The Final Form?

[jonpad01]

This will be my 4th bike frame. List of major components:

-Fucare Taurus frame and front fork (26" fat bike with 190mm dropout)
-3shul C350 V4 controller
-QS 205 4T Motor with the 175mm axle
-Home made battery - 72v 30ah (20s7p) using molicel p42a cells

Some special pieces:

-Got a torque sensor, from aliexpress, looks like some one stole a box of ERider sensors and removed thier label.
-Create my own throttle hacker that can read the torque sensor and send it to ADC1 on the controller
-Integrate grins analogue style brake lever into the 3shul controller for variable regen braking
-Added my 5 speed freewheel onto the QS Motor, it needed a small spacer about 2mm thick.

The frame as it came from Fucare


Here is the headset, had to buy cups for it


Cups installed


Top head tube takes a ZS44/28.6, bottom takes a ZS55/40, I'm using an adapter for a non tapered fork.



These cells came from battery hookup, it was a lot of work pulling them out of pre built packs.



The JK BMS is too large to fit with the back so I'm mounting it externally.



QS Motor laced onto a weinmann 26" DHL65 rim and sapim strong spokes bought from Grin Tech.



Fucare's frame, front fork, rear bracket, and rear basket.



A36 steel plates as axle spacers / torque arms cut with an angle grinder. Getting them to fit the axle slot perfectly with a dremel was a pain. QS Motor O.L.D. was 175mm with 0mm dishing offset, so I basically just needed 1/4" on each side.



Getting the rear brake caliper to fit was a challenge, the rotor is offset almost 1/2" from the mount because of the QS Motors spacinig + my 1/4" steel plate. I don't want to use a disc rotor spacer because the motors phase wires are already very close to the disc rotor. I found a Shimano adapter ISMMAF180SPA, and paired it with a PM to IS adapter that almost works. Eventually my rear brake lever will activate regen braking so I'm not too worried about getting this perfect. I found another Shimano adapter ISMMAF203SPA that will probably work better since it is for 203mm rotors.



It's not finished but it's pretty close! 4" tire on the front and 3" tire on the rear. I like the sound that 4" tire makes on the road but I am probably going to swap it out once I get a matching rim from Grin.

 

[Chalo]

What is it with folks using fatbikes for fast e-bikes? Fatbikes are for crawling slowly through soft crud, and that's the only thing they're any good at. Using fat tires (like 3.5"+) on the street only reduces your speed, range, and handling qualities without giving you anything good in return (and it marks you as a n00b and/or a dingdong).

After an adult lifetime of getting stoked and impressed by larger and larger bike tires, I was quick to try fatties when that was feasible for me. Trying them cured me of my infatuation right away. They're depressingly slow, with terrible steering that only gets passable if you overinflate them to the point that they don't have any of the cush or flotation their size allows.

That's a disc braked bike. You can use 29 x 2.5" or 27.5 x 3" wheels and tires for about the same overall diameter as 26 x 4", and your bike won't suck as much if you do that.

If you must go with 26" fatties, at least give yourself 65mm rims so you can use real tires in the 2.2" to 3" range once you figure out how disappointing fatbike tires are.

 

[nicobie]

Nothing wrong with building a bike for looks. However please realize that Chalo is correct.

 

[jonpad01]

The reason for the fat bike frame is simply this, I want a 7 speed freewheel on a QS 205.

As for the tires, I have no comment because I have never used 4" fat tires. The plan is to try 4" tires first, but the rear rim that I am lacing to the motor will be 65mm so I can fit smaller sizes if I don't like them. The front is an 80mm rim because that's the only size I could find that comes as a complete wheel. I might consider building a front wheel at a later date.

The other reason I wanted wider tires is because I had a 1.95" wheel spin out from under me and put me on the ground last year, broke my elbow.

My use case is all terrain for the most part, dirt trails with steep climbs, but also city streets.

 

[NuclearDolomite]

What is it with folks using fatbikes for fast e-bikes? Fatbikes are for crawling slowly through soft crud, and that's the only thing they're any good at. Using fat tires (like 3.5"+) on the street only reduces your speed, range, and handling qualities without giving you anything good in return (and it marks you as a n00b and/or a dingdong).

After an adult lifetime of getting stoked and impressed by larger and larger bike tires, I was quick to try fatties when that was feasible for me. Trying them cured me of my infatuation right away. They're depressingly slow, with terrible steering that only gets passable if you overinflate them to the point that they don't have any of the cush or flotation their size allows.

That's a disc braked bike. You can use 29 x 2.5" or 27.5 x 3" wheels and tires for about the same overall diameter as 26 x 4", and your bike won't suck as much if you do that.

If you must go with 26" fatties, at least give yourself 65mm rims so you can use real tires in the 2.2" to 3" range once you figure out how disappointing fatbike tires are.

I do agree with you, but having just purchased a kit and dolomite to integrate the kit into, I must accept the poor handling in exchange for stability and safety. Fat bike tires have the advantage of carrying about twice the load, and the only way my wife would okay this project is if I added a rear passenger seat she could hop on to go on little dates and cruise around town together.

I admittedly feel much safer doing this on tires that can easily handle all 315lbs of us while not succumbing to the imperfections of the road. 3000 watts is more of a safety and payload thing since the speed limit in our community is 45mph. I want to be able to get up to speed quickly if I need to but will probably hover around 30mph with the wife on the back.

3000 watts will also keep this thing fun while riding with a second passenger, and its enough to be really really fun when riding solo.

I do agree with you though, @Chalo . I had never ridden a fat bike before this dolimite purchase and it’s definitely a different experience, lol.

 

[Chalo]

Well when you wear out the original tires, you can get something like this, rated for 363 lbs per tire:

Pick-Up | Super Defense | Black-Reflex | 26x2.60 | Addix E | 11159372

SCHWALBE‘S FIRST TRUE CARGO TIRE. Due to its extremely stable double carcass, the Schwalbe Pick-Up becomes a real packhorse and at the same time offers excellent puncture protection. In addition, the ADDIX E-Compound ensures exceptionally good riding per…

www.schwalbetires.com

 

[jonpad01]

Original post updated.

 

[NuclearDolomite]

Well when you wear out the original tires, you can get something like this, rated for 363 lbs per tire:

Pick-Up | Super Defense | Black-Reflex | 26x2.60 | Addix E | 11159372

SCHWALBE‘S FIRST TRUE CARGO TIRE. Due to its extremely stable double carcass, the Schwalbe Pick-Up becomes a real packhorse and at the same time offers excellent puncture protection. In addition, the ADDIX E-Compound ensures exceptionally good riding per…

www.schwalbetires.com

Indeed! I am definitely going heavy duty for my next set of tires. I havent explored tubeless yet in detail, but I have an idea of what to look for.

Her and I will only ride doubles once a week or so, so it’s not like it will be an everyday thing. I think the stock tires are pretty good for now though.

 

[NuclearDolomite]

Original post updated.

Dude. That battery is insane. Your build is insane. Very clean. I hope to build my own battery soon but need to get a better understanding of my electrical theory, parallel, and series set-ups. It’s a little intimidating…. because they’re batteries… and can be scary, lol.

 

[jonpad01]

Dude. That battery is insane. Your build is insane. Very clean. I hope to build my own battery soon but need to get a better understanding of my electrical theory, parallel, and series set-ups. It’s a little intimidating…. because they’re batteries… and can be scary, lol.

I have accidentally reversed the polarity on an xt60 connector before when wiring some 48v batteries in parallel. Half of the connector turned into vapor and painted my face before the BMS cut off. Spot welding that battery very much feels like I'm welding on a live bomb.