'lightest.bike' 1.7kg 1000w mid drive

rivers said:

I purchased the offroad option and it works without further ado. There's a big R (Race) on the home screen.

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Update for clarification:
I have the 250 watt version.

My Home Screen. Throttle toggle, torque sensor toggle, no race button. Latest APK from Bikee site.

nervagon said:

I'm actually about to hop on the Photon train, dude. I can't take this shit anymore. Spreadsheets, unlock codes, very weird business decisions, etc.

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I can see why you're super frustrated.
Sent them an email to ask about the 48v/52v issue.

Also, look at the battery icon at the top of the app. 56.9 volt is showing as less than half a charge remaining. That is completely wrong on a 52V pack. I've double checked my battery settings. It just doesn't properly display the battery percentage.

So what the heck does that cell voltage selector do anyway if it doesn't adjust the meter... hmmm

neptronix said:

So what the heck does that cell voltage selector do anyway if it doesn't adjust the meter... hmmm

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I know, right? Like usual, I'm just left with more questions.

There's probably another "upgrade" to buy a setting to make a working meter display.

amberwolf said:

There's probably another "upgrade" to buy a setting to make a working meter display.

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Superhero Super-battery meter upgrade pack! On sale now for 88 euros! Get your QR code today!

Sad to that the noise is bad And the other issuses as well.
It would nice if you could post a little riding video of it, as it is very few of them.
And they seems to have very different sound the few of them i have seen.
The last one on the owners group on facebook didnt sound too bad.
So we can hope it quiets down with the time.

I'm still waiting on mine a 1000w high torque.
I am putting it on a Mondraker Foxy. I hope it turns out fine.

I dunno, this might be too boring and easy for you after this Bikee ordeal. Photon or TSDZ2, you had better start charging your battery because that literally takes longer than to install either of these motors and be ready to ride.

nervagon said:

I'm actually about to hop on the Photon train, dude.

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Golo said:

Sad to that the noise is bad And the other issuses as well.
It would nice if you could post a little riding video of it, as it is very few of them.
And they seems to have very different sound the few of them i have seen.
The last one on the owners group on facebook didnt sound too bad.
So we can hope it quiets down with the time.

I'm still waiting on mine a 1000w high torque.
I am putting it on a Mondraker Foxy. I hope it turns out fine.

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The worst part about the noise is that it isn't white noise that can be tuned out or in ignored by your brain. Because of the torque sensor based operation it goes rrrrr.....rrrrrr.....rrrrrr......rrrrr....rrrrrrr. It's not a steady sound. For me it's more tolerable in throttle mode.

Which brings me to cadence vs torque in theory vs in practice. For me, the best thing about torque sensing is the instant engagement. Beyond that, BBSHD cadence isn't really that inferior. On my BBSHD I have 10 levels of assist that I cycle through to fine tune my human vs machine power levels. The actual experience, or ride feel is not all that different from the ride experience on the Lightest kit. It might just be the torque sensor on the Lightest kit. It is modulating the PAS based solely on chain tension.

In my limited experience, any amount of pedaling instantly puts the chain under full tension, and there just isn't a lot of modulation happening between light pedaling and vigorous pedaling... and that makes sense... just look at the design. Once you have pulled the chain tight, that's it... how can the sensor receive more data beyond that. I'm not saying that there is no modulation, but it is very, very subtle.

If you are hesitant to go to dual chainring because you can't live without the torque sensor, I'm saying yes you can... you can live without this torque sensor. You will lose the instant engagement, but the experience won't be much different. What am I judging this against? I built a torque sensing GRIN-based rear hub bike for my wife. The torque sensing bottom bracket on that bike just had a premium and fine, granular feel that the Lightest kit just lacks. There just isn't any comparison between the two. The Lightest kit just feels more like basic PAS.

I don't know about this one but most torque sensors employ some sort of strain gage that DOES modulate power. Just because you can't see any more movement once the chain takes up all the slack, a properly designed strain gage captures micro movements that measure how much force you are putting into the pedals. Most are probably not really accurate in an absolute sense, but are in a relative sense, as in more pedal pressure gets you more assist, just not to a highly accurate level.

nervagon said:

Once you have pulled the chain tight, that's it... how can the sensor receive more data beyond that. I'm not saying that there is no modulation, but it is very, very subtle.

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So it has more of an an on-off switch type feel.. engaging per pedal stroke, then disengaging..
That's really unfortunate if so, basically it's a PAS, without the averaging/smoothing that makes a PAS roughly tolerable.

I wonder if this wouldn't be as bad on my 42T with a 48v battery.

neptronix said:

So it has more of an an on-off switch type feel.. engaging per pedal stroke, then disengaging..
That's really unfortunate if so, basically it's a PAS, without the averaging/smoothing that makes a PAS roughly tolerable.

I wonder if this wouldn't be as bad on my 42T with a 48v battery.

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Yes, my experience, and I just did a couple laps to make sure I'm not crazy, is that it is kind of an on/off feel while you ride. Yes, it feels like cadence PAS without the smoothness. For another example, I have trouble lightly pedaling through a shift... almost feel like I need a shift sensor, whereas on my wife's torque sensing bike I've never felt the need for a shift sensor. I've been through the calibration twice.

Also, I cheated the governor by setting the wheel size to 14" and running a GPS speedo app on my iphone. I would say for purely pedaling, anything above 27mph on 29" wheels is just not practical on 52V. I am already clown pedaling like crazy with my tiny chainring, but at 27mph the motor has already peaked. Again, due to my 36T chainring, pedaling that fast is just not enjoyable anyway.

And looking at Bikee's charts showing max speed of almost 25mph on 27.5" wheels, my experience of 27mph on 29" wheels tracks.

I think to comfortably travel at class 3 speeds and above, dual chainring is the way to go.

I feel like I should do 2 more things before bringing the Bikee adventure to a close. I should go do a throttle-only top speed on a flat stretch, and do a quick ride on my wife's torque sensing bike again for comparison.

OK, both tasks done.

Lightest top speed throttle only on flat with 29" wheels and 52V battery: 27.3 mph (via GPS) (Edit: mine is the 750W version)

Test ride on wife's GRIN-based torque sensor bike: totally different feel. The pulse...pulse...pulse feeling is not there like it is on the Bikee. Wife's bike has steady and consistent PAS based on effort. Felt very nice actually. Bikee doesn't compare. I don't know why.

Got some math back from bikee ppl.

You have to do this operation to get the rider cadence:
450 * pinion size / chainring size

For example with a motor pinion of 10T and chainring 36T you get:
450 * 10 / 36 = 125rpm

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450v turns out to be the unloaded speed on 48v. So we have a 9.375kv motor

So what is the loaded speed? let's take an educated guess with a motor of similar efficiency, shengyi sx2 standard winding ( peaking at 88.2% eff )

The difference between loaded and no-load speed is 12.5%

87.4% of 450RPM is 393.75

At 48v:
36T chainring: 109 RPM <-- approximately the max for a short mount
42T chainring: 93.75 RPM <-- approximately the max for a mid mount
46T chainring: 85.0 RPM <-- requires the hybrid or long mount to fit a chainring this large
48T chainring: 82.0 RPM <-- May require long mount

At 52v: ( add 8.3% speed because this is a 8.3% difference in voltage )

36T chainring: 118 RPM
42T chainring: 101.5 RPM
46T chainring: 92 RPM
48T chainring: 88 RPM

I would bet we're +/- 5 RPM from reality with these calculations.

I consider anything above 95RPM to be too high.

..yeah, the dual chainring system would be better because you could adjust chainring sizes and adjust the cadence to your preference.

It's been fun following your build. Thanks for the detailed documentation. Do you know the weight of the Bikee kit that's added to the bike? I just installed a Tongsheng TSDZ2 kit and it adds around 11 lbs to the bike (currently @ 42 lbs)

nervagon, you are just too much of a powerhouse and pulling the torque sensor to full deflection with ease!
In reality, results on torque sensing will vary by install as it looks like the standard and in-frame style torque arm are slightly different length and motor orientation/spacing probably affect sensitivity.
Is a stiffer spring on the torque arm a possibility?

Good thing you found a way to game the system, lol.
That's an impressive speed for a 36T chainring actually, i think this indicates the high cadence..

Are you sure you don't want to try a mid mount with a bigger chainring? i have a mid mount if you want it.

neptronix said:

Good thing you found a way to game the system, lol.
That's an impressive speed for a 36T chainring actually, i think this indicates the high cadence..

Are you sure you don't want to try a mid mount with a bigger chainring? i have a mid mount if you want it.

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Keep in mind, the chainring is invisible to the motor in this config. So 27.3mph is the max this motor can do with any chainring. Gearing above that doesn't make any sense.

I don't want to have my motor sitting half-way up my downtube. I freaking hated it. But thanks for the offer!

rhauff said:

nervagon, you are just too much of a powerhouse and pullIng the torque sensor to full deflection with ease!
In reality, results on torque sensing will vary by install as it looks like the standard and in-frame style torque arm are slightly different length and motor orientation/spacing probably affect sensitivity.
Is a stiffer spring on the torque arm a possibility?

Click to expand...

Yes, the thought has occurred to me that the spring in the torque arm is too weak for bigger dudes. That is probably the issue.

I would love to know how many human watts the testers of this motor were putting down. Probably 100W-150W.

Zambam said:

It's been fun following your build. Thanks for the detailed documentation. Do you know the weight of the Bikee kit that's added to the bike? I just installed a Tongsheng TSDZ2 kit and it adds around 11 lbs to the bike (currently @ 42 lbs)

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Haven't weighed the bike. I'll just say that without the 21Ah battery it still feels like a bicycle. Keep in mind, this is a heavy duty Police service bike to begin with.

neptronix said:

Got some math back from bikee ppl.



450v turns out to be the unloaded speed on 48v. So we have a 9.375kv motor

So what is the loaded speed? let's take an educated guess with a motor of similar efficiency, shengyi sx2 standard winding ( peaking at 88.2% eff )

The difference between loaded and no-load speed is 12.5%

87.4% of 450RPM is 393.75

At 48v:
36T chainring: 109 RPM <-- approximately the max for a short mount
42T chainring: 93.75 RPM <-- approximately the max for a mid mount
46T chainring: 85.0 RPM <-- requires the hybrid or long mount to fit a chainring this large

At 52v: ( add 8.3% speed because this is a 8.3% difference in voltage )

36T chainring: 118 RPM
42T chainring: 101.5 RPM
46T chainring: 92 RPM

I would bet we're +/- 5 RPM from reality with these calculations.

..yeah, the dual chainring system would be better because you could adjust chainring sizes and adjust the cadence to your preference. I doubt most people would prefer a cadence over 90RPM.

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So the 118rpm Cadence on a 36T chainring is tuned for Lance Armstrong's final sprint to the finish line! Perfect for the average ebiker, haha.