I did quite a bit of research prior to building up a Yuba Mundo - there were a few blogs that documented the build process. I found these super useful:
http://wiki.stevevance.net/yuba/specs
http://monumentallyafflicted.blogspot.com/2010/01/yuba-mundo-v3-upgrades.html
http://keller74.wordpress.com/tag/mundo-yuba/
http://mark.stosberg.com/blog/index.html
Mark's Flickr photos and tales of family commuting on his cargo bikes are truly inspirational.
One of the things you'll run into immedately when building up one of these amazing bicycles is that the rear dropouts are 14mm to support the standard 48 spoke 14mm solid rear axle. I considered buying the stock wheels, but opted instead to build a pair of wheels using Salsa Gordo rims with triple-butted DT Alpine spokes (36 h). I think the stock wheels take a 7speed threaded sprocket? Boo.
It's really really hard to find a disc hub, 135mm spacing with a 14mm axle for a reasonable price ;-)
Build highlights:
- Surly Big Dummy Fork
- Deore 6-bolt disc front hub
- XT 6-bolt disc rear hub (9spd)
- Salsa Gordo rims / 36 h / DT Alpine triple butted spokes
- Avid BB7s (Front: 200mm, Rear: 10mm)
- Soma Clarence bar
- Brooks saddle
- Thompson post (27.2 w/ problem solvers adapter)
- Ourey lock on grips
- SRAM 9 spd rear derailleur
- SRAM X5 9 spd shifters
- XT triple front crank
- Yuba wheel skirts
- Custom top deck and running boards
- Avid speed dial brake levers
Here is my Evernote build/to-do list.
So - what I wanted to get detailed around is the rear wheel / disc brake interface. It was massively frustrating to say the least. Here's how it works:
*NOTE: This is specific to Avid BB7 brakes*
- Rear is a standard disc frame tab (international standard I guess?)
- Rotor is 180mm
- Adapter is a 140 Front 160 Rear Avid adapter
- The bolts to attach the adapter are too long and will hit the rotor when fully engaged, they need one 10mm spacer on the outboard side of the adapter (standard brake flat/conical spacers that come with the adapters)
- If the caliper is attached to the adapter with the standard spacing setup, the rotor will not even move b/c there is not enough clearance between the caliper and the rotor.
- Add 2 10mm spacers to each side of the adapter to raise the caliper up over the rotor - there is still plenty of thread engagement to keep it secure, not to worry.
- Here's the tricky bit: Caliper is properly positioned over the rotor, the wheel spins freely, but when the pads are engaged, the outboard pad will not retract. I spent a lot of time at this point troublshooting and adjusting the pads and spacing. It would appear that everything would be adjusted properly, but when the brake was engaged, everything would be thrown out of adjustment. Here's the problem and solution:
- The small brass? pull on the brake pad is coming into contact with the adapter, being pushed over it, and is unable to retract back into the caliper body - it hits the adapter.
- You could add a few mm of spacers to the adapter to raise it up slightly (but at this point you're losing thread engagement from the caliper to adapter.
- I ended up filing the brake pad down slightly - it's about 3mm and the pad will easily retract. Done and done.
Other other major issue I ran into, probably related to the build quality of the frame itself (I would look to Yuba before I looked to Shimano)... the rear axle extended slightly (about 3 mm) beyond the dropout - what this means is that if you're using a 10mm standard axle (with Yuba supplied axle adapters to convert 10mm to 14mm) with a quick release, the wheel only partially clamps into the dropouts. I discovered this on the maiden voyage when pedaling hard - there is so much torque on the rear wheel as a result of the length of the bike, that pedaling hard would unseat the axle. In one of the pictures above I tried using an Ikea cabinet bracket (perfect fit for the quick release skewer, sharp edge to fit exactly over a small shelf on the dropout). It worked marginally better, but the axle still slipped.
I stopped by the LBS and Mundo dealer (http://www.joe-bike.com/) around the corner from my house and they took a look and provided me with a slightly concave knurled washer. It did the trick - no axle slippage.
The final change I'm going to make to the bike is to rebuild the rear axle with a 174mm solid chromoly axle and bolt it in. This should solve the slipping axle issue.
That's it, just wanted to jot down when learned.
Happy to chat about building up a Mundo. http://yubaride.com/



