DIY inquiry from those with homebuilt e-bikes

Alanzo

Active Member
I am posting this thread to get feedback from people with e-bike building and modifying experience.

If you have had success with a kit or custom build from scratch, what would you do different on the next DIY e-bike project? Have any homebuilders welded additional frame support in the bottom bracket to handle the the additional torque and stress on a non e-bike frame? Where have you purchased your motors and batteries?

Hoping to get some input of what to consider for a homebuilt e-bike project. My objective is to be self reliant on repair when needed. I use to wrench all my non e-bikes and hoping to do the same with a custom DIY e-bike.

Max speed of the motor system has to be in the lower 30's mph, No throttle assist. Battery capacity range from 50 min - 120 miles max depending on level of assist, Dual suspension with intended use as a road bike.
 

Dewey

Well-Known Member
I really like the BSB-1 Stabilizer Bar I got from California Ebike after 4 years of problems with my BBS01 mid-motor loosening the retaining nuts and rotating in the bottom bracket...no longer :) Essentially a torque arm for Bafang BBS motor kits, they also make a heavy duty version for BBSHD (BSBHD-1), and a version for full suspension bikes (BSBF-1).

Because you don't want a throttle, consider the 750w TSDZ2 motor that uses a torque PAS sensor, or any of the hub motor + bottom bracket PAS torque sensor kits from Grin Tech in Vancouver.
 
Last edited:

JES2020

Active Member
I would get a bigger motor, My suposed 1500w motor is just an over volted 750 probably. I would love even more power maybe 3k watts.
Diffidently love the throttle, quick starts for road crossings and hill management.
I would also stick with a geared hub motor for simplicity, read about too many horor stories with the mid drives. Also keep a controller that allows many parameters of customization, like the KT controllers/displays.
Make sure you sure up your tires to prevent flats, slime inserts etc. For sure get a very LOUD horn, makes all the difference in the world for the sleepwalkers.
 

Dewey

Well-Known Member
For sure get a very LOUD horn, makes all the difference in the world for the sleepwalkers.
Good tip, I fit an Anderson Tap from Grin Tech to power my lights off the battery, it has 3 DC jack's so you could power front and rear lights and have a spare jack left over to power a moped horn
 

m@Robertson

Well-Known Member
Region
USA
I've built a bunch of them. Geared hubs and mid drives, mostly frame-up. I started with the hubs and, when they couldn't handle the hills I wanted to ride in, moved to mids. Mixed into the middle were 2wd builds. You can read the project builds here, of which there is quite a bit of detail on installation and the thinking that went into each..


I spend a fair amount of time on DIY discussion groups and one of my favorite lines - the one that falls on deaf ears the most - is "DIY does not have to mean half-assed" and that is the charitable way to describe most DIY builds, it seems (here on this forum you'll see examples from people who know what the hell they are doing, thankfully).

A big plus is knowing basic and intermediate bicycle mechanics. Proper tools for the job. Knowing what a torque spec is and following it. Understanding why straight chainline is such a big deal with a mid drive. And so on. I actually wrote that blog above not to detail my builds but to put frequently-made explanations into a place where I could link and re-use them rather than having to write them up over and over again as the subjects repeatedly come up.

Where to buy stuff:
Mid drive motors: Luna, California ebike
Hub motors: Grin Technologies, Ebay, Ali Express (depends on how much handholding you want)
Batteries: #1: Bicycle Motor Works - a dependable USA seller who doesn't make a pack until you order it. Litespeed Bikes is another USA seller with a good rep. Luna Cycles has some good Made-in-USA packs that are unique in they are potted and have some unique attributes. Look for their Wolf and Dire Wolf packs for more. As a counterpoint, they are expensive and heavy though. If you absolutely must buy a Shark pack (you shouldn't), the only source I would trust is EM3EV. DO NOT EVER buy a cheap pack from an unaccountable Far Eastern source who *will* be much cheaper. Buy from pack sellers who have *perfect* reps only. This counts out UPP and Liitikala (I think I have that last one spelled right).

Do not screw around with frame reinforcement. Take a welder to a frame and all sorts of heat treatment issues come up. Besides, its never necessary. The mounts - even on a Cyclone - are what you want to reinforce, never the frame. For a BBSHD the dual hoseclamp trick can be done with thoughtfulness so no one even knows its there, plus more. (doubled up inner clamp rings tightened to 100 ft lbs each in particular).

Max speed in the lower 30's: Thats a taller order than you would be led to believe by many ebike builders out there. Working on hot rod cars, there is a common term everyone understands: The "butt dyno". The butt dyno of the car owner as s/he is seated in the driver's seat always measures horsepower and torque far more generously than a real dyno does. Same goes for reported speeds. The actual peak speed on a BBSHD is going to be 32-34 mph, and unless you are that mythical 130 lb rider, its going to take a bit to get up there. Add a front hub motor and ... no difference. It just gets up to that speed quicker. I will skip the (gearing and load) reasons why. Also if you want to be in the lower 30's, you should be using a 52v battery. 48v on say a geared hub is more likely to be peaking around 25-26. Now... if you want to do a Bafang G060, with a KT 35a controller... and a 60v battery... well now you have a bike capable of 40 mph. But range will be a lot less because physics. But that motor can take it and the battery can drive you up to that speed. On a mid: Get yourself a Cyclone, a 60a Kelly or beat the bushes for a Lyen controller and you have an inexpensive monster. Look at a Lightning Rods big block if you want big power but its going to be a project to assemble.

Lots of choices out there. Just look around and spend some time watching people screw up or succeed. thats your best way to learn without making expensive and painful mistakes.
 
Last edited:

m@Robertson

Well-Known Member
Region
USA
I would also stick with a geared hub motor for simplicity, read about too many horor stories with the mid drives. Also keep a controller that allows many parameters of customization, like the KT controllers/displays.
Those horror stories are pretty much always due to the builder not measuring up, or not knowing how to ride the bike, and often both. Hub motors are by far easier for beginners to not screw up, frankly. This is one of the topics I wrote up on that blog specifically because so many builders do a bad job and then blame the platform.

KT controllers FTW :) for geared hubs. They are all I use and I have yet to have a project they didn't do me right on.

I would also not do without a throttle. There's no law that says you are forced to use it and I can pretty much guarantee you'll find a benefit to its use on specific occasions. I am a pedaler myself but if you want to take my throttle you will have to pry it from my cold, dead thumb.
 

Alanzo

Active Member
I really like the BSB-1 Stabilizer Bar I got from California Ebike after 4 years of problems with my BBS01 mid-motor loosening the retaining nuts and rotating in the bottom bracket...no longer :) Essentially a torque arm for Bafang BBS motor kits, they also make a heavy duty version for BBSHD (BSBHD-1), and a version for full suspension bikes (BSBF-1).

Because you don't want a throttle, consider the 750w TSDZ2 motor that uses a torque PAS sensor, or any of the hub motor + bottom bracket PAS torque sensor kits from Grin Tech in Vancouver.
Thanks for posting which resulted in my search for Grin Tech. I just viewed the website. Looks like an excellent place to start with numerous options. Very cool!!
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Many of the same thoughts as posted by Mr. Robertson.

I like to build using a donor bike (must have disk brakes) and/or heavily mod a cheap production bike (with good bones and disk brakes!) that looks like a production bike when done. Only this "production" bike is very likely WAY different than something you can buy! Have done several of each now. All successful projects.

It's about craftsmanship. It's NOT about "see what you can get away with". Sure it take more time (to get the cable and wire lengths correct for instance), and maybe more money, but when it's done, it's right. It's not something that needs to be tinkered with constantly.

Huge on KT controllers too. I've done several KT conversions and just recently ran into my first "bad" controller (surging issue when running PAS only). The ONLY other controller that's impressed me is the one built into the Bafang mid drives (w/UART interface). That one is just over the top....

Recently tried a "fatty" and that one will be my last. Expensive lesson. If you aren't running on snow or beach sand regularly, there are MUCH better ways of doing things. If you're thinking along those lines, look at what they are calling the 27.5"+ wheels and tires (27.5x2.4"-2.8").

Last, it's easy to crack 30mph. It's MUCH more difficult to go very far at those speeds. You need a LOT of power/battery capacity, and a way to monitor your motor, temp cuz it's going to get hot fast.... -Al
 

Alanzo

Active Member
I've built a bunch of them. Geared hubs and mid drives, mostly frame-up. I started with the hubs and, when they couldn't handle the hills I wanted to ride in, moved to mids. Mixed into the middle were 2wd builds. You can read the project builds here, of which there is quite a bit of detail on installation and the thinking that went into each..


I spend a fair amount of time on DIY discussion groups and one of my favorite lines - the one that falls on deaf ears the most - is "DIY does not have to mean half-assed" and that is the charitable way to describe most DIY builds, it seems (here on this forum you'll see examples from people who know what the hell they are doing, thankfully).

A big plus is knowing basic and intermediate bicycle mechanics. Proper tools for the job. Knowing what a torque spec is and following it. Understanding why straight chainline is such a big deal with a mid drive. And so on. I actually wrote that blog above not to detail my builds but to put frequently-made explanations into a place where I could link and re-use them rather than having to write them up over and over again as the subjects repeatedly come up.

Where to buy stuff:
Mid drive motors: Luna, California ebike
Hub motors: Grin Technologies, Ebay, Ali Express (depends on how much handholding you want)
Batteries: #1: Bicycle Motor Works - a dependable USA seller who doesn't make a pack until you order it. Litespeed Bikes is another USA seller with a good rep. Luna Cycles has some good Made-in-USA packs that are unique in they are potted and have some unique attributes. Look for their Wolf and Dire Wolf packs for more. As a counterpoint, they are expensive and heavy though. If you absolutely must buy a Shark pack (you shouldn't), the only source I would trust is EM3EV. DO NOT EVER buy a cheap pack from an unaccountable Far Eastern source who *will* be much cheaper. Buy from pack sellers who have *perfect* reps only. This counts out UPP and Liitikala (I think I have that last one spelled right).

Do not screw around with frame reinforcement. Take a welder to a frame and all sorts of heat treatment issues come up. Besides, its never necessary. The mounts - even on a Cyclone - are what you want to reinforce, never the frame. For a BBSHD the dual hoseclamp trick can be done with thoughtfulness so no one even knows its there, plus more. (doubled up inner clamp rings tightened to 100 ft lbs each in particular).

Max speed in the lower 30's: Thats a taller order than you would be led to believe by many ebike builders out there. Working on hot rod cars, there is a common term everyone understands: The "butt dyno". The butt dyno of the car owner as s/he is seated in the driver's seat always measures horsepower and torque far more generously than a real dyno does. Same goes for reported speeds. The actual peak speed on a BBSHD is going to be 32-34 mph, and unless you are that mythical 130 lb rider, its going to take a bit to get up there. Add a front hub motor and ... no difference. It just gets up to that speed quicker. I will skip the (gearing and load) reasons why. Also if you want to be in the lower 30's, you should be using a 52v battery. 48v on say a geared hub is more likely to be peaking around 25-26. Now... if you want to do a Bafang G060, with a KT 35a controller... and a 60v battery... well now you have a bike capable of 40 mph. But range will be a lot less because physics. But that motor can take it and the battery can drive you up to that speed. On a mid: Get yourself a Cyclone, a 60a Kelly or beat the bushes for a Lyen controller and you have an inexpensive monster. Look at a Lightning Rods big block if you want big power but its going to be a project to assemble.

Lots of choices out there. Just look around and spend some time watching people screw up or succeed. thats your best way to learn without making expensive and painful mistakes.

m@Robertson

THanks! I'll start researching all the components you mentioned in the post. Lower 30's is not the avg speed I am after. Very limited use and no restriction accessing that speed compared to what I currently have. Also good to know I do not have to modify and existing frame with additional welding.
 

RunForTheHills

Well-Known Member
Region
USA
Thanks for posting which resulted in my search for Grin Tech. I just viewed the website. Looks like an excellent place to start with numerous options. Very cool!!
Grin is indeed very cool for DIY and has many great tools on their website such as the motor simulator. Grin sells hub drives, but they do have Bafang mid-drives in the motor simulator if you select the Show All option at the bottom of the motor list. You don't need to weld the frame, but make sure that you use torque arms if you are installing a hub motor. Grin sells torque arms, but not all kits out there include them.

https://ebikes.ca/tools/simulator.html
 

m@Robertson

Well-Known Member
Region
USA
You don't need to weld the frame, but make sure that you use torque arms if you are installing a hub motor. Grin sells torque arms, but not all kits out there include them.
Thats a good point. I will add that many torque arm designs are garbage, but the Grin ones are all well-conceived and manufactured.

Even if you have a motor that is iffy on whether it needs a torque arm... considering that the frame or fork will be irrevocably (unless you have framebuilding/dropout replacement skills) destroyed if things go bad... at least one torque arm is cheap insurance. I have been on the wrong side of this argument and had to wait weeks while a replacement fork was located, after screwing up and destroying a new build 15 minutes after it was completed. Lesson learned.
 

JES2020

Active Member
Good tip, I fit an Anderson Tap from Grin Tech to power my lights off the battery, it has 3 DC jack's so you could power front and rear lights and have a spare jack left over to power a moped horn
I often wondered how I would hook up my 48v scooter horn on a battery that did not have jacks built in, like my battery does. The Grin Anderson Taps are the solution.
Funny story, I removed my handlebar bag, because I really didn't need it, the next time I beeped my horn it hurt my ears, 😲 so I threw the bag back on !
 

RunForTheHills

Well-Known Member
Region
USA
I often wondered how I would hook up my 48v scooter horn on a battery that did not have jacks built in, like my battery does. The Grin Anderson Taps are the solution.
If you buy a Grin kit and a CA v3, it has a DC output at battery voltage that is typically used for lights, but would also work for a horn.
 

Dewey

Well-Known Member
I often wondered how I would hook up my 48v scooter horn on a battery that did not have jacks built in, like my battery does. The Grin Anderson Taps are the solution.
I too have wondered how to make it work, you can get DC jacks with black/red pigtails and that would be simple enough to plug in the jack and connect the negative wire to the horn ring terminal but then you need to wire the positive wire to a momentary switch, the off the shelf moped wiring relay harnesses I've seen typically have a fuse built in but are designed to plug into a 4 or 5-pin automotive 12v socket so I haven't quite figured out how you would wire it up to complete the circuit.
 
Last edited:

JES2020

Active Member
I too have wondered how to make it work, you can get DC jacks with black/red pigtails and that would be simple enough to plug in the jack and connect the negative wire to the horn ring terminal but then you need to wire the positive wire to a momentary switch, the off the shelf moped wiring relay harnesses I've seen typically have a fuse built in but are designed to plug into a 4 or 5-pin automotive 12v socket so I haven't quite figured out how you would wire it up to complete the circuit.
I just wired one of these into the circuit:
The wires are pretty thin but unless you are constantly riding the horn, they will hold up.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
I too have wondered how to make it work, you can get DC jacks with black/red pigtails and that would be simple enough to plug in the jack and connect the negative wire to the horn ring terminal but then you need to wire the positive wire to a momentary switch, the off the shelf moped wiring relay harnesses I've seen typically have a fuse built in but are designed to plug into a 4 or 5-pin automotive 12v socket so I haven't quite figured out how you would wire it up to complete the circuit.
Depending on your battery output connector it can be quite easy to fabricate a tap.
Mine has XT60 so I just soldered one up with dual output and put a 20a fuse for the motor and a 4a for accessories. Then I ran a wires to this switch and added a diode so that the momentary contact for the horn flashes the light.
 

Dewey

Well-Known Member
I just wired one of these into the circuit:
The wires are pretty thin but unless you are constantly riding the horn, they will hold up.
Thanks that looks simple enough, I'd read given the 36v current from my battery it would be good to wire in a fuse as Gionnirocket suggests
 

RunForTheHills

Well-Known Member
Region
USA
Thanks that looks simple enough, I'd read given the 36v current from my battery it would be good to wire in a fuse as Gionnirocket suggests
36V is the voltage and not the current. A headlight or horn won't pull very much current, but of course you could get a short and that is what the fuse protects you from. That is why @Gionnirocket used a 4A fuse for accessories.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
And make sure you use a fuse with the proper DC VOLTAGE rating.
I see far too many using automotive fuses or Glass fuses rated for use with AC voltages.
The difference being that DC requires a larger gap when blown
 

Dewey

Well-Known Member
36V is the voltage and not the current. A headlight or horn won't pull very much current, but of course you could get a short and that is what the fuse protects you from. That is why @Gionnirocket used a 4A fuse for accessories.
Thank you, then current is what I set in my BBS01 controller? So peak power at highest PAS setting would be 18A for me. The Time-Current characteristic curves in the chart Gionnirocket posted suggest as long as I just quickly press and don't lean on the horn button a 4A fuse could handle it. Somewhere I have one of those Wuxing big green buttons but as it has a Higo yellow connector I don't think I could just cut off the connector as I need two wires not three.