I was talking to an old school bike guy I know today, and he started telling me about how people would spray foam sealant( I don't know its technical term, but its sold at hardware stores, walmart etc. and comes in a spray can with a tube and is used to fill cracks in masonry I guess, it expands as it dries) inside of frame tubes, seat posts, handle bars, and generally where ever they could get it to go. It supposedly does worlds of good in reducing road vibrations while barely adding any weight. Is this a sound idea? I could see the bars and post if they are alloy, but I would worry it could trap moisture in the frame, though I suppose it woul do the opposite in a dry, clean, frame-saver treated environment.

There are two types of that sealant;

one that e x p a n d s,

and one that

not.


Regards,
J T

May the fleas of a thousand camels dwell in your bed if you ever do this to a nice frame.

Oh, I better actually say why I think its a bad idea.

The whole point of good tubing (even more than the lightweight factor) is that it is just a little bendy and springy. It feel alive. I cannot imagine any means to make a tube feel more dead than to make it not a tube any more.

jim

hey, it's not me who did it! I thought it sounded a little weird myself, but supposedly it was done on crap bikes to try and make them ride better.

It remains a common enough practice - in handlebars only - among owners of frames (usually aluminum) that seem to buzzzzzz at uncomfortable, hand-numbing frequencies.

Some of those foams absorb moisture. Some don't, they never say which.
The prvious owner of my tugboat has filled some sloppy joints with the stuff and when I pulled it out, it was like pulling sponges out and it had rotted the wooden bulkheads just exactly where it had been and nowhere else.
I'd do some research before I even used it on a house.

I've heard of bike tourists hiding illegal substances in the tubing when they fly back to America from abroad. That sealant will kinda defeat that purpose.

If you think it is a good idea why not try it on some cheap ol' frame that you don't care about and see what the difference is. I would not try it I would shop around till I found a frame that I liked the ride of. Not all frames give bad rides, I guesse just bad frames give bad rides.

Put the stuff in first then the sealant and then drill it out when you get where you are going.

My thoughts exactly.

That, and the moisture-trapping potential make this a really, really bad idea in my book.

If it was a good idea, they'd come that way and cost $xxx more.

One of the Italian brands, Bianchi? perhaps had an alloy welded frame a good while back that had some foam regions within the tubes to either tune the ride and or increase stiffness, it might do something other that increase the weight, but the results are by experiment I would think.

As reported earlier, there are a number of different types of "canned" foam, better results would come from the two part types I think.

If someone WERE stupid enough to do this, they would want to use "window and door" foam aka: minimally expanding foam. If the normal "Great Stuff" foam were used, it would split the tubes when it had finished expanding.

I didn't say I thought it was a good idea! I thought it was kind of questionable, but old guys tend to do alot of odd things younger folks like myself never would have considered.

I figure if it was a good idea, we'd all have heard of it by now.
Old guys do odd things. We have to stay awake somehow.

https://www.lordfulfillment.com/upload/SI3155.pdf

1908 can be put in a styrofoam cup then park a truck on it. I think the idea is to build an even lighter frame then put the foam in it for strength

ANYTHING you buy at HD will hold water. These items are what is used in cars

If you decide to do the foam trick, do it somewhere far from a flame. That stuff should be banned. The gas can ignite & burn with an invisible flame until it actually ignites something else like your home or shed. Bad bad stuff!

Filling tubes and frame rails with foam is very tried and true method of dampening vibrations and stiffening a frame. Honda has been doing this for decades but it had one major flaw. Moisture. Alot of the old Hondas have rusted out frames because the foam absorbed and held the moisture.

Many autocross racers still use a special expanding foan to stiffen the frames of their racecars.

Does it work? Yes, no question. Are there drawbacks? Yes, no question.

As posted earlier:

https://www.foamseal.org/auto_aftermarket.htm

Apparently this has been discussed before:

https://www.bikeforums.net/archive/in...p/t-53918.html

Around here when a bike gets stolen it usually winds up in the river,I spose if its filled with FOAM it will float to the top and we can get our bikes back (albeit wet) lol

well, I like it cause the crunchy outer shell envelopes a delicious honeycomb center...mmmm

There are two basic formulations of polyurethane foam-in-place stuff. The "open-cell" variety (Great Stuff and the like bought at home improvement stores) will pass water vapor, if not liquid water. The closed-cell foams are not available in a can AFAIK, but are packaged in bulk for large jobs (architectural). Closed-cell is vapor-impermeable.

Great Stuff is available in two varieties, low expansion for window and door (so it doesn't spring your fixed sash and make operating sashes inoperable!) and the "crack-and-crevice" type which is the stuff that causes nightmares when it's used for windows and doors.

I wouldn't use any of these for a bike, but I'm old-fashioned.

I try not to do something that is difficult to reverse. So I would not attempt it.

Bianchi filled the seat-tubes on their Boron steel frames in the late 90's early 2000's. Supposedly to reduce failures they were having with this superlight tube-set.

Sounds like it would be impossible to reverse. Even cut-off parts could be replaced, but how would one ever get that gunk out of the tubes once it's in there? Seems like a good way to permanently ruin a bike.