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Strap tubes – what are they, and should I use them?

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  • Strap tubes – what are they, and should I use them?

    it can be problematic*

    Since I’ve started selling replacement tubes and screws for Panerai Luminor watches, the question of whether or not to fit strap tubes has come up quite often, so I thought I’d take 5 minutes to explain what they are, what they are used for, and why I don’t recommend using them with any other watch than a Panerai. Many people don’t seem to know what function strap tubes have and so hopefully this will help… What are strap tubes? What are they used for?

    Although Panerai are now moving away from this system, traditionally a Luminor style watch would hold the strap to the case using a screw bar. This screw bar passed through one lug, through the strap, and screwed directly into the other lug. Panerai still use this system with many of the watches in the Luminor range. You can see in the picture of strap tubes and screws above, the male screw threads on the end of the screw bars which screw into a female thread on the inside of one of the watch lugs.

    This system is fine as far as it goes, but there is one flaw. The bar is tightened into the lug itself, and so should not rotate. When a strap is attached however the strap will move against the bar during normal wear, and friction from that movement will act on the bar and try to rotate it. Over time, this can lead the bars becoming loose, which is far from ideal as they hold the strap in place.

    Strap tubes were originally designed to be used in straps for Panerai Luminor watches to reduce the friction that acts on the screw bars from contact with the leather strap – the tubes are made so that the screw bars can slide through them, and are inserted into the strap at the point of attachment. When strap tubes are used, the screw bar now passes through one lug, through the tube inside the strap, and screws into the inside of the other lug. This means that the leather strap is not in contact with the screw bars directly, and because metal moving against metal results in less friction than leather moving against metal the risk of the screw bars working loose is reduced.
    Why are tubes only recommended for Panerai watches?

    Many other watch makers use screw bars instead of spring bars to hold straps / bracelets in place, but normally there is a separate screw head which screws into the bar itself, so the bar can rotate freely without becoming loose. For these watches, fitting strap tubes is pointless because the tubes won’t serve any purpose, and also, because the tubes are made to fit Panerai bars there’s no guarantee that the screw bars other manufacturers use will fit (Ennebi, for example, use a much heavier duty screw bar than Panerai – no way will it pass through a Panerai tube).

    Using a strap with tubes on a watch that uses spring bars to attach the strap is also pointless, and worse it can be problematic. Imagine fitting a strap with tubes onto a watch using spring bars….. no problem so far? ….. now, try to get the strap off. If the watch doesn’t have drilled lugs the tubes will prevent you getting a spring bar tool between strap and lug to locate the spring bar! The only option then is to hacksaw the spring bar to remove it – not ideal, and it almost always causes damage to the strap (and sometimes the watch too). I know people that have contacted me to tell me they have had this problem – don’t worry, I’m not going to mention any names <wink>. My Panerai uses a push-pin bar release – should I use tubes?

    When Panerai released the first “Luminor 1950” cases back in 2006 they introduced with them a new system for strap attachment. With this system the strap bar is not screwed into the lugs, but instead is held in position by the case itself and it can rotate freely (you can tell if your watch uses this system because if it does on the back of one lug each side there will be a small round “button” – pressing this button releases the bar and allows it to be removed). Tubes are not required if your watch uses this push-release system, but the bars for these watches are made to the same diameter as standard Luminor screw bars and so they will fit through a tube. In this case the strap tubes will serve no purpose but they won’t do any harm either, and so can be left in the strap.

    In short, my recommendation is that strap tubes should only be used with Panerai watches, and specifically only if your Panerai comes from either the “Luminor”, “Luminor 1950”, or “Radiomir 1940” family. If your watch uses the newer “push-release” bar system then tubes aren’t really necessary (but they won’t do any harm either), but I do recommend using tubes in straps for the older style screw bar system.

    I learned the hard way how problematic using certain bracelets with no slot on the inside. Never use them on non-drilled lugs! This Helson bracelet was designed to be used on a Helson which has drilled lugs. I think NFW Shumate bracelets are made the same way. There is no slot cut in the back of the bracelet tubes. That makes it almost impossible to remove from a case with no holes in the lugs unless you cut the pins.
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  • #2
    Good information! Thanks for posting this up, Mike.