Yamaha Y-01W AWD & Y-00Z MTB

[PedalUma]

It is not my thing but I can imagine it as being fun for studded tire Winter rides, maybe pulling a snowboarder. I just worked on a 150-pound two-wheel drive bike this morning. Again, not for me but the owner loves it.

 

[Catalyzt]

Something I pointed out in the comments of the Electrek article that talked about these bikes is the awd bike in the pictures is non functional. The motor has no cable coming out of it and its not fed from inside the fork.

2wd on an ebike is an enormous benefit, but its not the sort of thing you'll be able to grasp/understand without riding one. All the stuff about increased weight and the ability to do the same job with a more powerful rear motor melt away when you get out and ride one. Speaking of which, before some silly motorbike comments spring from certain lips, these bikes have throttles, but are effectively pure pedelecs. 2wd pedal assist providing distributed traction is a thing of beauty that has to be experienced to be appreciated.

The key to understanding 2wd ebikes is to get the increased power out of your head. 2wd doesn't really increase speed much at all. What it does do is distribute traction and torque. And shared traction between two motors transforms the bike enormously, letting it go places no bicycle ever could.

One of the first misconceptions that commonly pop up is the contention that there is insufficient traction on the front wheel to prevent it from spinning out or becoming unsafe. That concern disappears quickly when you ride one and see it doesn't happen.

Plus the ideal power load on the front wheel - to give you the benefits of front wheel traction without the negatives - is rather low. Furthermore, running two motors together versus just one decreases the heat generated by not a factor of two, but a factor of four. A motor that gets too hot to touch working singly becomes only barely warm when working as a pair. Also, on a 2wd mid+hub config, the front motor keeps the mid drive from having to grunt the bike up from a dead stop on its own, which in practice totally eliminates all of the wear-and-tear penalties of using a powerful mid drive.

There's more.

Dual Motor AWD Electric Bikes (the good and bad)

I like to build top-quality-component ebikes from the frame up. Quite a few of them are dual motor or AWD or 2WD or whatever you want to call them. Why would you build an AWD ebike?

talesontwowheels.com

This one is my sand crawler, dedicated to recreation. But my last two cargo bikes are mid+hub as well and rely on the low-front-power, distributed traction thinking.

View attachment 165591

Very interesting, Mr. R. What I would add briefly: There are only a few things I miss about the Trek kit bike (with a Clean Republic 35-50nm front hub throttle drive)

1) It's maybe two pounds lighter than the Marin build (and seven lighter than the Motobecane)
2) Front wheel drive is amazing on hairpins on a lightweight bike. There are some situations where the Trek's handling was just ridiculous-- you'd lean into an decreasing uphill hairpin at half throttle and-- like on a front wheel drive car-- nudge the throttle to 3/4 or full at the end of the turn without slowing down, lean the bike way the hell over, and the front wheel drive just pulls you right through.

My hunch is that #2 only works with #1 -- a bike that's 40 pounds or less + a small motor that adds just enough weight to the front wheel, no more.

Someday? I think I am going to restore the Trek kit bike, get a new controller for the motor. The range is only 15 miles, and I think it probably eats up the service life of batteries more quickly than most, but if my goal was to get across the eastern Hollywood hills as fast as humanly possible, and I didn't care about getting rattled to death on a bike with only stem and seatpost suspension, I think the old Trek / Clean Republic front hub drive would win.

 

[m@Robertson]

My hunch is that #2 only works with #1 -- a bike that's 40 pounds or less + a small motor that adds just enough weight to the front wheel, no more.

I don't do corners quite like that but even on heavy bikes, its a big help.

If doing it on throttle (only for something like a 90-degree street intersection right turn):

1. Cut the power to both wheels as you approach the corner. Usually this means stop pedaling and raise the pedal on the side of the corner to the top so you don't scrape it in the turn.
2. At corner entrance, nail the rear throttle. It will take a second for power to come on so it won't actually power the rear wheel until you are past the turn apex and beginning the corner exit.
3. Heel the bike hard over and make the apex. At this point you are still unpowered.
4. At corner apex, you already have the rear throttle engaged and its in its short lag period before power begins. Now engage the front throttle. There will be a lag that delays power delivery to when you have just completed the corner.

If you maintain front wheel power during the corner turn, you will elongate your turn radius right into the center of the road you are turning into. Maybe so much so you'll strike the center divider after executing the turn. Protecting against this will become second nature after about 2 or three turns on your first ride.

If riding as a cyclist (this is how I usually do it)

1. As you approach the corner, stop pedaling. Put your turn-side pedal up high so it doesn't scrape.
2. Heel the bike hard over and make the apex.
3. As you straighten the bike back up, start pedaling as soon as you have no worries about a pedal strike on the ground

The only thing you are changing while pedaling - vs a normal ebike - is... well, nothing I think. Your interruption in pedaling is just there to keep from scraping your pedal on the ground as you lean in the turn.

For a left turn in an intersection, I am in the road in the car lane, with other cars in front of me and to my side in the case of 2-lane turn lanes. I use throttle here exclusively to start off because I am directly intermingling with cars and I need to get out of their lane asap. If I am at the front and cars are behind me, I nail both throttles until I am able to rejoin the bike lane. This lets me accelerate faster than a car does in a turn lane and keeps me safe from angry drivers held up by a slow cyclist.

If there is a car ahead of me, I first hit only the rear throttle to keep myself from hitting the car in front of me (2wd accelerates fast, even if I have dialed back the front wheel power, which I do). About midway thru the turn arc I can add power to the front wheel to keep up with traffic until I can get to the bike lane and resume pedaling.

 

[m@Robertson]

BTW looking at the Yamaha implementation, I am pretty sure they are using a direct drive hub in front. Bear in mind the characteristics of DD hubs: Slow to lay in power, no moving parts to wear out and lower torque levels. That is ideal for any 2wd platform, both on the street and trail. I found in singletrack the ideal power level was about 250w. Just enough to grab and pull some, but not so much you waste battery power, nor so much you break traction, and if you hit a root and pop the front wheel up, it'll often come down in another direction. 250w is not enough to affect control when you land the wheel..

My cargo bikes use 45 Nm geared hub motors set to slowly ramp their acceleration curve. Similar result to what you would get naturally with a DD, which I can't use because of my small front wheel size.

 

[PDoz]

I'm surprised at such high torque figures on the front?

I'm asking because riders of the 2x2 motorbikes seemed to prefer front torque at 15-25 % of rear - and that's on bikes with ergonomics designed to allow riders to get weight ( traction) forward ! I'm left wondering if we missed an opportunity to explore 2x2 potential by staying with conventional looking bikes.

 

[m@Robertson]

I'm surprised at such high torque figures on the front?

I'm asking because riders of the 2x2 motorbikes seemed to prefer front torque at 15-25 % of rear - and that's on bikes with ergonomics designed to allow riders to get weight ( traction) forward ! I'm left wondering if we missed an opportunity to explore 2x2 potential by staying with conventional looking bikes.

Well my 'sand crawler' pictured earlier, and my original commuter bike not pictured (has about 7000 miles on it) both have 35a front wheel controllers and 80Nm motors, backed up by a nice big 52v pack with a BMS big enough to feed both motors at once.

The key to performance with these higher torque motors is simply to set them to slow-start - a feature KT hub motor controllers have. This makes all the controller amps available to the motor (there is also a way to dial those back, too) but rolls the power on with a shallower curve. This keeps the front wheel from doing a short burnout when you decide to use front wheel throttle and also keeps you safe in case you start pedaling with the front wheel turned sideways.

Front torque on unimproved surfaces (read: trails) at 15-25% sounds about right. Bear in mind I have a BBSHD in back of the sand crawler, so lot is coming out back, especially if I have it up on a big cog. But on pavement, two equally-powered motors (I slow start the back one, too) is freaking great. No issues except lots of fun and it seems the effortless acceleration from the distributed traction is just how a bike should work.

In actual deep beach sand, the sky is the limit on front motor power. You need more, and if you hit a drift you have to climb over, its all axles on deck. Just on flat dry sand, you need the power to the front wheel to keep it from submerging. The rear wheel pushes the bike forward and the front wheel wants to burrow in (but the motor in front keeps the wheel on the surface). On the remote beach I ride, I have never seen a single-motor ebike get more than about 30 yards, and those yards were torture for the bike and rider. Me I can go until the bike runs out of battery, which is extremely bad given how remote the area is. thus I have two 16ah packs parallel'd directly together, and the beach parking lot I arrive at a few miles down has an open power plug at the bathrooms.

Worth noting: Even on slow-start I can out accelerate any single-motor geared hub no matter how aggressive. I'm sure there is an e-moto out there that can beat me but even a quasi-legal ebike? Not happening. And if I turn on the giggle-meter (turn off the slow-start and allow full acceleration to both motors) I'll chirp both tires and leave pretty much anything in the dust. Its fun as a demonstration but not really practical from the standpoint of long term frame stress. Thats why I turned both motors down in fact. Started getting frame creaks after a few thousand miles and thought better of letting that much power hit the bike so hard.

This is the commuter, running 4.8" tubeless Snowshoes.

This is the commuter when I tried 2.35" tires on 80mm rims. Worked great. Rolled smooth forever. Looked stupid. Ride comfort did not exist. Rattled my teeth one time too many and changed them for slick 4.0's after a thousand miles or so.

 

[PDoz]

Thanks for that. I've done many thousands of km sand riding on motorbikes and can understand the 2wd benefits. Too many face plants when the front ploughs / sudden stops as the rear discovers the limits of physics.... I've got a mate who is silly enough to ride long distance remote sand on his human powered fat bike.....insane!

I'm quietly hoping this yamaha 2wd triggers some mainstream mtb companies to start exploring 2x2