Several Yuba Mundo Builds

Are the V4 torque plates available for sale yet? Didn't see any in the For Sale section.

Are the V4 torque plates available for sale yet? Didn't see any in the For Sale section.

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Pretty sure Kiwi is selling them now, he has sent me a prototype and they are sweet as. Can't recommend them highly enough. Send him a PM.

SOrry, yes I have had a bunch made from 4mm Stainless steel.
US/AUD $35 a pair to the states or Australia, includes freight.
Will put up listing on for sale section.
Also I might get a V4 this week! So lots of other accesories to come

Hey Kiwi,

I saw one of your yuba mundo bikes in Wanaka today. The driver and passenger had a couple of huge ev grins.

Clay

Thats Callums bike from the Thunder Bike shop. A pretty nippy set up on that.

Check out this documentary trailer.

[youtube]aVjFq0Yni0I[/youtube]

Thanks for posting that doco trailer up Kiwi, I will check out the whole doco.

My Yuba has changed our family life. I have two kids seats on mine, and 40AH of battery. I can pretty much cover my whole city carrying my two kids. So true what they say about the kids not wanting to get back in the car, my kids jump at any opportunity to get out on the bike, they scream with joy on it. I pick up and drop off my son to school on it everyday, and I can tell the other parents think I am some sort of hippy greeny, but I try and explain to them it is unrelated to the environmental benefits, it is just so much fun, so convenient, and just so pleasant.

If the above is a trailer, do you have the link to the whole documentary?

yea nice Vid makes me want to get a cargo bike.. would like to see more.

Kiwi said:

Thats Callums bike from the Thunder Bike shop. A pretty nippy set up on that.

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I'll have to stop in and see him. I don't get in that shop much. Actually I don't use any of the LBS's much as they generally don't have what I need, or I can't be bothered explaining.

It was nice to see another ebike in such a small town at the end of the world though.

Clay

Hi guys, I just wanted to share my latest build on a Yuba Mundo V3.3 Thanks

Nice work! I was about to design one of these, but now I wont bother. I have Nuvinci rear dropout adapters designed, available in 2 weeks, so with your mid mount and a nuvinci at the rear, some sweet Yubas to be had.

Kiwi said:

Nice work! I was about to design one of these, but now I wont bother. I have Nuvinci rear dropout adapters designed, available in 2 weeks, so with your mid mount and a nuvinci at the rear, some sweet Yubas to be had.

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Thanks. Yes, the Nuvinci will be a perfect match. I love how you can shift gear ratios while stationary. Works well when you forget to downshift before a complete stop.

UCS. I've got the developer's nuvinci hub and a yuba frame and hope that kiwi can come up with some good axle adapters. I'd like to input up to 2,500 watts into the nuvinci. Is you mid drive capable? Thx.

wow that thing sure is pretty

snowranger said:

UCS. I've got the developer's nuvinci hub and a yuba frame and hope that kiwi can come up with some good axle adapters. I'd like to input up to 2,500 watts into the nuvinci. Is you mid drive capable? Thx.

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Hi Snowranger,

It is safe to say around 2000w but that is pushing it, the kit comes with a 10T MAC motor and a 9 FET 4110 Infineon 30A Controller. You can upgrade to a 12FET 45A Infineon to easily output 2500W safely, without pushing the limits of the controller. Top speed Im getting right now is 38MPH, with an 8T MAC, 9FET 4110 Controller with a 72V 12A SLA 55lbs pack, and that's with a 14-28 7 speed cassette, it can easily go 40 - 41MPH with 11-34 cassette, maybe faster if I use a lighter battery pack. The 10T MAC will yield the same speed at higher voltages, but will run cooler and can handle lower RPM - high load situations.

Sonny

I will add all these to my for sale thread when they are manufactured and proven.

Here is the concept for the YuNu adapters. (note only for 171 series and developers kit. Not sure about 360 yet)

There will be 3 types of Nuvinci adapter for the Yuba.
1, YuNu keys. These simply fill in the missing space in the drop outs. They would be fine for pedal only setups or 300w or less setups. Also provide for chain tensioning. Needed to position the axle with the following torque plates.

2. Static Torque plates, like the plates for standard motors, only cut to suit the Nuvinci. You will need a chain tensioning device with these. Suitable for hi power setups. Good for mid drive setups if you can shift the motor mount to tension the chain.

3. Tensioning torque plates. These allow for the tensioning of the chain in high power mid drive applications. I will release these for standard rear hub motors, for use as single speed.

Keys shown below.


Static plates



Tensioning torque plates


And adjuster


Now, the reason the adjuster has indexing is so the weight of the bike always pushes the reaction plate against the frame tube.
If it was just a slot, then the reaction plate could slide down, effectively useless. So when you set it to tension your chain, you choose the index below so the plate pushes on the frame before the chain tension stops it from moving.

Complete




Not sure of cost yet. The keys will be cheap, the static arms will be about $40 a pair including the keys, the adjustable ones probably about $50 a pair. So not too bad.

Great work Kiwi. You addressed all my needs concerning the nuvinci.

I'm wondering how the disc brake compatibility works with an adjustable axle position.

...yep, thats a tricky one. Not very well. That would require yuba making slotted disk mounts at the same angle as the wheel drop out. If you had a large rotor, an adapter could be made.

Very nice work.

I'm considering a V4 Mundo with two rear hubmotors. One in the rear wheel, and one mounted just forward of the rear wheel driving the rear wheel via 1:1 cogs and chain. The cogs would be mounted on the motor disc mounts. The motors might be a pair of HS3540's. Do you think there is room for the chainline? Would it be difficult to mount the forward motor?

I am going to look at fitting the HS/NC/Xlyte in the space, but it looks tight. A simpler way would be to have the second motor in the front wheel.

Alan B said:

Very nice work.

I'm considering a V4 Mundo with two rear hubmotors. One in the rear wheel, and one mounted just forward of the rear wheel driving the rear wheel via 1:1 cogs and chain. The cogs would be mounted on the motor disc mounts. The motors might be a pair of HS3540's. Do you think there is room for the chainline? Would it be difficult to mount the forward motor?

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I was going to go that route before I finally settled into what I currently built for the V3.3/V4. Achieving a good chainline is impossible not unless you use a jackshaft and another fixed gear cog to line up to the rear motor's disc rotor mount. You will also be limited to using 26 x 2.0 or narrower rear tire. Chain rubbing on the side walls will be an issue too with wider 2.3 / 2.4 Maxxis Hookworm tires or Schwalbe Big Apples.

Interesting point. Wonder why there is not enough room for chain on the left side. Seems like no problem on the right side.

Maybe the disc brake mount is not far enough out. That probably depends on the motor in question.

Thanks, will look at that.

By the way, your motor setup looks nice. Which hubmotor is that, or what are its specs?

It's a MAC 8T Geared Hub Motor. The Hub's mounting holes are too near the rear drop out. If you situate a chain coming from the motor mount, it will rub on the chain stay. With the setup you mentioned, aligning both left sides of the hub motors will be hard plus the chain rub on the chain stay. As kiwi have mentioned, the second hub motor will be ideally up in the front fork.

Putting the hubmotor in the front fork is one way to do it, but it is far from ideal. I would prefer to have a suspension front fork, and this is not a good combination for a hubmotor. The traction of the front wheel is not great, and loss of traction there leads to an instant loss of control. With a heavy bike the rear wheel has nearly all the traction. The front wheel has only a fraction of it.

Doubling the power to the rear wheel is in many respects much more desirable. And if it can be worked out, much easier than dealing with all the front wheel issues.

Thanks for looking at this.

The biggest problem is finding a mounting and chainline for the central motor. Seems that folks have been able to do this with central motors on many other bikes, but perhaps the Yuba frame is in some way unsuitable. It looks like the V4 frame has a lot more space for this than previous frames, but perhaps this is not the case.

I have a Mundo V4 with front and rear BMC V2S hub gear motors and the arrangement works out very well. I have a left thumb toggle to cut the front motor in or out (both run from the same throttle) and actually only kick it in for hills. I do wish for some suspension, but 95% of the time it's a great ride. On the flats and low grades, the rear motor pushes things along nicely, but kicking in the second motor is like night and day. In a real pinch, a second left thumb toggle suppresses the CA current limiting and the two motors run flat out to chew up hills. This thumb toggle approach (w/o requiring release of the grips) makes it effortless to select the amount of motor/current to apply much in the manner of diddling an index shifter.

On pavement the front wheel spins briefly from a dead stop if I launch with both motors and no limiting to bolt across a high traffic intersection (not recommended to extend gear life BTW), but otherwise for street use the front hub motor is well behaved since the bike is usually already rolling along at a good clip when it's cut in for a boost.

So, I guess the point is that in my case, I do not off-road the heavy cargo bike and common stand-alone front motor issues do not arise in this dual motor application because of the controls and particular use case. If you give this a try, I'll wager you will like it ....