James Huang spends some quality time aboard Ellsworth's premier cross-country suspension mountain bike:
Mountain bike rear suspension has evolved in leaps and bounds over the past dozen or so years. Plenty of mistakes were made early on and some designs bordered on comical. However, a handful of those early themes, plus some new ones, have managed to survive the evolutionary cull including the ubiquitous four-bar linkage. True four-bar linkages are just about everywhere these days, but a common misconception is that they all work about the same. Pivot placement is critical in determining not only how the suspension reacts to trail features but also how it reacts to other input. In an ideal world, the rear end is always free to react to bumps and is completely immune to pedaling or braking forces but few designs manage to achieve this goal.
Like so many others, the Ellsworth Truth uses the ubiquitous four-bar linkage design but with a unique twist called Instant Center Tracking. This precise manipulation of pivot points is specifically designed to almost completely eliminate pedaling- and braking-induced suspension movement while retaining excellent bump compliance in all conditions. These are rather heady claims for sure as they represent the ideal case, but after a healthy dose of test time on a Truth, I suspect Tony Ellsworth really may really be on to something here.
The Truth is designated as Ellsworth's premier cross-country/endurance racing frame with four inches of rear wheel travel. This is a true four-bar linkage design complete with the critical Horst Link pivots just ahead of the rear dropouts. All of the pivots rotate on sealed cartridge bearings and movement out back are controlled by either a custom-tuned Fox Float R or Manitou Swinger 3-Way Air shock. Note that neither of these shock options is equipped with a manual lockout, nor is there another option for one that is so equipped (we'll revisit this subject later).
