Stretch Cruiser (Micargi Bronco) / 5000W build.

OldskoolGrimace

100 µW
Joined
Mar 12, 2022
Messages
7
Hey all, my first post here, just completed my first custom ebike last week and did my 40mi daily commute with it.
Gas prices being what they are, weather permitting I might be riding this a bit more often.

Frame: Micargi Bronco
Motor Kit: NBPower 5000w Fatbike Kit 26" (see Amazon)
Motor: QS205-4T hub motor.
Controller: Sabovton 72100
Batteries: 24s LiFEPo4 prismatic cells (76.8V - 25Ah) (rated continuous 3C peak 5C)
BMS: Daly 24s 100A
Fork: Himalo 34 double crown 135mm dropout (Will be replacing with an inverted fatbike fork with a 15x150mm through axle)
Front Brake: Shimano Saint Hydraulic Double Pot, Magura MDS 203mm disc
Rear Brake: TRP Spyke Cable, Magura MDS 203mm disc (lookign to enable regen braking soon.)
Seat: Brooks B67. (looks cool, but want to replace with something softer and with a back)

Length: 92"
Weight: 130lbs
IMG_0113.JPG

Electronics frame housing: cut out of 1/8" aluminum
Here's the internal mounting of the batteries. It just about fits. The mounts for the 100A switches are 3D printed, switches
just bolt into the frame. I also 3D printed covers for the battery bus bars and routing for the 25 wires back to the BMS.
IMG_0059.JPG

My first motor test attempt resulted in the original dropouts being bent and the wheel tearing off the bike under power.
I decided to design and have cut some custom torque arms in 1/2 thick stainless and bold them to the frame. They have the added plus of integrated disc brake mounts. I designed the outline in inkscape, exported to DXF and uploaded to Xometry to have them manufature it. Expensive, but in the end a result I'm happy with.
IMG_0053.JPG
 
Commentary:

Overall I am pretty happy with the NBPower kit. Took a month and a half to clear customs to get it, but after I got it It was pretty much plug and go. The torque arm included with the kit is not enought for the power of this motor at all. I think designing the torque arms that bolt to the frame was the way to go. The controller and display is nice, you select between 5 power levels (factory settings).
1: low speed: 12kph max 250W
2: Class 2 Ebike-ish: 26kph 750Wpeak/250W sustained.
3: Class 3 Ebike-ish: 42kph max, 2000w peak/750w sustained
4: Moped: 54kph max: ~3000w peak / 1800w sustained
5: Moped+ : 72 kph max: 5500w peak.

The double walled 26" rim is quite nice, and strong for a fat bike. I managed to find another identical one and will be building a new front wheel with that rim, 36 12G spokes, and a 36h 15x150mm hub
 
CONSIDERABLE SHOUTING said:
That looks nice dude! What drew you to those Lithium Iron Phosphates? And if you don't mind me asking, what did they cost you?

Mostly the price and the ease of assembly (and disassembly). The busbars bolt on and off with M6 bolts. I just needed to make the 22 bus bars and the design the insulative covers. I ended up changing the cell configuration to a mirror image for the 3x3 pack and unbolted it and rebuilt it pretty quickly. I got the case of 24 for $330 at battery hookup (they ran out of stock quickly, usual cost for these is double that.).

The other good part is that they should last 5000 charge cycles. So I can commute on this bike every work day for the next 20 years if I wanted to :). Also I was concered about safety as well, overcharging or damaging a LiFEPO4 is unlikely to cause a fire. Lithium-Ion can catch fire when damaged or overcharged.

https://batteryhookup.com/products/new-3-2v-25ah-lifepo4-topband-navitas-prismatic?variant=40145310941346

The bad part about these is that they are not as energy dense as Li-Ion cells (these LiFEPO4: 120Wh/kg, vs Li-Ion is 1.5x-2x this)
 
Nice work!
The litmus test (for me) on bikes is ... when I see it, do I get the "hey, I'd like to take it for a spin" feeling. Would definitely like to take a cruise on this one. The B67 / Flyer saddle is cool, but I bet replacing it with something cushier will make this a really comfortable ride.
For a big bike like this, LiFEPO4 batteries make a lot of sense. Last about forever, low risk, lots of punch.
Thanks for sharing.
 
Beautiful bike and excellent clean work sir. I absolutely love it. It is so good, such a cool stylish ride and no more stinking gas engines! Please tell us about the ride experience if you don’t mind brother. I would be so interested to hear how it it preforms compared to other vehicles you might have ridden. I would love to hear how powerful it feels and how it brakes . I really appreciate your sharing it Mr. Old School Grimace. Some of you guys on this site are so good you keep an average builder like myself very humble. More please! :thumb:
 
Nice job; that seat will be comfortable after 20 years of riding (but maybe not much before). I really like the Thudbuster on my MTB.
 
Super nice! :thumb:
Nice to see another sit down flat-footer. :)

Question on the remote Daly BMS. Balance wires,.. do you just plug the 24 pin flat-plug in, with no worries, or is there any sequence used? I have a similar set up, and thought that maybe the black balance wire needs to connect first, before the reds?
Maybe I worry too much.
 
OldskoolGrimace said:
CONSIDERABLE SHOUTING said:
That looks nice dude! What drew you to those Lithium Iron Phosphates? And if you don't mind me asking, what did they cost you?

Mostly the price and the ease of assembly (and disassembly). The busbars bolt on and off with M6 bolts. I just needed to make the 22 bus bars and the design the insulative covers. I ended up changing the cell configuration to a mirror image for the 3x3 pack and unbolted it and rebuilt it pretty quickly. I got the case of 24 for $330 at battery hookup (they ran out of stock quickly, usual cost for these is double that.).

The other good part is that they should last 5000 charge cycles. So I can commute on this bike every work day for the next 20 years if I wanted to :). Also I was concered about safety as well, overcharging or damaging a LiFEPO4 is unlikely to cause a fire. Lithium-Ion can catch fire when damaged or overcharged.

https://batteryhookup.com/products/new-3-2v-25ah-lifepo4-topband-navitas-prismatic?variant=40145310941346

The bad part about these is that they are not as energy dense as Li-Ion cells (these LiFEPO4: 120Wh/kg, vs Li-Ion is 1.5x-2x this)

Man, for that reason I'm hoping to find a LiFePO4 cell- especially one thats for automotive and not small stuff- for my own bikes. I know Du Shi Wang here had found some, but he is native Chinese so he has many advantages :lol:
 
Scootdan said:
Please tell us about the ride experience if you don’t mind brother. I would be so interested to hear how it it preforms compared to other vehicles you might have ridden. I would love to hear how powerful it feels and how it brakes . I really appreciate your sharing it Mr. Old School Grimace.

Two words: "Hang On" :)

But to expand on that, you are in an upright riding position with feet forward and swept back handle bars.
In the normal riding position, there is little weight on the feet and almost full weight on the saddle. Under light throttle it's quite comfortable for cruising and the upright position makes it easy to see everything around you without straining your neck.
I lean forward when gunning it and need to grip tight. I feel like an antique motorcycle rider doing this, (maybe I need a leather helmet and steam punk goggles to complete the look). However, since the battery weight is centered (and its a 130lb bike), the bike does not pick up the front wheel at all, even at full throttle from stop on hills.

The interesting thing about the weight is how much inertia it gives you. You can just roll a long time once you are up to speed.
One you are up to speed pedaling feels like a normal bike, but getting there you get quite a leg workout.

I'm happy I made the decision to use a half grip throttle since I can still grip with the back half of my hand and not affect my throttle control. It's a bit safer that way, and you get a free "cruise control" effect gripping both halves together at your given throttle.

It brakes better than anything I have ridden due to the fat tires and the large discs. With the long travel fork and low rake, the
bike dives a bit under braking, but since the front wheel is so far out and wheelbase so long, there is never any feeling the bike
will flip forward. In fact I can lock up the fronts from high speed. no problem.

The long travel fork with high rake in the front really soaks up the bumps nicely, even, potholes and curbs are not so bad to ride over at low speeds.. (for the front)... but the bike is still a hardtail, and the suspension seatpost and seat springs only help a little. Due to the lack of damping a good bump can spring you off the seat a little (like a Mr Magoo effect :)) Yep..gotta hang on :)
Also the high rake of the fork and slight lake of trail for that fork length means you need to keep hands on handlebars. No hands is not a possibility.

The disadvantage of the long wheelbase is the long turning radius. You need to lean into the corners a bit more than on a usual bike. It's part of the feel.

I originally rode this bike as a stretch cruiser without batteries, and even then it weighed 65 lbs.
 
APL said:
Super nice! :thumb:
Nice to see another sit down flat-footer. :)

Question on the remote Daly BMS. Balance wires,.. do you just plug the 24 pin flat-plug in, with no worries, or is there any sequence used? I have a similar set up, and thought that maybe the black balance wire needs to connect first, before the reds?
Maybe I worry too much.

Checked out your builds, wow super nice frame building there. love the round section near the bottom, reminds me of a Flying Merkel or something from that era!

For the Daly BMS, theres two connectors into the BMS for the cell monitoring, one 17 pin and one 8 pin, the 17 pin connects to ground and the positive of the next 16 cells. the 8 gives you the last 8 cells. I prewired the connectors into all the cells
I've plugged and unplugged these in all different orders and no problems so far. I think it doesnt matter since the BMS doesn't start itself right off the back.

The BMS takes a few little tricks to get started. The tip to connect the power ground input and ground output to start the BMS did not work for me. What managed to work for me is one of two things, either charging the batteries through the BMS (starts the BMS) or pressing power through a little battery level monitoring lightboard I bought seperately (I think the LCD touchscreen can do it too).

https://www.ebay.com/itm/334191662286

The BMS needed to be started before communicating via bluetooth to check battery levels and all.
 
Thanks OldskoolGrimace,.. hands on info that I can use! I should have bought the bluetooth version, I didn't know about the delay/V feature, not sure if mine works the same way; charge activated. Well, I think I got it covered with sequence, but if the magic-smoke pours out of my BMS, I'll know what to get next. :)

You've got a really nice clean machine there, with gobs of power and low slung weight,.. probably waiting for the good weather and
a long summer of cruising ,.. (me too). :wink:
 
Thank you for the excellent info sir. Man that looks so fun. I can imagine how dialed in you will have it soon. I would like to get your opinion on my latest project, since I will assume you have seen and ridden lots of different rides. It is really a big scooter, and I hope to post it on the escooter/emotorcycle build thread very soon. This is just a simple drawing but it is really close to the real thing. I will add a couple pictures of the rear end from awhile ago for scale. I just figured out my speedometer so I am getting really close to rolling this big sled. I keep looking, but I have not seen one this big anywhere, have you guys?
 

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The "Himalo" fork was flexing a little more than I liked in high speed stops, so I ordered a new inverted double crown/triple fork that is much stiffer up top (43mm vs 34mm) and uses a 15mm through axle instead of 9mm QRs.

To match this I needed to build up a new front wheel 15x150 36h hub, 12g spokes to match the rear and double wall 80mm 26"diam rim.
It was a pain to find this double wall fat bike wheel and the 36h 15x150mm hub (first time to order off of aliexpress) Also had some custom spokes made.

Huge improvement in stiffness and stopping confidence. Maybe a little less plush over the bumps, but I have yet to experiment with the air pressure settings

IMG_0151.JPG
IMG_0154.JPG
 
very cool build. I'm planning a "tamer" version of this - a bit less stretch but still low rider cruiser style, and around 1500w - so a more budget friendly build.

In your searches, maybe you came across similar frames but with a bit less reach? any suggestions?
 
Sweet ride

OldskoolGrimace said:
IMG_0053.JPG

I see you also subscribe to the "let me find what bolts fit" school of getting it done :D


OldskoolGrimace said:
Rear Brake: TRP Spyke Cable, Magura MDS 203mm disc (lookign to enable regen braking soon.)

Oh BIG time. With that strong a direct drive and that BEEFCAKE torque plate, you should 100% be running heavy regen -- like, 90%+ of your stopping power should be from regen.
 
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