3000w Mongoose girder

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Barncat   10 W

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3000w Mongoose girder

Post by Barncat » Dec 12 2020 6:36pm

I've built 20 ICE cafe racers over the past 15 years but figured I'd finally dabble in putting together an electric urban toy. Here in the flat FL Gulf Coast, top speed target is around 50mph... either 18 or 20s.

Will see how well these BOMA MY1020 motors work. Pretty beefy but they could have done a more aggressive press fit of the laminations on to the axle. The magnets are retained by two flat thin steel rings so that's good, i hope. Have drilled out the end caps for better cooling. The controller is huge sadly... a lot of aluminum.

Pretty skeptical that 25h chain will handle this setup but t8f rear sprockets stop at 54T. Using a freewheel, no regen.

Still harvesting cells from Ring packs (PITA) and deciding on battery details...

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Re: 3000w Mongoose girder

Post by Barncat » Dec 12 2020 7:55pm

Pic upload from Android failed. Trying again...

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Re: 3000w Mongoose girder

Post by Barncat » Dec 13 2020 10:24am

I see pic size limit is 512kb. No way to compress pics on my phone and no PC so no go...

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Re: 3000w Mongoose girder

Post by Barncat » Dec 31 2020 9:10am

Another pic upload attempt
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Barncat   10 W

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Re: 3000w Mongoose girder

Post by Barncat » Dec 31 2020 9:13am

Cool, it worked. Used the android Litphoto app to compress below 512kb.

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Re: 3000w Mongoose girder

Post by Barncat » Dec 31 2020 9:38am

The concept is speedway bike. Rear dropouts were extended by about 5 inches, I found a great aluminum fork for cheap on ebay and went with a nice 24" front wheel, a motor mount was carefully added to frame, custom footpegs, and seat post was cut and a small plate welded on for a temporary plywood seat pan mock up.

The girder frame has a unique look reminiscent of my Ducati, and it came with a rare disc brake rear hub.

Still deciding on battery pack layout but it'll be at least 18s in likely (3) 6s packs that can be balance charged.
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Barncat   10 W

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Re: 3000w Mongoose girder

Post by Barncat » Jan 10 2021 11:51am

FWIW, I detoured into the weeds to design a 10s7p enclosed solderless/weldless battery pack that assembles in about 10 minutes WITHOUT hundreds of vruzend style fasteners. High efficiency all copper buss bars. I'm not going to post pics yet as it may have patentable features. Have not battle tested it yet but all indications are it should work great. A perfect candidate for 3D printing...

I'm finding the aesthetics of building e-stuff to be frankly very annoying. It's unavoidable bulky heavy rectangular components that must be hung on a frame somewhere. Battery packs with any power/range and huge controllers suck. A quantum leap in those two areas is still sorely needed.

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Re: 3000w Mongoose girder

Post by Voltron » Jan 10 2021 1:45pm

You're right!
Bitching frame btw.

Here's a classic from the Sphere...🤣

[youtube]PW7M-vpFUkI[/youtube]

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nicobie   1 GW

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Re: 3000w Mongoose girder

Post by nicobie » Jan 10 2021 3:27pm

That is going to be one bad-ass bike.

It does remind me of Luke's Death Bike.
Take it easy... but take it. (Woody Guthrie)

my eTownie build thread: http://endless-sphere.com/forums/viewto ... =6&t=23701
Magazine article https://www.electricbike.com/nicks-etownie/

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Re: 3000w Mongoose girder

Post by Barncat » Jan 10 2021 3:29pm

(Per the video above) Ha! Little bit a torque there or what?

I really need to get this ride built for testing. As you all know the DIY battery stuff is very time consuming. I'm a regular motorcycle guy so some facets of this type of project are slowing me down.
Last edited by Barncat on Jan 10 2021 8:15pm, edited 1 time in total.

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Chalo   100 GW

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Re: 3000w Mongoose girder

Post by Chalo » Jan 10 2021 4:28pm

Barncat wrote:
Jan 10 2021 3:29pm
Ha! Little bit a torque there or what?
Motor is rated 5.4Nm of torque if it's the one I found specs for. Most of those MY-whatever motors come with 11t sprockets for ANSI #25 chain. That rear sprocket looks like a 90t to me. If so, that's 1:8.18 reduction. So not counting transmission losses, it will turn 5.4 Nm into 44 Nm of torque. About the same as a middling hub motor on a dockless rental e-bike.

It will make a lot more noise, though.

My very first e-bike was one I made using a 400W brushed scooter motor like the one above, only smaller. I used 12:144 reduction gears and a 700c wheel. It could sort of get out of its own way, maybe. I decommissioned it because I couldn't keep the chain on for very many miles at a time.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: 3000w Mongoose girder

Post by Chalo » Jan 10 2021 4:37pm

Barncat wrote:
Dec 12 2020 6:36pm
Have drilled out the end caps for better cooling.
Be aware of the possibility of the motor ingesting and holding onto any small steel debris that passes nearby. (Tire belt wires, swarf, small fasteners, etc.)
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: 3000w Mongoose girder

Post by Barncat » Jan 10 2021 8:06pm

Hey Chalo- you misinterpreted my "torque" comment. I was referring to the video clip posted above by Voltron.

The 3000w motor I'll be using is not exactly a monster but there are some good accounts of it elsewhere on the forum so long as you don't push it past 6000 rpm too long. Plan is to run it on 72V so should have some pep. I have both 12 or 13T front sprockets and the rear is 80T driving the 20" tire. My main concern is whether the 25H chain is adequate. And these motors are starved for cooling air so it had to be drilled, but duly noted. After experimenting with this bike I might build something else with an outrunner. Hub motors are too heavy for me.

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Chalo   100 GW

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Re: 3000w Mongoose girder

Post by Chalo » Jan 11 2021 12:19am

Barncat wrote:
Jan 10 2021 8:06pm
Hey Chalo- you misinterpreted my "torque" comment. I was referring to the video clip posted above by Voltron.
I see. That one does have some surplus torque.

Even if the performance of the first iteration of your bike is ordinary, the fact that it's earned will be satisfying by itself. It sure was with my first e-bike.
It was deficient by the standards I've become accustomed to, but it was amazing in its moment.
Going on 18 years ago? It was a happy thing that motivated me to try for more.

Of course you can revisit your bike as much as necessary to ramp up the jollies factor. That's easier than ever, these days.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: 3000w Mongoose girder

Post by markz » Jan 11 2021 4:41pm

I laugh every time I see that video of the guy losing his shoe.
I need to find the specs for the monster! The big gear on the rear wheel.
Video says 50,000 mid drive, 2012 Francisco Ebike HIll Clmb race.
Will do another search later.
Heres a link I found in the meantime, DrBass's rig
viewtopic.php?f=3&t=20592&p=1289993&hil ... e#p1289852

Voltron wrote:
Jan 10 2021 1:45pm
You're right!
Bitching frame btw.

Here's a classic from the Sphere...🤣

[youtube]

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Re: 3000w Mongoose girder

Post by Voltron » Jan 11 2021 10:14pm

It always reminds me of this...

[youtube]vJXU7EVXs2A[/youtube]

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Re: 3000w Mongoose girder

Post by Barncat » Jan 15 2021 4:46pm

Got around to setting up a test rig. Wheel spins up great. The only thing holding me up is the experimental no weld/no solder battery build which is almost done...

That and some paint and so forth and the toy will be on the road.
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Re: 3000w Mongoose girder

Post by Voltron » Jan 16 2021 3:30am

Looks fun... Lace those shoes on tight!

Joking aside, be real careful about getting anything stuck in the chain? What might seem like good clearance can change in a crash where the motor is stuck on and there's accidental contact.

Personal story.. was getting ready to leave work and sat on one of my higher power bikes just inside the doorway, and as I turned to say bye over my shoulder, the handlebars flopped over, and jammed the throttle against the corner of the battery. The bike launched from between my legs (luckily not taking my balls with it!) and did a wheelie out the door by itself for about 10 feet out onto a busy sidewalk, falling over with the motor fully spun up just before hitting the parked cars right there, and thankful not creaming some random old lady walking etc...🤦‍♂️

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Re: 3000w Mongoose girder

Post by Barncat » Jan 16 2021 9:43am

Hey Voltron- agreed it's imperative to be safety conscious. As referenced at top of thread I'm an experienced motorcycle test pilot with 100k miles on 20 different builds. I wring the bikes out pretty hard but only where it's appropriate to do so. Plus maybe 50k cycling miles in my younger days... So this is a 4hp toy by comparison, though you still don't want to get accidentally launched into an oncoming car...

You certainly don't want dangling shoe laces or anything else near an exposed chain. These $12 throttles have surprisingly good springback, the on/ off key works well and I'll add another left hand handlebar kill switch, and put a fuse on the battery + lead with an antispark xt90. Disc brake rear and caliper front. Will probably use a bike helmet-and a visor is critical to shading your eyes from glare. I always wear leather gloves.

There was a bit of a learning curve switching over to e-world but I've got a pretty good handle on the basics now. Battery building is sort of a PITA... Respect for you EE guys designing controllers and custom motors.

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Re: 3000w Mongoose girder

Post by Voltron » Jan 16 2021 11:49am

You get it. Sometimes idiots see things on here and do all sorts of dumb stuff (talking about me here ✋🤣)

After that episode I seriously thought about putting a dead man switch on the seat, or a pull out jet ski style lanyard...switched to long wheel base and loading up the front instead. Rectangular component overload!🤣
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And you're right about the batteries being the hardest part to just stick together out of parts. I've found running it in a backpack during the first few test rides helps decide if you even like the project before you waste a lot of time on fabbing a good mount.

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Re: 3000w Mongoose girder

Post by fechter » Jan 16 2021 12:37pm

markz wrote:
Jan 11 2021 4:41pm
I laugh every time I see that video of the guy losing his shoe.
I need to find the specs for the monster! The big gear on the rear wheel.
Video says 50,000 mid drive, 2012 Francisco Ebike HIll Clmb race.
Will do another search later.
It was a Zero motorcycle motor.
"One test is worth a thousand opinions"

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Re: 3000w Mongoose girder

Post by Barncat » Jan 16 2021 6:34pm

I see you managed to put a couple wheels on that battery there Voltron :).

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Re: 3000w Mongoose girder

Post by Voltron » Jan 16 2021 9:03pm

It's the best battery I ever rode 🤣
Seriously.. so stable during launches, and no speed wobbles. One straight roads used to lock the throttle on full, and stand up on the pedals with my arms out like wings... Magic carpet!
Btw, those are all salvaged from packs that had failed and would have gotten trashed... 20s👍
That evolved like the frame did...
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Sorry, hijack off! Lol

Barncat   10 W

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Re: 3000w Mongoose girder

Post by Barncat » Jan 25 2021 7:07pm

As mentioned above I've been working on a no weld/no solder 18650 battery design for about a month now. Just bench tested the 20s5p 2nd prototype, which I'm pleased to report spins up that back wheel, like, right now :twisted:

Will probably be able to do the first street test tomorrow.

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Re: 3000w Mongoose girder

Post by Barncat » Jan 30 2021 6:58pm

Was able to zip around a bit yesterday afternoon for the maiden voyage of this project. Had to weld battery mount brackets and chain tensioners a few days ago so decided to do the paint job at same time. Installed the brakes, throttle and kill switch so it's basically all done save for a better seat. Battery is still under wraps, literally, as I'm still testing and haven't decided how much to divulge of my design. So far it works great.

By my estimate the bike hits 45mph on the flat with the 72v battery. So almost exactly what I expected.

The throttle however is lurchy off zero throttle from a standing start even with a careful gradual twist. I hate that. I assume neither the throttle nor the controller is adjustable in my case. Opinions appreciated...

Suffered a big unforseen setback when the goddamn chain derailed on the inside of the rear sprocket today, which is why the wheel is off. Major PITA. Must build some chain guides for both sides of the 80T...
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