Electrifying a Specialized P3

[SamurAchzar]

I have this kickass hardtail Specialized P3 I'm thinking about making electric. It's not for commuting, more for fun and maybe some errands in the city.

What I'm looking for, above all, is "powerful". At the price of sounding like a redneck, I want it to pop a proper wheelie on the e-throttle, and it has to be able to deal with sustained loads (like climbing stairs... redneck ). I'm on the wrong side of 250lbs, so when I'm saying "powerful" and "robust", I mean it.

I'm a hardcore R/C heli guy, so I know my way around HobbyKing and high end R/C ESCs.
Are there any hub motors fit for this task? A hub motor + CC ICE160HV + 12s5p setup could be an easy enough solution, but I don't think hub motors can work with these loads (?).

If I'm going external motor, that involves much more fabrication, and I'm not sure existing MTB drivetrain components would stand up to this task.

I'm not looking for top speeds of over 40MPH, so maybe I can work with low enough gearing to provide me the power without going with a totally crazy power setup. What kind of power should I aim to anyway? 5KW? 10KW?

Your thoughts, gentlemen.

 

[MadRhino]

While I like the idea of building with a P3, I don't believe that a hard tail build is good for the purpose that you want to put it at. Riding the stairs, I do sometimes, and find it hard already on a good full suspension build, with the extra weight of batteries and motor. A few steps up is OK if I attack them fast enough, few steps down I prefer to jump them. Long stair ride is destructive with that kind of weight, unless you can do it either very fast floating, or very slow step by step. I would not like to do it with a hard tail.

 

[SamurAchzar]

I'll jump them no problem This is a bike for hooning around, nothing sensible. I figured a 12S5P setup would be around 7.5kg; motor another 2.5kg; adapters and others account for another 2kg. 12kg (25lbs) is not all that bad in the big picture. The P frame is exceptionally strong, with DH components all around. Pic attached.

I'm also toying with the idea of removing the crank altogether and fitting pegs (maybe from a ski bike conversion kit). I'm aiming for an extremely lightweight e-moto.

 

[AussieJester]

Sounds like you be in the market for one of Recumpence reduction drives and an Astro 3220 fitted to it...As you can see in the video Matt also does dual Astro 3220 setups if you have the coin and are happy to get a lobotomy before riding the bike after its fitted... It sounds like a hub motor wouldnt suit your needs, no matter how powerful, they are heavy and will weight the back end of your bike down I'm just guessing that this is something you would prolly wish to avoid? The rc motor setup, you can mount in the frames triangle or downtube keeping the bike well balanced for your antics LoL... If you go with an RC setup your already on the money with the hv160 thats the best non sensored controller we have found to work with these motors, everything elese has failed (when used on direct drive non friction setups)

All the best...

KiM

 

[SamurAchzar]

Where can I find these units for sale? How much money should I set aside for such a project?

 

[AussieJester]

Where can I find these units for sale? How much money should I set aside for such a project?

PM or email forum member Recumpence for both prices and the units, i give you fair warning that these setups are a lil pricey, with that said, they are also the very best quality. There is sometimes a wait time for these units, this is also Matts hobby not a full time job so bere this in mind. There are dozens of users on this forum that will back Matts work ethic and quality up, if you buy from him you will get quality gear. As too how much to set aside well, how deep are your pockets? If you want a kick ass setup, you will have to pay a bit for it IIRC Astros are upward of 450 dollars a pop HV160's around 300... the reduction drives will actually be some of the cheapest parts for the build aside from a throttle and wiring. There is of course nothing stopping you making your own reduction drives and mounts up, many have. You will need battteires, what i suggest is LiPO... Alot here are using the HobbyCity Zippy and Turnigy 18v and 22V packs 20C upwards...Those with cash are also now dipping into the newer Nano Tech chemistry... I dont need to tell you the dos and donts of lipo seeing your a RC enthusiast (as you will find a lot here are also...myself included LoL) Charging though might differ a lil from what your accustomed? Due to the lareg number of cells used in pack construction for the e-bikes alot here are bulk charging using Meanwel PSU usually 24v or 48v models. Balancing is taken care of by rc chargers or a dedicated balancer when needed Unlike rc flying we try to keep at least 20% in the packs rather than thrashing them to within an inch of their lives the cells we have found also stay very well balanced keeping with this regime. There is heap of info on these rc setups, check into the non hub section of the forum to find them...Forgot to welcome you to the forum last post so, Welcome to the form

KiM

 

[dogman dan]

What you describe isn't normally considered hubmotor kind of stuff. If nothing else, the 15-25 pound hubmotor makes that kind of riding very difficult if not impossible. The hubs have reliability, but 15 pound wheels don't handle that good.

But pump 50 amps of 100v (25s) into ordinary hubmotors like 9 continent 2807, and you will see 40+ mph. For sure. No doubt you will be able to scamper up some stuff with this kind of setup, but it's better suited to flatter land and hard cornering that riding up the stairs.

With low gear chain drive, much more is possilble, handling wise, and steep climbing.

I do dirt riding on fairly steep slopes like 15% using 15s lipo and a slower wind hubmotor. Top speed is 20 mph, but I can stand on the pedals and cruise the easier sections of local single track real nice with it. It can tolerate a lot of climbing, but the slow wind motors are not as easy to find lately. Everybody seems to be digging the fast hub motors. So that's what is usually for sale.

 

[SamurAchzar]

Ah, great info here, thanks. I've done research based on what I got in this thread, it appears to me like a 3220 pushing nearly 100v could be the ticket. What's the power level attainable by a single 3220 anyway? I've seen 6kw mentioned in AF specs but people here are pushing much more than that through the motor.

I'd also like to go with a dual-drive setup (two chains going to the rear, with dual freewheels). I've seen people doing this using the SRAM (like here), this could be just what I'm looking for.

Then go with a 24s2p and be happy.

Can anyone predict what kind of speed/acceleration/range I'm going to get with such setup?

BTW, as for a charger, I'm building up right now a charging station based around an FMA PL8 and dual 1.3kw 12v (2.6kw 24v overall) server power supplies (which BTW I'm pretty surprised not to see so much around here). The charger should be good for 1.3kw charging, and I might be able to get everything compact enough to carry along.

 

[SamurAchzar]

So I've been looking at it some more, apparently drewjet has built a setup nearly 1:1 with what I'm looking to do. This is fantastic.

What I might change is:
1. Higher voltage coming into the motor
2. Geared hub at the rear, if I can find something fit for this kind of abuse
3. Might use a sensored 3220. Reason is, I want exceptionally smooth pickup for low speed technical work.

Looking at 24s2p, 24s3p or 20s3p if the motor can't take 100v.
If you have a specific ESC in mind that would help me complete the picture, you're welcome to suggest.

 

[karma]

sounds good any geared hubmotor at high voltage will need the nylon gears replaced. i remember there being a thread somewhere on that issue :wink:

 

[SamurAchzar]

Oh I didn't mean hub motor, I meant geared hub like a Shimano Nexus or the SRAM DD.

Using the brilliant EVCalc (thanks swbluto (?)) I worked out 1:15 to be the optimal reduction ratio.
I've been advised to stick with the ICE160HV by recumpence, so I'm capped at 12S with that controller. For the simulation I've chosen a 12s4p configuration (8 packs) - 51v, 20Ah.

Assuming I'm using the program correctly, I'm seeing 35mph, 17miles of range (with a rolling coefficient of .02 and .75m2 frontal area, 0% gradient) at wide open throttle. The program predicts acceleration at 3.3 seconds to 35mph, which works for me (that's firmly in wheelie territory isn't it?).

So that seems like the baseline to me, run at 1:15 reduction and maybe add an internal shifting hub for some more speed when needed.

So I'm going to center on this, and make minor adjustments:
12s4p/12s5p
3220 137kV
CC ICE160HV
1:15 reduction
internally shifting hub (3sp Nexus or something similar)