AWD fatbike (first build, first draft..)

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AWD fatbike (first build, first draft..)

Postby sgds23 » Mon Oct 15, 2012 2:50 pm

About two minutes after buying an a2b ebike, I decided to try building my own. That was seven weeks ago, and I am finally at a point where I have something that rolls. (I started with very close to zero bike knowledge, resulting in all sorts of time wasted and erroneous purchases , confusing bb spindles with bb shells, etc.)

The picture below overstates my progress a bit. Brakes still need to be aligned, battery needs to be mounted in the frame somehow, everything needs to be wired together, etc..
But.. it finally is looking like a bike.

fullview.jpg
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front.jpg
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I should explain what I'm hoping to end up with. First, a bike for getting around downtown san francisco, often at night. (Hence the heated grips, shown.) Performance matters more to me than range, but ideal stats would be a 40mph top speed and 10 mile range. (My sense is those are achievable, but stretch goals.)

But I'm also very interested in messing around with "bike++" -- new abilities enabled by motors and sensors. Hence, the dual motor setup. I'd like to play with the bike equivalent of torque vectoring (when you detect a person wants to turn, shift the power to the front motor), launch control, electronic stability, etc.

Of course, for now I'm starting much smaller. I'm hacking ultegra di2 so I can have automated shifting. And I just started exploring the Recon mod live heads up display sdk for my bike hmi.



S.
(Oh, and credit where it's due: Ilia built the wheels. Mike helped with all the bike wrenching. Stupid shit, courtesy of me.)
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Re: AWD fatbike (first build, first draft..)

Postby johnrobholmes » Mon Oct 15, 2012 4:37 pm

What frame, what fork? Do the forks have alloy dropouts"?
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Re: AWD fatbike (first build, first draft..)

Postby Trackman417 » Mon Oct 15, 2012 5:36 pm

If you are still looking for a solution for putting the battery's in the frame, get the falcon EV frame bag. Greatest thing in te world :mrgreen: . Look up falconev.com . Send the guy an email and your set.
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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Mon Oct 15, 2012 6:58 pm

Oh, right. Lesse:

- 9:zero:7 titanium frame (170mm rear drop)
- carver carbon fiber fork (130mm)
- bmc v2t in front, crystalyte x5403 in back. Two 40amp infineon controllers.
- shimano xtr hydraulic brakes (w/ 180mm avid rotors)
- surley cranks
- weinmann 65mm rims, black floyd 120tpi tires. Two tubes in each wheel for failover protection.
- platform 1 pedals, controltech crossbow carbon handlebar, ergon seat, thudbuster, etc...


I'll have to take a look to see if fork has alloy reinforced dropouts. Sounds like I'm SOL if not... Do I surmise correctly?

S
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Re: AWD fatbike (first build, first draft..)

Postby Whiplash » Mon Oct 15, 2012 9:21 pm

It just means you will have to fabricate torque arms to keep from spinning the axle shaft and destroying the forks, possibly motor and YOU if it locksup or falls off at speed!
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Re: AWD fatbike (first build, first draft..)

Postby kudos » Tue Oct 16, 2012 2:34 am

Hey nice build, just a little bit different.

Are you using the AME Heated grips?

Also what size and type of battery you planning on using ?

So many questions! but did you lace those motors into the rims yourself? I really wish I could do this, it would save me a lot of tme money and hassle sending rims away to get laced.


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Build 1A Gary Fisher Wahoo Hardtail : Crystalyte HS3540 40A 49V : 31mph
Build 1B Gary Fisher Wahoo Hardtail : Mac 10T 30A 49V : 27mph
Build 1C Gary Fisher Wahoo Hardtail : Crystalyte HS3540 40A 82V :
Build 2 Mountain Cycle Fury FS : Mac 8T 40A 57V : in progress
Build 3 GT LTS FS : Mac 8T 40A 49V
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Re: AWD fatbike (first build, first draft..)

Postby Alan B » Tue Oct 16, 2012 5:55 am

I like the concept of an AWD fat tire bike.

What motors are you running front and rear?

Regen would be good for those SF hills!
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Re: AWD fatbike (first build, first draft..)

Postby kudos » Tue Oct 16, 2012 6:09 am

sgds23 wrote:Oh, right. Lesse:

- bmc v2t in front, crystalyte x5403 in back. Two 40amp infineon controllers.

S
Build 1A Gary Fisher Wahoo Hardtail : Crystalyte HS3540 40A 49V : 31mph
Build 1B Gary Fisher Wahoo Hardtail : Mac 10T 30A 49V : 27mph
Build 1C Gary Fisher Wahoo Hardtail : Crystalyte HS3540 40A 82V :
Build 2 Mountain Cycle Fury FS : Mac 8T 40A 57V : in progress
Build 3 GT LTS FS : Mac 8T 40A 49V
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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Tue Oct 16, 2012 1:50 pm

Yep, I have the AME heated grips-- they seem to work well, esecially with the CF handlebars.

And I actually do have one of those FalconEV frame bags, but it doesn't really fit (my frame is a "small") and I don't love its optics.

BUT... I also have a 48v 11ah battery that is meant to be mounted where the bottle cage goes. It's a tight fit, but...a fit.
I just don't understand how people actually mount them. The battery comes with a bar that it slides and locks onto. But to
physically slide the battery onto this mount would require _way_ more room than I have. I can imagine various schemes that could work (clamps that rotate, a keyhold based system) but all require significant fabrication. Has anyone seen an off-the-shelf solution?


thanks,
s.
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Re: AWD fatbike (first build, first draft..)

Postby waynebergman » Wed Oct 17, 2012 9:00 pm

Screen Shot 2012-10-17 at 6.45.48 PM.jpg
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Nice project. I love the fat tire concept. One advantage with no suspension up front on your bike is you could mount your 11ah 48v packs on the underside of the down tube (an not worry about the tire hitting the pack under suspension compression) and maybe do a double decker with a second pack on the upper side of the down tube. I include a photo of my bike in case you are referring to the samsung packs that are the same as mine so you can see how they could sit on the down tube. Looks like your front triangle has lots of room for this kind of placement. Laying them flat like I have will still give clearance with most crank arms I think.

You can maybe get some ideas from my thread on how I mounted my batteries and just clean up the design a bit. I was in a bit of a hurry to get my bike up and going so the design end of the battery mounts are a bit home made looking but they have help up really well with lots of off road abuse.

If I were you I would keep the batteries on either side of the down tube especially as you have no front suspension issues to design around and then you have got the weight about as low as you can go with that frame.

Good luck.
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Re: AWD fatbike (first build, first draft..)

Postby John in CR » Wed Oct 17, 2012 9:13 pm

Really nice looking ebike. Unless you have some real need for 2wd the 5403 is plenty of motor if you feed it properly. It doesn't need a helper motor, and with the torque it can produce there won't be enough weight for the front motor to do any good. The extra weight in front to help try to hold it down is the single benefit of the front motor. With that big heavy motor in back you'll find yourself often picking up only the front end and pivoting on the rear tire to turn the bike around in a small space, and the extra weight in the front wheel is a detriment to that.
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Re: AWD fatbike (first build, first draft..)

Postby cal3thousand » Thu Oct 18, 2012 2:11 pm

I want to know how you fair on sand. Mind making a video? :mrgreen:
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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Thu Oct 18, 2012 5:23 pm

That is a good point about the weight of the back wheel forcing you to pivot the bike, thereby making extra weight up front even less desirable. But I'm not sure I understand what you mean by, "...with the torque it can produce there won't be enough weight for the front motor to do any good"?

My reasoning was partly the redundancy (I've spent enough time in power boats to really like having a second motor), but mostly I wanted the ability to do torque vectoring / electronic stability contol / launch control type stuff.

For example... My plan is for a single throttle to go to an Arduino board in the back box. I can then implement logic to apportion power to the dual motors apporpriately, as determined by the motors different efficiency curves as well as sensor inputs. So if the handlebar torque sensor signals intent-to-turn, the Arduino will give more throttle to the front motor and less to the rear, to help pull the bike though the turn.

Is the objection that this simply won't work?

s.
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Re: AWD fatbike (first build, first draft..)

Postby John in CR » Sat Oct 20, 2012 1:21 am

There are definitely some advantages with a real 2wd that hubmotors make so easy. My point is that you have so much motor in that rear wheel that if you make real use of it the front will be so unweighted that it will have little traction. If you run the big X5403 at such low power that the front motor is useful, then you could run much less motor in that rear wheel and save 15 pounds or more.

That said, the motor control you're planning sounds really cool, so please be sure to share all the details as you progress.

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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Mon Oct 22, 2012 2:12 pm

Yeah, I've come to the same conclusion: the rear motor is just too damn big. What makes this partiularly galling is that I originally intended to use a HS3540.. But then was seduced by the brute force of the x5403. Sigh... next version! So with the benefit of hindsight, what motor would you recommend? I'm having a tough time finding definitive information distinguishing the HS35xx series, the 4xxx/G series, and the 530x phoenix series... not to mention Falco, 9C, etc.

Thanks!
s.
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Re: AWD fatbike (first build, first draft..)

Postby Drunkskunk » Mon Oct 22, 2012 3:28 pm

Looks Great. I've got Fat bike I'm building up with a 5404 as well. Mine's a full suspension, but a single motor.

Your speed sensing idea sounds interesting. But having the front motor automaticly getting more power when you turn could be a disaster. Imagine you're making a turn on a gravel covered road with the wheel near the limit of traction, then having the wheel get more power.

What about sensing the wheel speed off one of those tone sensors used on ABS tonal sensor. you could sense off the brake disk and let the Arduno split the torque based on RPM, but cut power if it sensed a wheel slip(sudden wheel rpm change). The front wheel actualy travels further in a turn than the rear, so you could add a speed factor so you get more front power at low speeds in tight turns, but a balanced 50/50 split at higher speeds
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Re: AWD fatbike (first build, first draft..)

Postby johnrobholmes » Mon Oct 22, 2012 3:41 pm

9c is a great choice for value and weight.
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Re: AWD fatbike (first build, first draft..)

Postby grindz145 » Mon Oct 22, 2012 5:06 pm

looks absolutely awesome. I love the heated grips. You've made choices that tell me that you really ride your bike :)
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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Fri Mar 15, 2013 11:55 pm

I'm not exactly sure why it took me so freaking long to get my (aggressively simplistic) bike back on the road... but the 37 redesigns probably had something to do with it.

overall.jpg
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First, I replaced the x5304 motor in the back – it was just too damn heavy – with an HS3540.

Then I went from using a Crystalyte and Grin controller .. to two LYEN controllers … to one Roboteq HBL2350. This was a big win because it allowed me to get rid of the Nanuk case on the rear rack (the Roboteq also obviated my two Cycle Analysts) and all the shakes and rattles that went with that.

Continuing, I replaced my Allcell 48v battery with a Batteryspace 50V 11ah – LiNiMnCo, but only 9 lbs, and most importantly, discharging 40 Amps.

Finally, I replaced the throttle with an OEM thumb throttle intended for ATVs. It’s a mechanical throttle so I glued a linear position sensor (by BI) into the case and wired that up to the controller.

throttle2.jpg
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I’ve got the most basic software working, apportioning power to the front and rear motor depending on current and desired speed. Now I get to actually ride the thing this weekend, so look for a report on the bike’s top speed soon..

s.

overall2.jpg
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throttleDet.jpg
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Re: AWD fatbike (first build, first draft..)

Postby Chalo » Sat Mar 16, 2013 1:44 am

That's a very cool build. Take care to securely anchor the axle in that plastic fork. It's the only thing about your bike that makes me wince.

Where did you get an HS3540 hub with a 170mm axle?

Please report back with your findings about those Black Floyd tires. Word on the street is that their turn-in qualities are highly dependent on pressure. I would hope that they are well-behaved and relatively free-rolling at very low pressures, because otherwise why bother? I would like to hear that they work great, because I'm scheming about building a bike around them.
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Re: AWD fatbike (first build, first draft..)

Postby Toorbough ULL-Zeveigh » Thu Jun 13, 2013 7:27 am

sgds23 wrote:I’ve got the most basic software working, apportioning power to the front and rear motor depending on current and desired speed. Now I get to actually ride the thing this weekend, so look for a report on the bike’s top speed soon..

s.


as he drove off into SF Bay.
never... to be seen... or heard from ever again.

let this be a lesson to you kiddies out there.
don't be lazy & only get 'most' of the basic software working.
if your gonna hang your butt on the line, you wanna buletproof all the damn bugs outta there.
and/or get someone else to be your test pilot.


c'mon man, awd is where the simplicity of hub motors can press their advantage.
were you ever able to work out the torque split to slip angle ratio?
software is the only missing component, the revolution needs you.
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the optimist engineer sees that the glass has a 100% safety tolerance.
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Re: AWD fatbike (first build, first draft..)

Postby sgds23 » Tue Jun 18, 2013 5:28 pm

Heh.. I certainly don't want to let the "revolution" down, but I have to admit that getting my bike working had the counter-intuiive affect of making me less bullish about e-bikes.

And not because my bike sucks-- it's actually pretty tight. Super-responsive (thanks to custom throttle code), reasonably fast (37mph even in its current amp starved state), and handles like a real bike (shockingly, not a single rattle!).

And yet.. Lipo just doesn't have the power density of gas, and even with my inherent bias to all things electronic, its hard not to notice that in terms of performance, that ducatti wipes my bike like I'm walking.

Obviously, the thing to do is change the basis of comparison. But I have yet to hear any really compelling advantage -- something my bike can do (yes, besides save the planet) that a motorcycle can't.

Err, sorry for drifting off topic..

S.
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Re: AWD fatbike (first build, first draft..)

Postby Anthony King » Tue Jul 02, 2013 9:46 pm

I am considering putting a hub motor on my cargo bike, which has a fatbike front wheel. To get to town I am mostly on an old railbed trail and the fat front tire makes the ride much smoother.

I have questions about the wheel builds for any one who has tried this. I know Weinmann makes some double-wall fatbike rims, but the single wall Surly rims aren't exactly flimsy. You can get the Rolling Daryl without cutouts. I can't imagine a >1000g rim being "too light" for anything, but I've never put a motor in a wheel.

Thanks,
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Last edited by Anthony King on Thu Jul 04, 2013 6:21 am, edited 1 time in total. View post history.
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Re: AWD fatbike (first build, first draft..)

Postby Ykick » Wed Jul 03, 2013 12:15 am

sgds23 wrote:Heh.. I certainly don't want to let the "revolution" down, but I have to admit that getting my bike working had the counter-intuiive affect of making me less bullish about e-bikes.

And not because my bike sucks-- it's actually pretty tight. Super-responsive (thanks to custom throttle code), reasonably fast (37mph even in its current amp starved state), and handles like a real bike (shockingly, not a single rattle!).

And yet.. Lipo just doesn't have the power density of gas, and even with my inherent bias to all things electronic, its hard not to notice that in terms of performance, that ducatti wipes my bike like I'm walking.

Obviously, the thing to do is change the basis of comparison. But I have yet to hear any really compelling advantage -- something my bike can do (yes, besides save the planet) that a motorcycle can't.

Err, sorry for drifting off topic..

S.


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Re: AWD fatbike (first build, first draft..)

Postby Chalo » Wed Jul 03, 2013 12:15 pm

Anthony King wrote:I know Weinmann makes some double-wall fatbike rims, but the single wall Surly rims aren't exactly flimsy. You can get the Rolling Daryl without cutouts. I can't imagine a >1000g rim being "too light" for anything, but I've never put a motor in a wheel.


The double-walled Weinmann rims will be stronger (which as you point out is probably irrelevant) and better able to withstand high tire pressure should you ever want high tire pressure, but they also cost less than half what the Surly rims do. Given that hub motors are already heavy items, I'd take the heavier but stronger rim at a much lower price every time for that job.

If you do use a Surly rim with side-by-side spoke holes, consider lacing to the opposite side of the rim to increase bracing angle. Hub motor flanges are usually pretty narrow, and lacing to the same-side holes of a rim like that would leave you with minimal lateral bracing.
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