20 inch fat bike build stared in good faith and then...

[Msim]

My next build started innocently enough. I wanted to build a fattie for my wife with a low stand over height. I happen to have an electric scooter that was having warranty issues, so I traded it back to the factory with some cash for what is called a youth's fat bike . It has a very small frame and 20 inch wheels. Here it is with my BBS build. The BBS is a 21inch frame for reference.

[Msim]

The bike is 36ov at low amps but is surprisingly quick and cruises easy at 20. The plan was to overvolt it to 48 and see what happens and then most likely go to a mac kit at 48v 30a.

[Msim]

But then I messed up and rode it. The thing rides great. There is something about the low center of gravity or whatever it is that makes the handling fantastic. So .. I had another scooter that was having a warranty problem and here we go again.

[Msim]

Then things got goofy. I started to take the bikes apart to plan my components. There is plenty of room for the controller and perhaps a cap pack and a dc to dc converter

[Msim]

So I started looking for parts and then the strange ideas hit me. I sourced a couple of silverfish batteries to upgrade. The first for the black build is 48v 20ah with a 30bms. The white bike I found a 60v 24ah with a 30bms. The white bike will be 1800w continuous.

[Msim]

I am currently waiting for restock of the Mac Motor Kits. I am going to do the 60v first and overvolt the 48 and fry everything that is stock . Should be interesting I am looking for power in excess of that of my BBS build which is the standard 1500. Next build will be a 72v conversion for my BBS when that becomes available. Further upgrades, brakes etc to come.

[Msim]

I got the batteries in and fitted them to the bikes. The 48v 20ah tucked in really nicely on the black. The 60v is a little ridiculous, but then I knew it would be.

[Msim]

First phase road tests stock controller.

black bike 36v stock 19mph no pedal. 48v (overvolt) 24mph no pedal 240lb rider

white bike 36v stock 19mph no pedal 60v 29mph no pedal 240lb rider.

I am quite impressed with the performance gains of the new batteries.
The 60v reaches nearly 30 on flat ground.

Can't wait to try an ASI controller.

[JPLabs]

I like those. My wife is too small for her fat bike, too, hmmm.

Love that the overvolt worked, and that you had nice data around the mods, too, thanks!

Nice view.

[Msim]

They are really fun to ride and surprisingly comfortable for taller riders. I am a little over 6 feet

[Msim]

Next upgrade. 203 mm front 180 mm rotors. Although still the stock calipers the unscientific measurement of feel definitely seems to have improved.
Full floating for the black bike and ultra light one piece for the white

[Msim]

Tires and rotor upgrade Going to add Shimano Hydraulic

[Msim]

Upgraded the white to Shimano M355 and added a 56t chainring. I harvested the stock microswitches. Of course I forgot to take pictures but I couldn't have done any better than these guys any way. The only difference is I used JB weld kwik.

[Msim]

[Brian7588]

Great builds. I just ordered a 19 inch mid drive with 24 inch wheels. I have been reading the smaller bikes are handling much better with the faster power.

[weetard]

amazing, you dont stop!