Modern Vespa

The mirrors on the new Vespas have a left-hand thread on the left side and right-hand on the right. I would assume most impacts will be from the front. This means that an impact will tighten the mirror and snap it off. If the threads were reversed the result of a front impact would be to loosen the mirror so that it might swing back and avoid damage.

So it seems to me that the arrangement is arse-about-face. Does anyone have any idea why it should be this way?

Trivia:

Same with HPE. And Primaveras since at least several years back.

(I'm using 2015 era Primavera mirrors on my HPE because they are longer than regular hpe but same style as hpe)

They tighten in the wind. It's entirely logical.

What speed do you travel at?

As fast as the wind.

Must be good exercise to have to push the bike whenever the wind stops

The frame of reference is the scooter.

Guess I won't get any sensible answers here!

You actually got one but must have skimmed it.

If they were both right hand thread the left one would loosen from the wind. Likewise the right side if both were left handed thread.

I would posit that if you're being hit hard enough to cause the mirror to bend/break, you likely have bigger (and much more immediately important) issues to tend to.

Sensible answers? I have never heard of the wind causing a mirror to loosen. Have you?

As for bigger issues, I don't have any. I haven't had an accident in the last 35 of my 64 years of scootering, but I have bumped my mirror a few times squeezing the scooter out of the carport past the car. I was talking about any hypothetical impact situation.

Oh okay.

I wasn't aware you were looking for a bunch of people to just agree with you rather than offer a plausible explanation.

My apologies for misunderstanding the reason for your post in the first place. I'll be sure to leave you to it for the foreseeable.

My 1986 Shadow had right hand threads on the left mirror. I lived in Salina Kansas. While riding I spanked a pheasant with my left mirror going 60. The mirror broke and unscrewed. I always wondered what would have happened with left hand threads.
My WAG is that it saves time at the factory. If they come to work with a hangover they might spend a lot of time switching the mirrors back
Google says "Most motorcycle manufactures use a combination of left and right hand threads on mirrors so they fold back in a fall". I call BS because they loosen when turned forward. Even ADVrider is full of guesses.
I think your in uncharted territory captain.

Since when have you been logical. Is someone holding your family hostage

Unfortunately, I have had a mirror come loose from the wind at a very inopportune time. I guess it was just not tightened enough and the force of the wind did it's thing.

Have no plans in crashing but if I do my Vespa would be the least of my worries.
Also as an ex-insurance adjuster in CA most bikes that went down ended up being economic total losses and customers get paid actual cash value, plus tax and pro-rated registration.

Ferret, I didn't take Znomit's reply seriously because in 60 years of right-handed mirrors I have never heard of one coming loose due to the wind. You obviously took it as a serious reply. Would have to ask Znomit whether he meant it seriously.

Please stop your accusations, that I didn't understand the reply, that I have problems, that I just want some people to agree with me. These accusations are all rubbish.

I just asked why, and haven't received what I regard as a serious answer yet. I guess no-one knows what goes on in the designer's heads.

Postscript: I have just realised the logic behind it - in an accident I would probably be thrown forward onto the mirrors, so with the threads as they are the mirrors would loosen instead of breaking or piercing my ribs. Problem solved!

So CaliforniaCruising was right in worrying more about himself than the scooter. That's where the answer lay.

Wind and vibration loosens a right hand thread mirror on a left handlebar. That's the answer.

This, absolutely. Over 50 years of scooter and motorcycle ownership I have found several, not all, with left hand threads on the left mirror. Those with right hand threads on the left mirror required tightening and repositioning with regularity. I routinely carried an adjustable wrench with me so I could fix them on the road. I found it to vary from brand to brand, and even within a brand. I had BMWs that were both ways.

No, no, and no. Don't get me wrong: I loved your whimsical speculation. But nobody ever died from hitting a mirror. The mirror is going the same speed you are. Your problem is going to be the ground or the parked car. And the wind? Are you kidding? Hyabusa mirrors are both right hand threaded and never loosen. Neither do the mirrors on Buell. In fact, they're about the only thing that doesn't shake off a Buell.
I have it on Very Good Authority that this development is directly related to Globalization. Current mirrors are, like so many other Vespa parts, made in China and often installed in Asia as well, often Vietnam. These people are obsessed with martial arts beyond reason. These mirrors are not installed by high tech robots as you might imagine. These aren't Hondas after all. They're installed by children who have become incredibly adept at the task. They start them as young as 11 and by the time they're ready for Junior Olympics they're virtually unstoppable, so thoroughly have they mastered the "wax on, wax off" technique. All their factories are set up this way. If you doubt me visit for yourself, and pay particular attention to how well sanded the floors are, and how well painted are their fences.

Vespa mirrors have been left and right thread for decades. This isn't a recent change.

My 2009 gts was not left on left.

I think it was around 2013 they changed.

My 2012 has two right hand threads, and I hate it.

My 2015 and 2018 GTS300s didn't have any left-hand threads.

But my 2023 model was made in Vietnam. Maybe that makes a difference (Chinese influence? )

Hmm, my 2006 GTS was left and right in the US.

My 2009 GTS is right handed on both sides.

13 motorcycles, 3 Vespas 2 scooters, I have never had to revisit a loose mirror after I've personally tightened it

But you've seen Enter the Dragon, right? You know how insane these Pacific Rim nations are for martial arts. When everybody is kung fu fighting you need more than expert timing; you need the kind of muscle memory that can only be honed via thousands of repetitions-a day!

Anecdata, but I had a mirror on one of my "same-threaded" Like 150is that came loose to the point of moving while driving pretty often. Suuuuper annoying. I was pretty stoked coming over to the world of Vespa where that was unlikely to be a problem going forward.

Yamaha has used a reverse thread right mirror since time began. Some of the Taiwanese companies with links to Yamaha did the same thing. This thing with Piaggio and a Left mirror with reverse threads is relatively new. Right and Right threads has worked well for Honda, Piaggio, Kymco, Suzuki, Kawasaki, the Germans, HD, and just about everyone, except Yamaha, since mirrors on motorcycles began. I think it's Piaggio's dumb, not well thought out, way of making people buy the OEM mirrors. Because none of the companies that make aftermarket mirrors would ever be able to figure it out and make their own aftermarket mirrors with a reverse thread left mirror.

I replaced the shorty mirrors on my 2023 GTS because I couldn't see behind me. The replacements had longer stems and were also Piaggio made, but had a different thread size. So I had to get two thread adaptors, one left-to-left and one right-to-right.

Hence my involvement with this whole issue.

The adaptors only came in pairs, unfortunately, and I now a have a spare one of each.

It has happened to me as well.

mine kept coming loose when riding lots of bad roads _until_ I used some dome washers (which were supposed to be there but were missing)

Tree that resist wind break in storm. Tree that bend, survive!

I've had the opposite happen a few times. Haul on the brakes and the mirror wants to keep going.

I think it is more than just the force of the wind. At higher speed the wind applies a constant pressure AND the irregularities in the road apply a series of minor impacts which result in the thread loosening (with a RH thread on the left side). It is only the left side mirror which I have ever had loosen in this situation.

Now let's be honest...
How many times has the mirror gotten loose and you've tightened the nut with your fingers, with the mirror not quite where you wanted it, then pulled the mirror in place to tighten it? In my case, it's a lot. And the mirror kept loosening up.
And how many times have you made sure there were two washers between the mirror and the threads? In my case only after buying a mirror with the washers included, then asking myself where they were supposed to go.

Once I figured out the washers are necessary and used an actual wrench to tighten the nut, then loosened it and tightened it with the wrench if it was too far forward or backward, instead of trying to do that by pushing or pulling on the stem of the mirror, the loose mirror problem solved itself.

By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.