I don't know if this is the same noise you are hearing, but after a few days of riding my new Rad Mini, I noticed a "clicking" noise when I rode on a tractor trail in the woods. Through process of elimination I traced it to the place where the bike folds. The latch was tight, but it's metal-to-metal where the two halves come together. A spray of WD-40 took care of it.

I just received my new Rad Mini 4 this week. I intend to use it mostly for maintaining my horse trails in the woods, and the local roads are gravel. It came with very smooth road tread tires, CST Big Boat tires that don't provide any traction on dirt trails. On Rad's website it looks like the most aggressive tires are Kenda Krusade 20" x 4", and they are out of stock. does anyone know of other tires available that are as, or more, aggressive that are available elsewhere?

It's great that the Rad Mini 4 has protective liners between the tire and tube, but would it help to spray in tire sealant? Or would that be a waste of time?