Light dirt bike, QS 120 70h motor, custom steel frame

did some weight optimizations and removed the gold color from the hub

now doing CAD (cardboard aided design / compass aided design) for the aluminum sprocket spider:

3TOUnbH.jpg
 
Are you going to be charging the Battery Pack, through the Balancing Wires ( 18 wire/JST-XH Plug ) ?
or
Through the Main Discharge +/- wires ?

What size wire ( Awg ) did you use for your custom JST-XH Plug and Wires ?

Looks like you made your own JST-XH plug by cutting one and splicing it in between the others.



Overclocker said:
finishing pack 1 of 2. 17s6p. no BMS, shown here w/ 18-pin balancing port. sand-filled 40A slow-blow fuse

B7gI0SG.jpg
Click to expand...
 
ScooterMan101 said:
Are you going to be charging the Battery Pack, through the Balancing Wires ( 18 wire/JST-XH Plug ) ?
or
Through the Main Discharge +/- wires ?

What size wire ( Awg ) did you use for your custom JST-XH Plug and Wires ?

Looks like you made your own JST-XH plug by cutting one and splicing it in between the others.
Click to expand...

glad you noticed the fatter balance wires, for faster balancing. i'll be charging through the main. not sure what AWG, just use the fattest that'll fit in the perf board

yes it's a DIY connector. i simply plug a typical 7-pin connector (w/ the locking lugs removed) into any point along the 18-pin array for monitoring/balancing
 
Looks good man, I like the heavy drivetrain! What max speed are you shooting for? 17s and 17in moto @ 4:1 should be around 33mph (and ALOT of torque with 18fet)! I'd try up around 80amps if the controller is cool with it, but you'll probably keep the phase amps around 2:1 unless the ride is really heavy/big/stout. Even 200ph was ridiculous on mine lol.
 
nutspecial said:
Looks good man, I like the heavy drivetrain! What max speed are you shooting for? 17s and 17in moto @ 4:1 should be around 33mph (and ALOT of torque with 18fet)! I'd try up around 80amps if the controller is cool with it, but you'll probably keep the phase amps around 2:1 unless the ride is really heavy/big/stout. Even 200ph was ridiculous on mine lol.
Click to expand...

yeah it's overkill. i could probably shave some more weight from the steel 53t sprocket but i'll probably do that later. i decided to use heavy #420 because i need this thing to ride through a wide riverbed of loose volcanic ash to get to my favorite trail. so with this setup i'll probably not have to worry about drivetrain wear for a while

Fk0qecO.png


id be happy with 45 to 50kph. i'm not too sure about that "percentage when loaded" term which defaults to 70% so your estimate is most likely more accurate
 
28mph
Click to expand...
I was just guessing w/33mph. That 70% "loaded" is getting close to the highest efficiency and the torque fall off (~85% rpm imo), so if that's your target speed you'll be happy. The motor will get to 100% pretty quick though if you give it the power, and that looks like nearly 40mph based on the calc :twisted: !!
 
How is it going? Update us.

I'm on the verge to buy pit bike components for rear wheel from CN.
CNC alum rear hub 32 holes - 40usd
alum rim 17'' 1.6width 32 holes -35usd
spokes, and tyre will get locally for 25usd
but i see a lot folks to using bicycle components therefore it's hard to justify additional weight using pit bike components.
 
My 17'' tyre and 26 wheel sketch looks even less proportional.

rear: 572mm 70/100 Duro 17''
front: 700mm 3'' 26 Kenda Flame

I may switch front rim to 24'' or might increase rear wheel. Not sure which way it might turn.
 
The noise is not too loud indeed; it is very silent on low RPM, alnost no sound, so you can crall in low speed like with hub but not generating as much heat in the motor. The sound is not too loud because it's is low kv motor. If it was twice kv it would be a lot noisier.

I have option to use 70kv motor and I tend to use it with 8M belt over 420 sprocket. The problem is that rear pulley has to be over 100teeth with 22'' diameter (17'' mc wheel) wheel taking into account that front pulley is 22teeth. And pulleys are scarce and expensive due to their unpopularity. I believe things might change if we are lucky but it's not up to us. Masses control a market. QS is manufacturing pulleys with 103 teeth but they are for 12'' scooter rims, with flanges.
In recent few years, I found the only one used Zero rear 130teeth pulley which cost over 100eu. That's how popular rear pulleys are in second-hand market.
 
how much you pay (in usd or euros) for your rear hub? Can I see it for sale on some web shop?
 
skeetab5780 said:
Nice fab skills man, looking really nice
Click to expand...


Vk6HyNZ.jpg


i'm getting concerned about the strength of my motor mounting plate. it's 2.8mm mild steel. you think it'll hold up?

i think you had you had issues w/ bending your motor mounts in one of your vids
 
Ehh its a bit thin now that I notice there are slots cut in it, at first glance I figured it would hold up. Maybe double it up or add some bracing underneath if you see it flex

I bent the aluminum mounts on the motor itself because they weren't completely seated on a steel surface. The bike also weighed a ton

Swing is looking really nice, how do you adjust the rear wheel/chain slack?
 
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