Retrograde Complication Question

So I was staying up late last Sunday night to watch my new Bi-Retro day hand flip back from Sunday to Monday. (Even though I had an early Monday wake up call).  When at about 11:50pm, I looked away for a second, and when I looked back at the watch, it had already flipped to Monday!  I couldnt believe I missed it!  Anyway, that got me to thinking.  For such a high quality calibre watch, shouldnt the flip (since it only takes 1/10 of a second) take place exactly at midnight?  If so, then is my watch off a bit?



its like practically all calendar watches and even truer for day/date
11/29/2007 - 15:52

or more functions.

I don't have this wonderful watch so I went back to check the article I had written about a year ago:

At 11.30 PM the hands start moving to the next day/date, by midnight the day hand has made the next jump and by 12.10 AM the date indication has done the same. Both hands jump without quivering and place themselves exactly on the correct indication. This is even more true when the day and date hand has to move from Sunday to Monday and from 31 to one when they have to instantly go back to the starting position.


The main reason behind this is that the spring which "pushes" the hand to the next increment gathers energy during the day and releases that energy around midnight. The fact that this watch has a day/date function both needing to jump to the next indication at the same time complicates matter. Either both hands jump exactly at the same time (at or very close to midnight) but that would result in a huge loss in energy and amplitude causing the watch to loose accuracy (due to the springs letting off energy exactly at the same time) or, and this is the solution which is most commonly used (may it be VC or others) is that both hands jump to the next increment around midnight one slightly before and the other slightly after.

It may not be the most aesthetic solution but the best in mechanical and accuracy viewpoint.

Hope this helps

Thanks Alex...
11/29/2007 - 21:17

That helps.  I wasnt exactly sure how the retrograde functions work so now i know a little bit about what is going on inside.