The e-book offers plenty of tips to overcome these challenges including how often to check and relubricate motor bearings, the best way to avoid misalignment and how to deal with issues like soft foot.
They're also dust and dirt repellant -- they seem to absorb dirt particles and then relubricate themselves, whereas, the traditional ball- and needle- bearings have to be regularly cleaned and relubricated." And what about the occasions where the bicyclist rides into less-than-dry environments?