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injecting foam in frame(27 posts)

injecting foam in framecmcd
Sep 28, 2003 9:20 AM
would injecting foam in the tubes of my aluminum frame work to dampen vibrations? i guess i would use the foam you use to fill cracks in walls.
I've had the same idea...biknben
Sep 28, 2003 10:09 AM
I bought some of the expanding spray foam a few weeks ago but keep hesitating to use it. My idea is the same as yours. Will the foam stop the accoustic effects of the thin aluminum tubes?

Personally, I think it would help. The question is, "How much would it help?". The creaking is my biggest complaint about Al. Any material can creak. Al just seems to be worse. Maybe because of the thinner wall and larger diameter tubes. The noises just ring like a bell and drives me nuts.

I thought about spraying it in the seat tube and the down tube. Each in the BB area. I've hesitated for a couple reasons. (1) Will the foam inhibit any moisture from moving around? (2) I don't want to have to clean that sticky foam out of my BB threads if I screw up (the foam is a sticky mess). (3) I've never heard any solid evidence of anyone ever doing this.

Hopefully someone else can offer some insight.
I've had the same idea...feathers mcgraw
Sep 28, 2003 10:22 AM
Bianchi did it one year. They might still be doing it. Sampson is doing it now.
What kind of Al frameLeroy
Sep 28, 2003 6:11 PM
do you have that creaks? That can't be right. For it to 'creak' you have to have movement somewhere there's not supposed to be moving, if you get my drift. Why would you want to fix a frame like that? Sounds to me like you just have a bad frame. Just curious.
Movement isn't in the frame itself...biknben
Sep 29, 2003 4:41 AM
FWIW, it's a C'Dale CAAD7. The creaking is not caused by the frame. The sound just seems to endlessly resonate through it and drives me nuts. For me, the most common culprits are BB, seatpost, and saddle rails that cause the squeaks. The frame seems to amplify the noise and makes it difficult to diagnose. Noises from one place often sound as if they are coming from somewhere else.

All bikes will develop squeaks and noises regardless of material. I believe that the thinner the walls of the tubing, the greater the noise. Compound this with the larger diameter tubes used on Al frames and they seems like a bullhorn for noises.

I have to admit I'm annal about the noise. I enjoy doing my own maintenance. In my mind, the noises just reflect poorly on that. I take it personally. :-)
Movement isn't in the frame itself...Spyky
Sep 29, 2003 10:15 AM
I case you haven't heard this, my solution to my Cannondale BB creak:

Teflon Tape ($.99 at a home improvement store). The creak seems to be caused by the aluminum on aluminum interface in the BB.

Works perfectly, several thousand miles on it and no reapearance of the creak.

re: injecting foam in frameRich_Racer
Sep 28, 2003 12:19 PM
I want to do this too but I don't know exactly what foam to buy and exactly where to squirt it! Would indeed be worried about it getting in the BB.

re: injecting foam in frameHumma Hah
Sep 28, 2003 1:10 PM
If you want to try it, remove the headset and BB until the deed is done.

Great Stuff polyurethane foam has a tendency to continue expanding long after you inject it, and seriously overfill whatever you're trying to fill. However, it carves away easily. After filling the frame, you could carve out any that got where you didn't want it.

It does stick fairly aggressively to bare metal, so any spot from which you wish to remove it should have a thin coat of grease BEFORE you apply the stuff.

It sticks to skin better than anything, so use the gloves they provide and work over newspaper or a disposable drop cloth.
Probably not very much ...Humma Hah
Sep 28, 2003 1:06 PM
... I would expect it to dampen acoustic vibrations (if you tapped it, it would sound pretty dead), but probably not have much effect on the lower-frequency vibration you're finding objectionable.

I use foam grips on my cruiser, and have been trying foam tape on my roadbike. The grips on my cruiser made me abandon all thoughts that I needed front suspension on the bike.
Use sandAtombomber
Sep 28, 2003 1:54 PM
or lead shot.
Use sandbburgoyne26
Sep 28, 2003 1:57 PM
sounds like an audiophile!
Or cork the frame ;) -nmfiltersweep
Sep 28, 2003 3:12 PM
I thought vibration traveled through the metal, not the air inside the tube.firstrax
Sep 28, 2003 2:17 PM
Energy will always travel the path of least resistance. Filling a tube with foam or any other material will not decouple the source from the termination. The path length and resistance will remain the same.
I thought vibration traveled through the metal, not the air inside the tube.dgangi
Sep 28, 2003 7:07 PM
For vibrating energy to travel, the material it is traveling in must be able to flex back and forth at a certain a wave does in water. Injecting foam inside an aluminum tube would make it less succeptible to freely moving back and forth at frequency, thus dampening the ability for those vibrations to travel.

However, I think such an idea would work for higher frequency vibrations. I do not think the foam would stop the lower frequency vibrations, which require its medium to move only a small amount at a low frequency. Foam is probably not rigid enough to stop the lowerer frequency vibrations.

I respectfully disagree.........firstrax
Sep 28, 2003 8:26 PM
Flex impedes the travel of energy. Any flex will lengthen the path, force a change in direction and speed thus allowing more time for decay. The more rigid a material the more efficient energy will travel through it.
re: injecting foam in frameSkip
Sep 28, 2003 3:54 PM
Apply these all over the frame:
Now there's a wacky (or whacked?) idea!Kerry Irons
Sep 28, 2003 5:36 PM
Let's see, we add weight, seal in moisture, and perhaps accelerate corrosion. Only one way to find out! Great idea. Let's go!
Great idea...lyleseven
Sep 28, 2003 8:26 PM
Another great idea for aluminum bikes!
Be careful !Jack9
Sep 28, 2003 8:39 PM
My neighbor was insulating his house with that stuff, put a little too much behind one wall and blew the wall out. Don't use too much!
re: injecting foam in framestriker
Sep 29, 2003 1:58 AM
Maybe try injecting a small portion? What about injecting a set of handlebars?
So I was sitting around with a can of spray foam and one thingSnowbird
Sep 29, 2003 4:54 AM
So I was sitting around with a can of spray foam and one thing lead to another...
get a carbon fiber frameDougSloan
Sep 29, 2003 7:03 AM
Carbon fiber damps vibrations magnitudes better than metals used in bike frames. I'll see if I can locate my source...

Don't worry I have my own source...biknben
Sep 29, 2003 7:24 AM
I've been riding Al for quite a while. A more harsh ride is par for the course for me. I once tooled around on a friends OCLV and immediately noticed
i something different.
It was just around the parking lot and doesn't even qualify as a test ride but I was surprised. It was smooooth!!!

Unfortunately, my choise of frame has often/always been determined by budget. My "friends" at the shop deal mostly with Al. The carbon stuff they offer is beyond my limits even with huge discounts. :-(
Sawdust would come close to the OCLV feel...nmdivve
Sep 29, 2003 7:50 AM
what do you want from a bike frame?DougSloan
Sep 29, 2003 7:56 AM
Do you prefer an Indycar stiff bike that allows you to feel running over a piece of paper? This might be useful in crit, where good feel while cornering at the extreme could allow you to better stay on the edge of control. However, I'd bet 99% of riders never corner at those limits, and would prefer as much damping as possible, while still having a frame that transmits all their power to the rear wheel and goes where they point it (that is, "stiff"). I never have understood the "dead feel" complaint.

I'm happy where I am now...biknben
Sep 29, 2003 8:23 AM
Sorry, I was trying to side-step the whole Carbon vs. Al debate.

I'm very happy with my Al. I'm not much of a century rider. The bike I have is well suited for the type of riding I do. I try to think of the ride as "Responsive" instead of "harsh". :-)

The OCLV I tooled around on just felt different. I can't say for better or worse, dead or lively, etc. I didn't want to imply that one is better than the other.
same hereDougSloan
Sep 29, 2003 8:34 AM
I sold my C40 and ride mainly my EV2 now. The C40 was a better ride, but I think that aluminum is just fine for shorter distances or if the roads are fairly smooth. Carbon seemed better for long hauls, particularly on rough or chip-sealed roads.