms on each side I'm not having issues with axle rotation, so I'm curious what torque arms you're using that still let the axle rock enough to break the dropouts?


I know that it *can* be a problem, as I broke the dropouts on a Manitou Skareb fork just with a bike upside down for testing, with no axle nuts at all or torque arms, using the X5304, just spinning up the wheel on a little tiny 20A controller testing out the used kit it came from. But...that was with no axle nuts. And later I spun that same motor ina 20" wheel right out of thin steel "funky" dropouts on the rear of the SB Cruiser trike, even with a box wrench torque arm on the outside, but it is also a monster of a motor and those dropouts were not normal, plus I was using EABS "active" braking and hard acceleration, over and over, *trying* to break things.


When I first installed the 9C 280x 26" on the Suntour alloy fork on CB2, I did worry a lot about it breaking something, since I do use regen and hard acceleration, at least a dozen times each way on my daily commute, but with no signs of issues I stopped worrying about it a while ago, and actually just plain forgot I was ever going to try to custom make torque plates for the fork.


So that's why I'm curious on the situation that let or caused yours to break, so I can be sure to avoid it on mine (as I don't really have the option of a steel fork that will do good enough suspension on mine; teh alloy one barely does what is needed and I couldn't afford to buy anything else to do the job--not having suspension at least in front isn't an option and I frequently wish I had it in back too).

If yours is torquier than mine I won't worry about improving mine, but if yours is less so, then I might need to look at making those torque plates anyway.

I think the Zokes are alloy, I'll double check. This is a $600 Novara mountain bike from REI I bought many years ago and didn't ride much. Alloy frame. I'm pretty sure there is some steel in the forks, but I think the dropouts are alloy, they are fairly thick. There's no great place to land torque arms on the fork tubes. I could fab something but there will be a lot of force in the forward direction on the dropout which is not a normal stress for front fork dropouts, and not a lot of dropout material in that direction.

Definitely alloy front forks, even the fork crown is alloy. The inner tubes are steel, the outer tubes are alloy.

Motor wheel is ready, will pick it up soon. No shipping this way, but I'll have to drive into SF.

Have not ordered steel forks yet, probably won't get to it till next month.

Have most of the parts for the electronics, need to design a circuit board perhaps.

Ordered a few Multistar 6S16AH packs, so re-doing this battery pack will be part of the update. Take it from 18S 10AH to 16AH.

Have been reviewing simulations, looks like this motor combo will climb 15% without overheating. It will do 20% for awhile before it overheats.

amberwolf said:

I did a little poking around and couldn't find the thread about the bike, d8veh; which one is it?

I'm just curious, because you don't specify what "powerful" means.

My CrazyBike2 is 40A 12FET controllers front and rear, "48V" battery, for at least 1500W-2000W each wheel (I don't know the Nm torque values), and it's also really heavy (around 340-350lbs with me on it) so it pulls hard on the fork during acceleration (and pushes hard on it during braking) whether I'm using 2WD or just FWD, and I don't see the skipping you've had, either. I pretty much always use full throttle, instant start controllers, so full current from zero to 20MPH which is the AZ speed limit.

Even just using box wrenches for torque arms on each side I'm not having issues with axle rotation, so I'm curious what torque arms you're using that still let the axle rock enough to break the dropouts?


I know that it *can* be a problem, as I broke the dropouts on a Manitou Skareb fork just with a bike upside down for testing, with no axle nuts at all or torque arms, using the X5304, just spinning up the wheel on a little tiny 20A controller testing out the used kit it came from. But...that was with no axle nuts. And later I spun that same motor ina 20" wheel right out of thin steel "funky" dropouts on the rear of the SB Cruiser trike, even with a box wrench torque arm on the outside, but it is also a monster of a motor and those dropouts were not normal, plus I was using EABS "active" braking and hard acceleration, over and over, *trying* to break things.


When I first installed the 9C 280x 26" on the Suntour alloy fork on CB2, I did worry a lot about it breaking something, since I do use regen and hard acceleration, at least a dozen times each way on my daily commute, but with no signs of issues I stopped worrying about it a while ago, and actually just plain forgot I was ever going to try to custom make torque plates for the fork.


So that's why I'm curious on the situation that let or caused yours to break, so I can be sure to avoid it on mine (as I don't really have the option of a steel fork that will do good enough suspension on mine; teh alloy one barely does what is needed and I couldn't afford to buy anything else to do the job--not having suspension at least in front isn't an option and I frequently wish I had it in back too).

If yours is torquier than mine I won't worry about improving mine, but if yours is less so, then I might need to look at making those torque plates anyway.

Click to expand...

The front motor was a BPM at 64v (16s) and 30A. The rear motor was the same, plus it had a middle motor at 48v and 22A, so about 5kw total and 2kw in the front.

I've built a few bikes with a BPM motor at 36v and 30A with a single torque arm. They never broke. On a 2WD, the front wheel gets unloaded by the torque from the back one, which makes it spin up to maximum, then it hits the road and gets a massive impact as it's immediately slowed to bike speed. That happens about four or five times every time you accelerate away from a stop. The front forks sort of bounce. Maybe it it would be better with better damped ones, but I wouldn't want to risk my money.

If you zoom in to this picture, you can see the torque arm anchored to the disc caliper mounting. On the other side, there was no anchor point, so I had to use a jubilee clip around the fork:

A triple motored 2WD ebike. Gives you lots of options. Cool.

d8veh said:

On a 2WD, the front wheel gets unloaded by the torque from the back one, which makes it spin up to maximum, then it hits the road and gets a massive impact as it's immediately slowed to bike speed. That happens about four or five times every time you accelerate away from a stop. The front forks sort of bounce.

Click to expand...

Ah...on mine that doesnt' happen, probably because of the length and weight distribution of the bike. There's no way to do a wheelie even slightly on CrazyBike2.

(maybe if I had the trailer on it, improperly loaded so ti forced the tongue/hitchpoint down, but that would take a lot).

I suppose I can see where the problem could arise on a regular bike, though.

Managing the speed of the front vs rear wheels is something I'll be looking into. Protecting the clutches, gears and dropouts from mechanical shocks is important for long term reliability. I would suggest reducing the phase current maximum of the rear motor enough to avoid lifting the front end when using the front motor. Dividing the traction between the front/rear to make the system perform better.

I picked up the gearmotor front wheel from Ilia today (ebikesSF.com). This "high torque" model has dual parallel phase wires, and a Kv similar to the DD rear 9C on this bike. Outer flange diameter is about 185mm so much smaller than the 203mm disc brake. "That's a generator to charge my battery, of course".



The 6S 16AH Multistars arrived a few days ago as well. 8)

As discussed earlier I had decided to go with a CroMoly steel front fork instead of the existing alloy suspension forks. Since the hubmotor and wheel have arrived, it is time to start moving this project ahead, and the fork is the next big component.

After a bit of measurement and further analysis it appears that the Surly 1x1 fork initially selected for this project is not a good fit in terms of the axle to crown length compared to the stock forks on this bike. A winch type cargo strap was used to compress the front fork fully so measurements could be made of the axle to crown distance in both relaxed and fully compressed situations, and this was compared with the specifications for the 1x1 fork. The front would have been much taller than the stock forks and this would change the bike's geometry which is not desirable. So a further search of available forks was made. It was found that the Surly Big Dummy forks were a much better fit. These heavy duty CroMoly steel forks have a crown to axle length within the range of the existing suspension forks, so it will have the same geometry as it would if the suspension was partially compressed, which is the normal situation. Fortunately this was determined before the forks were ordered and a potentially difficult and expensive return was avoided.

The one dimension that may need to be adjusted on the Surly Big Dummy forks is the dropout slot width which is not stated in the Surly documentation but is quoted as 9mm in one online vendor's data. The BMC motor was measured at 10.0mm on the axle flats. Additionally the steerer tube is longer than required, but this is a normal situation, and will require cutting to the proper length.

So if the dropouts are 9mm some filing will be required to provide an extra mm of width for the axle to fit in. Hopefully that isn't the case, but it is a CroMoly steel fork so it should be okay.

I also ordered two stainless steel torque arms and C washers as I don't what this fork to fail!

I have some Nordlock washers that I plan to use as well. A new star nut will be employed and the headset bearings will be re-used unless they are found to be damaged or inadequate when they are removed and inspected.

Anybody with a Surly Big Dummy? I'd like to know the slot width on the front fork dropouts??

The Surly Big Dummy forks arrived, and they appear to meet all the requirements. The dropouts measure 9.8mm due to powdercoat, and the width is 100mm. so a little file work should take care of fitting the dropouts.

This All Wheel Drive Mountain Bike project has been somewhat delayed by a number of events. I have the front geared hubmotor and steel forks in hand, and of course the rear wheel driven bike was operable before. It is waiting for a project restart.

In the meantime I built up a lightweight mid drive that in some ways overlaps this project. In any case it is up and running and was a very easy project.

The Diamondback Ridge Runner



More on this project here: https://endless-sphere.com/forums/viewtopic.php?f=28&t=78722