TEKTONIC 2 - mid drive system
I been working on this bike for past 2 years, I went through 3 prototypes before I designed this one.
This bike has serious punch and is currently running on 3KW brushless motor.
Its capable of reaching up to 40mph, it's my daily commuter and been reliable.
I don't know what's your local regulations about ebikes, better do some research before getting into this build.
Main benefit of having mid drive system is that motor is linked to your rear gears. That allow you to climb steep hills or fast ride downhill without stressing motor, it feels like riding motorbike.
Thanks to freewheel mechanism I'm able to pedal without engaging gearbox.
Obviously bikes have different geometry, It fits Boardman comp large size frame, you will have to design your own brackets for different kind of frame.
These parts need to withstand strong forces, print it in 100% infill.
I recommend PETG filament or any other high strength plastic (PLA won't do)
This is difficult assembly, you gonna need various tools as well as be able to make threads using tap and die.
In general you need bike with decent components like:
Good quality rear wheel (cheap ones aren't strong enough and freehub will break)
I recommend Mavic Crossride wheels, they are MTB wheels slim enough to fit road bikes.
I been riding it for 10 months without problems
I STRONGLY recommend to use hydraulic brakes, with all that extra power and weight you will need decent brakes, I tried mechanical disc brakes and they weren't sufficient.
Decent rear derailleur, something like SRAM X9 or better.
Front and rear suspension makes big difference.
Battery - any LI-PO battery with 4cells (4S) and capacity around 10000mah, you gonna need 2 of them connected in series to create 8cell (8s) battery. Reason for using 2x 4S batteries is because its hard to find charger that can charge more than 6 cells.
You will need to modify front chainring - My bike has 2 speed chainrings, main ring is driving main chain, second smaller one is linked to gearbox. Its important to increase space between these two chainrings. In order to do that you have to buy bolts for 3 speed chainring (they are longer) and fit spacer between chainrings:
Using M12 Die make threads on both ends of the rod. Remember to make one thread longer to fit freewheel.
Drill locking holes for pulleys
Pulley set 1:
Pulley set 2:
Home made freewheel adapter. I made one using drill stand its not perfectly straight but works fine. To make one you need large diameter die with bicycle type thread (hard to obtain). If you have trouble making one contact me and I might make one for you.
Daily commuting for 2 years wear and tear update:
Gearbox works perfectly fine, its maintenance free.
Aluminum bar sticking out is part of belt tensioner, if your belt is slipping you need go add one. Its basically 3 bearings sandwiched between aluminum bars.
Wear and tear on sprockets:
By looking at the chain and sprockets I cannot see any significant wear, everything looks like after regular cycling .
You can see mild still rods rusting, unfortunately I don't have tools to tap stainless steel, if you can then go for it.
After 1 year of cycling my rear Mavic crossride wheel got damaged. Keep in mind that I'm often cycling offroad at high speeds.
I replaced it with stronger Mavic crossmax offset wheel. Offset should compensate for extra forces generated by motor.