'lightest.bike' 1.7kg 1000w mid drive

[Pilot Engineer]

I recently decommissioned my recumbent bike and decided to give fitting the drive on a regular bike another try.

Half a day was spent getting the best chainline, tension, etc to no avail.. the best i can do, is with the medium mount, cover 1/4 of a 46T sprocket. 46T is the absolute limit when accounting for the chain not being able to touch the top of the chainring.
View attachment 361765

Even in this scenario, with the power off, pedaling causes the chain tensioner to move forward significantly, the chain skips on it, then the chain skips on the chainring.. regardless of gear. It will skip with maybe 5% of my leg power applied.

I decided fine.. let's go back to the dual chainwheel configuration.
But.. despite my alignment being +/- 1mm.. the wobble in the lightest bike cranks causes the drive chain to constantly fall off and i have no idea why.

View attachment 361766

Next day after cooling off from the long running frustration, i try a poor man's inframe mount, trying to maximize chainring contact..

View attachment 361775

..now i finally have ~40% chainwrap on a 48T.. maybe enough?

In the tallest rear gear, the chain is not slipping along the gears anymore, but as i shift down to lower gears, the chain starts skipping over the chainring again.. on the lowest gear, the bike is unpedalable and just as bad as the above setup.

When i do have the bike in the largest rear gear, and it's not slipping, i find the feeling of sludgy notchiness coming from the idler quite irritating.

Looking at lightest's page about the different mounts, i notice that even the bike with the inframe mount, which should give an ideal amount of chainwrap, has ~30% chainwrap, which isn't enough to prevent this problem.. so i'm betting this is a problem with all installations.

View attachment 361777


Luckily one of the permutations of dual chainring setup actually works for me w/o the motor chain dropping itself.. it's identical to the the setup that worked on my recumbent.

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Quite a bummer that there's no way for me to avoid this dual chainring setup.. i actually don't see how the single chainring setup could work well..

@neptronix if the idler arm has the plastic sprocket in a too advanced position, then you can move that in the other holes, so that the movement when you pedal will be less. If your chain is skipping, you can install the other chainguides.

 

[neptronix]

Okay, i'll try that.
I have much better crankarms on the way too.

 

[neptronix]

Update from the indiegogo:

42 motors have been shipped! Many of you will soon receive your Lightest ebike kit, and we can’t wait to hear your feedback. If you’ve already received yours, let us know how it’s performing!

New gears are here – and they’re even quieter! We’ve just received the latest gear samples, and after testing them, we’re thrilled with the results: they reduce noise by 12 dB! This marks a significant improvement, making your riding experience even smoother and more enjoyable.

Even more importantly, this reduction happens in the frequency range where the human ear is most sensitive—between 1000 and 2000 Hz—which means a much quieter and more comfortable riding experience.

? What’s next?
We still need to complete full-scale testing over the next two weeks before proceeding with production orders. If everything goes as planned, the motors will start shipping from our facility with the new gears within six weeks.

We’re continuously working to enhance the performance and reliability of the Lightest kit. Thank you for your patience and support—it means the world to us! ??

Stay tuned for more updates, and happy riding! ?‍?

 

[neptronix]

170mm Shun freewheeling crank installed on mine.
Keeping on the freewheel that comes on the Shun crank, the crank wobble is reduced to what i'd expect is normal for a bike crank ( ~1.5mm of total lateral wobble )

I would feel confident about trying the original single chain configuration with these cranks.

Outward offset on the cranks is +1-2mm versus the original 165mm Bikee cranks. Good, that's not hurting the Q factor much.



I have the legspan of a 6" 2' person so the 165mm pedals never felt right, like i couldn't get enough power into the cranks. The 170mm is just allright in that aspect. I really want 175mm.

The Shanmashu big dog pedals i recently bought help counteract the added Q factor. They have the pedal closest to the axle. So if your foot wants to go inward, it can while still having something to leverage against. I notice i ride the inner edge of this pedal.

This can allow you to step -10mm inwards if that's what your body likes doing.


Between these two changes, i should be effectively within a few millimeters of the bike's stock Q factor so that's pretty awesome.

Love the swappability of parts on this thing.

 

[amberwolf]

New gears are here – and they’re even quieter! We’ve just received the latest gear samples, and after testing them, we’re thrilled with the results: they reduce noise by 12 dB! This marks a significant improvement, making your riding experience even smoother and more enjoyable.

Even more importantly, this reduction happens in the frequency range where the human ear is most sensitive—between 1000 and 2000 Hz—which means a much quieter and more comfortable riding experience.

I wonder: is this because they are made more precisely and better mesh? Or is it because they are made of something that deforms under load more in some way to dampen the vibrations generated?

 

[neptronix]

I'm told that the machining is improved.

 

[neptronix]

Bought a 29er and now that i have cranks that are straight, i'm going to attempt a single reduction configuration so that i can get the 'director's cut' experience

 

[Atos62]

Found something nice:

 

[Atos62]

https://www.ratiozero.com/VID_20230623_082049-2.mp4