Making a stealth mirror to mount on your sunglasses

 

 

 

I started making my own cycling mirrors about the mid 1970's out of desperation as there was really nothing else acceptable on the market back then. Whatever there was (and still is) were all large geeky-looking things and I refuse to ride around with one of those. Call me vain if you like. My early ones had quite long arms (not as long as the geeky ones though) and they have evolved over the years to very minimalist efforts. I realized that as the mirror came closer to the eyeball it could also become much smaller too - and still provide a full field of view behind.

My two latest creations have arms of 2.5" and 3.5" (shown in the pics).

The downside to my short-arm small-mirror design is the fact that their adjustment has to be very precise and the frame's fitting to the glasses has to be very firm because just a micron of movement means that you lose your adjustment and won't be able to see behind. This is the reason that it's just about impossible for me to make them for others - I have to be in possession of their glasses to do the custom tailoring job and the fact that with such needed precision, they take so darn long to make.

Even when I make one for myself - which I do every time I buy new cycling sunglasses - I usually am only happy with my third attempt which means the first two go in the garbage.

My mirrors are all "cantilever" design - to prevent gravity pulling them out of adjustment. They are all totally specific to a particular set of glasses. The no-hinge Oakleys in the pics below might be out of production now and I don't use that set anymore but it shows how specific that mirror was to the geometry of the glasses' arm.

I cut my mirror glass 1.5cm square. The distance of the mirrors from the glasses range from 3mm away to maybe 1cm. The mirror stock I use comes from ladies' powder compacts and is very thin and light. Someone suggested mirror from pets' toys at petshops. I've never looked into that but it might be a good source.  I wonder if dollar stores sell such pet toys.

If anyone trying to make one of these mirrors lacks patience and determination it's best not to start as the learning curve will be steep and you might have to make a few samples (trying to modify each one better & better) before you achieve perfection. As I said earlier - I've been doing 'em for nearly 40 years and usually make three before I'm happy with the last one.

The adjustment is soooo precise as they are so small and so close to the glasses. You need to turn your head maybe 10-15 degrees to see over your shoulder. Even though the glass is tiny I can see as much out of it as through my car mirror. Most people will get impatient, fed up and abort the process before they get a working model. The normal geeky long-arm large-glass store-bought varieties have much more tolerance for mis-adjustment. I first adjust mine while sitting on the bike in the drive and then go for a shake-down ride on quiet roads with two sets of needle-nose pliers in my pocket to perform the arm tweaking.

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Needed supplies -

Mirror stock (ladies' powder compacts or maybe pets' toys)

Glass cutter.

Glass cutter lube.

6" steel ruler (measuring and glass cutter guide)

5 minute epoxy.

Old double-butted spokes (lots!)

2 pair needle-nosed pliers.

Side-cutter pliers.

Bench vise.

Matte model paint (those very tiny bottles at model airplane shops).

Small paint brush.

Tiny sticks for daubing on the epoxy.

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I'm not going to go into great detail in telling you how to make the mirror as close study of the pics will tell you lots. Remember - a picture is worth a 1000 words.

Here are some tips -

First of all, snip the thick ends off a few old double-butted spokes. Just work with the 1.8mm diameter center section.

Cut a 1.5cm square piece of mirror. If you're hopeless at glass-cutting like me you'll break a few pieces into useless junk. Use your pliers to nibble any miss-shaped edges. The edges don't have to be too perfect as epoxy will cover all raw glass edges. Nibble off the corners very slightly.  Google "glass cutting" and watch vids on the subject.

Bend up the end of a spoke to get a 1.5cm square. See pics for details. The mirror will be epoxied to it as one of the final stages.

Now comes the tricky bit! You have to decide, from very close scrutiny of your glasses arm, just what form the wire is going to take. We need to do a "cantilever" design to resist the weight of the mirror. Even though these things are very light, unless they have a cantilever resisting gravity, they will always be going out of adjustment.

Bend using two sets of needle-nosed pliers and use the bench vise to snug up tight bends that are impossible to do with pliers alone.

The bend, fit & check cycles are enormous! This is total custom work and the reason why, unless someone is willing to pay by the hour, I won't make them for anyone but dear friends. And those people get them for free. I'd have to charge anyone else $50 ~ $100 for one.

In my pics you can see the subtle "pre-load" bend. This bend is extremely important as it keeps the mirror tight on the glasses' arm (along with the snug U-shaped bends of the mirror arm). Without it, it would move around too easily. and any movement, even the slightest, would result in the mirror being unusable. Mine never go out of adjustment.

My pics show three designs of cantilever. The one with the doubled wire coming back over the glasses' arm was one I made for a friend of a friend as a favor. Never again!! The glasses had to be shipped to me across Canada. I tried making two versions of my normal cantilever but they didn't work. They went into the garbage along with about 3 hours of my time. I figured out that I had to go over and back over the arm with the wire, hence the double wire over the arm. When I finally got a working design I probably had 6 hours of my time into it.

The fitting has to be very precise to prevent any movement at all but the mirror arm must be removable from the glasses' arm. The glasses' arm will suffer a bit of trauma as the mirror arm will have to be fitted and removed a hundred times during the making and adjustment process. If you're hung up on keeping your $500 sunglasses pristine then don't even start the job as the glasses' arm will get scratched and marked.

When you're happy with your mirror arm then get ready to epoxy the mirror to it. Use 5 minute epoxy and first do a thin layer just to glue the mirror to the arm. When this has dried (give it an hour or so even though it's 5-minute stuff) then mix up some more and fill-in the back between the frame and the glass. When that has set, daub epoxy around the sharp glass edges with small slivers of wood. Be neat here. Don't set the mirror down as the epoxy will run, sag and make a real mess. Keep turning the mirror until the stuff has firmed up.

Paint with your favorite color of plastic airplane paint - I use matte battleship grey or matte black.

Now comes the make or break fine adjustment time. If this doesn't go to plan then all your efforts so far are wasted. I've done dozens of these things and I never make one right the first time. My latest one took three tries, as do most of them.

Schedule a bike ride that is just for mirror adjusting. Use very quiet roads. Carry your two sets of needle-nosed pliers. Word of warning - only ever bend the straightish part of the arm just behind the mirror and only ever do the bending using two sets of pliers. Don't think you can do this with your fingers and especially don't pry the wire down against the resistance of the glasses' arm. Use the two sets of pliers only and do very tiny adjustment bends.

What you're aiming for is this - to have to turn the head to the left (if you're riding on the right side of the road!) about 10 ~ 15 degrees. The mirror is so close to the glasses that it's not possible to adjust it to see over your shoulder and down the road while the head is facing straight ahead.

During the test ride, ride in the position on the handlebars where you spend the vast majority of your riding time.

I start in my driveway by mounting the bike, getting in my normal riding positon and leaning on the fence. Can I see the garage door directly behind me? I remove the glasses, remove the mirror and do tiny bends until I can. I still remember my highschool physics lessons about reflection and refraction. We need to think hard about which way to angle the mirror to get the needed view correction and it's usually always the opposite way to what seems obvious.

You might need to do many tweaks and remember, they're all very tiny ones. Eventually you will get it as perfect as it's going to be - the head won't have to be tipped up or down but it will have to be swivelled sideways slightly. You will probably see a small bit of your left shoulder but you should be able to see the whole width of the road from ditch to ditch. That's what you're aiming for.

This whole process will try the patience of a saint and it maxes out my fine mechanical skills but the outcome has always been worth it for me. I wouldn't ride a 100 yards without one of my mirrors.

 

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Explanation of pics -

1.  My traditional "cantilever" style.
2.  Top - non-traditional cantilever style. I hope I never have to repeat it.  Bottom - traditional one.
3.  Painted epoxy finish.
4.  Epoxy before painting.
5.  Shortest one I ever made.
6.  Same.
7.  Non-traditional cantilever.
8.  Same.
9.  My old Oakley "no pivot" glasses one.  I needed a haircut.
10.  Same.
11.  Same.
12.  Where the mirror epoxies to.  (Goes on the side towards the glasses!)
13.  The ONLY way to adjust the view.  (the program wouldn't let me number this pic for some strange reason)
14.  My new mirror showing its size and the epoxy job.
15.  The cantilever job.
16.  Check out the very important "preload bend".
17.  Length for these glasses.
18, 19, 20 - showing the snug fitting and the pre-load bend.  Showing the closeness of the mirror to the lens.
21, 22, 23, 24 - Same mirror off the glasses.
25.  This is the mirror in pics 14 ~ 24 re-painted in matte black.  It's now the Super Stealth version.

Pics 14 ~ 25 - this is the best and most useful design of the three shown.  It will fit most styles of glasses.  I've made lots of these but only one each of the other two designs.

Please note - Sorry, but I don't sell my mirrors. I have made them in the past, for friends and friends' friends, but it's just too time consuming for me. Reasons -

1. I have to have your glasses in my possession as the design and fit is totally custom and needs to be exact.
2. For that I usually make 2-3 frames before I'm happy with one.
3. All of the above usually takes at least 3 hours of my time.  No-one will pay me what that would be worth.

I'll support anyone who tries to make their own though.

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