LightningRods new Big Dummy cargo bike drive

Hello all,

It's been quite some time since I started looking into ebikes--about a year ago now. I was originally going to get a hub motor, then a Bafang, and then I heard about the LightningRods mid-drive, and put down one of the earlier deposits. About the time I would have gotten the drive (Christmas or so, I would bet), Mike announced that he was looking at adapting his kit for cargo bikes like the Big Dummy and the Lunacycle, and perhaps the Xtracycle line and/or the Yuba Mundo (though, if he is still going to adapt for them, I do not know--you'll have to ask him). After communicating with him a bit, I decided to give up my place in line for his BB mounted drive and ship him my Big Dummy frame so that he can use it as the model for this new drive.

The drive uses the same basic components as the BB mounted drive, and uses the small block motor. The BD is just too narrow to use the big block (unlike the Luna, which has plenty of room for the big motor). Instead of mounting at the BB, this drive mounts in the "extra" triangle that the BD and many other cargo bikes have. This is a perfect place, I think, for a drive, and it is a commonly used mounting point for drives like the Stokemonkey.

Anyway, I should have the bike back in a week or so (maybe two), but until then I wanted to tease the community with a few of the progress photos that Mike has shared with me. Once I get the bike back, I will do the remainder of the assembly and add to this thread as I work, and hopefully top it off with a few ride videos and a performance report!!

Here it is (drive side, mounted to my frame):

IMG_4022 by deanwvu, on Flickr



Profile, with primary reduction in place:

IMG_4021 by deanwvu, on Flickr



Secondary reduction (non-drive side), unmounted:

IMG_4016 by deanwvu, on Flickr


Enjoy! More photos and build/testing to come!

Looks rad! It'll be super fun.
Watch those pantlegs on that chainring

Yah, the final build will have guards for the belt and the chain drives.

OK! So, my Big Dummy arrived back from Mike on Friday, and I've been putting some work into it.


Forgive me for not documenting more of it, as my timeline is tight. I got the bike (with motor installed) on Friday, and my family and I are traveling (on vacation) starting on Monday (tomorrow), so I had to race in order to get this bike to a rideable ebike in just 2.5 days, and that is with other daily responsibilities. Besides, Mike already built the drive to the frame and sent it to me already attached, so I could not document that portion of the build anyway. Basically, over the last two days, I have had to reassemble all the bicycle parts (front fork, wheels, handlebars, brakes, etc), and install the ebike hardware (controller, charger, throttle, etc). I also had to route all the wiring that goes with that hardware.

The bike is not currently rideable. I had the suspicion that I would need an idler wheel to alter the path of the bottom chainline, and that suspicion is correct. With Mike's drive, the bottom chain path goes right into the Big Dummy frame. I have ordered a Terracycle idler. Once installed, it should solve my problems, and I will have a rideable 2.2 kw ebike!

If I used a single speed or a Rohloff, this problem goes away--the issue is with derailleurs and the path back to the jackshaft. A single speed would have a much higher lower chain, and will clear the frame. Still, even when/if I get a Rohloff, I will need a chain tensioner, and the Terracycle idler will serve as a tensioner.

Also, I can't install my CA3 yet... This is my first ebike, and I had no idea that I would HAVE to run the throttle to the CA3, not to the controller. I thought I could run it in "legacy mode" similar to the CA2.3, but I cannot.... I do not have the JST-SM connectors on hand to connect the throttle to the CA3, so I must wait until they come in. Honestly, I didn't have time to mess with the CA3 anyway with my tight schedule, so I don't mind putting that off. I will simply have to take care to keep the battery in a safe range of charge (without the CA3 display to tell me). I have a 24.5ah battery, so I should be fine for a lot of the trip

There were a few "hiccups" with the kit, which I have discussed with Mike. One is a simple fix, and that is the reversal of the CNG motor. The motor must run backwards (compared to Mike's BB kit). The wiring for Mike's BB kit will not work. Instead, I used:

Controller: Motor:
HALL:
Yellow Blue
Green Yellow
Blue Green

PHASE:
Yellow Yellow
Green Green
Blue Blue

This wiring worked perfectly. Mike sent me that wiring instruction (which he got from Lyen himself), but he had never tested it. I was worried I'd be spending an hour or so testing combinations of hall/phase wires, but this combo worked! So, problem #1 was simple.

Problem #2 was a slight clearance issue with the rear chain. There is a cam-locked adjuster for the output jackshaft that has a tab that comes very close to the rear chain. Note that this kit has two chain runs--one from the crank to the jackshaft (freewheels), and the output chain from the jackshaft to the rear wheel. I just took an angle grinder to that tab and ground off 1/3 to 1/2 of the material. I doubt there will be a chain problem now, but if there is I can grind off a little more. Mike is aware of this and will be changing the tab on that cam, so this will never be a problem for another buyer.

Enough chatting, Here's the bike!

Full bike, drive side:

Non drive side by deanwvu, on Flickr


Close-up of drive, showing the drive itself, the crank, the charger, and the controller:


Non drive side by deanwvu, on Flickr


Crank (note that Mike's urethane clamp bolts were perfectly spaced to mount my Lyen controller to it! I used the bolts for the top of the controller, and a zip-tie for the bottom):

Non drive side by deanwvu, on Flickr

Non-drive side:


Non drive side by deanwvu, on Flickr




When I finish the 2nd chain run (with Terracycle idler), I will take photos of that as well. Once the JST connectors come in (and we are home from vacation), I will install the CA3. Later on, I will also be adding torque-sensing.

Mike will be designing and sending me some guards for the primary and secondary reductions. For now, I need to watch my pant legs

Final drive (chain) is installed and I got the bike running last night for the first time.

You can see the drive with the Terracycle idler here (you can also see why I needed it):

20150730_180740 by deanwvu, on Flickr


The bike ran great--it was a blast! I don't have any stats like speed/watts, etc, as I can't install the CA3 until I get back home from vacation. But, for now, I got a great bike for the beach this week!

Congratulations. I saw those pictures and I broke out in a smile. Hope you enjoy it

Can't wait to get my kit to connect to my cargo bike.

Thank you for the pictures. I will be studying them.

If I am to go mid-drive, this is the unit I would buy for sure!

This is awesome. I was considering this for my own BD but couldn't wait and ended up going with an eZee hub drive. Seeing these pictures though I might have to move my hub drive over to another bike and get this!

I'm very interested to hear how you are going to do the torque sensing. Looking at the photos, it looks like with the placement of the motor you are able to use a standard single crankset (though the crankset you have looks to have a very long spindle - length?) which would allow you to use a Thun or TCDM torque sensor BB. That would make it plug and play with a CA3 which would be great.

I am going to use the Prodeco BeamTS. I already have it, but I have not yet looked into mounting it. I am still spending time riding the bike and getting things slowly finished/added on.

I got the CA3 installed on Monday, and I now have the throttle routed through the CA (instead of direct to controller).

I still need to figure a method to install the brake cutoff. My brakes dont have an easy mounting position.

This is a pic of the Beam and roughly where it will be mounted. I need to ask someone at grin if it can be wired to the same input as the THUN on the CA3.

IMG_4076 by deanwvu, on Flickr

Heard back from Justin at Grin. He believes this torque sensor will work fine with the CA3. However, I will have to add a cadence sensor as well, as the CA3 requires both torque input and cadence. Makes sense, as you need both to calculate work output.

Should be in by next week.

Awesome build Deanwvu! Thanks for the details and pics. I stokemonkied my dummy before Mike's foray into longtail, so the LR will have to wait for my next build. Keen to see how the torque sensing works.

Did you customize the kickback taco to fit? I returned mine and still use std kick stand as I was paranoid about the wrong shape and edge-only contact first breaking the taco then/and deforming the bottom tube. I found xtracycle and surly both pretty useless on this issue.

Tear up some towpath for me ( canal/Great Falls a favorite). Best regards.

Hello Nordic,

I see you are familiar with my area--you live nearby?

By "taco," do you mean the contact pad on the bottom of the stand (where it touches/supports the frame)? When I got the stand, it had 2 of those pads, and one is made for the BD frame--it is an oval shape and conforms well to the frame. I don't think it will be a problem.

Torque sensing should go in sometime later this week--hopefully I'll have the time to install it!

Hi Dean,
Grew up in in your area. Biked everywhere, loved the C&O.

The kickback I got was not sized to match my large BD. When mounted, the taco would not face flush, only point of contact was the leading edge. If the support arms were offset 3/8" more the taco would have faced flush. Moreover, the taco's oval contour did not match the contour of my bottom tube, only met at two points on the sides.

I could have scrapped the taco and built one that fit out of sugru or some such, but it galled me to be gouged $150 for a kickstand that I would have to fix to make work, and xtracycle wouldn't budge on any discount/credit so I sent it back.

The OEM $7 kick stand is still working. I should pack a spare for when it finally gives. :?