Too much vibration for bike light...plz help

Hi,

I mounted a home brew HID light on my bike handle bars, battery on back pack rack. But even on small bumps it vibrates the light & causes the beam profile on the ground to move up & down in small movements, which gets irritating on the eyes. Almost looks like the light is flickering on & off very fast

What are some good materials & setups to minimize vibrations when lights are mounted on handle bars?

I have everything as stiff as I can, & centered to minimize as much vibration.

Any advice is needed, thx.

...Not sure but, perhaps a cushion support system. :thumbsup: A dampening semi-memory foam or soft foam insulation 'ring', gasket, or sandwhich layer between light unit and the stiffened support bracket may help. In a sense, a floating suspension, with just the right amount of self dampening springiness, like a miniature 'shock absorber' between the light unit and bracketing set will help. Without this, vibrations will tend to concentrate on the light unit, (as it tends to be at the end of the moment arm of rotation).

Sometimes a 'dampening' mass on the bracket near and/or before the suspension system can help. This can just be a small weight, sinker, heavy washer or even a small rock. I did this on the original "LightSward" searchlight. I had a fan that vibrated the HID bulb and caused similar vibrations. I mounted the heavy ballast near the reflector and bulb making sure the 'suspension' system went between the fan and the light bulb itself. This totally eliminated the fan's vibrations from reaching the bulb. I know this is a bit different but I think this may be at least part of the answer.:twothumbs

Maybe the system you have is just too solid.. having said that then surely the vibration (movement) of the light unit helps to convey a true reflection of the surface and ground that you are on.

I have two lights on my bike. One is attached via an adaption from the cable holder of a BMX brake (that is to say the actual holder goes through the steerer and sits just below the handle bar stem) and is like an additional stem ring spacer, this keeps it dead centre and where the cable would go through I have attached nuts and bolts and a small metal platform and a thick piece of rubber.

This minimises vibration yet gives a very steady holding system.

The other light is attached by an upside down Hed Doctor (or stem star bolt system) in the underneath of the suspension fork steerer. This has a T shape bracket that when tighten to the fork the top of the T pulls into the fork and forms a very solid fixing point. The extended part of the T is attached the other light and this too sits on a solid piece of rubber. Now this system is a little bit of bobbing when on really rock downhill stuff but the spread of light is as such that I don't mind because it is cushioned by the suspension fork absorbing most of the vibration.

This image is off the old system where I had the light actually mounted on the suspenion bridge but the forks have been changed and the system described above is where it's at. Both systems were very good.





I think your key is to find or shape a thick pice of rubber to sit underneath the mounting system that you currently have.. Good Luck.

I got it the best I could, given that its not exactly a small compact light.

There are small vibrations, but nothing I can do.

I'm more worried that the small vibrations might damage the HID bulb?

EFmax, an HID will actually flicker from vibration, because the arc is perturbed. That doesn't help reflect anything.

I don't think you need to worry about the vibration damaging it, though.

I Had the same problem with a fork-mounted LED light. The solution in my case was to make a doubler for the aluminium strip that supports the head light, making it more rigid. Doubler is drawn in green on the image below:

Perhaps it is possible to relocate your mountingpoint closer to the center of gravity of you light? This should also reduce movement due to sudden acceleration of the handlebar.

Benson said:

EFmax, an HID will actually flicker from vibration, because the arc is perturbed. That doesn't help reflect anything.

I don't think you need to worry about the vibration damaging it, though.

Click to expand...

Maybe I am lucky cos on my 2nd light, the one in the picture, that is a 30w HID and it has no issues with flicker and has survived well for the 8 months that I have run it, so maybe it is down to that thick bit of rubber that I am using.

I have banged the crap out of my HID's for several years with no ill effects that I can see so far.

The one on the helmet I guess does not count because your body is a dampner, but I have whacked it on branches and vines many times.

My lights don't flicker at all, even when bombing down a mountain riding on a path of baby head rocks, but all my connections are soldered and tight.

Wasn't sure if your problem was intermittent electrical connection or mechanical in nature??
Are all the electrical connections tight and no parts move inside the light?

EDIT

Correction below..

I thought that I would just grab this on me phone camera..


You can see here the platform that I have used and the Hope Hed Doctor that I have inserted upside down in the underneath of my suspension fork.. It is about as solid a mounting that I could wish for without making things look to ugly.

In this image (bike is upside down)


Here the light is attached by a small platform which is attached to the steerer as if it was a spacer..

Again both lights are dead center but I forgot to mention who your biggest friend is.. HOT GLUE.. makes for great absorbing material plus being functional.

EFMax said:

...snip...

Click to expand...

That second one is pretty pimp (hed doctor's are expensive for doing that to)
Is it something like this?
http://www.chainreactioncycles.com/Models.aspx?ModelID=34886

herulach said:

That second one is pretty pimp (hed doctor's are expensive for doing that to)
Is it something like this?
http://www.chainreactioncycles.com/Models.aspx?ModelID=34886

Click to expand...

SPOT ON... OMG I have been looking for another one of those but did not know what they were called. The one I have, I came across in a backstreet cycle shop ages ago but I am so thankful for you as people have asked me where I could get another one from and now I know.. THANKS..

EFMax said:

SPOT ON... OMG I have been looking for another one of those but did not know what they were called. The one I have, I came across in a backstreet cycle shop ages ago but I am so thankful for you as people have asked me where I could get another one from and now I know.. THANKS..

Click to expand...

glad to be of help. off to dig out my meccano for the mount

In that second picture is the light you are using just the top of something like this? http://www.dealextreme.com/details.dx/sku.16541

EFMax said:

I thought that I would just grab this on me phone camera..

You can see here the platform that I have used and the Hope Hed Doctor that I have inserted upside down in the underneath of my suspension fork.. It is about as solid a mounting that I could wish for without making things look to ugly.

In this image (bike is upside down)

Here the light is attached by a small platform which is attached to the steerer as if it was a spacer..

Again both lights are dead center but I forgot to mention who your biggest friend is.. HOT GLUE.. makes for great absorbing material plus being functional.

Click to expand...

K_Labs said:

In that second picture is the light you are using just the top of something like this? http://www.dealextreme.com/details.dx/sku.16541

Click to expand...

No, it's the LUPINE Wilma 8 unit.


When both lights are on (off road) they produce this -