- This is expansion foam.
I could give you a list of reasons this long
to put it inside the walls of your houses,
and I could give you a list this long
of why you should put it inside your bike.
(upbeat music)
So what is this normally for?
Well, it's to fill gaps.
It can fill in the gaps around piping,
it can insulate, it can make something quieter.
We use this all over the inside of Alexander's van
to try and keep the noise down
and keep it nice and warm in the wintertime.
And so, we could put it inside
a little hole in my bike frame
and fill the entire frame with foam.
But why?
Well, I heard through the grapevine
that there're actual race mechanics
that will fill bikes or parts of bikes with this stuff
to make it quieter.
Now, keeping bikes quiet is really important.
If your bike is really quiet
and you're only hearing
the things that are supposed to be happening,
the second you hear something is off,
you know something's wrong.
And in a racing situation, that's important.
And I personally like riding with a quiet bike.
I like to hear the tire sounds, and the cassette,
instead of things rattling.
This is supposed to stop that.
And so I guess we should just
go in this little port in the bottom
and fill my frame with expansion foam.
(intense music)
Not so fast.
This is the type of thing you really wanna think through.
Every single forum post I can find on this
ends with the community stopping the original poster
from filling their bike with expansion foam.
And then there's always somebody at the end that's like,
hey, if you do decide to do that,
can you let us know how it turns out?
(upbeat music)
So the first concern I saw people really worried about
was that this stuff was just gonna expand
and break the bike frame or somehow weaken it.
I'm not worried about that at all,
but I'm gonna test that.
I have this clear tube here.
I'm gonna plug up one end with this here tennis ball.
Gonna drill a little hole next to it.
And so now we are going to spray expansion foam into here.
And what I think is gonna happen
is it's gonna work its way up the tube.
(liquid sloshing)
(upbeat music)
(foam spraying) Ooh.
Doesn't appear to be expanding much at all.
Looks like you have to keep spraying it in
for any expansion to really happen.
But let's keep an eye on it for a few minutes.
Okay, nothing alarming happened here.
In fact, I'm alarmed at how much it didn't expand.
And so we're not gonna spend any time
on worrying about the bike exploding,
not with hardware store expansion foam.
But that doesn't mean this is an awesome idea.
Let's consider some of the other reasons
you wouldn't want your bike frame
permanently loaded with expansion foam,
starting with internal cable routing.
As you've seen in many bikes,
cables run through the inside of the frame.
If it was filled with foam,
it'd be pretty hard to get a new one through.
Now, this frame already has liners for cable housing.
And so if I wanna run a shift cable through,
it'll just pop out the back.
And so we don't have to worry about that one.
But if I wanna hook up a wired dropper post on this frame,
it goes through the down tube,
so we're gonna install a liner first.
(upbeat music)
Okay, so now there's a tube running from here
up into the seat tube.
And so if that's surrounded with expansion foam,
we can still run a dropper cable.
The tube should stay still
because it's gonna be surrounded with the expansion foam.
(laugh)
So now that we have this bike all prepped
to fill with expansion foam,
let's talk about the biggest reason
why you shouldn't do this:
Limited gains.
If this stuff is gonna make my bike quieter, (scoffs)
it's pretty quiet in the first place.
And so to make even an attempt at measuring a difference,
we took this bike down the rock garden.
We attached a decibel meter to it
to get the loudest sound out of the bike.
We attached a GoPro so you can hear the audio.
Take a listen.
Okay, three runs, bike butted up against here.
Try and take the same line.
(tires bumping)
89.5 max DB.
And we got a whole buncha clips
of me just dropping the bike in the shop.
Take a listen.
(bike rattling)
And so now, without any further ado,
let's fill this thing with foam
and see if there's a difference.
(intense music)
(foam squirts)
This stuff expands.
Let's leave it for an hour.
(upbeat music)
All right, time to test it.
But first,
get that outta the way.
Get our maskin' tape off of here.
Whew, you can smell it.
Inside the part that I ripped out, it's a little gooey,
and so we're gonna let it cure for a little while longer.
(upbeat music)
Okay, so first of all, (tires bouncing)
I don't know if I notice a difference.
(knuckles knocking)
I think it's deader.
Let's get it out to the rock garden.
Okay, run number one.
(tires bumping)
86 decibels.
That could be just a coincidence.
Okay, run number two.
(tires bumping)
87.9.
(tires bumping)
85.3.
All right, interesting results.
Let's go do the indoor drop test.
So I've watched all the clips,
both of dropping the bike 10 times in succession
and riding down the rock garden three times.
It doesn't sound quieter,
it just sounds more dead.
But I'm hyper aware
of the possibility that I'm just imagining that.
(tires bumping)
(bike rattling)
Now, the decibel meter is where it gets interesting,
because I didn't expect this data to be very useful,
because (shriek) it's just measuring the loudest sound
and telling us what the decibels were.
It could be the tire making a popping sound off the rock,
it could be a cable slapping.
We don't know that it's the actual frame.
But both on the drop test in the garage and outside,
it's showing an average of two fewer decibels.
Over two.
And this is consistent.
Anybody who's tested anything in a scientific way
knows this is not conclusive,
but it's interesting.
Damn.
(mellow music)
So did we come to any conclusions today?
Or better question would be, did we even learn anything?
Well I'll tell you what I would do different
if I were to do this experiment over.
First of all, I would weigh everything before and after
so we could have a definitive answer
to how much weight we added to the bike.
Another thing I would've done differently
is I would've secured the crank set
so that it couldn't move during the drop test,
because it would've been cool to isolate it.
I might have even taken off the chain
when going down the rock garden to just isolate that.
And so, the results are not as perfect as they could be.
However, if there is a difference, it's very small.
And to get there, you gotta fill your bike with spray foam.
It's sticky, it's nasty,
it can make running cables difficult in the future,
and it's pretty much impossible to undo.
It's like, it's there.
And so in all those forums
where the original poster is eventually convinced
not to do this,
it seems like they're getting sound advice.
And so now, I've gotta dig this expansion foam
out of my bottle cage bolt.
And I gotta fill all my other bikes with expansion foam.
That was awesome.
So I don't know,
do any of you guys know anything about this?
Filling a bike with expansion foam?
Do you have anything to add here?
I just did this for fun.
I heard about it, I wanted to try it
and see if there was a big difference.
There wasn't.
But I hope somebody learned something today.
And if not, I hope you at least found this entertaining.
And if you're digging what we're doing here on this channel,
we've got merch, we've got the new E t-shirt
where I'm jumping onto the airbag in front of a full moon
with my friend Oscar here.
And we have wonderfully comfortable jerseys.
They're all on the link below.
Thanks for riding with me today,
and I'll see ya next time.
What else would I change?
Oscar, stop!
Stop! No.
No.
I'll get you a brand new tennis ball.
I'm sorry, buddy, I had to use it.
Halt.
Halt, Frenchy.
(chuckle) You may not pass.