The Electric Next Iron Mongoose Build

[thoxbui]

It's going to be a full suspension dual hub motor bike.
The bike is being put together from 3 bikes.
1. Fork from an Iron Horse something or another.
2. Rear triangle from a Next bicycle
3. Front (main) frame came from a Mongoose cx24v450 electric bike.
It's a little tricky, replacing a 20" wheeled bike with 26" wheels with hub motors.

View attachment 5

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Next step is to replace the shock, and install the hubs. I have two of these, a 800W brushed rear, and a 600w BL front. I will drive two controllers with one (for now) 36volt, 10Ah pack of lithium polymer. There is plenty of room for more (as long as the shock doesn't disintegrate).

Bye for now

 

[thoxbui]

The shorter rear shock came in today, it has black springs--perfect match.

Added the motors today. Does anybody know where I can get those torque washers (the ones with the tabs) to keep the motor axles from spinning? The motors I have have only them on one side, and I'd be more comfortable with both sides locked down.

At any rate, the bike handles well under pedal power. The lower steering angle will provide more trail and will help the stability at high speed that will come with the 1400+ watt (eventually). I'm glad I didn't chicken out and went with 24" wheels. I think it looks alright as is. And I didn't even have to pull out the welder!

Next major dilemma: where to put the controllers, just enough so I can ride it under power...

 

[maydaverave]

Really cool idea. Looks like the perfect battery location especially for a dual hub motor set up. Should be a great trail bike.

 

[thoxbui]

Really cool idea. Looks like the perfect battery location especially for a dual hub motor set up. Should be a great trail bike.

The battery space should be big enough for a decent amount of LiFePo. My plan is to get 2 packs. The throttles were put in place tonight.

The original intent was to wire them to the same throttle, but after reading the various threads here about dual motors, I decided to keep them completely independent of each other. If one drivetrain die for what ever reason, I will still have enough power to get home.
Testing the ergonomics suggests that I can activate both throttle with one thumb movement. But if want to connect them later, I'd probably just use one of these black paper clips.

I should look for throttles with bigger thumb lever to optimize, but it seems to work pretty well as is.

Tho

 

[thoxbui]

I wired up the bike with just the front motor and rode it around for a while. Everything seems to work, handling is good. Even with just 600Watt, the bike shows some decent speed and stable handling. So back to the real construction.

I decided to mount the controllers beneath the seat. Below is the mockup of the rough location where the controllers will be


And I could never resist the urge to make something out of wood, so the mounts for the controllers are made of 1/2" thick wood.

 

[thoxbui]

The controllers are mounted onto the wooden platform.
View attachment 1

And the some wiring cleanup with zip ties.

 

[Kingfish]

Nice assembly! Can you summarize the final specs please?
Specifically: Volts, Ah, controllers, motors (presume Crystalyte but I don’t own one), top speed, and distance.

Intrigued by your genius, KF

 

[spinningmagnets]

Very clever! I am a fan of published "no-weld" solutions for the millions of apartment-dwellers out there. The parts really look like they were designed to be together that way!

If paired with a popular system such as the 9C/Aotema, and just enough LiFePo4 to avoid voltage sag, you could really sell these. Even if many turn their nose up at Chinese steel frames, we must admit that half the parts you show are available as used and cheap.

Gas shocks are expensive, but they ARE an option that drops in to improve suspension feel (also available used), later as funds allow.

Just a note: for those who want a 20" or 24" wheel, you can add a fairly "easy to make" extender to the shock mount to 'clock' the rear suspension down, so your pedals aren't too close to the ground with the shorter wheel.

 

[thoxbui]

Nice assembly! Can you summarize the final specs please?
Specifically: Volts, Ah, controllers, motors (presume Crystalyte but I don’t own one), top speed, and distance.

I can't quite yet...it's still in progress, but will try to get something together when I'm done.

 

[thoxbui]

The saga continues...
It turns out that one of the thumb throttle is kaput, so I had to order a replacement. It arrived a couple of days ago, so I wired everything together.
As I mentioned on a previous post, the only spare battery pack I have left is a rather small lithium polymer unit. It came with the front wheel motor and BLDC controller.

There is no power switch to the Brushed (rear) controller, I used a 50 amp switch to act as a main power switch. Real simple circuit:


A wooden platform for the battery pack is added, and I bungeed the battery pack in place. The spec on the battery is 36V, 10Ah; but it seems awfully small compared to my LiFePO4 pack of equal capacity.


The bike seems to scream for more battery


All good now? Of course not. I took it out for a test ride, and it showed excellent acceleration...for about 5 minutes, then the low battery light came on and I'm out of juice! Took it back inside to check: 40A fuse is still good. I suspect that maybe the battery is not capable of supplying as much energy as it used to. Either that or there is an internal BMS that shut it down early due to excessive current drain. Maybe I should ride with just one motor for a while to see how long the battery lasts.

Whatever the reason, it looks like this project is on hold until I can justify for some more lithium :-(

Tho