Advice on hub motor project?

W

Weavecol

100 µW
Joined
Jan 18, 2024
Messages
7
Location
Washington
I'm attempting to turn a SSR 110 pit bike into sort of a hybrid mini Rokon with a front hub motor and a few other modifications. Although, I don't have any experience with electronics and I'm having a hard time sourcing information. I'm really just looking for where I even need to start and what components I'll need to make it functional optimally without burning it up. l'm looking for a lot of torque over speed. I was able to source a lifepo4 battery off amazon with good reviews but is there a better option? Additionally I’m trying to use some taller and wider ATV tires, approximately in the 20x6 range but I’ll work with whatever is closest with hub motors. I would really appreciate any help.
 
Weavecol said:
I'm attempting to turn a SSR 110 pit bike into sort of a hybrid mini Rokon with a front hub motor and a few other modifications. Although, I don't have any experience with electronics and I'm having a hard time sourcing information. I'm really just looking for where I even need to start and what components I'll need to make it functional optimally without burning it up. l'm looking for a lot of torque over speed. I was able to source a lifepo4 battery off amazon with good reviews but is there a better option? Additionally I’m trying to use some taller and wider ATV tires, approximately in the 20x6 range but I’ll work with whatever is closest with hub motors. I would really appreciate any help.
Click to expand...
This is a work in progress, but the first link, "Parts of an Ebike System" from Grin's website, may provide some of the fundamentals
endless-sphere.com

DIY Newb FAQ?

I think I've read through all of the stickies in the ebike forums, which provide great guidance. Yet, I see a lot a new folks getting into ebikes and posting questions that are not in the stickies, or are embedded somewhere among the existing stickies. Another observation is there are...
endless-sphere.com endless-sphere.com
 
Weavecol said:
I'm attempting to turn a SSR 110 pit bike into sort of a hybrid mini Rokon with a front hub motor and a few other modifications. Although, I don't have any experience with electronics and I'm having a hard time sourcing information. I'm really just looking for where I even need to start and what components I'll need to make it functional optimally without burning it up. l'm looking for a lot of torque over speed. I was able to source a lifepo4 battery off amazon with good reviews but is there a better option? Additionally I’m trying to use some taller and wider ATV tires, approximately in the 20x6 range but I’ll work with whatever is closest with hub motors. I would really appreciate any help.
Click to expand...

Some thoughts:


With a 6"+ tire, you're probably going to have a very long axle. You'll need to measure the fork you're going to use for it's inboard dropout width, and then find a motor that has a long enough axle to fit that. It's a fair likelihood you'll end up with a (large) motorcycle hubmotor, or have to get something with a custom axle, etc. QSMotors has been known to do those, and they can probably supply it built into whatever rim size you need for the tires you want to use.

Then you'll need to custom make mounting hardware (torque plates, clamping or pinching dropouts, etc) to secure the axle to the fork (since your fork is almost certainly not designed to secure a hubmotor axle). This hardware will be designed around the specific motor's axle you get, as well as the specific fork you have.


To find out how much motor you need, how big a controller, what kind and size of battery, etc., you'll first need to define the specific job you want the system to do for you (speed, range, acceleration/torque, features, etc), under what specific riding conditions you have (terrain, slopes, winds, total weight, etc). Defining a budget at the same time is helpful.

Once you define those things, then you can use simulators and calculators like those at ebikes.ca to guesstimate how much power (watts) it will take to do what you want, and what voltage and current combination works best to provide that power for your needs/conditions, and what power usage over time you expect (wh/mile) to guesstimate how much battery capacity you need to get the required range.
 
Contacted QS Motor and was recommended their 3000w v3 mid drive motor. They claimed it was rated IP67 but also said you can’t put it into water. Apparently at that rating it could be submerged in 3ft of water for 30min so I’m confused. Any recommendations on a waterproof motor?
 
I’m trying to set up a mini bike to be 2wd but with the solution I’ve come up with I’ll be adding 60lbs of motor and battery. Is there a lighter option for a 4000w motor that would work with atv tires?
 
Last edited:
Well the motor I currently have picked out weighs 27lbs and with the battery I’d need the gross weight will be 60lbs.
 
I haven't seen any hubmotors that are truly waterproof.

You can watch Justin_LE's video from several years back on the Grin Tech ebikes.ca blog pages to see the various problems with waterproofing one.

Water resistance is relatively easy, but it's easier to coat the insides with rust-prevention materials and install drains for water that does get in than it is to keep *all* of it out.

If it's waterproof enough to keep *most* water out, it will *also* keep all the water in that does get in there. :(


What are your riding / usage conditions that require waterproofing? Maybe knowing what you need to do, suggestions could be made for dealing with it.
 
amberwolf said:
I haven't seen any hubmotors that are truly waterproof.

You can watch Justin_LE's video from several years back on the Grin Tech ebikes.ca blog pages to see the various problems with waterproofing one.

Water resistance is relatively easy, but it's easier to coat the insides with rust-prevention materials and install drains for water that does get in than it is to keep *all* of it out.

If it's waterproof enough to keep *most* water out, it will *also* keep all the water in that does get in there. :(


What are your riding / usage conditions that require waterproofing? Maybe knowing what you need to do, suggestions could be made for dealing with it.
Click to expand...
Thanks for the reply👍 I’ll be riding through a lot of rain storms, snow, and deep puddles.
 
Unfortunately, motor wattage isn't a useful metric by itself to help you pick a motor.

To pick a motor, you have to know the actual mechanical specs your system will require, such as axle length (and any diameter limits), dropout width, max motor diameter and width, torque required, speed required, battery voltage, tire diameter, rim type, duty cycle, etc. Must also know what your max motor weight limit is.

Knowing at least those things, you can eliminate any motors that don't have all of the characteristics required.

Things like rim type are needed because if you are using a spoked rim the motor must have flanges for that, spaced for the rim's holes.

Things like speed required / battery voltage / tire diameter are needed to know how fast the motor has to be able to spin at the voltage you have.

Torque required plus diameters are required to know if a motor will give you sufficient torque.

Duty cycle is needed to know if the motor has to do this full capability all day long, or if you only need short bursts of full capability, with the rest of your ride being much less (how much less?) hard on it.


You might also need other info to be sure it would work.
 
If they don't salt your roads, you can probably get away with coating the insides (there's posts and threads about that in the various waterproofing and/or motor cooling threads, and the rust-restoration ones), and installing a drain for the water that does get in. There's stuff about goretex vents, too.

If they salt the roads, you might have to be more extreme in sealing the important bits inside away from that stuff.
 
Ok, this is gonna sound nuts...

3m's waterproofing spray.

I know, you are thinking "for clothes right?" Yup, thats the stuff.

When I was in the army, we had shiney new night vision units that ya strapped to your brain bucket, and ... if it was even misty they died. (Gen 3 for anyone wondering) and this was a regular issue, I was getting my ass handed to me for my unit constantly sending them in for bench repair because they would flicker/stop working when it was moist out (I was in Georgia, it was *ALWAYS* moist out) as a young officer I tried my best to make the army work for my troops, not the other way around.

It took a bit but I finally went to the e4 mafia and asked for an answer, 10 minutes later I was signing off on a dodgey medical excuse and receiving a case of spray cans. Yes, we fixed the problem by spraying the shit out of the units before every op. No more failed units, no more bench repairs and another win for the E4 mafia...

My plan with the dual hub-motor unit I have on the bench now includes a shit tone of 3m spray while it is raining and I know my 12 y/o is gonna snatch that beast the minute I am out of the room.
 
I have a 3kw motor in my garage, it don't weigh shit, which is why it is in the garage with a burnt coil... The variability of a 3hp electric motor is kind of wacky doodle all over the place. I have a .75hp pump unit that the motor weighs in at like 1.4kg, and it never hiccups even under max load. I have a few bench tools with 3hp motors, one works perfectly, the other is pulled and is awaiting my time to replace the motor because the one it came with is a POS.

You have *some* datum there.

You want a lighter motor because motor+batteries weighs 60 pounds.

That is awesome, but is that 2 pounds of batteries and a lead motor weighing in at 58 pounds?

What voltage are you looking for?

size constraints? or just weight? (you can loose motor frame mass but have to make it up with greater surface for cooling)

the folks here put up with my ignorant bum, but they do require you cough up more details than "it is blue, which everyone know is slower then the red ones" The more detail you provide, the better answer you get.
 
What kind of axles does this bike have? motorcycle axles? bike axles? do you need chain drive?
 
DaLanMan said:
I have a 3kw motor in my garage, it don't weigh shit, which is why it is in the garage with a burnt coil... The variability of a 3hp electric motor is kind of wacky doodle all over the place. I have a .75hp pump unit that the motor weighs in at like 1.4kg, and it never hiccups even under max load. I have a few bench tools with 3hp motors, one works perfectly, the other is pulled and is awaiting my time to replace the motor because the one it came with is a POS.

You have *some* datum there.

You want a lighter motor because motor+batteries weighs 60 pounds.

That is awesome, but is that 2 pounds of batteries and a lead motor weighing in at 58 pounds?

What voltage are you looking for?

size constraints? or just weight? (you can loose motor frame mass but have to make it up with greater surface for cooling)

the folks here put up with my ignorant bum, but they do require you cough up more details than "it is blue, which everyone know is slower then the red ones" The more detail you provide, the better answer you get.
Click to expand...
I’m new to this so I’m going off the specs that are listed with the products. The battery is a 72v 30ah LifePO4. It claims to weigh 42lbs. The motor is 4kw v3 mid mount motor from QS Motor and they say it weighs 27lbs. So it’s actually almost going to be 70lbs total.
 
neptronix said:
What kind of axles does this bike have? motorcycle axles? bike axles? do you need chain drive?
Click to expand...
I’m using it to replicate the front tire drive assembly you see on the more recent Rokon motorcycles. But instead of using a crankshaft that limits turning I’ll be using an electric motor. I think I’ll also benefit from this hybrid build for if one drive system fails I can still get out of somewhere without pushing it 20 miles. Regardless, it will be using an axle for a 7in wide, 10in diameter atv rim and a chain drive system from the motor.
 

Attachments

  • IMG_3414.jpeg
    IMG_3414.jpeg
    227.5 KB · Views: 7
Why not use a marine motor designed for boats or ejet boards? Like:
flipsky.net

Fully Waterproof Motor Brushless Sensorless 85135 140KV 8000W for Efoil | Ejet boards

Spec: Dimension/mm:D85L135 Shaft diameter/mm:Φ12 KV(RPM/V):140KV Volt range :28~100.8V(6-24S) Max current/A :190 Max power/W:8000 Rate power/W:4000 Operation voltage:8.5V Max torque@60%(N*M) : 21.8 Waterproof level：IP68 Max RPM: 10584 Number of pole pairs:5pairs Current without sensor@8.4v: 1.5A...
flipsky.net flipsky.net

For connectors, just cut them off and use solder seals:
 
..we're referring to something with a motorcycle chassis, right?

Moved this thread to the moto section so you can get better help.
 
Moved your thread to the motorcycle area so people aren't as confused on this thread.

Two hub motors on this vehicle would be super nice.. it would eliminate all the friction of the chain and you could keep the all wheel drive factor.. but it may be significantly heavier IDK..

I don't know anything about motorcycle-sized things so i'll let the crowd pick it up from here.
 
I merged all of your various threads for this project into your original one to help people help you, by keeping all the info and questions about it in one place, so you don't have to keep answering the same questions over and over (or not answering them and leaving your helpers unable to do so).
 
You must log in or register to reply here.

Similar threads

kylerlaird
geared front hub motor for Mongoose Kong?
Replies
5
Views
448
kylerlaird
kylerlaird
D
Crazy Trike concept, need some help/advice
Replies
3
Views
2,188
klocwerk
K
C
First ebike build – advice wanted!
Replies
10
Views
2,041
skyking
S
Back
Top