I'm working on an article that has allot of good info regarding Handlebar vibration issues..
Look for it in a day or two...
Bar Vibes....
Well its been a day or two 
Looking forward to reading this as I have alot of vibes i'd like to get rid of
Looking forward to reading this as I have alot of vibes i'd like to get rid of
Last edited by Uzi on July 6th, 2007, 11:24 pm, edited 1 time in total.
1982 XR200
1985 CR500 86' Motor
1990 CR500 85' Motor
2000 CR250
1985 CR500 86' Motor
1990 CR500 85' Motor
2000 CR250
There are many methods folks use to try to lower the vibrations felt up through the handlebars.... here are some things to consider... Important stuff to ponder I put in BOLD...
How to Eliminate Handlebar Vibration:
Some fill their handlebars with a rubber butyl sealer, or silicone, from a caulking tube/gun. Many report that the vibration went away, but be sure to completely fill the bars. The best way is to slip a clear piece of tubing over the caulk tip, then insert it into each bar end before filling. Make sure the tubing is at least half the length of the bars to ensure complete coverage.
A suggestion from another rider is to fill the bars with birdshot. Filling the entire bar would probably be too heavy but a combination of the caulking compound to seal a portion of the bars that creates a space in the bars and then adding the birdshot in the ends would work.
Others have used the weighted bar ends... like those available from FASST Racing.
http://www.fasstco.com/products/insert.shtml
I hear these work very well to eliminate most all of the vibration. Just a thought....
I guy who seems to have allot of information on this subject is John Higgins. This is what he had to say....
John Higgins wrote:
"There are just a few ways to try to mitigate a vibration problem in general I think. You can try to dampen the vibration (rubber like material inside the bars, (lead "bb's" might be better energy eaters and would add beneficial mass). You can try to change the resonant frequency of the bars so that the bars do not respond to the external vibration at different engine speeds (stiffer bars will tend to cause the high amplitude vibration to shift to higher speeds, longer or weighted bars will tend to cause high amplitude vibration to shift to lower speeds), or you can try to isolate the bars ,or yourself , from the vibration by positioning a soft--low frequency spring along the path of vibration (foam grips between your hands and the bars or something to isolate the bars from the rest of the bike at high frequencies--no ideas here). You might try some combination of treatments.
If you put a really good engineer to work to try to solve your problem using model analysis tools, he/she would probably spend as much time trying to figure an effective fix as you would by simple experimentation.
The bike is a complex mechanical system and any one modification is likely to change several modes of vibration in the bike and give you an unintended result.
Bar ends, I believe, change the resonant frequency of the bar so it vibrates at a different rpm but do not *eliminate* all vibration. In many cases, that's enough. If you can change the resonance to a frequency that the bike rarely generates or a rpm you are unconcerned about - fine.
Unless I hear a good reason to try something different, I'll probably go with the Butyl rubber. I saw a 10 oz tube at the Home Depot for under $2. Even if I need 2 tubes for my taller bars, it's a cheap fix.
If you wanted to compute the resonant frequency of your bars the mode shape would probably look something like the action of a tuning fork. This frequency would be inversely proportional to the square root of the effective mass of the bars--with weight at the ends of the bars contributing most to lowering the resonant frequency of the bars. It would also be directly proportional to the square root of the stiffness of the bars--imagine putting a winch across the ends of the bars, pulling them together slightly and measuring the force and displacement of the tuning fork. The ratio of the force/displacement is the stiffness of the bars for the resonant mode shape.
Anyway, longer bars, or bars with weaker walls which deflect more, as well as heavier bars with more mass concentrated at the ends will lower the resonant frequency, which might drive your bars away from the high rpm excitation frequencies drifting up from the engine.
Adding caulking can help damping, which is another story, but the caulking also adds mass which lowers the frequency of the of the " Tuning Forks" also.
With everything being under a square root function these types of change are not as effective as you might hope--cutting the stiffness to mass ratio by 50% lowers the resonant frequency only about 30%--but as they say, a small change could mean a lot of comfort.
Okay. So that's why mass is beneficial. So let me really screw up the concept. What do you think about this: What if I fill the central "U" with butyl rubber and the ends with lead shot or lead shot AND rubber? Do you think having the lead shot loose is better (like a deadblow hammer)? Would the size of the shot make a difference? Or have we gotten to the point of arguing the number of angels on the head of a pin? :-)
Have you ever stopped to consider trying to resonate or vibrate a brick or 20 pound chunk of concrete! This would require enormous amounts of energy at a very low frequency. So adding 1-2 pounds of lead in your bars won't hurt a thing. I like the idea of putting a 8"-12" tube on the tip of the caulking gun and adding a wad deep in the bars. Then you load them with lead shot of any diameter and then seal that into the bars with another wad of caulking. This should deaden that bars really well!!
I want to come back to a point I glossed over earlier, which is the distinction between vibration mitigation by damping and mitigation by adjusting the frequency response of the bars.
The bars all by themselves have about 2% critical damping, which means that if you whack them with a steel hammer they will vibrate several dozen times, each time with a little less amplitude, until they stop vibrating enough to be felt. If we fill the bars with pookey, or just touch the bars near the ends they will stop vibrating much sooner. The reason for this is that the damping, or ability to absorb vibrational energy and convert it to heat, has been increased substantially.
In my discussion I tried to focus on means for preventing either the handle bars or the rider's hands from picking up much vibrational energy from the rest of the bike. One way to do this is to change the resonant frequency of the handlebars so that they don't match up so well with the frequency content of the bike vibration which is the root of the problem. If for whatever reason, you design handlebars that vibrate at a lower frequency they just will not pickup as much vibrational energy from a high frequency bike vibration.
The idea about adding something which sloshes around like lead bb's, maple syrup, or maybe silly putty is interesting and in fact will take some of the energy of vibration out of the bars. But if you think about hands and forearms acting as dampers on the bar motion also, they are probably more effective energy eaters than almost anything you can put inside the bars--and we already know that they're not effective enough to suit our comfort threshold.
That's why I think you might want to focus on preventing vibration buildup in the bars, rather than trying to take it out by adding damping--that's just too late in the game.
My guess is a good way to decrease the frequency of the bars "enough" is to double the weight of the bars and focus the weight change near the ends of the bars. I still like thought about locking lead bb's in a fixed location (near the ends of the bars) with rubber sealant.
There is also an effect caused by the frequency of the bars. Vibration is caused by a wave moving through the vibrating object. The more rigid (and simple) the structure the better a wave moves through it without dissipating. Pipes, bars and tight wire (guitars, pianos) carry a wave best. Soft materials (rubber, caulking compounds, cloth) carry a wave the least.
Vibrations in the same direct will accentuate each other and in opposite directions cancel each other out. One result of this is a standing wave. A standing wave is a vibration whose wavelength matches the length of the handle bar (or any bar or pipe, etc) or where multiples (2,3,4...) of the wave length match the length of the bar. The vibration moves along the bar reflecting off the end and traveling back up the bar. As the waves meet they either accentuate or cancel each other. Waves of the right frequency always cancel each other out at the same point(s). The visible effect of this is that the wave appears to stand still rather than travel up and down the bar.
The closer to a standing wave you get the greater the size of the vibrations as they feed each other rather than cancel each other out.
If you get a vibration generated in the frame at a frequency that matches a standing wave frequency in the handle bar then the bar will resonate. The closer to the standing wave frequency, the greater the resonance and the more the bar will vibrate. If you change the frequency of the handle bar to one not generated on the bike then the vibration will be lower. Alternatively if you change the bar so that it won't hold a standing wave the vibration will also be lower.
Changing the length or shape of the bar (even by a small amount) will change the frequency of the standing wave. Alternatively filling the bar with rubber or epoxy or whatever will absorb some of the standing waves energy and dissipate it without resonating to it. Lead shot will do the same thing. The more random the vibration the better as this tends to result in vibrations canceling each other out more.
To decide which has the most damping effect I suggest a short experiment.
Get a two foot (about that anyway) metal pipe (copper perhaps) from the local hardware store, drill a small hole in one end and hang the bar by fishing line, like a wind chime. Gently strike the pipe with a piece of metal (hammer, iron bar, whatever) and listen to the sound it makes. It should be a nice clear note.
Next add the filling compound to the top ½ of the bar and when set strike it again, the note should be significantly muffled. Next add lead shot (small like bird or rat shot) to the rest of the bar and cap it with some more of the filling compound. Again strike the bar to hear what the effect has been. I think smaller shot would be better as this give more contact between the shot and the bar and the greater number of pellets would create more random vibration.
Finally remove the plug, take out the shot and re add it mixed thoroughly with the filling compound. again wait till it sets and listen to the change in sound. I suggest the combination giving the dullest note would vibrate the least.
You may want to try tape recording the sounds so you can replay them and hear them all at the same time, to remove some of the subjectivity."
OK who wants to give this idea a go?
Well, there you have it ... It seems that for a 500, you want a long bar, with most of the mass out at the ends.
Most guys who ride 500's, tend to be larger dudes anyways. Next time you buy bars, go W I D E , stop by Home Depot for some Caulk, Get that lead sot, and your home free..... right?
How to Eliminate Handlebar Vibration:
Some fill their handlebars with a rubber butyl sealer, or silicone, from a caulking tube/gun. Many report that the vibration went away, but be sure to completely fill the bars. The best way is to slip a clear piece of tubing over the caulk tip, then insert it into each bar end before filling. Make sure the tubing is at least half the length of the bars to ensure complete coverage.
A suggestion from another rider is to fill the bars with birdshot. Filling the entire bar would probably be too heavy but a combination of the caulking compound to seal a portion of the bars that creates a space in the bars and then adding the birdshot in the ends would work.
Others have used the weighted bar ends... like those available from FASST Racing.
http://www.fasstco.com/products/insert.shtml
I hear these work very well to eliminate most all of the vibration. Just a thought....
I guy who seems to have allot of information on this subject is John Higgins. This is what he had to say....
John Higgins wrote:
"There are just a few ways to try to mitigate a vibration problem in general I think. You can try to dampen the vibration (rubber like material inside the bars, (lead "bb's" might be better energy eaters and would add beneficial mass). You can try to change the resonant frequency of the bars so that the bars do not respond to the external vibration at different engine speeds (stiffer bars will tend to cause the high amplitude vibration to shift to higher speeds, longer or weighted bars will tend to cause high amplitude vibration to shift to lower speeds), or you can try to isolate the bars ,or yourself , from the vibration by positioning a soft--low frequency spring along the path of vibration (foam grips between your hands and the bars or something to isolate the bars from the rest of the bike at high frequencies--no ideas here). You might try some combination of treatments.
If you put a really good engineer to work to try to solve your problem using model analysis tools, he/she would probably spend as much time trying to figure an effective fix as you would by simple experimentation.
The bike is a complex mechanical system and any one modification is likely to change several modes of vibration in the bike and give you an unintended result.
Bar ends, I believe, change the resonant frequency of the bar so it vibrates at a different rpm but do not *eliminate* all vibration. In many cases, that's enough. If you can change the resonance to a frequency that the bike rarely generates or a rpm you are unconcerned about - fine.
Unless I hear a good reason to try something different, I'll probably go with the Butyl rubber. I saw a 10 oz tube at the Home Depot for under $2. Even if I need 2 tubes for my taller bars, it's a cheap fix.
If you wanted to compute the resonant frequency of your bars the mode shape would probably look something like the action of a tuning fork. This frequency would be inversely proportional to the square root of the effective mass of the bars--with weight at the ends of the bars contributing most to lowering the resonant frequency of the bars. It would also be directly proportional to the square root of the stiffness of the bars--imagine putting a winch across the ends of the bars, pulling them together slightly and measuring the force and displacement of the tuning fork. The ratio of the force/displacement is the stiffness of the bars for the resonant mode shape.
Anyway, longer bars, or bars with weaker walls which deflect more, as well as heavier bars with more mass concentrated at the ends will lower the resonant frequency, which might drive your bars away from the high rpm excitation frequencies drifting up from the engine.
Adding caulking can help damping, which is another story, but the caulking also adds mass which lowers the frequency of the of the " Tuning Forks" also.
With everything being under a square root function these types of change are not as effective as you might hope--cutting the stiffness to mass ratio by 50% lowers the resonant frequency only about 30%--but as they say, a small change could mean a lot of comfort.
Okay. So that's why mass is beneficial. So let me really screw up the concept. What do you think about this: What if I fill the central "U" with butyl rubber and the ends with lead shot or lead shot AND rubber? Do you think having the lead shot loose is better (like a deadblow hammer)? Would the size of the shot make a difference? Or have we gotten to the point of arguing the number of angels on the head of a pin? :-)
Have you ever stopped to consider trying to resonate or vibrate a brick or 20 pound chunk of concrete! This would require enormous amounts of energy at a very low frequency. So adding 1-2 pounds of lead in your bars won't hurt a thing. I like the idea of putting a 8"-12" tube on the tip of the caulking gun and adding a wad deep in the bars. Then you load them with lead shot of any diameter and then seal that into the bars with another wad of caulking. This should deaden that bars really well!!
I want to come back to a point I glossed over earlier, which is the distinction between vibration mitigation by damping and mitigation by adjusting the frequency response of the bars.
The bars all by themselves have about 2% critical damping, which means that if you whack them with a steel hammer they will vibrate several dozen times, each time with a little less amplitude, until they stop vibrating enough to be felt. If we fill the bars with pookey, or just touch the bars near the ends they will stop vibrating much sooner. The reason for this is that the damping, or ability to absorb vibrational energy and convert it to heat, has been increased substantially.
In my discussion I tried to focus on means for preventing either the handle bars or the rider's hands from picking up much vibrational energy from the rest of the bike. One way to do this is to change the resonant frequency of the handlebars so that they don't match up so well with the frequency content of the bike vibration which is the root of the problem. If for whatever reason, you design handlebars that vibrate at a lower frequency they just will not pickup as much vibrational energy from a high frequency bike vibration.
The idea about adding something which sloshes around like lead bb's, maple syrup, or maybe silly putty is interesting and in fact will take some of the energy of vibration out of the bars. But if you think about hands and forearms acting as dampers on the bar motion also, they are probably more effective energy eaters than almost anything you can put inside the bars--and we already know that they're not effective enough to suit our comfort threshold.
That's why I think you might want to focus on preventing vibration buildup in the bars, rather than trying to take it out by adding damping--that's just too late in the game.
My guess is a good way to decrease the frequency of the bars "enough" is to double the weight of the bars and focus the weight change near the ends of the bars. I still like thought about locking lead bb's in a fixed location (near the ends of the bars) with rubber sealant.
There is also an effect caused by the frequency of the bars. Vibration is caused by a wave moving through the vibrating object. The more rigid (and simple) the structure the better a wave moves through it without dissipating. Pipes, bars and tight wire (guitars, pianos) carry a wave best. Soft materials (rubber, caulking compounds, cloth) carry a wave the least.
Vibrations in the same direct will accentuate each other and in opposite directions cancel each other out. One result of this is a standing wave. A standing wave is a vibration whose wavelength matches the length of the handle bar (or any bar or pipe, etc) or where multiples (2,3,4...) of the wave length match the length of the bar. The vibration moves along the bar reflecting off the end and traveling back up the bar. As the waves meet they either accentuate or cancel each other. Waves of the right frequency always cancel each other out at the same point(s). The visible effect of this is that the wave appears to stand still rather than travel up and down the bar.
The closer to a standing wave you get the greater the size of the vibrations as they feed each other rather than cancel each other out.
If you get a vibration generated in the frame at a frequency that matches a standing wave frequency in the handle bar then the bar will resonate. The closer to the standing wave frequency, the greater the resonance and the more the bar will vibrate. If you change the frequency of the handle bar to one not generated on the bike then the vibration will be lower. Alternatively if you change the bar so that it won't hold a standing wave the vibration will also be lower.
Changing the length or shape of the bar (even by a small amount) will change the frequency of the standing wave. Alternatively filling the bar with rubber or epoxy or whatever will absorb some of the standing waves energy and dissipate it without resonating to it. Lead shot will do the same thing. The more random the vibration the better as this tends to result in vibrations canceling each other out more.
To decide which has the most damping effect I suggest a short experiment.
Get a two foot (about that anyway) metal pipe (copper perhaps) from the local hardware store, drill a small hole in one end and hang the bar by fishing line, like a wind chime. Gently strike the pipe with a piece of metal (hammer, iron bar, whatever) and listen to the sound it makes. It should be a nice clear note.
Next add the filling compound to the top ½ of the bar and when set strike it again, the note should be significantly muffled. Next add lead shot (small like bird or rat shot) to the rest of the bar and cap it with some more of the filling compound. Again strike the bar to hear what the effect has been. I think smaller shot would be better as this give more contact between the shot and the bar and the greater number of pellets would create more random vibration.
Finally remove the plug, take out the shot and re add it mixed thoroughly with the filling compound. again wait till it sets and listen to the change in sound. I suggest the combination giving the dullest note would vibrate the least.
You may want to try tape recording the sounds so you can replay them and hear them all at the same time, to remove some of the subjectivity."
OK who wants to give this idea a go?
Well, there you have it ... It seems that for a 500, you want a long bar, with most of the mass out at the ends.
Most guys who ride 500's, tend to be larger dudes anyways. Next time you buy bars, go W I D E , stop by Home Depot for some Caulk, Get that lead sot, and your home free..... right?
I used sand.....I mean the real "fine" stuff from the dunes I sometimes ride in. I taped up one end so the sand wouldnt fall through, flipped the bar over and filled it up to about 1 & 1/2 inches from the end and dropped some silicone down it. When the silicone dried I flipped the bar back over, removed the tape and dumped out enough sand to leave 1 & 1/2 inches on the end again, banged the bar on the carpet a few times to make sure the sand was packed super tight, and dropped silicon into the remaining end. The reason I left space in the ends was so I can still use wrap-around type hand guards.
I used to get a little arm pump before, sometimes so much in the left arm that my clutch hand would give out. With the sand, it eliminated all those problems.
I used to get a little arm pump before, sometimes so much in the left arm that my clutch hand would give out. With the sand, it eliminated all those problems.
99 CR500R
2006 Honda CBR 1000RR Fireblade
My Drinking team has a Racing problem !
2006 Honda CBR 1000RR Fireblade
My Drinking team has a Racing problem !
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Rosco-Peeko
- Posts: 823
- Joined: June 1st, 2007, 2:47 pm
I also use the inserts while I can't say that they completely eliminated the vibration they definately changed the frequency of the vibes. About the time that I installed the inserts, I installed new bars and hand guards which also changed the vibes. I only had one ride on the whole set up before I found my frame was cracked which was defintely throwing out some strange vibes.
Did you use the inserts in the pic rob?
By flex bars do you mean 1 and 1/8" or are they regular 7/8"
Are flex bars similar to twin wall renthals?
Stock clamps and bar mounts?
Inquiring minds want to know
Did you use the inserts in the pic rob?
By flex bars do you mean 1 and 1/8" or are they regular 7/8"
Are flex bars similar to twin wall renthals?
Stock clamps and bar mounts?
Inquiring minds want to know
1982 XR200
1985 CR500 86' Motor
1990 CR500 85' Motor
2000 CR250
1985 CR500 86' Motor
1990 CR500 85' Motor
2000 CR250
-
iggys-amsoil
- Posts: 3602
- Joined: June 1st, 2007, 6:09 pm
- Location: Just North of March Airfield CA
Flex bars are 1-1/8" so new bar mounts are needed. www.pitposse.com have the cheapest ones.
www.fasstco.com
www.fasstco.com
Trinity Racing mild porting FMF
62 pilot, EGH needle, 172 main
03 Gen III CR250 frame
2013 Dodger Charger 5.7 Hemi
http://www.prisonplanet.com
Your Amsoil Customer # 350882
62 pilot, EGH needle, 172 main
03 Gen III CR250 frame
2013 Dodger Charger 5.7 Hemi
http://www.prisonplanet.com
Your Amsoil Customer # 350882
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crashing_sux
- Posts: 40
- Joined: February 14th, 2008, 9:40 am
- Location: Portland, OR
I have the flexx bars and their anti-vibe inserts. There is almost no vibration over about 5k rpm but unfortunately as a woods rider I lug the bike all of the time, tend to ride 3-5k rpm all day so it's constantly vibrating. When I have some spare time I still need to try alternatives, in my case if it vibrated at highe rpm instead of lower I would be happier.
"the game of life of is not so much in holding a good hand as playing a poor hand well"-
teemtrubble
- Posts: 2269
- Joined: October 11th, 2007, 2:15 pm
- Location: simi valley, ca
AV one osx bars
Last edited by teemtrubble on November 9th, 2008, 9:11 pm, edited 1 time in total.
Mike
teem trubble works CR500
(Gen 3 125+CR500 motor)
If I wanted a Yamaha I would have bought a piano!
teem trubble works CR500
(Gen 3 125+CR500 motor)
If I wanted a Yamaha I would have bought a piano!
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dannygraves
- Posts: 8020
- Joined: June 1st, 2007, 2:03 pm
- Location: Las Vegas, NV
jumping from my gen-1 to gen-4, I do notice fewer vibes on the sunline bars vs/ protpers. Its minimal, but noticeable. both motors were completely rebuilt in august including new main bearings and topends and new rods and wrist pin bearings.teemtrubble wrote:AV one osx bars
I'm gonna try getting those inserts for both.
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
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britincali
- Posts: 8207
- Joined: May 31st, 2007, 7:10 pm
- Location: Barstow, CA
-
100hp honda
- Posts: 4394
- Joined: July 4th, 2007, 6:57 pm
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dannygraves
- Posts: 8020
- Joined: June 1st, 2007, 2:03 pm
- Location: Las Vegas, NV
AlisoBob wrote:britincali wrote:I filled my AF bars with cock, definatly felt better after.
well, Brit, good for you that it fit in there AND felt so good. please don't do it at camp though, I can go without seeign that!
'09 kx450f 4-Poke
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
Gen-4 trail bike --SOLD--
Gen-3 badass trail/mx bike --SOLD--
Gen-1 built dunes bike --SOLD--
'05 klx110 --SOLD--
'95 pw80
-
britincali
- Posts: 8207
- Joined: May 31st, 2007, 7:10 pm
- Location: Barstow, CA
-
dannygraves
- Posts: 8020
- Joined: June 1st, 2007, 2:03 pm
- Location: Las Vegas, NV
