Here it is July and the problem is back.  If I am riding at low speed, very light throttle, and then start pedaling....the bike starts switching back and forth between 750 watts and whatever light throttle wattage I am using.  It is very strong bucking, and actually spins the rear wheel on gravel (when it kicks to max power).  As I noted in May, this motor is definitely stronger than the one I removed.  Hmmmm....??

If I am riding PAS only (no throttle) the bike is fine until I try to add even a tiny bit of throttle.  Then it goes into the same crazy action.

The ONLY part that has not been changed is the PAS sensor and left crank bearing.  It looks like the sensor on Rover 6+ may be reading the ball bearings in the left end of the crank shaft.  Reading bearings has been a common ABS system function in many cars, for about 15 years or more, and so it is not an unproven system.

Because I have the original harness (changed during the long process), I am going to make a "pig tail" with access to all 3 wires.  I will operate the bike with a portable oscilloscope and see what the PAS sensor pattern looks like.  I think I can create a "drag" condition with the bike up on my bike holder (a Park unit).  I will be able to operate the pedal by hand, working against a rolling drag load against the rear tire (so as not to damage the brake).

I am suspicious that the "timing" of the "bucking" conditions is in sequence with a bad ball in that left side bearing.  The balls, in that type bearing, do not pass the sensor at the same speed as pedal crank rotation.  They would be "walking" around the inside of the outer race based on the speed they are driven by the pedal crank shaft (the inner race for those bearings).

If I can get an oscilloscope pattern (and store it) I should be able to calculate the frequency of PAS sensor signals.  Hopefully, I can see if there is a glitch and figure out the next step of repair.  This will take a few days, and I am sure it will be trickier than I want. 

I may try using my Fast Fourier Transform spectrum analyzer to see if it can "hear" a bad bearing and display a frequency.  Unfortunately, my current FFT does not have a magnetic accelerometer or clip-on microphone (which are the real "magic" for bearing diagnosis).

They are for 5 x 0.80 mm bolts.

Actually....I don't know their purpose, but in the production world I often saw "jigging" equipment  that was used to perfectly locate components during weld manufacture.  Seeing that there are three holes on each lug, I would suspect they are manufacturing aid.  Precision bolt up makes for better quality manufacture.

In the auto factories I have seen things such as "complete engine assembly" spray painted off-color to identify it as "fit test component" (and not to be moved or modified).

The important part of this message is DO NOT use them for mounting accessory loads, etc.  Jig equipment is used at points not necessarily intended for high load, to be sure that "deep weld" areas are not susceptible to excess heat outflow, during the build process.

The world sure has become complicated!

Serious weight reduction (bike and rider), friction reduction (ceramic wheel bearings), better suspension seat post and handlebar shock damping (allow higher tire pressure without full suspension), longer wheelbase (within reason, to reduce pedal thrust angle displacement).

There may be some gains available in chain/sprocket development where finer chain pitch provides lower cyclic torque variation.  Honda learned that lesson in the early 1960s during development of its chain-drive DOHC Grand Prix motorcycle engines.  They used paired chains, offset 1/2 tooth from each other, to smooth the driven rotation of the camshafts.

Modern car/truck engines have gone to very small (short pitch) timing chains to improve accuracy and durability of the camshaft drive.  Back in the early 1970s the "big, strong" double row timing chains would hammer the cam followers and shafts. 

Sometimes "less" is a lot "more".  Just remember....anything you engineer that you find making ANY heat, is lost calories of energy.  That applies mechanically or electrically.

Maybe of little interest, here, but last week I rode the "practice loop" on my Rad Mini ST.  My good friend (younger guy, only 71 years old) rode my spare Mini ST.

The first thing you see painted on the rock is "Just as hard".  That lets you know you are in for all the steep stuff, deep sand, holes, cracks, etc. that are part of the main loop.

This was my "50 years anniversary" of my first Slickrock ride, done on a Honda Trail 90.  This trail is actually a motorcycle trail, originally conceived and laid out for small motorcycles.  There are more mountain bikes riding it, these days, and the riders and bikes are "very fit".

The folks running the Park told me I am the "oldest original years rider" to come back and try it.  That was a bad sign.

The practice loop (which actually measured 2.6 miles) was a brutal eye opening to my age, my recent stroke, and the small wheels/limited suspension of my Mini. Many of the downhills were too steep for me to trust my riding.  I had to walk the Mini down them, with both brakes locked and the tires squealing all the way. 

Some uphills were unrideable because each stroke of the pedals, with full throttle applied, resulted in intermittent tire squeal followed by violent "pop up" wheelies.  We had to walk and push the bikes up.

Many of the more level trail areas are steeply side-sloped.  This gives many "pedal strikes" that try to flip you over sideways.  In some areas, a fall can put you over the edge with fatal results.

My friend and I made it through, but we were pretty used up at the end.  We met many riders who turned back after a few hundred yards, and called it quits.  I kept thinking, "I will get the hang of this...I've done it before!"

This was not a very smart thing to try.  The bike did as good as it could, but the rider made a bad choice.  The Mini did get me through, after a fashion, and that's pretty decent.

I only use LPS 1 in "low pressure" load conditions.  It doesn't have the viscosity to be as effective in something like a freewheel.  I don't use it on chains, either.

That's my experience, anyway.

LPS 1 has some unique uses.  It works wonders in the 12 volt switches in your RV, especially the ones in the bathroom.  I also use it in exterior light sockets on my RV, when they quit working even though the bulb is good.

My first introduction to LPS 1 was in the mid-70s.  I was in south-eastern Colorado for a motorcycle race that used to run in the Purgatorie River (yes...in the water for many miles).  My friend had his Honda idling in the driveway with the ignition points cover removed.  He said, "Watch this!" and sprayed the LPS 1 on the points.  The engine didn't miss a beat.

Then he turned on the garden hose and started spraying water on the points.  The engine kept idling smoothly!  I guess you just had to see it to believe it.

This stuff is not at all like WD40 (which has many good uses....especially as a hand cleaner.)

I hope this is helpful to someone.  I get my LPS 1 in the manual spray bottle, off of Amazon.  The spray-can type seems to lose it's "gas" too quick.  Because of the lube quality, the spray bottle pump keeps working for years, and it is easier to make very small squirts into the brake cables.  It only takes a very small amount and it finds it's way all through the housing.

Correct.  Those E10.11 fit the Mini calipers....not the Rover 6.

Check Amazon for Tektro E10.11 pads.

I will definitely get more pads.  These are actually thinner material than the pads in my Mini's.  Fortunately, this bike is for my wife who doesn't ride mountain bike trails anymore.  They will last her a while.  At my age, I am better off riding the trails on my Mini.  The rougher ride forces me to slow down. 

I did check to see if the Mini pads would fit the caliper.  I would have to grind the edge of the metal back plate (slightly) to fit them in, but I don't know if the extra thickness will work.  I will probably try it, at some point, because I have many sets of those pads on hand (there was a 2 for 1 price on Amazon last year...and I went a little overboard).

Rad sent me a new rear wheel, which completely cured the problem.  It is also noticeably stronger climbing the steep street to my house.  PAS 1 now actually has some assist (which was very faint with the problem motor).

The wheel is remarkably easy to change if you take the right side 18mm nut completely off, and pay attention to the lock washer on the left side which goes INSIDE the frame.  You can easily do the job from the sidestand if you have someone to hold the bike (rocked over) and be sure to have the rear gear in 7th position.

I unbolt the rear brake caliper and swing it out of the way, before removing or installing the wheel.  When you put it back in place, don't fully tighten the two mount bolts until you are holding the rear brake lever engaged.  This will make the caliper properly center when you finish tighten the two bolts.

I have never got more than 250-350 miles out of my Rad bike brake pads (most of my miles are on mountain bike trails).  At 800 miles, I would expect the pads to be very thin or gone, which will increase the lever travel.

That's my "off the cuff" guess.  The pads are really easy to change.

It these are cable brakes, you could have a corrosion problem inside the outer sheath.  We saw this 50 years ago when I was a motorcycle mechanic. 

The outer housing is flat metal wound in a spiral.  If water gets into it, and sits, the metal will start growing as it rusts (a pound of steel weighs one-and-a-half pounds when fully rusted and gains that much volume). 

We saw cable housings grow in length on some of the early foreign product motorcycles, after the bikes were ridden in deep water.  The spiral windings were forced apart by corrosion, and rust is a very powerful force.  I use a little LPS 1 lubricant in the cables of my RAD bikes (this is the product used by the Air Force at Davis-Montham for long term storage of aircraft). 

It is very thin, buy not greasy (it is also used on food processing equipment).  I have seen it make rust "come apart" when nothing else worked.  My RAD cable brakes all work easier with a little LPS 1 in them.  An ounce of prevention is worth a pound of cure, as Grandma used to say.

Wire harness installed this morning but no change in the condition.  I have let RAD know and will wait to see what comes next.

I have been working on a similar problem (with RAD's help).  If I am pedaling the bike, and try to add a little throttle, the bike starts bucking and jerking.  If I am in PAS 1 (pedaling) and try to add a small amount of throttle, the Watt meter starts jumping back and forth between 41 and 750.  I was able to send them a video of the condition.

It does not occur when riding PAS only but is a little jerky on "throttle only".

The bike is seriously down on hill climbing power compared to the four "Mini ST" I have bought over the last 2 years.  PAS 1 is so weak it is almost undetectable on level ground in a paved parking lot.

So far, we have tried a new throttle and then new controller.  Today I received a new wire harness which I will install tomorrow.  I will post the results when I get done.

Just a side note:  My son has a lot of experience with high performance permanent magnet motors in very high-level RC racing.  He has run into motors that were mechanically mis-built, where the "timing" of the components is actually clocked wrong.  He said the bucking is called "cogging" and it goes along with reduced power (in relation to the actual watts fed).

We have had good luck with the Wing Man plug-in (end of bar).  You install the included rubber plug, and then push the ball end into the socket.  I put about two wraps of electrical tape around the ball, and the mirror holds adjustment well.

These are really good on the trails...when I fall off and crash, the mirror just pops out without breaking!  Sometimes I knock it off on a tree, without crashing, and I can just walk back and pick it up undamaged.  Great item for "old and clumsy".

It shows current not available on Amazon, but I have found them in some bike shops.

https://amzn.to/3wqyMHW