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The Yuba Mundo Thread

195K views 376 replies 72 participants last post by  derekageorge 
#1 · (Edited)
Yuba Mundo is now a fully established cargo bike with many owners worldwide. Let's share our experience from riding her, loading her and upgrading her. Here is mine with a fixie in a tow, with a 1940 vintage S&K velocipede, parked at home next to a coat rack, and a detail of her winter shoe. Mine is stock V3 with a front rack, Avid bb5 upgrade and few small things to make the ride for my kids more comfortable. Post pictures of yours, show us the improvements you made on her...
 

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#201 ·
Depending on which generation Mundo you have, you may also need a new headset. At the back you may have a hard time shifting to low gears, so a longer bottom bracket axle or a different rear hub may be needed (take a look at my Yuba at the beginning of this thread.
 
#203 ·
You have to look at these fork characteristics - axle to crown distance, width, offset, trail (trail is a result of fork-frame-wheel combo, so you will not find it). Both Yuba and Surly should be able to tell you other data. Then choose an offset and the axle-crown distance closest to your current fork. My old version Surly fork came pretty close. It put the bottom bracket a bit higher and gave my Yuba a livelier feel, which I find as a good think in the end. Good luck and post the picture after you are done.
 
#204 ·
Fresno check out Motormans Fat Mundo thread for some more detail of his build.

Some fork comparison numbers;
Yuba standard v4 fork axle to crown 418mm, fork offset 59mm
Surly Pugs fork axle to crown 447mm, fork offset 43mm
Surly Big Dummy fork axle to crown 425mm, fork offset 43mm

I imagine that the higher than usual fork offset if the Yuba is designed to give a more stable ride. I don't know, but that it might be more important if using the big front rack loaded?

When I put the numbers through a trail calculator putting a BD fork on gave the same trail numbers as my rigid MTB, which is probably why folk with that set up report it feeling more nimble. I guess it also makes it feel more normal.

The Clown shoe rim and Moonlander fork are probably overkill unless you have a specific purpose.

If you go with the Pugs 100mm fork you could use the standard rim or perhaps a standard front wheel with a 42mm - 50mm.

It's worth considering the effect of much larger tyres and longer forks raising the BB. Good for off road clearance, but harder to control the loaded weight when starting and stopping
 
#205 ·
My Yuba has two months and around 800 km. It serves well and during its operation I am identifying things to improve. One of them is the gear ratio. On my way to the downtown there is a long, moderate descent. On my road bike I use to go there around 60 kmph. Yuba has a 24/34/44 chainwheel and that in the combination with the 14 rings on the smallest freewheel means, that the bike is slower in the traffic. (I realized this when I tried to overtake the bus leaving the stop: we were going side by side around 200 meters and I was not able to go before it, pedaling as fast as I could. :D )

A solution could be changing the chainwheel to something like 22/39/53. I don't need small differences in the possible gear ratios but I still need light ratio to go uphill with a loaded bike.

Do you have some experiences in changing the front chainwheel? Should I expect any complications?

Thanks
 
#207 ·
I'm not sure what kind of cranks the stock mundo has. If the rings are removable, you could get a 48t chainring and maybe a 50t if you're lucky, assuming 4 bolt 104mm bcd (bolt circle diameter).

The more pricey but easy option would be to get a road triple crank and chainring setup, such as a sora or tiagra one. (it's 9sp but that won't matter, worst case scenario, you might need to upgrade the chain too, I don't know what the stock yuba has and can't tell from pics on their site, 8sp chain will work great as upgrade)
I google it and found one for <90, but you can probably do a bit better looking around
Shimano 2011 Sora 9-Speed Triple Road Bicycle Crank Set - FC-3403 : Browse All Products
(edit: just noticed this one doesn't include the necessary hollowtech II bottom bracket, look around as I think you can find a road triple for around this price that does include bb.)
Sugino makes a nice forged square taper crankset that *might* work with your current bb, but this depends on its length and once again, can't tell this spec from the yuba site (though no manufacturer gives this detail)
here's the sugino: Sugino XD600 26/36/46 Triple Crankset in Tree Fort Bikes Cranks (cat119)
and you might need to buy a new bb too, but you won't know until you measure the old one (spindle length[~100-125mm range]) and compare it to what the sugino requires.
Once you have 5 bolt 110mm bcd you have a lot more chainring options. I have a cheapo steel 50t 5 bolt ring I got for nearly free from a shop that does used bikes.

The complication is that your front derailleur should roughly match the curvature of the big ring for good shifting. If you go substantially bigger than what you have now, your derailleur might be sub optimal, but you can probably live with that. You just have slide it up the seat-tube until the derailleur cage clears the big ring.

I'm not sure about how small of a gear you can have on the rear wheel, as this is an unusual wheel, but you do have the option of putting a regular cassette w/ 3/8" to 14mm axle adaptors and then you can go up to 10sp and down to 11t, though changing the number of gears would require new chain, shifters, etc. Replacing your cranks would be the cheap place to start.

Regarding Fox's comment, yes high bottoming will be more problematic in off-road situations, so this could be applicable, depending on where you take the bike.
 
#206 ·
I would not recommend switching to a much bigger chainring. Since Mundo's wheels are further apart than on a regular bicycle, it's bottom bracket (and the largest chainwheel) is relatively lower to the ground when riding over bumps on a changing slope off-road. Would a 13 tooth freewheel fit over the rear axel? Or next time ride behind the bus and overtake it while it stops to un/load passengers:)
 
#210 ·
Does anybody have a child seat for larger child (5+ yrs) mounted on a Yuba? I hope my daughter will ride her own bike as much as she can, but for longer rides or for travelling through the dense traffic and with no child-safe bike routes the seat is necessary.

The only applicable product that I have found so far is the GMG Classic 911 (sorry, I can't post link here :nono:, you must substitute dot for .: www dot rijwielreus dot nl/yepp/1351-kinderzitje-achter-911-met-voetsteun-8715362002075.html). I am not sure about the mounting. Can be the seat mounted to the rear carrier as is delivered, or some special adapter/DIY work is needed?

Is the width between the seat's leg supporters sufficient for Yuba?
Sometimes it can be useful to have only the child seat without the leg supporters (for a big box or Go-getters mounting) - is it possible to remove the supporters? I have found a picture (again, I can't attach the picture :nono: www dot senselife dot co dot uk/GMG/GMG_911_underside_2500.jpg), it looks like the horizontal part of the supporters can be unscrewed, but what about the vertical one?

Perhaps there is another child seat like GMG Classic 911, you can recommend it to me :)
 
#213 ·
heavy bulky load

Just brought home two shoe cabinets, about under hundred pounds each on the loaders. The bike handled just fine. Cabinets seemed to be easier to carry when tied on the bike in the tall position and forward rather than low and partly beyond the rear axle. Looks like getting the center of gravity higher is less of a problem than moving it backwards. Happy new year!
 

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#215 ·
I tried to load them both vertically and horizontally. Horizontally placed boxes sucked, there was too much load behind the rear axle. Vertically placed boxes were surprisingly easy to carry. But those boxes were only 4ft tall. Good luck and post a picture!
 
#216 ·
Yes, placing something behind the rear axle is really tricky, when my wife and daughter sit on the rear carrier (without child seat), the daughter sits in front and it can be seen on the bike maneuverability. Inverse order of passangers is impossible, my wife serves also as a backrest for the child :)
 
#217 ·
This is why having a solid front basket/rack can be especially helpful. When weight is unavoidable behind the axle, you can make the bike a lot safer by adding weight to the front wheel so you still have proper handling and good steering traction.

I just use a cheapo rack that mounts to the fork, but hope to eventually get the yuba frame mounted one or find someone to fabricate one for me. Even with only modest weight behind the axle, I am more confident with some weight up front balancing things out. for example, when I put 40lbs of groceries evenly distributed across the rear rack, I like to strap a 12 pack to the front rack. It shows the world my fine choice in beer as well.
 
#223 ·
Yestarday I was going to work on my older bike and had some technical difficulties during ride, so I had to leave it locked halfway near a shopping mall.

In the evening I came with my Mundo and for the first time tried towing. The second bike (with a front carrier and a box on it) was attached to the left side, all lights turned on and the ride could start. The bikes were perfectly ridable, only minus was the weight (both bikes had almost 50 kg together) and it was slight uphill from the mall to my home - I feeled it like a steep uphill in fact. Streets were empty at that time. Fog, no pedestrians, only few cars, but their drivers were looking curiosly and surprised, like the did not believe their own eyes :D

Before action
Tire Wheel Bicycle tire Bicycle wheel Bicycle wheel rim

Ready to go
Wheel Tire Bicycle wheel rim Bicycle tire Bicycle wheel

Mission completed
Wheel Bicycle tire Tire Bicycle wheel Bicycle wheel rim
 
#226 · (Edited)
Reasons like this are why I avoided the complete. Fortunately, you can get bmx-style 3/8" to 14mm axle adapters and use a modern cassette hub. rear qr axles are 10mm and 3/8" is ~9.5mm, so you have to file out a bit of material, but it works well with a very tight qr (275 lb load plus my 190lb). Modern cassette hubs tend to be much longer lasting than multi-speed freewheels. and you have a wider range of gear options such as a 9sp 11-36t slx cassette.

If the freewheel is just siezing, a penetrating or other thin oil dripped in from the back side (best choice is to do this with freewheel removed from hub to avoid washing out hub bearing grease) will often make it happy for many more miles.
 
#227 ·
Wow! I really like the idea of full fat yuba! Must have took all the tractor abilities from both worlds! :thumbsup:

I like the idea of fat bikes and I also like cargobikes. This could be such crazy thing I would do myself if got the coin for it. :cool:
 
#228 ·
I finally completed my fat Yuba. I used an old Surly fork with Surly tire in the front and NuVinci360 hub and Remerx Jumbo rim and Surly Endomorph tire at the back. The rear cog is 22 teeth Surly with the original Yuba crank and 42 teeth in the front (I could go as low as 40 teeth). This allowed me to move the chain enough to the right that it does not rub the tire. I had to keep the derailleur to keep the chain properly adjusted. The ride is perfect, you sit higher and kids at the back are happier (more cushioning from 4 inches of a tire). Suddenly the curbs are no obstacle to this monster. Snow, mud, grass, rock gardens - no problem!
 

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