major vibration break thru!!!

I've used lead shot in the handlebars before too with good results....

Your gonna bust the fasteners to the motor! Might read through this? http://motorbicycling.com/f6/rubber-not-27364.html

Some people will never be convinced.
I will NEVER insulate my engine from my bike. Been building and riding not as long as others but have built 5 HT's since 3/2009. You need to have the engine installed correctly and that means a flush engine mount to the tube.

Lazy Dog said:

I was going to keep my mouth shout about this but after doing 3 bike around mt house. I feel like I have to tell.

one day in a drunken argument with a friend (who doesn't even ride) say fill it with foam. You know the old light bulb click ding ding. SAME BIKE, SAME SET UP.


A little expanding foam in the down tube and seat tube "Fill'em up" has an amazing affect on vibration. Almost just absorbs it all, I do have the standard rubber motor mount raps but that did very little any ways.

Hope this can work as well for you guys as it does for me and my group.

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Kinda seems like Lazy Dog is saying fill the inside of the downtube and seat post with spray foam.

I cant see anything about rubber mounts in this particular post and I also agree they are a no no.
I would be inclined to agree that the spray foam Inside the down tube and the seat post may help dampen the vibrations a tad too.

Reminds me of my brothers tail shaft that snapped in half a week or 2 ago since he more than doubled the power in his ute, it was filled with foam too.. Just an alloy shaft approx 90mm in dia. 5mm thick walls filled with foam similar to what is used in a lounge chair.

Lazy Dog said:

yep, tape of the inside of the crank housing and fill it up with expanding foam. It has worked very well 3 bikes now.

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Getting foam into the seat tube is easy.
How do you get foam into the front down tube?

i also use spray foam in the frame and handle bars on bikes that vibrate (always a grubee) works really well. be carefull though as it will eat after market paint.

2door said:

Just to clear the air, I'm not questioning the use of foam to possibly dampen the buzzing vibration in handlebars, etc. My issue was mounting the engine with rubber 'isolation'.
I've never tried the foam trick but I've not had an engine that produced enough vibrations to be concerned with.

What I do know is that there is the potential for rust and corrosion to form inside the tubing. Back in the custom van days there were guys spraying foam on the interior walls of vans before building the custom interior. Many of those vans experienced sever rust on the walls that ate through to the outside. Just a thought, especially if you live in a wet or salty climate.
Tom

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Unless your planning to use heating and air conditioning inside your frame tube the chance of premature rusting or structural failure is unlikely. In the van's case it had three different temperatures, outside on the surface, in the wall and the temp of the interior. The three temps create gallons of condensation without proper constraints. A foam filled bicycle frame would have a fairly uniform temp thru out.

I am going to give the foam filling a go, there must be some science here. I can't think of the name of the percussion musical instrument but it looks like a xylaphone only with tubes and you strike it with a mallet. This instrument has a pedal that plugs the tube and dampens the sound(vibration) instantly! Less sound, less vibration and less fatigue has to be good thing

skitchfish said:

I can't think of the name of the percussion musical instrument but it looks like a xylaphone only with tubes and you strike it with a mallet. This instrument has a pedal that plugs the tube and dampens the sound(vibration) instantly!

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you talkin about a vibraphone?

You would have to be a drummer to know that brother!

There are several topics in play here, But the issue really comes down to dealing with vibration. First thing to dealing with vibration is eliminating the source of the vibration. Rubber mounting may work on heavier machines like cars, motorcycles and industrial machinery basically because the mounting base the car, motorcycle whatever is substantially heavier than the engine. Acting as a stable platform. The resistance of the platform is greater than the force of the vibration. that doesn't apply with a light mounting base such as a bicycle. Allowing more movement by the engine will only result in more vibration and also results in additional stress forces being placed on the frame reducing the life of the frame. So make sure everything is as tight as possible, check every bolt on the bike not only the mounting bolts. Then address any mechanical issues fuel mixture, ignition system, and fuel quality. Then check your drive system make sure your sprocket is centered, chain is tight, and wheels are true. After that I address contact points, places where the rider contacts the bike, grips, saddle and pedals. If you are able to replace grips this is an area that can greatly reduce vibration fatigue. If you are unable to replace your grips then invest in some good quality biking gloves. Mountain biking gloves are designed to reduce the effect of vibration produced by riding over rough surfaces. a saddle with good springs is a worthwhile investment, But you may also think about bicycle riding shorts. I know right now ever guy out there is saying "there is no way I am wearing spandex!" I don't know if it is well known in motorbiking but in mountain biking it is common knowledge that the pressure applied to the male parts while riding can actually effect future performance....Your choice! And if you wear the shorts under street clothes nobody will know anyway (Please by all means wear them under your street clothes! Can you picture some over weight middle aged man on a motorbike in spandex!!!) you maybe tempted to go out and buy the biggest softest seat you can find this is usually a bad idea. Softer seat have so much padding that they can apply pressure to to nerves and blood vessels restricting blood flow to some pretty important areas. A contoured firm seat is usually a better plan. As far as pedals go larger platform pedal disperse the pressure more evenly than smaller pedals and a good shoe with thick insoles will work wonders. As always I've probably have rambled on more than necessary but the most important thing is to enjoy this way of life as much as possible. Happy motoring!

God Speed, Mark

2door said:

I don't remember saying anything about "premature".................

Hmmmm, let's see; bicycle sets in a cool garage all night, you take it out in the morning into strong sunshine then ride it during the day then put it back in the garage at night. And you don't see any chance of condensation?

Okay, if rust happens then you probably have several, maybe many years before there is any chance of compromising the structural integrity of the frame. Nevertheless, trapped moisture will react to temperature changes in the form of vaporization/condensation and unless you live someplace with zero percent humidity, there will be some degree of moisture inside the frame. The foam will prevent that moisture from evaporating normally and over a period of time rust, or corrosion if you have an aluminum frame, will result.

Given the normal lifespan of a bicycle, even a motorized bike, this will probably never become a problem. The situation worsens when there is high humidity and/or in salty environment (coastal areas).

Can we agree to disagree and move on?
Tom

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No disrespect Tom, I will agree to agree with you! The potential is there and the foam will hold it there. Saltwater would be a disaster. Was just conveying my point on the van as I always learn the hard way. The van met a premature rusty death.