LightningRods mid drive kit

Look up torque vs power Gab. I am sure there is another thread on this message board devoted to it.

Doubling the gearing drops the torque by 50%. But, that is overall torque. There is still a torque relationship between each component that comes into play. The only way to reduce torque between the jackshaft and the cracks is to change the radio between the motor and the jackshaft or from the jackshaft and the cranks. If you increase the ratio from the cranks to the rear wheel, you will actually load up the secondary chain higher than before.

Matt

i should add that i didn't notice speed improvements changing the driver sprocket from 15T to 18T while driven was 80T and i have 3 driven and 3 driver sprocket, as speed is something i have been obsessing about much to the dismay if this group
i'm going to try and switch to 65T/12T as 12T seems to have thicker teeth

My approach is to gear the motor reduction down to give a reasonable pedaling cadence and then adjust the final drive from cranks to rear wheel to give the desired top speed. Since the stock 12/80T secondary matches pedaling cadence pretty well at 48-50V (97 rpm), the bike's top speed is going to be about the same as it was before the kit was installed. If you want to go faster you have to increase the final drive speed (best) or the secondary motor drive and blow your pedaling cadence. Unfortunately many bikes don't have room around the chain stay for a larger final drive chainwheel.

Reducing torque to keep from damaging weak brackets is NOT what I want. I want to be able to run the motor as hard as it will tolerate and to be able to gear it for maximum torque and speed. There's nothing for it but to strengthen the weak spots in the mounts.

I'm working on models for the new sheets right now. I hope to get this finalized this weekend so that I can get the parts in production on Monday. We'll have about a two week wait from that point.

For reference, the Bafang BBS02 Crank RPM maxes out around 120, which is at the very high end my own cadence, and perhaps even a little beyond. 120 Crank RPM has allowed me to get up to 46 MPH on steep downhill runs with my BBS02. This is with a 48T Front chain ring and a 11T rear Sprocket and 26" Wheels.

Funny about all this pedaling talk. I bought the kit so I never have to pedal again haha. So far it has been working like a dream! My aim for gearing is to have to highest speed that I can in first gear while maintaining incredible climbing in first gear. Right now I am working to change my gear ratio to gain about 30% more speed in first gear. I figure that is the sweet spot for me. That sweet spot will obviously be different for what power level you plan on using and what voltage you are using (I am using 100 volts). I am going to use about 2000-2500 watts on trail, which seems to be about the most power this noob can handle without the bike flying out from under my ass and crashing into the trees.
btw I had to use a 36 tooth main sprocket due to clearance issues on my bike while most you you guys are getting a 44 tooth sprocket with the kit which ends up almost the perfect gearing I want for first gear.

Okay, this is where we are right now. I've looked over the photos of damaged upper sheets, the hugely helpful stress analysis that Nacent posted, mixed it with my own wish list and blended until frothy. This is what I've come up with:

Broad strokes- Bolt in front shear plate, bolt clamp and hose clamp rear hanger with clamp bolts outside of sheets, unnecessary slots removed from plates, extra material added to top front of sheets, torque brace mount added to top of right sheet. I'm still considering upping the gauge on all sheet parts to 10 gauge.


The rear mounting plate will have three rows of clamp bolt holes for different sizes of front downtubes up to 3". There will also be at least one set of hose clamp slots. Contact areas of plates will be coated with tool handle dip plastic.


You can see the extra meat added to the front of the sheets in this side view.


The upper mount is offset to the right because of the way that it attaches to the motor.


And a couple of exploded views:




This should do it without the torque brace. Adding a diagonal stress plate inside of the new front cover would add more stiffness to that plate and transfer stiffness to both side sheets. All three plates have to deflect for any of them to deflect.

I'm going to make these the standard upper sheets. The front torque plate will be optional because not everyone is going to be running over 2000 watts. For those not completely power crazy 1000-1500 watts makes a nice commuter bike and does not require the Army Corps of Engineers to design a support structure. I've already had several people hungry to line jump who say that they're fine with getting the current sheets.

Another advantage of eliminating the bolts on either side of the jackshaft is that you'll now be able to get a lockring wrench in to tighten the jackshaft lockrings. A blade screwdriver and hammer works, but come on kids. Use the proper tool.

This is your window to make comments and ask for stuff. I'm off to the laser cutter on Monday before I have a lynch mob out in front of my shop. Half of the e-mail I get says "Yeah! This is what I've been waiting for! Go for it!!" The other half says "Will you EVER stop messing around with these parts and just ship my kit???" If you want the current parts e-mail or PM me. The queue is all blown up from people wanting to wait for the new parts. And I don't want a bunch of left overs in the back of the shop growing mold.

first of all anyone who thinks L-R is "messing around" with this kit should hop over to my build thread http://endless-sphere.com/forums/viewtopic.php?f=28&t=63741&start=75#p961807 and see the current pretzel like shape of my kit, and that's 2000 watts in a few days, if you are a heavy person like myself you're DEFINITELY wanna wait.

i would advice really rounding the shape of the edges of the downtube brace, because they look like a recipe for tearing much needed flesh from the knees, say if you jumping forward from the seat ,and stand above the top tube.

i'm assuming all the bolts and allens are the famous grade 8 stuff i won't be able to strip or brake?

can you display how the jack shaft will lock into the upper sheets without the bolts?

Hi LighnightRods - I sent you an email but not sure you got it....

I'm considering building either this bike:
http://www.bikesdirect.com/products/gravity/fat-bikes/fat-bikes-deadeye-monster.htm
or this bike:
http://www.bikesdirect.com/products/motobecane/fat-bikes/fantom-fat-bikes_fb4comp_xiv.htm

will your kit bolt-on easily with little mods? And can you suggest a controller that would allow regen-braking?

Thank you.

Hey Mike. I looked over your design and I like the elimination of the bolts on either side of the jack shaft. Good job. I recommend that you do go ahead with the 10 gauge since the weight difference will be minimal (20% more weight but the sheets are so small that it is nothing) and there will be no guess work if it will be good enough, go big now so you do not have to go big later. Safer rather than sorry and all the jazz. Remember, people are trying to break your kit, don't let them.
I have a couple of questions. Is there a reason why you did not go with a one piece design for the upper sheets? Would it not be less expensive, easier to manage and stronger just to make it all one piece like you did for the lower sheets? If this is a clean sheet design then I think it might be the best option.
You can probably get away with adding some holes on the front plate without losing strength while losing weight.
Also, I am sure you have done this but maybe you should double check the clearance of the downtube brace bolts to the large belt pully. It will be a tight fit I think.
Last thing. Where does the diagonal stress plate go and what does it look like?

born2drv said:

I'm considering building either this bike: or this bike:

will your kit bolt-on easily with little mods? And can you suggest a controller that would allow regen-braking?

Click to expand...

If you're able to get the cranks and bottom bracket off of your bike you won't have any problem getting the kit on those bikes. They're both good fat bikes and a great deal from this seller. I'd go with the single run version and a big block. The fatties with their 100mm BBs and already portly stature were made for the big block. I have visions of huge power slides with sod piling up behind like loose carpet.

No regen with my kit because of the freewheels. When you coast the freewheels disconnect the motor from the rear wheel.

I've added more detail to the rear mount bracket in Photoshop. The corners are rounded off but mostly to save a few ounces and to be prettier. The bracket is behind the pulley on the left and behind the secondary chain line on the right. Nancys who have their bloomers in behind the chain line have more to worry about than the corner of the bracket.



This image shows the diagonal brace that could be welded to the inside of the front brace. It seems to me that it's still possible to get a three way Mamba going even with the three plates attached. If one of the three dancers had some added torsional rigidity the other two couldn't move.

The two rows of bolt holes on the right side of the bracket is my attempt to accomodate people with freakishly large front downtubes. They're out there.



The front plate has to be removable so that the jackshaft can be installed between the side plates. I have room for a 1/2" bracket extension on the left side without getting out past the edge of the motor. The large pulley clears the motor and so should clear the bracket. This concept model isn't 100% to scale.

I forgot about the jackshaft. I am noticing that the downtube brace might not be able to pivot back and forth much. That could be a problem with the way it sits on different down tubes.

The spacing on the rear mount is one of those 'universal kit' considerations. When it's possible to suck the upper sheets in tight to the downtube it looks and works better to do so. If all bikes just had regular old school straight round tubes on the front downtube there wouldn't be a problem.

You're probably right. I should compromise and make the hangers longer.

Here is one example of a torque brace on a GNG. Some people want to add one, and this flange extension makes it look more professional...Not needed for 50V X 25A...Christerljung was using 100V...

http://endless-sphere.com/forums/viewtopic.php?f=28&t=42785&start=525#p660286

Just my .02 cents...but I think square tube frames are much better for the motor.
I have the stock gng motor without the twisting issues from what i can tell (must inspect more closely)
I know most bikes are roundtubes so this info may be useless..but perhaps your next bike frame.
The square/rectangular tube has more resting area for the motor and is wider and flat

OK... So you think the 1 speed is the way to go.... Since there are no gears I'm assuming the top speed is limited to the 1 gear? Any idea what top speed would be with 72v and 40 amps?

Is your big block kit also $800 and what is the max nominal wattage for that one?

I think that a big block with a one speed could be a lot of fun. Like Matt Shumaker's kits once you have a certain level of electric power you don't need gears any longer. The same gear that has too much power at takeoff will do 50 mph. If you want to go faster than 50 on a bicycle you are crazier than I am and I can't help you. You should contact NASA. They have a rocket sled you might enjoy.

The small block motor will handle 72V 40 amps. If that's your target save 5 lbs and $200 on the big motor. We don't know the limits of the big motor yet but my guesstimate is at least 60 amps. I recommend single speed for the big motor and multiple gears for the small motor. There are several people wanting a fat bike for trail packing use and are going to run the big block at 50V and 40-50 amps. In that case the gears will work if you don't hammer the shifts.

Square frame tubes are easier to secure the motor mount on. The way that I designed my mount bracket if there is a round frame tube it will settle into a vee that will give better contact with it. If there's a big flat tube there is flat area outside of the vee to catch that profile. My life would be easier if it would just be one way or the other.

oh i almost forgot , i'm assuming that front brace will be "rubberized" to minimize the scratching to the frame , right?

also the 72 x 40=2880 watts are considered peak loads, don't try to to go 3000 watts for a continuous amount of time in that wattage.

The new bracket concept looks awesome. Its a pity you're now having to incorporate what looks like welded parts (the nuts, and the cross brace)? It'll add to the cost I'd have thought.
I take it that its to keep shipping costs down (and add a little extra metal) that you're not making the front and side plates from 1 piece (and then without the cross brace)?

Offering up the current stock as the 1500w max version is an excellent idea.

I've sent you an email already about my kit (which will be 2kw+ so I'll be waiting).

t0me said:

The new bracket concept looks awesome. Its a pity you're now having to incorporate what looks like welded parts (the nuts, and the cross brace)? It'll add to the cost I'd have thought.
I take it that its to keep shipping costs down (and add a little extra metal) that you're not making the front and side plates from 1 piece (and then without the cross brace)?

Offering up the current stock as the 1500w max version is an excellent idea.

I've sent you an email already about my kit (which will be 2kw+ so I'll be waiting).

Click to expand...

Thanks Tom. There are a lot more welded parts now. Luckily I have a new welder and I'm eager to play with it. When I was first having the lower adjusters made with the one welded nut, the laser shop was charging me $3 per nut to weld them. It takes less than a minute to do! That's not a bad pay rate!

I've mentioned it before but the front plate has to be removable so that the jackshaft can be installed. Also the top adjuster plate. I'm not sure that having it brake formed out of one large piece of steel would be much cheaper. All of that extra steel is not needed by the better behaved among us.

I'm going to use tool handle dip on the bike frame contact areas of the rear hanger. Partially to protect the frame but also because it's sticky and will help grip the tube.

These parts are going in to the laser shop tomorrow. I'm also having new aluminum pant rings made that won't hit the crank arms. I have a pile of motors with modded shafts ready to go out, lots of jackshafts, all of the parts that typically hold me up. When the new sheet metal comes back I'm going to be shipping a lot of kits. I can't wait to see the build threads!

is there any chance you could make L-R v2 (revenge of the mike - coming in a few months) narrower so it could accept the thun sensor? 8)

additionally, i can't remember if this was addressed before,but the welded part of the lower sheets makes it really hard to slip in a hex wrench, any chance that could be bolted as well?

A thun botton bracket has Plastic cups, so how do you want to clamp the L-RKit with plastik cups?

--freeride-- said:

A thun botton bracket has Plastic cups, so how do you want to clamp the L-RKit with plastik cups?

Click to expand...

those plastic cups held the ecospeed kit rather well, and it's not like the cups on the isis are sturdy stuff.