Just a note from some work I did on a 6+:  if the pedal rotation sensor wire is broken or disconnected, the throttle won't work.  I don't mean that the throttle won't work if you are not pedaling, the system just needs to see that "wiring" live in the harness.  I don't know why.  I made a "break out" harness that fit between the pedal sensor and the main harness, so that I could look at the pedal sensor with an oscilloscope (working on a different issue...without success).

I also took the right handgrip off and slid the throttle out on the handlebar to make sure there was not interference from the rear brake lever (it has a hall sensor, as does your throttle).  If in doubt, disconnect the brake lever switches and see if the throttle comes back.

My MiniST developed a bad rattle, which turned out to be the battery in its mount.  I now use two of those little bungee cords (the little ones with metal ends) and the rattle is fixed.  Because most of my miles are on mountain bike trails, this is a good fix.

I put them around the battery and controller, just above the hoop in the frame for the battery.

I have an "exercise" loop (when weather allows) that is about 40 miles.  My MiniST is fine with this distance.  It only has a few hills and is certainly not as flat as "rail trails".  I typically get home  with 2 bars still showing on the battery meter.  Most of the rail trails I have ridden are pretty much gentle climb (one direction) and almost coast (the other direction).

My wifes Expand5 is lighter and would do even better with narrower tires.  The Expand5 is noticeably lighter and definitely steers better than my MiniST.  In my family we have 2 MiniST and 4 Expand5.  None of them have ever given us trouble except replace the cheap "plated" front wheel bearings with good 1/4" hardened bearings.  Rear bearings have never been a problem (I am over 4000 miles on my ST).

The lower effective gear ratio of the smaller wheels probably helps improve the range.  My friends Rad Rover 5's get lower on battery charge, on the same ride.  They have to pedal harder, but they are 30 years younger than me.

If you go with the Expand 5, get a "wired" bike speedo, not the wireless type.  It makes it nice to track your miles accurately.

Hope this helps.

This one fits, Lixada on Amazon, about $22 right now.

https://amzn.to/3XTvPvX

 I tested my longer 12.9 grade bolts, with heads machined to fit the casting.  The longer thread and stronger bolt is easily torqued to 20 lb-ft.  The owner's manual calls for up to 17 ft-lb, with a max of about 19 lb-ft.

The 20 lb-ft pull felt like a good "set", based on my lifetime of mechanic work (over 66 years of experience in that employment.)  I set a long 8mm nut in my shop vise and tried to break one of my machined bolts.  At 25 lb-ft the nut was deforming, but the bolt was in perfect condition when I pulled it out.

I'm satisfied with my fix.  My local NAPA store charges $2.50 for each of these bolts.  It sure seems like a lot of money for one bolt, but Fastenal was even higher.  It takes about 20 minutes on the lathe to get the head sized just right.  The hardened grade has to be cut really slow, to keep from breaking my carbide bits. 

My lathe is an old Logan (1951) that still has tags on it that say, "Mack Truck Corp, Pump Room Lathe No.4".  This is one of the old ones that uses the wide, flat, leather belt drive!

I pulled the bolt from my wifes new Expand 5 and found it is only 10.9 hardness rating, and only 22 mm long.  The bolt head is 10.83 mm diameter.  These are 1.25mm thread pitch, which is right for aluminum (coarse thread into soft metal, fine thread into hard metal).

I took a 12.9 rating Allen bolt, 30 mm long, and found the bolt head was over 12mm diameter.  I turned the head down to 11.70 mm diameter (in my metal lathe) and found the stronger bolt fits perfect and actually engages threads all the way though the aluminum casting.  These bolts are hard enough to break an Allen wrench before they "deform" like the original Chinese bolts.

I have, over time, replaced various bolts on my RAD bikes due to the heads deforming.  Now I have to make up a couple bolts for my son and daughter-in-laws Expand 5s.  Where strength is the real issue, I am not a big fan of stainless bolts.  Good old "hardened steel" has worked for longer than any of us have been alive.

A little different, but.....Mom always told me, "There will be times in your life when you just can't help yourself.  When that happens, go help somebody else."

It was good advice.  After my latest stroke I was barely getting around, etc.  Now I play music with volunteer groups that entertain for free in senior living places, and such.  I know people who get rides with folks helping such situations, even just to have another soul to sit at a table and play some cards with little old ladies.  The stories you hear can sure brighten a day.

You might find some chances to be a "helper" and have rides available from like-minded folks.  It grows your circle and makes life more interesting (even with some new forms of "aggravation" but with folks worse off than we are!)

I learned a lesson with this conversion, just 3 days ago.  If you try running very low pressure, and then use full power while "standing up pedal hard" up steep pavement....

It rips the valve stem right out of the tube!

Duh....sometimes I don't think things through.

My son rides his RAD on bike trails that have a lot of thorns.  He pulls them out each day, and says this stuff actually works.

https://a.co/d/45UBVA0

He said the Kevlar fine strands actually get into the hole and tangle themselves to hold the sealant in place.

I'm going to try it, myself.

Thanks for your note.  Rad did send me a complete new wire harness, display, controller, motor (wheel assembly) and nothing changed.

I have confirmed that riding about 5 mph "throttle only", with PAS set to "0", the bike still surges full power as soon as I rotate the pedals.  If I disconnect the PAS sensor, I can use throttle while pedaling and there is no unexpected result.

Of course, pedaling with no throttle and no PAS is pedaling a very heavy bike.

The only piece of wiring that has not been changed is the short PAS sensor section (which I have tested with an oscilloscope while pedaling on my test stand), and the push button controller on the left side of the handlebars.  I already tried disconnecting the lights and saw no improvement.

RAD is looking at the next step and I will post if I learn more.

P.S.  I did ask them about the new paint finish (possible frame ground problem?), which probably sounds dumb...but about the paint;  Over the years I had several cases of our high perfomance turbo model where customers blew them up and needed a new "short block" assembly.  After installation, the cars had repeated "check engine light" problems indicating the Knock Sensor was not working.  It turned out that when the factory makes "replacement short block" assemblies, they double paint them to prevent corrosion in possible years of storage in a parts warehouse.  The extra paint, in the thread hole for the knock sensor, was insulating the knock sensor from responding to the 8.8 kHz frequency that occurs in that particular bore diameter during a "knock" event.

So....Paint too thick on the new Rover 6+?  Probably not the issue, but my personal history makes me think about it.   At this point, be glad you are not one of the nice folks at RAD who have to work with someone like me.

To their credit, RAD has already said they can replace the bike, if we can't fix it.  It is just such a strange thing, and I spent my life career fixing difficult problems. 

It seems that we (and me) are missing something simple, here.  There is some link between the PAS sensor circuit and the throttle.  When I made the breakout cable to look at the PAS signal with the o-scope, I discovered that if any of the PAS sensor wires (3 wires) are open circuit, the throttle will NOT work.

That relationship between throttle and PAS has got to be the source of the problem.  However, if the throttle is disconnected, the PAS system still works just fine.  I am going to try learning how to test that Hall sensor (for the PAS).  Maybe something is going on that disturbs the 5 volt circuit that feeds the throttle.  In all this work, the PAS sensor has not been changed (nor have any lights been changed, and I haven't changed the air in tires  .)

Display did not fix it.   We have now changed the complete wire harness, controller, throttle, display, and rear wheel (motor).  The PAS sensor signal is clean (confirmed on an oscilloscope).

If anyone has an idea, here is the symptom:  Ride about 5-6 mph throttle only on flat ground (very little throttle).  As soon as I start to rotate the pedals (but not actually loading the chain), the bike goes to full power.  It hits so hard that it spins the rear tire on gravel!  I have to stop pedaling and hit a brake.

Riding PAS only, the bike works normal and fine UNLESS I turn in a little throttle.  Then it goes weird, again. 

This is not a wear problem.  This bike has less than 16 actual miles on it, in the 2 months we've owned it.  It did, in fact, work right the first time I rode it with the new rear wheel, but the next time it was bad again.

Does anyone know if there is a ground path used through the rear axle/frame contact point?

750w mid motor....carry a spare chain, masterlink, and tools.  That's what the fellows in the Oregon woods are telling me.  It's a small amount to pack, but they find they can break the chains when the rear wheel goes over something like a root, that makes it give a little hop.

There can be a lot of power through your gear reduction, for sure.

Yup....my wife thinks I should have a custom hat made, to read:

"I write cursive and drive a stick shift" (which is true...stick shift Jeep Rubicon).

Latest news on my wifes bike is that the pedal sensor signal is clean and normal.  It really only switches about once or twice per pedal rotation, serving simply as a PAS "turn on" trigger.

The speedo display, however, does actually have some functions related to motor control.  It is the only part we have not tried, and so, RAD is sending me a unit to try.

When I get it installed, I will post the results.

P.S.  Those "dash mount tuning forks" were a GM item.  You simply adjusted the fork stopper up or down, and read the frequency where the fork vibrated best.  During my years in the field, I often travelled with an Ono Sokki CF-250 FFT.   It was a wonderful unit, and could perform raster display.  That function allowed me to "see" the frequency of things that come and go, while driving.  One of the most interesting cases involved a particular "oppressive" hum in the passenger compartment of a new "sport model' sedan. 

The condition only occurred on certain freeways (concrete joints), while driving at certain speeds.  It turned out to be the "pipe column resonance" of the smaller front tires, on that model.  A tire is nothing more than a tube, bent into a circle.  The length of the tube (just like in old church pipe organs) determined the frequency response, fed back into the unibody and using the roof as a big "speaker".  A small change in tire spec, and bonded "weight insulation" in the roof, effected the cure.

We have to give folks like RAD a lot of credit for dealing with all the complex new problems that go along with product development.  It is NOT simple and easy!

I was able to build a "plug in" test wire harness for the pedal rotate sensor.  I haven't borrowed an o-scope yet, but my Fluke 87 is showing really dramatic voltage fluctuation off of that Hall sensor when I rotate the pedals slow and steady.  Any ideas.....anybody?

Maybe tomorrow I can learn a little more.  My iPad FFT is too crude to see anything cleanly.

I had thought that the pedal rotation sensing was strictly to identify the pedals rotating forward.  It doesn't seem logical that a fluctuating signal would be causing this strange problem, but who knows??

Hey "JiminPT", do you remember those adjustable tuning forks we could hang on the dash to identify the frequency of buzz or sounds....before the high tech tools came along!  And...then we had to do the math to figure out what component could be vibrating at that freq of RPM or driveshaft, or wheel, or whatever!  Luckily, we had those handy "slide rules" to do math quickly.