The TiLite ZR. Out Run (L)imitations. WHY TITANIUM? Reason No. 1: Titanium Absorbs Vibration. Reason No. 2: Titanium Won't Break. Reason No. 3: Titanium has the Highest Strength-to-Weight Ratio of Any Metal on Earth. INNOVATION. The Z's 1.25" Mono-Tube frame is 20% lighter than its predecessor but retains titanium's 44% strength advantage over 7000 series aluminum. Bullet caster housing reduces weight and gives the ZR a stylish look. SlipStream Single-Sided Fork with Integrated Bumper (patent pending). Performance 5-Spoke Soft Roll Wheel weighs just 1.6 ounces, 40% lighter than the original 3-Spoke Wheel. TiShaft back release bar makes folding and unfolding the backrest easy from any angle.