At about 650 miles of riding, it was time for new brake pads on my Sondors Fold X. I had completely worn out the rear brake pads to the point where there was nearly zero stopping power. It was a little dangerous to ride like that to be honest. Moreover, the front pads were squealing loud enough to wake up the entire neighborhood. They both needed replacement. Unfortunately that was more difficult than it needed to be.
In stock form, the Sondors Fold X from 2019 comes with Tektro brake components. Given that, the stock pads are Tektro E10.11 pads. They are not uncommon in theory. But given the circumstance of things today – like Covid delays – they were hard to find from a reputable source. Sondor's own website didn't even carry the parts. Super lame!
At first I assumed I needed those exact Tektro brake pads. But after some searching I found the following information: Shimano B01S pads are direct drop-in replacments for Tektro E10.11 pads. Some people even remark that they are superior.
Once I installed these new pads, which also come with the opening spring and extra Cotter pins, I was imediately impressed with the new found stopping power. Additionally, the lame squealing was also cured. These new pads are quiet, for now at least. I bought two pairs for about $30 from Ebay. While this price seems high, the peace of mind of getting a known quality part was worth it.