LightningRods mid drive kit

KONAKID said:
LightningRods said:
A couple of corrections:

My motor case width on the small block kit is 78mm. The GNG motors are 68mm.

On the 219 secondary drive you also have the option of changing driver sprockets. The range is 12T through 18T. The way that reduction affects the performance and the riding experience of the bike is interesting. You have a range from slow pedaling cadence and incredible torque with slow top speed up to impossibly fast pedaling cadence, weaker climbing and acceleration and more gearing than the motor can pull. I don't recommend a 18/64 secondary combination but it's available.
Click to expand...


Ohh..? o.k.! soo that totaly changes the picture! thats great! since my biggest descision at the moment is what final drive sprocket to order..as I was not sure what kind of final speeds i would be getting..
So i made up a speed calculator to try and help me decide! but now i will have to ammend the calculator to accomodate these options too.. since this allows for more flexibility in the system..then i will post it for review.
still not sure if i will be able to keep both front chainrings with the kit installed or not... :cry: and this is critical to the speed issue..
Was Vincent D able to keep both of his?? do you know? his seems to be the closest build to mine so far..(the frame is maybe a 2008?..a year newer than mine i think)
I will correct the info page to..and re-post it.
Thanks
Tim
Click to expand...

order several, trust me, if you want to experiment, that's the only.

addtionally only the 80T and 75T driven sprockets can accommodate the the pant guard. if that's a concern.
 
One of the advantages of the stretch brackets is that the adjuster hardware is well out in front of the chainwheel area. I'm pretty certain that running two chainwheels on the Stinkys is not a problem.
 
i should also add that i've reached top speeds at 53 kph on my 29er using 48v battery packs and on 80T and 15T reduction scheme. jdevo has reached 65 kph on his rig with 100V. is really worth packing up a twice the volts for only for 10 kph increase , it's not like your gonna ride this thing on highway.. right..RIGHT? :shock:


just to make it clear, the 4000 watts is peak performance, it doesn't mean you can run it continuously for 20 minutes at the wattage.
 
Merry Xmas ! too all here!..
Hope your enjoying it..
Just wanted to post the corected "info page" i made up for the "small block" kit.. for your review - and to hopefully help others on there builds.
info page1.JPG



Have a great one!
 
Hi Kona —

Merry Xmas back atcha!

Nice one-stop data summery!

I’ve also been deconstructing the power and drivetrain specs on LightningRods kit. Good job summarizing the published data as it stands (a spelling typo or two, but then everyone knows engineers can’t spell their own names half the time). I’ll probably run the numbers myself in the next day or two.

You might wan’t to include the torque constant of the motor which I think is equal to the Kv of the motor when the speed is expressed in rad/sec... I’d double check that notion first though.

I’d also like to see someone put the kit on a dynamometer to get a feeling for the mechanical losses and where they occur, but those who have the kit don’t seem to be doing that as that would take time away from getting out, riding and having fun. Damn those people...

And a Happy New Year to all!
 
Torque (lb.ft.) = (HPx5250)/rpm.
So at 3000 watts and 100 volts at 80% efficiency the torque at the motor would be ((0.8*3000/750)5250)/6700=2.51
If your secondary gear was configured at 12t to 80t the torque at the chainring would be ((0.8*3000/750)5250)/(6700/5/(80/12)) = 83.6

That is 83.6 foot pounds of torque on a bicycle. That is a lot.
 
TriPhase said:
Hi Kona —

Merry Xmas back atcha!

Nice one-stop data summery!

I’ve also been deconstructing the power and drivetrain specs on LightningRods kit. Good job summarizing the published data as it stands (a spelling typo or two, but then everyone knows engineers can’t spell their own names half the time). I’ll probably run the numbers myself in the next day or two.

You might wan’t to include the torque constant of the motor which I think is equal to the Kv of the motor when the speed is expressed in rad/sec... I’d double check that notion first though.

I’d also like to see someone put the kit on a dynamometer to get a feeling for the mechanical losses and where they occur, but those who have the kit don’t seem to be doing that as that would take time away from getting out, riding and having fun. Damn those people...

And a Happy New Year to all!
Click to expand...

Thanks!
next i will be posting my "transfer ratio/ actual speed" chart....:)
just have to redo it to include this " new data" about the option to change the driving sprockets too...
i would love to make a torque chart too.... but have no idea what the real efficiency of the motor is...???
Mike?? Anyone?? Have any idea? What the real number is? 80?70?%
 
I have the Zach J's 73mm BB to Big Block lower bracket sorted now. It ended up coming together pretty tidy. The motor is now centered as it needs to be and is well braced. I fabricated a custom lower adjuster bracket by hand that ties into the BB mount and makes everything quite rigid. The crank arms clear on both sides with the 25mm belt drive in place, but just.

68BB1.jpg


68BB2.jpg


68BB3.jpg


68BB4.jpg


The great news here is that the Big Block will fit all four sizes of bottom brackets: 68mm, 73mm, 83mm and 100mm.

We are hard at work and are bringing up a large number of orders in a group. Our plan is to be completely caught up with all back orders within 30 days. We're excited about 2015! Happy New Year!
 
I want to build a bike around this! Couple questions. Iv read most of this.

I want to cruise at 25 -30 mph but be able to top out around 40mph for a couple miles. Is 48v enough? Do I need the larger motor?

Looking at the em3ev 50v 25r pack with the 12 fet lyen controller.
 
The small block does 32-33 mph comfortably at 48V. To hit 40 mph you will need more power. Increasing the voltage is less apt to make the motor hot. If you want to hold 40 for any length of time the big block is a better bet.
 
Thanks for the fast reply! My build is a couple months out. I can't find a mid drive kit like yours! Impressive build quality :mrgreen:

I understand more volts = faster motor speed.


When you say more power will more amps work too? I see 30 amps is the sweet spot.

What about distance at 25mph with a 20 Ah battery pack.

Thanks! I'm going to continue my research. Dumping 3 grand into this, don't want mistakes. I keep coming back to your mid drive kit!
 
More volts = faster motor speed. Moving more electrical power by spinning the motor faster.
More amps = more torque. Moving more electrical power through current flow.
Amps create more twist at lower speeds but tend to generate heat. 30 amps is good for continued running on the small motor. But even the small motor can stand brief bursts of 40 or even 50 amps. Above 30-35 amps more and more energy gets converted to waste heat.

You can get more speed with either more volts or more amps. If you have run out of gearing (your motor is at max rpm in top gear) you need to raise the gearing or add voltage. If your motor won't pull the existing gearing (won't reach full rpm in top gear) you can add more amps for more speed with the same gearing.

In regard to range, let's say that it takes 1,000 watts for your bike to do 25 mph. If it's a 48V system that's about 20 amps of current. If you have a 20Ah battery it should flow 20 amps for one hour. So one hour is your approximate run time. If you multiply one hour by your mph you get your range. In this case 25 miles. This is all approximate based on a couple dozen variables.
 
Wow, I really appreciate the explanation. It's all starting to come together and make sense now :shock:

So at higher volts you will use less amps to create the same watts.
A 72v 20Ah batter pack will get better distance at 25mph. Correct?
 
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