Any DIY mid drives that provide a stock q factor and equal distance from frame center line to both pedals?

[ebike4healthandfitness]

As a reference point the typical human powered mountain bike has a Q factor of 168mm to 170mm. (This q factor is currently achieved +/- 5mm by integrated frame mid drives (e.g. Yamaha, Bosch, Shimano, Bafang) found on factory pre-built ebikes.)

P.S. The typical human powered road bike Q factor is 145mm to 150mm and the typical human powered fat bike Q factor is 200mm to 230mm.

 

[ebike4healthandfitness]

This one claims 175mm q factor for 68mm BB:

Lightest ebike kit

Lightest ebike motor is an innovative bicycle drivetrain which combines superior performance and lightweight design.

lightest.bike

With a Q factor of only 175mm for BSA 68mm bottom bracket, the Lightest ebike kit has the best Q factor comparing to other ebike kits. It will feel as if you're pedalling on a regular bike

 

[docw009]

Have you been following the lightest ebike motor threads? Its' pretty dreary to me as an outside observer.

I've been lucky in that the Q-factor doesn't affect my pedalling. I own a BBS02B, TSDZ2 and hub motor ebikes with 68mm and 100mm BB widths. I really cannot tell the difference, but I know it causes pain for some people with knee issues.

 

[ebike4healthandfitness]

Have you been following the lightest ebike motor threads? Its' pretty dreary to me as an outside observer.

I'm reading the main thread at the moment.

There is a new double chainring configuration now:

'lightest.bike' 1.7kg 1000w mid drive

Thanks for your advice! With the mid mount, I'm a couple millimeters away from clearing the head tube. If i managed to clear the head tube, it would look incredibly goofy because it'd look like the front of the bike has a motor boner. :LOL: It is true that with the inframe or hybrid mount...

endless-sphere.com

I guess the question is how much drive side offset does this add compared to the single chainring configuration?

And when the resulting unequal pedal distance to R and L pedal spindles is corrected by a larger crank offset on the non drive side how much does q factor increase?

P.S. I Really like this dual chainring configuration due the various gearing options it adds going beyond small wheel diameter bikes.

 

[neptronix]

I guess the question is how much drive side offset does this add compared to the single chainring configuration?

And when corrected by a larger crank offset on the non drive side how much does q factor increase?

I see an additional 3mm offset on the right pedal on my 123mm wide bottom bracket i got with the lightest kit.
The stock bottom bracket for 68mm is 127mm wide but the narrower one works fine with this kit.

The Revel Propulsion kit looks like it would maintain normal pedal spacing like the lightest but it needs a 36v battery, weighs more, has less power, costs more, and is probably less efficient than the lightest.

I don't know of any other kits that have very close to normal Q factors. You can rule out Bafang, Tongsheng, CYC, GNG, MXUS, etc for sure, they all use goofy spacing that compromises biomechanics

 

[ebike4healthandfitness]

I see an additional 3mm offset on the right pedal on my 123mm wide bottom bracket i got with the lightest kit.
The stock bottom bracket for 68mm is 127mm wide but the narrower one works fine with this kit.

Thanks. Did the q factor change?

Am I correct in that the chain line moved inward a bit?

 

[neptronix]

Everything moved inward a tiny bit, the motor sprocket has to be flipped or repositioned with spacers to accommodate this slightly narrower configuration.

If you're okay with ditching the chainring freewheel, you could get even narrower.

 

[ebike4healthandfitness]

Everything moved inward a tiny bit, the motor sprocket has to be flipped or repositioned with spacers to accommodate this slightly narrower configuration.

Thanks.

Do you think it would be possible to run the motor sprocket on the inner chainring and use the outer chainring for pedaling?

The reason I ask is because I am intrigued by the idea of using a big chainring for the motor (to increase gear reduction) while using the outside chainring (for pedaling) to preserve chainline for use with wider tires.

The Jones HD/e frame would allow me the opportunity to use a very large chainring on the inside:

 

[neptronix]

Yes that's the idea of the dual chainring configuration for the lightest.

This would allow you to run oversized gearing ( 13-14T as your lowest gear ) and still be able to hit the top speed of the drive ( 30-32mph? ), at the expense of ~2% efficiency ( extra chain friction )

Alternatively if you have a 29er then you could get a mid mount and run a 42T-48T chainring.. this should hit ~30mph with the right gearing in your cassette and you'd get to keep the efficiency of skipping a reduction stage.. but oversized gearing for a drivetrain reliability boost is basically out of the question.

Adjusting the chainline should be no issue, the way the lightest is adjusted is highly flexible and you're always a couple spacers away to get a perfect chainline.

 

[ebike4healthandfitness]

Yes that's the idea of the dual chainring configuration for the lightest.

This would allow you to run oversized gearing ( 13-14T as your lowest gear ) and still be able to hit the top speed of the drive ( 30-32mph? ), at the expense of ~2% efficiency ( extra chain friction )

Alternatively if you have a 29er then you could get a mid mount and run a 42T-48T chainring.. this should hit ~30mph with the right gearing in your cassette and you'd get to keep the efficiency of skipping a reduction stage.. but oversized gearing for a drivetrain reliability boost is basically out of the question.

Another thing to consider is the advantage of using shorter cranks (which of course need lower gears to compensate for the lower torque).

Why Shorter Cranks Are Better (According To Science) - Pinkbike

There aren't many win-wins in mountain-biking, but shorter crank arms could be just that.

www.pinkbike.com

For people who haven't studied this topic yet (or read the link above) keep in mind High cadence at low torque = low cadence at higher torque = same pedal speed for both combinations (re: pedal speed is the same is because although the short cranks travel more revolutions per unit time the distance traveled per revolution is less than the distance the long cranks travel per revolution).

 

[Zambam]

Measured my TSDZ2 mid drive to have 210 mm Q factor. (My carbon fiber road bike Q is 160 mm).
Pics show the crank offsets which is around 20 mm each. I'd like to try less offset but it's not a parameter on cranks listed for sale from what I've found. I think my right crank can be zero offset and still clear the chain stay, left crank can accommodate a 5 mm offset. Where can I find and buy them at a reasonable price?