Small variations in linkage design, if considered to an improvement, are patentable. Older patents for suspension design may expired by now, or, similar to Canfield, be only for incremental improvements.
Not to nerd too hard on the whole patent thing, but the opening statements of this article aren't correct. Once an application has been filed, it is safe to show an invention to the general public. Nobody can take an invention from someone else if it is disclosed too early; worst case scenario is that an inventor loses his or her 20 years of monopoly granted by a patent- that is still pretty bad, but it isn't outright theft.