The ZR is a double locking tremolo and is the first Ibanez trem to feature a "Zero-Resistance" (ZR) ball-bearing pivot system. The use of ball bearing connections to mount the bridge to the body of the guitar (rather than a more typical two-post and knife-edge design) allow the ZR to effortlessly tilt up and down and return to its neutral position. The ZR is one of very few tremolo bridges in the market relying on the ball bearings as pivots, with Kahler and Vigier being the suppliers of the most notable other examples.
The ZR also incorporates a "Zero Point System" (ZPS) which is an extra set of springs which enhances tuning stability by helping to return the tremolo instantly to its "zero-position" or neutral point, which is the position at which the string tension is balanced by the spring tension with no pressure on the tremolo arm and the strings are in tune. The ZPS system facilitates simpler set-up of the tremolo and easier string changes. In addition, it is touted with an ability to maintain the tune of the remaining string should a user break one string while playing; it seems that while the ZPS helps somewhat in this situation, this claim is largely overblown. Should the user want a fully floating tremolo with more "flutter" when it is returning to it's stable position, the ZPS system can be removed.
Other features of the ZR tremolo include a built-in intonation adjustment screw which is stored on-board the tremolo body, an arm torque adjustment to allow the user to adjust the force needed to pivot the tremolo arm and offset saddle locking bolts to prevent the string getting in the way of accessing the bolt. A thumbscrew to allow adjustment of the spring tension without a hex wrench was added to the ZR for 2005.
A seven-string verson, the ZR7, was also produced as was a version with a Downshifter D-Tuner on the low E string.
A new ZR2 with an evolutionary design was introduced for 2008. The ZR2 features a redesigned push-in tremolo arm holder in place of the screw-in arm holder on the ZR which was prone to breaking. Otherwise the two trems are identical. The ZR2 was offered on the upscale Prestige line, while the original ZR continued to be used on the standard models.
Other Ibanez bridges that borrow some design elements of the ZR include the SynchroniZR (ball-bearing pivot and thumbwheel spring adjuster) and the Edge Zero/ Edge Zero II (ZPS stabilizer and thumbwheel spring adjuster).
The ZR was discontinued after 2015. This decision seems to have been made due to a patent claim against some of the design elements of the ZR tremolo from Geoffrey Lee McCabe. With the Floyd Rose patents also expiring in this same timeframe, it seems that rather than pay royalties to license McCabe's patents the decision was made to switch back to FR style knife edge designs (such as the Lo-Pro Edge) for which royalties were no longer required.
- ↑ Solving a Two Zero Point Tremolo Problem; Innovation Fascinations (blog); June 2, 2015; archived from the original November 2017