Warning regarding fork on older Mundos
EDIT: I see post 169 of this thread beat me to the punch. I guess it can't hurt to repeat the warning, and perhaps my engineer's eye added something to the discussion.
For discussion and photos of failed forks, see this thread on Endless Sphere:
https://endless-sphere.com/forums/viewtopic.php?f=3&t=40902&hilit=yuba+mundo+fork
Yuba is using round cross-section forks on the new bikes. I know of no problem with these.
The issue is with the tear-drop cross section forks used on older bikes. Especially if disk brake is installed.
The teardrop cross section has poor resistance to the torsional load that exists where the fork blade transitions to the crown.
This area is further weakened by the distortion/slight collapse of the tubing that occurs as it is bent into shape. This is quite obvious on the fork I replaced, though I have no paint chipping or other signs of imminent failure.
The disk brake caliper reaction puts increased load on the left blade. Rim brakes still put substantial load on both fork blades due to braking forces. Contrary to the title of the ES thread, the load on the fork does not depend on disk diameter. If you can almost skid the wheel, you are putting maximal stress into the fork. A larger disk will do that with less lever force, and less fade, but the reaction at the caliper mount on the fork will be identical.
The teardrop cross section resists flexing of the straight section in the fore-aft direction with loads from bumps and braking, which concentrates stress at the crown bend.
Even though the "kid" I haul on my mundo has four legs, rather than two, I felt this was a very serious problem, and replaced my fork post haste. To be clear, I experienced no problem with the fork over more than a thousand miles...almost all on pavement, but with the usual curbs, bumps, potholes etc. I'm a Clyde, and the mudo is a hauler, so there was a substantial load for all of those miles...a 15# dog in the front basket most of the time as well.
Yuba has new, beefy round section forks available, listed at $80 I do not know what concession they might or might not be willing to make.
Surly Big Dummy forks are available at ~$100 and work fine. That is the option I chose. They come with a bit longer steerer, and I am tall. Maybe I'll get it painted orange to match at some point, but for now black is the new black.
Round section unicrown forks have a decent track record on MTBs. I don't worry about that.