LightningRods mid drive kit

If you're having an issue with the upper adjuster nuts coming loose (when double nutted? Really?) try using a Nylock nylon insert nut for the second nut on top. If you use two wrenches and tighten them against each other I can't imagine them coming loose. Locktite or similar would be more of a pain to deal with if/when you need to use the adjuster again.
 
That's what I figured with loctite.
I thought of all sorts of lock washer type fixes...nylon nut didn't even cross my mind (d'oh), I'll try that!

Maybe a couple washer spacers along the bolt to take some of the clamping force would help reduce vibration play. I'll figure something out and try to remember to update with results.
 
I put split lockwashers in-between the two locknuts, I do that because there was a few times when I was tightening two nuts against each other and I damaged the threaded stud by giving it a little too much oomph. If they ever loosen, I would definitely use locktight as the next step...

When the split locknut is flattened from tightening it down...thats a visual indication that I am close to done.
 
LightningRods said:
Here is something that Dean and I are working on with Grin Technologies for the Big Dummy kit.

Since the human power is isolated from the motor power on this drive there is a chain run that's ideal to take strain readings from for a torque sensing throttle. We've started out with a BeamTS strain gauge and a magnetic PAS cadence ring. The information from these two sensors feeds into the CA3 and provides basically the same data that the torque sensing bottom brackets do. Except that we are reading the pedal drive chain which is the output of both cranks instead of just the left one. On torque sensing bottom brackets only the left side crank is measured for strain. Starting out with the right crank (most people's dominant leg) will not produce any throttle input.

Dean just has the components physically hooked up on the bike. Hopefully it will be working this week. Thanks to Justin, Robbie and the other brainiacs at Grin for their support with this project.
Click to expand...


It works!! I had a small CA3 setup snafu that the people at Grin helped me out with, but the BeamTS torque sensor along with the 12-pole cadence sensor from Grin feeds data to the CA3 and the CA3 is sending output to the motor in proportion to my physical effort.

I used this method for portions of my commute today and it worked very well. I still have some calibrating and tweaking to do. One thing I must correct is the actual work statistics to make sure that the work the CA3 reads is at least close to my actual input.

I'll update my build thread soon.
 
That's so cool Dean! The Thun bottom bracket is way too confining as a method of providing torque sensing. This new method will work on a fat bike with a 100mm BB, as long as there is a pedal power only run of chain to read the strain on.
 
LightningRods said:
I still get PMs and e-mails from people wanting adjustable sheets for their GNG kits. Because of the 10mm difference in motor widths between the GNG and my small block mid drives, my current brackets and jackshafts won't fit the GNG motor. I'm already extremely busy producing complete mid drive kits so I've stopped making the GNG width parts. I've also noticed recently that GNG has integrated the upper bracket into the motor case. So now not only is the geometry wrong and the tensioner useless, Jon has made it much more difficult to fix the problems.

Sorry pchen.
Click to expand...

For which reasons did you decide to change the motor ? Is it lighter/cheaper/ more convenient ?
What is the price of your kit (small block) without the Cranckset+ BB (68mm in my frame)?
I want to build a 3kW mid-drive and use 3-4 gears (to keep the chain a minimum straight)
 
pchen92 said:
I want to build a 3kW mid-drive and use 3-4 gears (to keep the chain a minimum straight)
Click to expand...
no need to stay with 3-4 gears. my middrive uses 8 out of 9 gears w/o the slightest issue with chain line. i don't use the 9th gear because it's only 12 teeth and i want to avoid chain skipping.
 
The narrow 68mm GNG motor is not available anywhere except through GNG or Conhismotor. Both of these companies sell the replacement motor for over $200 plus shipping. I can get a 10mm wider and more powerful motor directly from the factory. Another reason that I did not want to buy from GNG was that they could cut off my supply of motors at any time if they felt that my mid drives were competition for theirs.

I'm sorry that I don't have time to provide replacement parts for the GNG along with my other work.
 
Here's something else that I've been working on.

When I started designing the big block mid drive for the Qulbix Raptor 140 I could see right away that the entire drive needed to be bolted securely to the battery box of the Raptor. No adjustable lower bracket. So I designed a 219 chain idler tensioner.

219_tensioner.jpg


It's completely manual but easily adjusted with two readily accessible M6 hex bolts. The idler is a regular steel 219 sprocket. It has a sintered bronze sleeve bearing in it for quiet, low friction rotation.

The lower bracket for the Raptor kit has no slides. Only holes for M6 bolts in fixed mount. I still needed a two part lower bracket to adapt the width of the motor (102mm) to the Raptor bottom bracket (83mm).

Everything went together super solid. Even without being bolted to the battery box the solid mount with adjuster was stout. It got me to thinking...

Most of the bitching about my mid drives has been the fussy lower slide adjuster with all of the bolts and screws and hardware. It's also a PITA for us to assemble here. So I've decided. Once the current stock runs out, they're history. No more slide lower adjuster brackets.

The good news for people with the slide lower brackets on their existing L-R mid drives is that the new sprocket tensioner will retrofit to your kit no problem. If you're not having problems with your brackets slipping (a lot of people didn't) you can just add the sprocket tensioner. If your brackets have been slipping you can just drill additional new holes and bolt the slide in place.

I'm having the first batch of these made right now and they're all going onto production kits. If there is a lot of interest in retrofitting I'll have as many made as necessary.
 
Love the look of the tensioner... I may need that at some point...

So I still haven't 100% successfully got the bike just right. I have ridden it around numerous times and have had a hell of a lot of fun, but the problem still persists.

The symptoms are; the chain eventually gets looser and looser due to it being too taught and then too loose at different point in the cycle of rotation. I have finally figured out this is due to the 80T gear not being in parallel rotation with the crank shaft. Ie, when I freewheel the crank (backwards pedaling) the gear wobbles like a plate when you drop it on the table at a very slight angle. This is causing the chain, at certian points of rotation to be too tight, and then too loose, and then slapping.

What could possibly be causing this? Bent crank!?!?
 
I don't think that the bottom bracket spindle is bent. I've noticed that backwards pedaling lateral wobble before on brand new assemblies. The 219 sprocket spins true on the freewheel, and when you turn the cranks forward the sprockets seem to rotate true with the crank arm. Have you checked these other ways of rotating the crank assembly? Lateral wobbling when pedaling backwards isn't a real problem by itself and won't cause the chain to loosen. I'm not sure what is causing that but I can play with it further to try to find an answer for you. My immediate thoughts are the angle of the threads on the right crank arm or the BB freewheel.
 
Ozzie, is it your upper or lower adjuster that's shifting?
I just posted earlier about my upper adjustment screws coming loose recently, are you having the same?

My chainwheel was slightly crooked like that initially too...it was just the way it was seated, fitting was real tight. A couple taps with a mallet trued it up for me.
 
My bet it is quite common to have some level of imperfection in the system such that the chain length changes with the rotation. I also have tight spots if I over tighten the chain - not sure if it is bent shafts, imperfect sprockets or alignment issues. Probably a combo of all of these issues.

With a spring loaded idler, this would not be an issue and the chain would be under a more constant tension. Is there a reason for using a bolted on idler Mike? Efficiency/Complexity?

I like the idea of a fixed bottom sheets as fiddling with all those bolts is PITA for me too! I'm glad to see the continuous improvements in this kit. That torque sensor is way cool. I wish we could have something like that on a FS bike!
 
In the reading that I've done on various designs of chain tensioners there was, again, a lot of complaining about spring loaded tensioners. Most of the serious off roaders wanted a fixed tensioner that was going to be constant and not reacting to the driveline all of the time.
 
The chain is loosening off because at a certain point in the cycle the chain is just far too tight, so something has to give.
Once I can figure out why the chain is tightening and loosening i'm sure that part of the problem will cease. lightning, the
back pedaling (with my hand ie. no weight on the system) is whats causing the chain to tighten and loosen (if i put my hand
on the chain I can feel it tensioning and untensioning...

Just can't figure out what's causing it...
 
I think it's that the threads on the crank arm for the freewheel and the bore in the crank arm for the ISIS spline are not absolutely parallel to each other. Either that or something mysterious in the freewheel. I don't think it's the BB. A used one that had been beat around off road maybe, probably not brand new ones.

If these crank arms that I buy from Cyclone have a tendency to not be parallel inside to out, the only alternative that I know of is TrialTech. 1.37" x 24 tpi threaded crank arms aren't exactly common.
 
the threads on the crank arm for the freewheel and the bore in the crank arm for the ISIS spline are not absolutely parallel to each other
Click to expand...

This is most likely, but most freewheels are not perfect also. Spin any number of them backwards while on a wheel and you can see the cogs tip and runout. Most of this stuff is made for a derailleur to tension out the slight variations or a bit of chain slop. Not high tolerance stuff. I can see how the isis arms would be much easier to center parallel than a square taper for turning true on center and threading. Looks like a difficult setup to say the least.
 
That was funny at the end lol.

That wobble happens on my HD freewheel from white industries / sick bike parts that I have mounted with a 48t sprocket on my hub motor.

I use MC spring loaded chain tensioner on it though so don't notice any pull or what you have here.

Can't see the wobble or even the tensioner doing much here at all. But may be at least proof of concept for others possibly looking for a way to keep tension on the drive train with larger sprockets. The tensioner is not designed for bicycle chain, so I just carved the shape into the rubber.

[youtube]DQAMQLQdF-w[/youtube]
 
Hahahaa yeah I forgot that I got that in this video.

That's a god idea with the tensioner, but my understanding is that this kit doesn't need one...

I'll try and take a better video tomorrow from the side so you can see how much it effects the chain tension. Basically it's causing it to slap when I ride, because if I went any tighter the pedal wouldn't turn at the taught part of the rotation...
 
LightningRods said:
In the reading that I've done on various designs of chain tensioners there was, again, a lot of complaining about spring loaded tensioners. Most of the serious off roaders wanted a fixed tensioner that was going to be constant and not reacting to the driveline all of the time.
Click to expand...

Can the tensioner be retrofit to the SB as well? If so, give me a price. I want first in line please. A method of adjusting chain tension that doesn't involve the belt as well is a big benefit. It will allow me to keep the jackshaft parallel and still adjust chain tension. It should even allow removal of a link without having to mess with the bottom assembly. :)

Mike, if you need someone to beta test a retrofit on a SB, I volunteer. :D When people realize the full benefits, everyone is going to want one.

In the picture, the tensioner is at minimal tension in the adjustment range. However, it seems as if the chain is near maximum desirable deflection.
 
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