Bicycles can be categorized in many different ways: by function, by number of riders, by general construction, by gearing or by means of propulsion. The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bikes. Less common are tandems, low riders, tall bikes, fixed gear, folding models, amphibious bicycles, cargo bikes, recumbents and electric bicycles. Unicycles, tricycles and quadracycles are not strictly bicycles, as they have respectively one, three and four wheels, but are often referred to informally as bikes or cycles.
Light Reflectance Value (LRV) is the total quantity of visible and useable light reflected by a surface in all directions and at all wavelengths when illuminated by a light source. (ref.
FFR is a three-letter abbreviation that may refer to: 1  Fellowship of the Faculty of Radiology of the Royal College of Surgeons in Ireland (RCSI). 2  Fractional flow reserve, a technique used in coronary catheterization to measure pressure differences across a coronary artery stenosis.  Frequency following response.