World of Watches (Singapore) - - Features -

The right bezel can greatly en­hance a watch’s func­tion­al­ity; the chal­lenge lies in nar­row­ing down the avail­able op­tions. Should it ro­tate? If it should, in one or both di­rec­tions? What type of mark­ings should it have?

The Op­tions

Ro­tat­ing bezels tend to come in two vari­a­tions. A diver’s ro­tat­ing bezel only turns counter-clock­wise, and comes with count up mark­ings to al­low its user to mea­sure elapsed time by align­ing the marker at 12 o’clock with the minute hand. Other time­pieces, such as pi­lot’s watches, tend to have bi-di­rec­tional ro­tat­ing bezels con­tain­ing ei­ther count up mark­ings that func­tion sim­i­larly, or count down mark­ings that func­tion as re­minders for time sen­si­tive events.

The al­ter­na­tive to these are bezels with spe­cific mark­ings that must be used to­gether with the chronograph sec­onds hand. These are usu­ally fixed bezels, al­though man­u­fac­tures in­clud­ing TAG Heuer have made ro­tat­ing ones in the past.

The most com­mon one is the tachymeter, which al­lows the wearer to read off its mark­ings for the hourly rate of an ac­tiv­ity, by mea­sur­ing the time it takes to com­plete one unit of it. Start­ing the chronograph and stop­ping it af­ter a car has trav­elled for one kilo­me­tre, for in­stance, will give the car’s speed in kilo­me­tres per hour – the wearer just needs to see where the chronograph sec­onds hand is point­ing to on the tachymeter. The unit does not mat­ter; one can ar­rive at the num­ber of cook­ies a per­son eats in an hour by mea­sur­ing the time he takes to fin­ish one cookie.

The pul­some­ter and teleme­ter func­tion sim­i­larly to the tachymeter, but are more spe­cialised. A pul­some­ter gives the heart rate of a per­son (in beats per minute) by us­ing the chronograph to mea­sure the time it takes for a cer­tain num­ber of heart beats, usu­ally 10 or 30. The teleme­ter, on the other hand, in­di­cates the dis­tance to an event, such as a light­ning strike. The chronograph is started when the event is seen, and stopped when it is heard. By as­sum­ing that light trav­els in­stantly, while sound’s av­er­age speed through air is around 300m per se­cond, a cal­i­brated scale – the teleme­ter – can be made, and the dis­tance to the event read off it.


The tachymeter is an easy pick here for be­ing the “Goldilocks” bezel – it is nei­ther too gen­eral to make proper use of the chronograph, like the diver’s bezel, nor too spe­cialised, like the pul­some­ter. The flex­i­bil­ity in­her­ent to the tachymeter is also an im­por­tant ad­van­tage – any event can be timed and in­stantly con­verted to give an hourly rate.

Longines Pul­some­ter Chronograph

Tu­dor Fastrider Black Shield with tachymeter on bezel

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