Double Take Mirror- a new (and better) Dual Sport Mirror

[hilslamer]

I'm not speaking for Ned here(or trying to be Devil's advocate), these are just my opinions but I hope they shed some light on your issues:

Originally Posted by eakins

ok. with my short arm i can't ever tighten it enough to make it complely a solid unit. i'll flip my arm and see what happens, but maybe the the 2" arm end does get as much leverage as the ball as the 3"?

anyone else w/ 2" arms???

The short arms and long arms will both get to the same clamping force eventually - but the shorter arms get there faster(as in, fewer turns of the screw), because there is less strain distance("flex") in either half of the short arm assemblies as you tighten the screw on them. Ultimately, though, there is no "ratio" involved in either short or long arm(because the screw is centered between the clamping cups, that hold the spherical balls on either end)other than that of the screw and the mechanical advantage it provides for you to get to whatever "tight" is with your wrist/handstrength.

Also, it will never be a totally, 100% rock-solid unit - that's the point. You are relying on friction to hold things in place and the threshold of that static friction is high enough in most cases to hold them damn stiff until you strike something or they need to swing out of the way on their own in the event of a crash, etc.

Originally Posted by eakins

so i flipped the arm and now it locked solid.
i flipped it back and it moved???
so that was it & i have no idea why as i see no diff.
maybe the one side is clamping tighter???
anyway. thanks.

More than likely this has to do with the shape of the spherical cups in the halves of the arm, and the way it grasps the sphere molded onto the end of the mirror. Also, it might be possible that having the arm flipped allows you personally to get a better angle/more leverage/better grip on the screw, and "tight" in this orientation is tighter than in the other way.

Originally Posted by El Scorcho

I have the 2" arm and find that when I get the bike bouncing around offroad the mirrors flop down. I have the knob tightened as best I can by hand. I am thinking of dipping the mirror ball in some plasticote to give the arm something to grab onto a little better.

You're probably going to have trouble getting the Plasticote to stick to the mirrorball, because molded Zytel is not a very good bonding surface. More than likely it will help, but if the tightened assembly is somehow bumped and moved, it will peel the Plasticote right off and you'll be back to square one.

Lastly, aren't you folding the mirrors up when you turn off the pavement? Isn't that the point of this design? That's what I do...when I said earlier that they stayed put at high speed over rough ground, I mean gravel road or rough pavement - not whoops or rock sections. No mirror stays put over really truely rough terrain, IMO.

[duanew1]

Originally Posted by hilslamer

Lastly, aren't you folding the mirrors up when you turn off the pavement? Isn't that the point of this design? That's what I do...when I said earlier that they stayed put at high speed over rough ground, I mean gravel road or rough pavement - not whoops or rock sections. No mirror stays put over really truely rough terrain, IMO.

For the people that like having a mirror off road so that you can see if your buddy is still back there, I would say that another point of the design is that there is a pivot down low on the stalk instead of a threaded arm and a lock washer. This makes the mirror more likely to pivot than to break off the mount on your brake master cylinder.

You might could get some plastic paint to stick to the mirror ball that would provide a little more friction on the Ram arm.

[c.vestal]

Great stuff Tim!

I want to agree on the Plasticote and bonding issue. I thought of roughing up the surface of the (Zytel) ball end before dipping in the Plasticote. This will likely make it out of round and I will then have bigger issues. I also thought of drilling small 1/16" holes for a relief and gripping points. Likely the Plasticote will still peel off in between the reliefs, so still not a good ideal.

Latest idea: I may try knurling the ball end of the mirror, or roughing with 80 grit and see what happens.

[c.vestal]

Also, I use my mirror off road a lot. I often ride with a group and want to keep an eye out for others. I crank it real hard and it works great. It will move when I whack it with a branch on the trails or jump the bike. As it has been stated here many times, that is the point of the design. Parts will move and not break. When it happens, I simply move it back in position.

[hilslamer]

Originally Posted by duanew1

You might could get some plastic paint to stick to the mirror ball that would provide a little more friction on the Ram arm.

Originally Posted by cvestal

Latest idea: I may try knurling the ball end of the mirror, or roughing with 80 grit and see what happens.

Before you do any of this, try some cheap Aqua-Net hairspray...again, probably only good for a few uses...and might wash off in the rain...but not permanent as an experiment...

[hilslamer]

As a side note, the ultimate solution is probably along the lines of an overmoulded ball on the end of the mirror(I think this was suggested somewhere before?) - with some UV-resistant rubber, maybe .030" or so thick(on the radius of the sphere), and probably 80-100 on the Shore A scale. This would certainly provide the grip we all need, with the slip to allow easy adjustment and also crash/collision survivability.

Trouble is, this probably triples the cost of the mold and molding process, and the price will likely reflect that. Also, the existing mold probably couldn't be used because you'd need to mold the plastic sphere smaller...so two whole new molds would be on the budget for that design.

[DougZ73]

I am surprised to see many having issues with the mirror moving. I have had mine for a couple weeks now, and have had it offroad about a dozen times. The last 10, I have not even bothered to turn it in..I just leave it where I normally have it. Its good for seeing if the the guys behind you see where you are turning on the trail, or if you have to stop and wait for them.

Of all those times, I have had to only adjust it once..and that was cause I hit a branch that almost was enough to knock me off the bike.

On the road, I have no issues.....my DRZ 400 is gear 14/44....so my top speed is about 75...which I barely ever push it to.

The only thing that may be helping in my case, is, I am using a 1.5" arm..since I had it. I get it nice and tight at the start of the ride..and pretty much never have to mess with it again. Not sure if it makes any difference either, but the adjuster knob is facing me, as I am riding on bike.

[dad2bike]

I don't see the mirror moving what little it did for me as an issue. Rather doing its job of folding back vs breaking. What I threw at it this weekend was way more than expected. I could have tightend up more on the clamps. Just chose not to. Too busy holding on for dear life.

[sonoran]

Originally Posted by hilslamer

I'm not speaking for Ned here(or trying to be Devil's advocate), these are just my opinions but I hope they shed some light on your issues:



The short arms and long arms will both get to the same clamping force eventually - but the shorter arms get there faster(as in, fewer turns of the screw), because there is less strain distance("flex") in either half of the short arm assemblies as you tighten the screw on them. Ultimately, though, there is no "ratio" involved in either short or long arm(because the screw is centered between the clamping cups, that hold the spherical balls on either end)other than that of the screw and the mechanical advantage it provides for you to get to whatever "tight" is with your wrist/handstrength.

Also, it will never be a totally, 100% rock-solid unit - that's the point. You are relying on friction to hold things in place and the threshold of that static friction is high enough in most cases to hold them damn stiff until you strike something or they need to swing out of the way on their own in the event of a crash, etc.





More than likely this has to do with the shape of the spherical cups in the halves of the arm, and the way it grasps the sphere molded onto the end of the mirror. Also, it might be possible that having the arm flipped allows you personally to get a better angle/more leverage/better grip on the screw, and "tight" in this orientation is tighter than in the other way.


You're probably going to have trouble getting the Plasticote to stick to the mirrorball, because molded Zytel is not a very good bonding surface. More than likely it will help, but if the tightened assembly is somehow bumped and moved, it will peel the Plasticote right off and you'll be back to square one.

Lastly, aren't you folding the mirrors up when you turn off the pavement? Isn't that the point of this design? That's what I do...when I said earlier that they stayed put at high speed over rough ground, I mean gravel road or rough pavement - not whoops or rock sections. No mirror stays put over really truely rough terrain, IMO.

I tried flipping the arms but same result so I dipped the ball ends into plastidip and let em dry overnight. It seems to have bonded pretty well to the Zytel and now the arms have a much better grip on the ball. I don't have to use nearly as much torque on the knob to get a firm hold.





We'll see how it holds up over time. If it peels off it's no biggie to re-apply.

I normally don't fold in my mirrors unless I'm going to go thru some tight stuff. The main reason I went with this design was to prevent breakage in case of a crash. The coating will certainly wont prevent the mirrors from moving if that happens.

[theantipaul]

My humble opinion would be on the next run of parts, while they have the tool hung, to have them run a few shots with striaght Zytel, no glass to test, the molder should have some laying around. If they run it first they won't have to purge the machine and shouldn't cost much. It'll shrink up more, but it'll test the concept.

With 43% glass it's a plastic hammer, you'll never break it, but it's also a bit overkill. Straight Zytel will mush a little giving more surface contact, and from the looks of the design shouldn't impact any of the strength or vibration constraints, if fact might help with vibration as something completely rigid will act more like a tuning fork and with that design you'll never break it with Zytel anyway.

Roughing up one or the other surfaces will eventually make them just wear when swinging them back and forth. Then you're tightening and tightening.

Overmolding would be the best and the existing tool could have just the ball end modified by inserting that detail to a smaller ball, but a new tool would have to be built and tested and maintained. Overmolding wears tools out quicker and can be crashed easier that other tooling, so hardened tooling is usually recommended and that isn't cheap.

2 cents

[hilslamer]

Originally Posted by theantipaul

My humble opinion would be on the next run of parts, while they have the tool hung, to have them run a few shots with striaght Zytel, no glass to test, the molder should have some laying around. If they run it first they won't have to purge the machine and shouldn't cost much. It'll shrink up more, but it'll test the concept.

With 43% glass it's a plastic hammer, you'll never break it, but it's also a bit overkill. Straight Zytel will mush a little giving more surface contact, and from the looks of the design shouldn't impact any of the strength or vibration constraints, if fact might help with vibration as something completely rigid will act more like a tuning fork and with that design you'll never break it with Zytel anyway.

Roughing up one or the other surfaces will eventually make them just wear when swinging them back and forth. Then you're tightening and tightening.

Overmolding would be the best and the existing tool could have just the ball end modified by inserting that detail to a smaller ball, but a new tool would have to be built and tested and maintained. Overmolding wears tools out quicker and can be crashed easier that other tooling, so hardened tooling is usually recommended and that isn't cheap.

2 cents

All excellent info...the only comment I can add to this is that Zytel in pure form tends to "smear" a bit; but in any case it would be an interesting experiment. The worst that would happen is that if the sockets of the RAM arms were contacting on anything less than a broad zone of the spherical ball on the mirror body sphere, it would leave a "track" in the ball that would promote movement in that direction again - and it's most likely the way you don't want it to move again(down, in the case of a jump landing, for ex.).

Sorry everyone for all the Engineer-eese...

[c.vestal]

Originally Posted by theantipaul

My humble opinion would be on the next run of parts, while they have the tool hung, to have them run a few shots with striaght Zytel, no glass to test, the molder should have some laying around. If they run it first they won't have to purge the machine and shouldn't cost much. It'll shrink up more, but it'll test the concept.

With 43% glass it's a plastic hammer, you'll never break it, but it's also a bit overkill. Straight Zytel will mush a little giving more surface contact, and from the looks of the design shouldn't impact any of the strength or vibration constraints, if fact might help with vibration as something completely rigid will act more like a tuning fork and with that design you'll never break it with Zytel anyway.

Roughing up one or the other surfaces will eventually make them just wear when swinging them back and forth. Then you're tightening and tightening.

Overmolding would be the best and the existing tool could have just the ball end modified by inserting that detail to a smaller ball, but a new tool would have to be built and tested and maintained. Overmolding wears tools out quicker and can be crashed easier that other tooling, so hardened tooling is usually recommended and that isn't cheap.

2 cents

All good in the world of manufacturing, but not the case when persons have to work with lawyers and patents.

[neduro]

All great discussion here!

With regard to mirror movement, there are a few reasons we didn't do a rubber over-mold. I won't go into all of them here, but suffice to say, I believe there are pros and cons... if they are moving on you, go ahead an experiment, you won't hurt anything. They don't move for me, so it's not a problem I can comment very directly on.

One easy idea a customer reported testing (and liking) is to put a wrap of electrical tape around the ball, it may not be a forever solution but it is easy and cheap!

Originally Posted by theantipaul

to have them run a few shots with striaght Zytel, no glass to test

We tested about 10 different materials at different points, and I've run all different qualities of Zytel with and without varying amounts of glass thru the final mold.

After all our testing, we went with the exceedingly stiff 43% glass compound because the other versions seemed to amplify any vibration present in the handlebar, in the picture viewed in the mirror. The 43%, being very stiff, will obviously vibrate if the bar it is attached to is vibrating, but presents a very clear picture.

Really glad people are liking them!

[skibum69]

Just picked mine up yesterday and they look great, only 2 more flights today and I'll get to mount them up tomorrow and actually see them in action

[Krabill]

They fold up nicely and worked great for me all last weekend



I'm with the people who would like to see a little more grip on the ball end, though. I'll play around with it and see what I can come up with.