"peak power" - Trek 4300 20" Magic Pie build.

neptronix

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What's up yall..
Just got the 20" magic pie wheel in... as recommended by Luke and a few others in the pike's peak race thread.

magic-pie.jpg


Holy crap, that rim is no joke. Put a 2.3" tire on it and the tire looks narrow on this rim. Very happy about this - Golden Motor hit the nail on the head when they designed this rim!!!

magic-pie2.jpg


Diameter is about 11in, versus the MXUS / 9C diameter is about 9.5in.
Width is roughly the same.

This thing is and effing monster and takes off like a scalded cat even at 57v( 15S ) / 33a on the stock phase wires with a saggy 5AH of 20C lipo. Almost threw me and a local friend ( Tom Tom on ES ) off the bike when we would hit the throttle too sharply.

This is faster to accelerate on 1800w than my MXUS motor on 4000w.
It's as about as fast to accelerate as my MAC on 4000w, which was in a word, kind of terrifying.

However, she only goes about 20-25mph on 57v nominal, so i think 72v is going to be the minimum required.

More concrete data later on.. but so far... this motor is looking real good.
 
The rim is basically a giant chunk of aluminum bolted to where the spokes would normally attach.
It's more like a car or scooter rim than a bike rim, and if it breaks or is warped, you're basically screwed.

I don't worry about that too much though, it's tough as hell, looks tougher than any spoked bike rim! A 2in. wide tire is the minimum that you could ever fit on this rim, so a big fluffy tire should prevent any serious aluminum fatigue, unless they are using some real junk for aluminum.

I love the rim, i see how it could essentially act as a big heatsink for the motor.
Those shiny 'petals' you see on the case of the hub motor are also extruded a little.

This seems to be a hell of a sleeper motor. I'm surprised that these aren't more commonly used! i'll do more testing tomorrow..
 
Subscribed. Want to see what kind of sustainable power this motor can take, and at what speeds it will do continuously before overheating.
 
I'm looking forward to the Pikes Peak test!!!

Are you going to leave the 26" wheel on the front ? Can't wait for pics.

people really underestimate how good the pie actually is.

True you do have to put voltage into it, sometimes I think a faster wind would be nice, it would still have plenty of torque!

Don't drill the covers yet, see how you get on maybe!

In the 26" wheel my speed on the steepest part of the mountain 16% was about 13 mph on 16S LiPo, bogging down generated a lot of heat. I forget the controller settings, but it was pulling 3500 watts, so from what I've learned here the 20" will have better torque and might actually get up faster?

It will be interesting to find out how you get on with different voltages, but I think I'm learning that more voltage is better than more current.
 
Thanks for your kind words folks :)

OK, so i took the bike out today on 72V / 56A finally..

[youtube]omkOKLWosjc[/youtube]

[youtube]9ifc_YLJCMM[/youtube]

It's really hard to show how fast this motor is on video. You really have to ease into the throttle or it'll throw you backwards.
I will get more video later on, with a spedometer and all that stuffs. :)

After a few runs around the block, the motor had not even warmed up. I couldn't tell if it was any hotter than the outside air. Couldn't believe it. The MAC and MXUS would have been really hot after that.

I do agree with scorpion... this is a very unappreciated motor, and i'm surprised it hasn't got more air time here on ES. 4000w and it feels like it can take more speed :shock:
 
Looks real nice. :mrgreen:
Might have to snap one of these up before MPIII take over.
What kinda speed you lookin at in the video? 30mph?
What controller?

I want an honest 40mph/64kph on a 20" rear.
What do you think about 24s LiPo, 40mph?
A Hx3540 in a 20" shows over 40mph @88v40amp
Guessing the pie is a bit slower.
Maybe H.V. Lyen controller and try 30s or 36s. :twisted:
I love the thought of not having to deal with spokes/alignment.

Keep us posted.
 
Damn thanks for sharing that is a pretty sweet looking ride. Can I ask where and how much ?

When looking into the magic pie motors it was hard to figure out a US distributor with a website
that was not a pita to navigate. So I think that may be one reason.

I also made a mental note on Justin's last video where he stated when testing different motor types the magic pie
was to similar to the 9c and the reason he did not carry it. I could have heard that wrong and I also admit at normal
voltage 36/48 that would probably be true , but I can easily see how the motor could more easily shed heat.
 
Hello,

Do you know what would be the bike efficiency at 25-30 mph? 4000W is a lot. Your lipo pack should be depleted in 10 minutes :lol:

What would be the bike speed at 72V 10AH? (or 96V10AH) I was thinking about getting NiCoMn battery but to keep them alive I have to only use around 1C.
 
Looks pretty quick but your missing a few parts yet? I know you just gotta make a test run as soon as it's even remotely possible. I did the same but almost hit some unsuspecting police ociffer cuz of it. Have fun and be safe.
 
Alan B: To be honest, i have not. Just really impressed with the acceleration per watt. I wish i had more motors to test.

Brentis: I'd recommend it if you've got the high voltage this motor wants :)
I'm not sure about the speed, i tried to get a spedometer today but the bike shops out here were closed. Feels like low 30mph figures. I think 40mph would require about 26S but that's just a guess..
I used a 12FET set to about 56A, and 5AH of 20C lipo ( was probably getting 10V of sag )

30S would be a good voltage to get this baby up to low/mid 40mph figures, but we'll see.. maybe it will saturate or bump up against another limit. I need a HV controller too.. my limit is 100V :(

cwah: No idea yet. A cycle analyst will be on order soon since i can't use my turnigy watt meter over 60v..

biohaz: Yup.. you're looking at what i just threw together in a few hours cuz i couldn't wait.. i think i'm going to keep the pedals off, but it definitely needs a rear brake or at least a strong regen.. :lol:
 
Maybe time to trade in my old 20" brushed motor

does it come with a 6 speed cassette ? what is the tooth count on the small sprocket ?
 

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neptronix said:
What's up yall..
Just got the 20" magic pie wheel in... as recommended by Luke and a few others in the pike's peak race thread.

Link to thread ??
 
:?:
jmygann said:
neptronix said:
What's up yall..
Just got the 20" magic pie wheel in... as recommended by Luke and a few others in the pike's peak race thread.

Link to thread ??



:arrow: http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=31490&hilit=pikes+peak+magicpie&start=165#p466034




:?:
iovaykind said:
Want to see what kind of sustainable power this motor can take, and at what speeds it will do continuously before overheating.

:arrow:
Alan B said:
Very nice, thanks to Justin et al.

So the Magic Pie has no advantage over the 9C on the dyno. Interesting.
 
I think the 9c would be a faster wind but wouldn't have nearly the torque of the Pie, and would probably burn up with the same power a lot faster!

That's looking good Dave, 23S LiPo might get you to 40 with 120% setting maybe more!

That's a lot of voltage and will mean more watts, it's 87.4 volts nominal x 10 ah will be 874 watt hrs. That's twice what a 12 s 10ah pack would be, could you fit that in the bag? That will give you a range of about 12-15 miles, that's not bad for some serious fun, then just back off the throttle and you will easily get 25-30 miles!

I can't wait for batteries with 2-3x capacity, it would change things for sure!

By the way were the pedals hitting the ground?
 
I think the diameter of the motor really helps it along. 11 inches versus about 9 inches for the MXUS / 9C style hub.. i'm told that this leads to an advantage in torque.

I could fit 8x 6S packs into the bag just fine, that would give me 24S / 10AH just fine..

The crankset i had on it previously ( 165mm ) have about 2-3 inches of ground clearance now, which is a problem waiting to happen.. currently

This build is still coming along for sure, needs regen enabled, a cycle analyst, probably a high voltage capable 18FET, regen enabled + a back brake, handle bars need to be dropped lower for good aero/wheelie prevention.. proper camera mount.. front suspension.. the list goes on..

Expect my other build thread 'Trek 4300 MAC' to be crickets for a while... :)
 
Neptronix,

The pie should be 20% stronger than a 9c in the same wheel at the same watts. But you are using a wheel that 30% smaller thats why the pie looks so strong.
I dont have a pie but I do have a MXSUS and a MAC and at 3kw the MXSUS is still gutless but the MAC is very strong.
 
Oh dude.. this thing is slower than i thought.. it sure feels fast.. but yeah.. it's not :(
Charged the lipos up to 3.8v/cell exactly.. just to get a nice median speed..

Top speed on 10S: 15mph, 18mph on 120% setting.

Top speed on 20S: 27mph, 32mph on 120% setting.

A fully charged 10AH will get me a few more mph.. 76v versus a fully charged 84v makes a difference. 5AH introduces some sag too..

A cycle analyst will be on order so i can measure my amps. Currently, all i've got is a turnigy watt meter. I will get back to you guys on those numbers.

I think an 18FET controller with 4115's, plus 30S will get me into the speed level i need for basically hitting top speeds that will be good on the streets ( ~35mph ).

Or maybe i just need to ditch it, empty my savings, and get the cromotor or something equally crazy :)
 
so .... what hub motor would be preferable ?
 
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