By the early 17th century, the familiar shape of the dumbbell, with two equal weights attached to a handle, had appeared. There are currently three main types of dumbbell: •
Fixed-weight dumbbells are
weights created in a dumbbell shape. Inexpensive varieties consist of
cast iron, sometimes coated with
rubber or
neoprene for comfort, and even cheaper versions consist of a rigid
plastic shell that is filled with
concrete. •
Adjustable dumbbells consist of a metal bar whose centre portion is often engraved with a crosshatch
pattern (
knurling) to improve grip.
Weight plates are slid onto the outer portions of the dumbbell and secured with clips or collars. Shown to the right is a "spinlock" dumbbell, whose ends are threaded to accept large
nuts as collars. Alternatively, a dumbbell may have smooth ends with plates being secured by a sprung collar. •
Plate-loaded (adjustable) dumbbells (a.k.a.
loadable dumbbells) • Spin-lock • Spring collar clips • Compression ring collar • Ironmaster quick-lock •
Selectorized (adjustable) dumbbells are adjustable dumbbells that allow you to easily alter the weight or number of plates while the dumbbells are resting in the stand. This is accomplished through controlling the amount of plates that follow the handle when lifted, for as by turning a dial or sliding a selector pin, rather than physically adding or removing plates. This makes it simple to adjust the weight of the dumbbell between exercises, and the stand is typically used to hold extra weights that aren't required for a certain exercise. There are different types of mechanism: • Block type • Dial type • Glide type • Twist type • 2-in-1 dumbbell/barbell
Variations •
Thomas Inch dumbbell, also known as "172" ( handle, weighs ) • Millennium dumbbell ( handle, weighs ) • Circus dumbbells: historically used in traveling
circus acts, these dumbbells have exaggerated ends and wider handles, and just like normal dumbbells, come in various weights and sizes. ==See also==