Several Yuba Mundo Builds

[ryan]

Hahaha! Awesome! I want to see it get some air.

[thewall241]

Nice Kiwi, good to see the yuba tearing up the track. Hey there is a cromo-lite frame on TM at the moment, not quite a d-8 but could still be a pretty solid start for a FS build.

[Kiwi]

Yeah I saw that. I really want the d8 as the shock is out of the way. I plan on cutting the frame and mid mounting a dd hub motor driving a nuvinci at the rear. I might be better off to start from scratch.

[ryan]

Hi fellow Yuba builders. Just wanted to let you know that I'm gaining ground on my v4 build with running board battery enclosures. The last of the parts are coming in over the next few weeks. I figured I'd share a couple shots along the way.

running-board 1.jpg (131.14 KiB) Viewed 569 times

running-board 2.jpg (152.77 KiB) Viewed 569 times

running-board 3.jpg (155.18 KiB) Viewed 569 times

Any other builds lately?

[ohzee]

I am going to do one in about a month or start and wow I think I know what I want to emulate.

love your holders how does that extra weight feel front wheel seem any different ?

Great work man.

[ryan]

Lol. No weight just yet. All talk so far.

My batteries get here later this week. I'll be running 18S4P (roughly 66.6v32Ah or 2131W-hr) in the running boards. It's going to be a tight fit, but I'll make it work.

My new motor (x5404) is still in China, so who knows when it gets here. I'll run the 5304 until it comes.

Here's the build thread.

[teklektik]

ryan- To minimize flex you may want to consider bolting up a front-to-back piece of angle or square tubing roughly parallel to the chainstay, under the bottom sideloader and inside the Mundo sideloader frame. An alternative might be a long rectangular solid inner panel fastened between the top and bottom decks on the inside face with cutout on the bottom for axle nut/derailleur. When you hit a bump, sideloader batteries pretty much try to launch into orbit and then re-enter to the core of the Earth. There's a lot of mass in play there that really wants to have its way; if it's attached to the sideloader, the unsupported area of the sideloader near the axle nut tends to flex up and down while bolted points around the edge are held in place.

With a separate metal/rigid battery box hung out on the sideloader things aren't too bad, but in your case the Mundo LDPE decks may result in cell assembly twists and flexes on every bump (Bzzzt! Bzzzt!).

I have sideloaders made of HDF which are loads more rigid than the Mundo ones, and they still get twanged pretty good by attached battery boxes. Anyhow - just a heads-up for something to keep your eye on - or maybe a little time-filler add-on while you're waiting for parts to arrive .

[itselectric]

Hi fellow Yuba builders. Just wanted to let you know that I'm gaining ground on my v4 build with running board battery enclosures.

Ryan:
That is an excellent idea for battery storage! May I copy your idea on my next Yuba build?

How are you planning to keep the enclosure water proof?

Ken

[Kiwi]

Hi All.

I have ordered 32 Yubas!
Anyone in NZ want one?

Also in development, universal battery case internal 300x150x110 (ping upto 36v20 or 48v15) or lipo.
Designed for Yuba but will fit most rigid frames.

Front and rear torque plates available, also nuvinci rear adapters available, both static and adjustable for chain tensioning.

Perhaps, later, a midmount bracket. Have worked it out on paper, still cant fit a 9C or xlyte, maybe if we turned of the spoke flange.

In build a 72v conversion using ezee batteries, lyen controller, NC 2808 front.

Kiwi.

[ryan]

Ryan:
That is an excellent idea for battery storage! May I copy your idea on my next Yuba build?

How are you planning to keep the enclosure water proof?

Ken

1) You can only copy if you promise to improve it. (and then share it here for others to improve on)

2) I'm unsure right now. I'm thinking of wrapping the packs in some yoga mats for padding. And then heat shrink most everything else. I don't typically ride in down pours so if it's generally resistant I'm probably alright. Any other ideas?

[ryan]

teklektik - You're absolutely right. As I'm laying everything out it's becoming clear that the boards are not as solid as I thought. Your strut support may do the trick. I wonder if I can cut a square tube at the ends to leave a single panel at both ends. Then drill some screw holes and screw that piece into the first and last running board screw holes. If that makes any sense.

[teklektik]

Makes perfect sense - I considered the same approach. But, after thinking about it, I don't believe there is much gained by fastening to the Mundo tube. Just bolting the stiffener tube end to the deck adjacent to the sideloader tube leaves little measurable deck to flex. But, if your stiffener tubing is thin enough not to shim up the deck too much (steel instead of aluminum), it certainly won't hurt to do as you describe.

My current batt boxes and decks are temporary but I tried to do a fair job with the decks because of the heavy Headway cells I'm using. So far they are working out okay without the extra strut. I did counter-bore the bottom of the decks to clear the protruding insert tops so the decks lie flat on the sideloaders for support, but I think you already may have this effect because of the mounting slots in the Mundo decks...

[teklektik]

ryan - Apologies if this is obvious but just trying to pass along some past Mundo-think :

Flex in the long narrow sideloaders isn't in itself bad, it just needs to be appropriate for the inherent dimensional stability of the internal cells and the flexibility of the cell interconnects. Something like a long naked Headway battery composed of Headway plastic spacers and bus bars or cylindrical cells with spot-welded bus tabs will do badly with much flexing. But, break this into several smaller bricks with internal stiffeners then interconnect those with flexible wiring, and all is well.

So - the plan seems to be to do the best we can with the twangy sideloader nightmare and then package up cells appropriately instead of necessarily relying on dimensional support from the decks...

On another front - here's a little anecdote that you can make of what you will:
I am temporarily using heavy plastic toolboxes for battery enclosures with flat plywood stiffeners in the bottoms. They are quite sturdy and are rigidly affixed to the sideloaders. A couple of weeks ago I ran over a 1" stick about 24" long on the roadside - no big deal for fat tires. Except this time The Evil Spirit of Jousting caused the branch to leap up and jam between the immovable Earth and unstoppable front of the right battery box. A split second later I had a thoroughly impaled and shattered battery box . Fortunately the boxes are intentionally oversize for battery experiments and the upper impaled 1/3 was empty of vital organs...

Definitely a freak accident but it brought home the increased vulnerability over frame packs -- sideloader packs can do with any help we can afford to protect them from bits of the world that will inevitably get in the way.... (e.g. Kiwi's steel ammo boxes)

[ryan]

Ouch. Any photos of the carnage?

[teklektik]

Nope - no camera at the time and I couldn't ride with the piece of forest sticking out of the bike for a later shot. If there had been flames, sizzling, and melting, the discarded case would have been photo-worthy.

[Alan B]

Lining with plywood in the forward and inside sides might be prudent. Even thin plywood would slow down a blunt spear significantly.

[teklektik]

Very good idea - no room on the side but I can slip a little armor in the front w/o problem. I'm done experimenting with different XsYp setups and so hopefully can replace these boxes with a final aluminum 'thick deck' version this Spring.

[ryan]

I want to see some closeups of your build, tek. Do you have a build thread up? Post pics here if you have them.

[teklektik]

I've been putting a build thread together with a fair bit of detail.
Thanks for the interest - I'll get it posted very soon.

EDIT: 2WD Electric Yuba Mundo Build

[es2150]

Things looked great until I realized yuba has no disc brakes.

[teklektik]

Things looked great until I realized yuba has no disc brakes.

Google: "yuba mundo disc brake"
Google: "site:endless-sphere.com yuba mundo disc brake"

Yuba Discs: Yuba: Disc Brake kit Tektro Io
DIY: Yuba Mundo BB7 Disc Brake Installation

[ohzee]

Yea his post confused me as well.. I LOVE my BB7's on my yuba.. I can stop on a dime.

[Philistine]

Things looked great until I realized yuba has no disc brakes.

Disc brakes are standard. But if your rear hubmotor doesn't allow rear disc brakes (my motor didn't at the time - was a non-disc 5304 old school), then you will find the disc brake stress on the front forks a problem if you work them too hard http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=40902&hilit=+yuba+disc.

Otherwise, if your rear hubmotor allows discs, then you can get one working with some spacers and tweaks. It requires spacers because whilst the Yuba suggests (by virtue of the spacing of its disc tabs in the rear) that it wants a 203mm rotor, it doesn't (because this will rub with most hubs on the frame), it needs a 185mm rotor, but needs a random bizarre spacer to get it to work. Still don't understand how that came about in their design, I really don't, but have seen it working.