CEF50 full carbon, Bafang M820 budget build thread

[forsa355]

I've started this thread to share my lightweight DIY Bafang M820 build, including future upgrades. I used the CEF50 carbon frameset, lots of inexpensive (but decent) components mostly from Aliexpress and used/takeoff forks and shock. Total cost was ~$3,000 U.S. and the result is a machine that packs way above its cost!

Completed weight is 45lbs including pedals and tire sealant. The battery is a rather heavy 720 Wh one. I'll be building a much lighter, caseless one soon. Should be able to get the weight under 40lbs, even with the heavier components I'm currently using. The bike is a beast, super playful to ride and gets tons of compliments on how it looks!

Here's a video I made that shows the full build process and a complete component list is below


Frameset (including custom paint).motor and 720wh battery: Unique Products To Sell Online 2023 29er Full Suspension Carbon Mountain Bike Frame Matte 29er/2.6" Non Toxic Bafang M820 - Buy Carbon Suspension Mtb Frame,29er Full Suspension Carbon Mountain Bike Frame,Frame 29er Full Suspension Product on Alibaba.com

Fork: Rockshox Yari 160mm. Used from Pinkbike
Shock: Fox Float takeoff from a Turbo Levo. 210x52.5mm. Gives 157.5mm rear travel

Custom Wheelset: 85.85￡ |29 Inch Tubeless Mtb Wheel | Koozer Sunringle Wheelset | Koozer Mountain Wheelset - Bicycle Wheel - Aliexpress
Tubeless valve stem kit: 3.0￡ 38% OFF|Tubeless Valve Core Bicycle | Alloy Cycling Diy Accessories - 2pcs/1pair 44/60mm - Aliexpress
SLX shifter/derailleur/cassette/chain combo set: 78.66￡ 50% OFF|Shimano Slx M7100 Groupset 1x12 Speed | Group Shimano Slx 1x12 Kit - Shimano Slx - Aliexpress
IIIPro E4 4 piston brake set: 7.82￡ 32% OFF|Mountain Bike Hydraulic Disc Brakes | Hydraulic Caliper Bicycle Brakes - Bicycle - Aliexpress
Dropper seatpost: 52.13￡ 40% OFF|Ks Exa Form 900i Adjustable Height Seatpost 30.9/31.6mm*395mm Hydraul Seatpost Internal Cable Remote Control Dropper - Bicycle Seat Post - AliExpress
Dropper lever: THE LOAM LEVER GEN 2
Carbon Fiber handlebar: 8.16￡ 34% OFF|Brand New Raceface Next Mountain Bike Matt 3k Full Carbon Fibre Bicycle Handlebar Carbon Mtb Handlebar Red+black Color Free Ship - Bicycle Handlebar - AliExpress
Stem: Ranger V2
Brake rotor: 0.41￡ 92% OFF|Stainless Steel Rotor Disc Brake | Stainless Steel Bicycle Parts - Bicycle Brake - Aliexpress
Head badge: 0.47￡ 91% OFF|Bike Head Badge Soft Aluminum Decals Stickers For Mtb Bmx Folding Bicycle Front Frame Steam Cycling Accessories Emblem Tube Diy - Bicycle Stickers - AliExpress
Grips: 4.04￡ 22% OFF|Odi Mtb Cuffs Mountain Bike Grips Cycling Handles For Bicycle Handlebar Lock On Knob Fists Silica Gel Bar End Silicone Cap Bmx - Bicycle Grips - AliExpress
Carbon fiber bottle cage: 5.17￡ 75% OFF|Carbon Fiber Mtb Road Bike Bottle Holder | Ultra Light Carbon Bicycle Holder - Full - Aliexpress
Pedals: 12.58￡ 31% OFF|Bicycle Pedals Mtb Aluminum | Sixsixone Pedals | Bike Pedals - Sixsixone Sealed Bike - Aliexpress
Chainring: 1.57￡ 81% OFF|Deckas 104bcd Oval Narrow Wide Chainring Mtb | 44t Chainring 104bcd Deckas - Bike - Aliexpress
Star nut fitting tool: 1.55￡ 30% OFF|Bicycle Front Fork Star Nut Fitting Tool MTB Bike Steerer Tube Headset Components Tool Maintenance| | - AliExpress
Shock bushings: 2.6￡ 6% OFF|Shock Absorber Bicycle Mtb | Bicyxle Shock Bushing - Mtb Rear Shock Bushing Bike - Aliexpress
Chainstay protector: 1.73￡ |Protection Chain Bicycle | Mtb Bike Protector Cover Guard - 3d Silicone Mtb Chain - Aliexpress
Chainring lockring tool: 2.3￡ 46% OFF|Bottom Bracket English Thread | Cartridge Bottom Bracket Tool - Bike 8 Bottom Bracket - Aliexpress
Headset: https://www.chainreactioncycles.com/p/nukeproof-neutron-zs56-headset-int-cable-routed
Saddle: https://fortnine.ca/en/deity-speedt...IzD5wj3LMZoroZKdQYj912KxoCrSAQAvD_BwE#76=1272

 

[DirtyCurty]

I was the one asking questions on youtube. Great writeup here! Thank you for all the info. I will be doing a post on my bikes when they arrive! Dealing with Jean was/is great on Alibaba.

 

[forsa355]

I was the one asking questions on youtube. Great writeup here! Thank you for all the info. I will be doing a post on my bikes when they arrive! Dealing with Jean was/is great on Alibaba.

ya considering they are in China, Jean has been great with communication... she'd even wait until morning in North America before contacting me even though it was super late in China.

I think a lot of people are skeptical of sourcing their parts from China and doing a build. The way I look at it, if you build a bike with a factory direct frame from China and components from Aliexpress etc., it's like you are the bike company. You're essentially eliminating the distributor and retailer. Sure, you need patience and it comes with some risk, but in the end you save a lot of money, get a bike spec'd exactly the you want and you get the satisfaction of crafting (or learning to craft) something yourself. I found it very fun building this bike and ended up with a great ride. Not for everyone, but highly recommended!

 

[DirtyCurty]

Very well said I had the same thought.

 

[forsa355]

I've been hopping log and rocks very carefully as I'm paranoid of the reports of the CEF50 motor cover cracking. Will order the updated one, but I did apply the downtube protector they sent with the frame to the motor cover to provide a but more protection. So far working ok, but been avoiding strikes to it as much as I can

I've also upgraded the pads on the cheap 4 piston ///Pro brake set I put on (7.84￡ 32% OFF|Mountain Bike Hydraulic Disc Brakes | Hydraulic Caliper Bicycle Brakes - Bicycle - Aliexpress). For the money (~$100us for complete set) they rock! But the pads that come with them suck... sound like sandpaper on the rotors and come on too quickly. Found out the actually use Hope E4 pads, so got these Cooma metallic ones. Muuuuuch better.... great modulation and pull hard. The pads that came with the brake set have cooling fins, but tbh not something I miss 4.13￡ 50% OFF|Bicycle Disc Brake Pads | Hope Tech Evo 4 Pads | Hope Brake Pads E4 | Brake Pads Hope 4 - Bicycle Brake - Aliexpress

 

[salvaparraes]

Hola forsa, quiero montar tu bicicleta con los mismos componentes que tú, he comprado Deckas-plato ovalado para bicicleta de montaña, piñón 104BCD, que indicas, este plato al ser ovalado se puede instalar en el motor bafang m820. gracias.

 

[patdam]

Hola forsa, quiero montar tu bicicleta con los mismos componentes que tú, he comprado Deckas-plato ovalado para bicicleta de montaña, piñón 104BCD, que indicas, este plato al ser ovalado se puede instalar en el motor bafang m820. gracias.

you can instal (104 BCD) but oval plate will not functioning on Ebike (all). you have an freewheel in the motor, the crank arms changing position in regards of the plate

 

[salvaparraes]

Hola, me puedes pasar los tornillos para sujetar el amortiguador trasero, medidas o enlaces gracias.

 

[salvaparraes]

Hola Forsa Feliz Navidad, antes que nada gracias por tu ayuda, pero agradecería que para un novato como yo pusiéramos un esquema del par de apriete de los tornillos cuandro y motor, como indicastes que revisastes revisamos el cuadro completo y engrasado. No quiero romper el marco apretándolo demasiado.
Muchas gracias y feliz año nuevo 2024.

 

[sandnap]

Thanks for creating the YT video and this thread. You and Rob Rides EMTB inspired me to do a custom build. I am going for a budget LCE930 build using the brakes (+ metallic pads), groupset, wheelset, and dropper post from the links you provided. I am impressed with the quality of the components so far. Just waiting on the frame to put them on.

 

[forsa355]

So I decided to go with a smaller capacity battery to drop some weight as I have, for the most part, been doing short rides on trails near my house and figure a more playful bike is more important than range to me. I replaced the factory 720Wh 36v with a homemade 360Wh 36v battery. I designed a custom 3D printed case for it and the whole thing reduced the weight of the bike by 5lbs! It now weighs just under 40lbs so I guess it could be considered a super light emtb now?

This is my battery next to the factory 720Wh one

I video'd the build process if anyone is curious how to build a custom battery (and also see the inside of a CEF50 frame and how the battery mounts).


If anyone wants the 3D print files, let me know. I plan to upload them to Thingiverse. Also here's a parts list for the components and tools I used:

20 x Samsung 50E 21700 5000mAh 9.8A Battery cells. I got them from 18650 Battery Store - Trusted Supplier of Lithium Ion Batteries
- Spot welder 3.54￡ 79% OFF|99 Gears 8V 24V Spot Welder Kit Digital Power Adjustable Spot Welding Pen Control Board Nickel Sheet For 18650 Lithium Battery| | - AliExpress
- 10S Battery BMS 0.4￡ 90% OFF|Bisida Bms 24v/36v/48v/7s/10s/13s Different Ports Rechargeable 18650 Lithium Battery Protection Board For E-bike/e-scooter - Integrated Circuits - AliExpress
- Heat shrink wrap 1.7￡ 49% OFF|PVC Heat Shrink Wrap Tube Insulation of Width Length 1M Battery Packs30/50/70/200±2MM for Big Battery Pack Power&DIY Projects| | - AliExpress
- Grid nickel strips 2.3￡ 49% OFF|2p 3p 4p 21700 Spcc Nickel Plating Strip Battery Nickel Tape For Battery Spot Welding Machine Welder Equipment Diy Battery Pack - Spot Welders - AliExpress
- Straight nickel strips 2.39￡ 39% OFF|Welding low internal resistance pure nickel strip lithium battery pack Pure nickel sheet power lithium battery connection| | - AliExpress

 

[KnollyBro]

So I decided to go with a smaller capacity battery to drop some weight as I have, for the most part, been doing short rides on trails near my house and figure a more playful bike is more important than range to me. I replaced the factory 720Wh 36v with a homemade 360Wh 36v battery. I designed a custom 3D printed case for it and the whole thing reduced the weight of the bike by 5lbs! It now weighs just under 40lbs so I guess it could be considered a super light emtb now?

This is my battery next to the factory 720Wh one View attachment 133624

I video'd the build process if anyone is curious how to build a custom battery (and also see the inside of a CEF50 frame and how the battery mounts).


If anyone wants the 3D print files, let me know. I plan to upload them to Thingiverse. Also here's a parts list for the components and tools I used:

20 x Samsung 50E 21700 5000mAh 9.8A Battery cells. I got them from 18650 Battery Store - Trusted Supplier of Lithium Ion Batteries
- Spot welder 3.54￡ 79% OFF|99 Gears 8V 24V Spot Welder Kit Digital Power Adjustable Spot Welding Pen Control Board Nickel Sheet For 18650 Lithium Battery| | - AliExpress
- 10S Battery BMS 0.4￡ 90% OFF|Bisida Bms 24v/36v/48v/7s/10s/13s Different Ports Rechargeable 18650 Lithium Battery Protection Board For E-bike/e-scooter - Integrated Circuits - AliExpress
- Heat shrink wrap 1.7￡ 49% OFF|PVC Heat Shrink Wrap Tube Insulation of Width Length 1M Battery Packs30/50/70/200±2MM for Big Battery Pack Power&DIY Projects| | - AliExpress
- Grid nickel strips 2.3￡ 49% OFF|2p 3p 4p 21700 Spcc Nickel Plating Strip Battery Nickel Tape For Battery Spot Welding Machine Welder Equipment Diy Battery Pack - Spot Welders - AliExpress
- Straight nickel strips 2.39￡ 39% OFF|Welding low internal resistance pure nickel strip lithium battery pack Pure nickel sheet power lithium battery connection| | - AliExpress

Very nice! I enjoyed watching both your builds and look forward to hearing about how the bike actually performs. Where abouts are you located? What kind of trails do you like?

 

[Kfec]

Very nice work, congratulation

 

[salvaparraes]

We enjoy your videos and tutorials, you wouldn't be able to indicate the torque of the engine with the frame. Thank you

 

[Regular_Michael]

Love this video, do you think there is enough space for a 48V setup?

I'm looking to DIY my own with a 13S2P setup using 21700 cells that would deliver 10ah and 468wh.

I recon this would be a perfect balance between weight and range for me.

 

[forsa355]

Very nice! I enjoyed watching both your builds and look forward to hearing about how the bike actually performs. Where abouts are you located? What kind of trails do you like?

As soon as the trails are rideable here (don't want to erode them with the current winter conditions) I'll be doing a full ride review video. I live in the Okanagan region of BC Canada. I like flow trails but really enjoy good rocky technical stuff

 

[forsa355]

Love this video, do you think there is enough space for a 48V setup?

I'm looking to DIY my own with a 13S2P setup using 21700 cells that would deliver 10ah and 468wh.

I recon this would be a perfect balance between weight and range for me.

13s2P would totally fit. In fact the case would be about the same size as the 10S2P I built. The case I built actually has spacers front and back because the length of 10 cells lined up is shorter than the spacing of the factory mount holes. So I had to make the case slighter longer to fit the screw spacing. Adding 2 more cells would be about the same as removing the spacers in the case. Does this make sense? Sounds confusing as I type it

 

[KnollyBro]

As soon as the trails are rideable here (don't want to erode them with the current winter conditions) I'll be doing a full ride review video. I live in the Okanagan region of BC Canada. I like flow trails but really enjoy good rocky technical stuff

Frameset (including custom paint).motor and 720wh battery: Unique Products To Sell Online 2023 29er Full Suspension Carbon Mountain Bike Frame Matte 29er/2.6" Non Toxic Bafang M820 - Buy Carbon Suspension Mtb Frame,29er Full Suspension Carbon Mountain Bike Frame,Frame 29er Full Suspension Product on Alibaba.com

I was wondering how much you paid for the frame, motor, battery etc as listed in your link which is currently seems to be selling for $1700 US? After watching your video and looking at your parts list I was wondering if you are able to choose different options like the smaller battery, no shock or cranks if you want, when ordering?

 

[Regular_Michael]

13s2P would totally fit. In fact the case would be about the same size as the 10S2P I built. The case I built actually has spacers front and back because the length of 10 cells lined up is shorter than the spacing of the factory mount holes. So I had to make the case slighter longer to fit the screw spacing. Adding 2 more cells would be about the same as removing the spacers in the case. Does this make sense? Sounds confusing as I type it

Love it, let me know when you list the STL files to borrow/steal

 

[LAnton]

Please post them in this thread. DIY bike 3D print files

 

[forsa355]

I uploaded the 3D printer STL files for the battery case (including cell holders) to Thingiverse. Grab them here: CEF50 10S2P 36v Ebike Battery by forsa355

I also linked them in the 3D print files thread

 

[Phatty]

I was wondering how much you paid for the frame, motor, battery etc as listed in your link which is currently seems to be selling for $1700 US? After watching your video and looking at your parts list I was wondering if you are able to choose different options like the smaller battery, no shock or cranks if you want, when ordering?

Yes you can choose motor voltage (36,43,48) and battery size (360,480,700,720) depending on your motor volts. My first bike I ordered the 36v/720wh and then I just ordered a second for my kid 48v/480wh. had the 48v/700wh option been available when I ordered my first bike I would have gone that route. Ideally there comes an option available for an extender and I think the 48v/480wh is perfect for most everyday rides, and the option of the extender (300wh) would be for a big day in the saddle.
Ive been getting 26 mile routes (3000 feet verticle) and using only 17% of my battery (36v/720wh) which equates to roughly 125wh used for 26 miles, or roughly 4wh per mile. Very happy with the efficiency and lightweight setup of the CEF50.

 

[KnollyBro]

Yes you can choose motor voltage (36,43,48) and battery size (360,480,700,720) depending on your motor volts. My first bike I ordered the 36v/720wh and then I just ordered a second for my kid 48v/480wh. had the 48v/700wh option been available when I ordered my first bike I would have gone that route. Ideally there comes an option available for an extender and I think the 48v/480wh is perfect for most everyday rides, and the option of the extender (300wh) would be for a big day in the saddle.
Ive been getting 26 mile routes (3000 feet verticle) and using only 17% of my battery (36v/720wh) which equates to roughly 125wh used for 26 miles, or roughly 4wh per mile. Very happy with the efficiency and lightweight setup of the CEF50.

Those stats sound great! What size bike did you order for your kid? I am looking to put together a rig for my wife but she is only 5' 1" and even a small might be too bike for her.

 

[Phatty]

Those stats sound great! What size bike did you order for your kid? I am looking to put together a rig for my wife but she is only 5' 1" and even a small might be too bike for her.

A small. Going with 27.5” wheels. He is 5’ right now and growing like a weed. Probably go to 29” wheels next summer and then pass the bike onto sister with the 27.5 again