PaulD's lightweight mid drive development

[maiz]

The short answer is yes. I do still plan on making another batch. I can't pinpoint the date yet, but it will be this year. I'm bogged down with a few big projects right now.

Exciting! Can you point me in the direction of where technical details live? Curious about q-factor and symmetry between cranks.

 

[PaulD]

Exciting! Can you point me in the direction of where technical details live? Curious about q-factor and symmetry between cranks.

Q-factor is about 180mm for a 73mm BB. Q-factor for a 68mm BB is about 175mm. Offset is 3mm towards the driveside. If you use an extra pedal washer or two on the non-drive side that would be pretty close to symmetrical. More info is here: Mid drive kit — Revel Propulsion Ebike Mid Drive Conversion Kits

 

[neptronix]

Interesting!

I noticed on the website you mention a lower Q factor pedal or bb or something..
I was wondering if the Q factor improved, if so by how much.

The lightest.bike mid drive can go all the way down to 122mm x 68mm bottom bracket and has even pedal spacing. So basically, the same spacing on a 7 speed mountain bike.

I don't expect it to be as good as lightest, because of how the drive mechanism is set up here. But i'm looking for something better than a BBS02.

 

[neptronix]

Oh wow, the total Q factor on a regular mountain bike is 170mm, so 180mm with 3mm of offset is great!

Two Q's:

- What's the price of a kit w/o battery, and will it operate on either 48v or 52v batteries?
- Any additional hot rod capability in it, or is the ~650w the thermal stasis point? or will your lawyer not allow you to comment..

 

[PaulD]

I noticed on the website you mention a lower Q factor pedal or bb or something..
I was wondering if the Q factor improved, if so by how much.

The lightest.bike mid drive can go all the way down to 122mm x 68mm bottom bracket and has even pedal spacing. So basically, the same spacing on a 7 speed mountain bike.

I don't expect it to be as good as lightest, because of how the drive mechanism is set up here. But i'm looking for something better than a BBS02.

122mm must be the BB spindle length, not the q-factor. Even pure road bikes have 150mm+ q-factor. You need to add the offset from the crank arms.

At this time, the numbers I mentioned above are the only option. This is limited by the torque sensing BB.

 

[PaulD]

- What's the price of a kit w/o battery, and will it operate on either 48v or 52v batteries?
- Any additional hot rod capability in it, or is the ~650w the thermal stasis point? or will your lawyer not allow you to comment..

- I'll have an update with new pricing in the next few months. And only 36V batteries are compatible. Higher voltages result in motor and crank speeds that are too high.
- No hot rodding allowed There isn't much thermal overhead, and with a small battery more power is just going to drain your pack too quickly. This kit is intended to add minimal weight and that means it intended for small batteries. I am even considering reducing the peak power a bit to move this more inline with the latest generation of lightweight EMTB motors. Although 650W is nice with a fully loaded cargo bike. I have about 3000 miles (between my wife and I) on a kit on a 80lb Yuba long tail, usually with a kid on the back.
This kit is aimed more at people who don't mind pedaling. There is no longer a throttle option. If you want a kit that converts your bike into a lightweight motorcycle, there are lots of options out there.

 

[neptronix]

What a bummer. I actually pedal a ton, but i need more power because there's mountains to climb and couple mile 35mph sprints across roads with traffic that have no bike lane to do. I also have very high rolling resistance tires due to a goathead protection layer necessitated by the locale ( high desert ) . These two factors combined mean i need 1200w of power, and another 300w at the leg ( doable for short periods of time )

Non compatibility with 48v batteries is a bummer because the largest and most common batteries come in that voltage. I like a light motor and a huge battery.

Anyway, good luck.

 

[maiz]

- I'll have an update with new pricing in the next few months. And only 36V batteries are compatible. Higher voltages result in motor and crank speeds that are too high.
- No hot rodding allowed There isn't much thermal overhead, and with a small battery more power is just going to drain your pack too quickly. This kit is intended to add minimal weight and that means it intended for small batteries. I am even considering reducing the peak power a bit to move this more inline with the latest generation of lightweight EMTB motors. Although 650W is nice with a fully loaded cargo bike. I have about 3000 miles (between my wife and I) on a kit on a 80lb Yuba long tail, usually with a kid on the back.
This kit is aimed more at people who don't mind pedaling. There is no longer a throttle option. If you want a kit that converts your bike into a lightweight motorcycle, there are lots of options out there.

The q-factor specs are impressive. I also like the commitment to weight. A bump to 48v would upset the balance, you think? Will this me batch be a v4 with new features/improvements or another v3 batch?

 

[maiz]

Q-factor is about 180mm for a 73mm BB. Q-factor for a 68mm BB is about 175mm. Offset is 3mm towards the driveside. If you use an extra pedal washer or two on the non-drive side that would be pretty close to symmetrical. More info is here: Mid drive kit — Revel Propulsion Ebike Mid Drive Conversion Kits

I wonder about crank lengths as well. I prefer shorter cranks, 155mm, will that be an option or will it be compatible with off the shelf cranks?

 

[PaulD]

The q-factor specs are impressive. I also like the commitment to weight. A bump to 48v would upset the balance, you think? Will this me batch be a v4 with new features/improvements or another v3 batch?

I wonder about crank lengths as well. I prefer shorter cranks, 155mm, will that be an option or will it be compatible with off the shelf cranks?

Going to 48V would increase the crank/motor speed by 33%. That is more than it is designed for. V4 will be very similar to V3.
Off the shelf low offset JIS square taper ebike cranks are compatible. Miranda makes 155mm i believe.

 

[neptronix]

Changing the winding of the stator to accommodate 48v would take the motor speed back to approximately what it was before.