Did Watt Wagons Get Rid Of "Phantom Shifting" with their design?

Ebiker33

Well-Known Member
So Court just tested another brand of ultra, let it remain nameless as I don't want to attack that brand.
It seems that the WW design with the gates belt and IGH might have eliminated this problem.
But he had this to say about it.

  • The biggest downside to this setup that I and my friends noticed after taking multiple test rides is that the powerful mid-drive motor pulls so hard on the drivetrain, that it flexes the rear swing arm a bit and can cause phantom gear shifting if you’re in the highest gears. This can damage the chain and rear sprockets, you can hear them crunching during parts of my ride test when I climb a very steep hill at 30:47. You can reduce this by accelerating more gradually or using the lowest gear (or gears that are more inline with the chainring). The phantom shifting may be more pronounced for heavy riders, those operating in the highest level of assist, and those climbing steep hills.
On the plus side he has this to say about the motor
  • Great motor choice, given the heavier weight of the bike and possibility of larger tires (like the 26″ x 4″ on my demo model) the Bafang Ultra M620 was a good choice. It delivers an incredible 160nm of torque and the motor controller listens for rear wheel speed, pedal cadence, and pedal torque. (And this isn't even with the upgraded controller from WW)
 
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scrambler

Active Member
This is why an Ideal high power bike benefits from separate drive train, one for the motor and one for pedaling.
It lets you use very high throttle power or pedal assist without putting any strain on the pedaling chain and gears.
Example of such a setup are the LMX-64 and the SEM venom.
It does make for a more complex setup...
 

Ebiker33

Well-Known Member
This is why an Ideal high power bike benefits from separate drive train, one for the motor and one for pedaling.
It lets you use very high throttle power or pedal assist without putting any strain on the pedaling chain and gears.
Example of such a setup are the LMX-64 and the SEM venom.
It does make for a more complex setup...
Interesting design out of France on the LMX-64
 

smorgasbord

Well-Known Member
Region
USA
Using a belt drive will obviously remove any flex/play caused phantom shifting.
However, we haven't yet ascertained whether Court's bike just needed an adjustment to reduce the play.
 

pushkar

Well-Known Member
Ill preface this by saying that IMO this is not an ideal use of throttle for the Ultra, or any regular ebike. Goldenmotor equipped bikes (e.g. surron and the variants) do well since goldenmotor can ramp up to a high RPM with a clutch.
Some observations fro the video
1. The climb is pure throttle, starts from dead stop and goes up hill. Unrestricted throttle is essentially 160Nm.
2. It is not clear if the riders are in the right gear.
3. It is not clear if the riders were gunning the throttle at all times. Feathering the throttle on a climb will lead to some uneven torque on the drivetrain.

Noise ?
1. Could be from the chain slipping. (If its not in the right gear)
2. The 2 loud noises at the end could actually be the hub pawls slipping . ( I mean the ones the cassette mounts on actually slip internally!) It does happen (though not as common).


Frame flex -
Frames flex even with normal human power. If you put 150/160Nm torque (that is a human putting their entire weight on the bike while going uphill), from a dead stop, in the wrong gear, it will result in frame flex on any bike. more so on a FS bike. I don't know why the riders are expecting anything different on an e-bike.

Will this happen on WW bikes?
Our throttle is limited to 750W, but the PAS is unrestricted. I would say the flex will be lower since throttle is not putting out that much power.
Riders can actually pedal uphill :) faster than a throttle will take them.
 

pushkar

Well-Known Member
@pushkar
Interesting, what is the recommended gear for climbing steep hills only pedaling then with the Ultra/Gates/IGH ?
Not sure tbh. Lower is better. That being said it depends on what speed the rider had before hitting the incline, what is the grade of an incline,and how much assist you have from the motor.

Anecdotally, Even from a dead stop I’ve almost never needed to go below gear 3 or 4 on the Rohloff / Kindernay. The only spot I had to do gear 2 is at a 30 degree incline that I purposely stopped and started on mid-climb.