- This is a bottom bracket maintenance video,
in particular we're lookin' at press fit bottom brackets
because I know it's something that often
gets asked about on Ask GMBN Tech.
Now it just so happens that my bike's
not been overly maintained throughout the summer.
It's very dusty and it is actually creaking down there.
So this is a perfect opportunity
because hopefully you're gonna get to see all those things
that make a bottom bracket creak.
So we're gonna start off by removing everything,
giving it a clean, and putting it back in fresh.
So this is how you do it.
(dramatic swooshing)
Okay, so there are a lot of different bottom bracket types
out there but they kinda fall into a few different camps.
There's the classic threaded one.
So you get the cups, aluminum cups, on the outside
of the frame, they thread in, the bottom bracket bearings
sit outboard, axle goes through the middle, all done.
Then you get the BB30 or the BB90 style ones,
in which case the cups are part of the frame,
and the bearings literally just sit into those cups.
Now it's a very expensive way of doing it
because you'll either need a very expensive carbon frame
that has that designed,
it's an integral part of the bottom bracket shell,
or an aluminum frame or any other material
where it's machined into the frame.
So of course the tolerances have to be exceptional
in order for it to work.
So it's a very expensive process.
You don't see it on many frames.
And the final one is press fit bottom brackets,
which is a similar principle to the BB
in that the bearings sit into the frame,
except they sit into these little composite
or nylon cups which push into the frame.
Now it's cheaper and more simplistic
for the manufacturer to make the frame
'cause it just has a bare bottom bracket shell,
and all the hard bit is done
by the bottom bracket manufacturer
with the little composite cups that the bearing sits into.
But because of that, they have to aligned perfectly
in the frame and installed perfectly,
because any sort of movement
can create creaks at a later point.
Now creaks will occur with any of those sort
of press fit bottom brackets if
A, they've not been installed correctly in the first place,
B, it's not been installed using some kind
of anti-seize assembly compound
or a press fit retaining compound,
or, the other option of course,
is just wear and tear on bike.
So moisture has got in there,
and those cups start moving around
which is known as walking.
As soon as there's any movement,
you think all your body weight and all the torque,
if your transmission goes through
that bottom bracket spindle.
So any sort of movement there is gonna end up in creaking.
So it's one of those annoying things
that when it does happen,
you're gonna hafta deal with it.
So let's take a look.
So the tools you're gonna need will vary
depending on your Particular bike
and whether you're running, say, SRAM or Shimano cranks.
In this case, I need an eight millimeter Allen key.
I need a torques T25.
I need a mallet preferably with a soft
or a plastic ending on there.
I need some carbon or assembly compound.
I need some press fit retaining compound,
and the primer that you need to put on your shell first,
which I'll explain why.
You need a bottom bracket rocket tool,
or something to remove your bottom bracket safely
from your frame.
You need a bottom bracket press.
It's just a press for putting those bearings
back in place absolutely bang on straight.
You're gonna need some protective gloves.
In this case, it's gonna be a pretty messy job down there,
a set of nitrile gloves is a great idea for that,
also gives you a bit more grip whilst you're doing it.
And some sort of cleaner this can evaporate.
In this case, I'm gonna use some brake cleaner.
Okay, so first up you wanna get the cranks off your bike,
and it's a good idea to shift your gears
until the smallest sprocket in the back,
or the hardest gear there.
Just means you got a bit more slack on that chain there.
Now, like I said, in this case I need an eight millimeter,
but, if you've got a Shimano crank,
you'll need a five millimeter
and you'll need that Shimano tool
to remove the pre-load cap.
Obviously, every crank does differ so just check with yours.
Bear in mind as well that on some cranks,
say, like a Race Face, the bolt,
well actually to remove the crank,
would actually be on the drive side.
On this case, it's on the non-drive side.
So I'll just need the 8 millimeter Allen key into there,
and then I'll do it against this one.
Now you might need a little the tap on the crank there
with a mallet just to free it up on the end
depending on how long it's been since you've removed yours
'cause it can kinda get stuck on just with duration.
This one seems to be coming off.
(bike pedal moving)
There we go.
As always, put things back on the workbench
in the order that you removed them.
So also means you can give 'em a clean
and inspect them as you go.
So, my crank is loose,
just need to make sure that I undo my chain guide
that's on this particular bike,
and just let it slide up slightly and out of the way.
In this case, it is just that little four,
that's enough.
I don't need to remove off the bike,
just need to slide it up and out of the way
so the chain will not hinder that.
Now there's no set rules to the way
that you take your cranks off.
The way I like to do it,
now that I have my left hand crank off,
is just to put the cage lock
'cause I've got a SRAM derailer here,
just to hold that and the chain goes slack.
Now I'm just gonna remove the chain off the crank set here.
I'm just gonna let that dangle out of the way there.
Won't be needing that.
Now, if I'm extremely lucky,
the crank set will actually slide out,
but, more than likely,
I'm gonna need to shock it with that mallet
at the end of the axle.
Actually, coming straight off.
That's a stroke of luck, to be honest.
And as you can see from this,
it's absolutely filthy behind here.
So the creaking might not even be the bottom bracket,
it might just be the crank itself.
That said, I'm gonna remove everything
and do a fresh installation so I know that
there's a minimal chance of anything creaking.
So as I just explained,
my bike is pretty dirty so this is ideal time
for me remove that chain right off there.
It's a direct mount so it has three torques,
T25 bolts to remove that,
and I'll give it a complete clean,
a tiny bit of grease when I slide that back in place,
and I'll put some fresh threadlock on those bolts as well.
So I know that that is secure, that is clean,
that is one factor out of the equation.
Think of it as you're just trying
to eliminate every possible part of the bike that can creak.
I'm pretty sure that it is my bottom bracket,
but I'm gonna check this anyway.
So on most pressed fit bottom brackets like this SRAM GXP
have these little covers over the bearings,
and note that this one is covered
in dust and sand and stuff on the outside,
but pretty good on the inside there.
I'm actually quite impressed that.
I'm also just taking off the non-drive side
at the same time.
It's ina similar sort of state.
Now comes a bit you need to be a little bit careful with
is getting these cups out of the frame.
Now in an ideal world, you would have a tool like this.
This is also known as a rocket tool,
it's a bottom bracket removing tool.
Now the idea is you slide it into the bottom bracket shell
and these locate behind the cup there.
So it actually puts all the pressure behind the cup
in the right place.
You use a mallet to tap it back out.
Now be aware is that when you do tap it back out
it's likely to fire across your workshop,
wherever you're doing it,
so you wanna take something of little or no value
just to catch it like an old T-shirt,
or in this case a very helpful GCN workshop apron,
just like the GMBN one I'm wearing.
I'm just gonna hang that over the bike,
and hopefully that's gonna stop it flying out everywhere.
Now important thing to say is, of course,
this is a very specialist tool.
It's a really good one to have
if you have got a press fit bottom bracket,
as I'm sure you're gonna hafta work
on it many times over the years,
But if you haven't gotten one of these,
you can also do this with a large, flat screwdriver.
Now it's very important if you do this to be very delicate
and make sure it lines up on the inside,
because you can easily damage your bottom bracket.
If you do that, you're on your own.
So the correct tool will always win,
and it does make the job a lot easier.
So that is the non-drive side cup,
and this may well be the culprit.
There's no anti-seize compound in it at all.
It's completely dry so I suspect it might have
just been walking slightly in the frame,
which could lead to a creak.
So I'm just gonna take out the drive side one.
You're gonna see this one pop out now,
and we should be good.
So as you can I've removed this press fit bottom bracket.
It's the SRAM GXP, this particular unit.
So as you can see these composite cups
mimic what the BB90 or BB30 system will do,
by, say, this is the actual BB shell
and the bearings push into it.
But of course these bits still hafta
push into the blank shell.
And also you can see how simple this shell is as well.
Part of the reason that manufacturers
are choosing to use press fit is
because the fact it's a lot easier
to manufacture the bottom bracket area of a bike.
The longer it takes, the more expensive it's gonna cost.
Therefore you can expect them
to standard or accept composite cups like these,
and, provided you put them in right,
they can work very well.
Now the whole point of this exercise is to make sure
that everything is cleaned, lubricated, greased,
and you've put all the appropriate stuff on there
so it doesn't creak.
Now, you also want to be making sure there's nothing wrong
with your bottom bracket in the first place.
This particular one is still got a decent amount
of grease in the outside.
The bearings are really smooth.
There's no play in it so I don't see any reason
to change this.
And generally bottom brackets will keep going
until they completely fail,
and then just replace them.
On a more expensive units,
you can replace the bearing themselves,
but generally, with press fit cups,
the cups can be deform.
So it's actually a good idea to get new cups
at the same time or a whole new bottom bracket.
So you just wanna make sure you clean
around the bottom bracket area,
inspect it as well for damage.
It could be important especially if it's carbon frame.
When you're cleaning this,
make sure you're using something that's not too abrasive,
that's not gonna be damaging to the carbon itself.
If in doubt, just use some water,
just use some soapy water on there.
It'll be fine because you're not needing
to use degreaser as such or anything powerful down here.
So something carbon friendly,
or something that's non-aggressive is a good idea.
Now in this particular case,
it's so clean anyway.
There's almost nothing in there,
it's just a bit of dust.
I think this is okay.
Same applies to the cups as well.
Just give them a wipe down.
Now because there's cartridge bearings in here
you definitely don't want to get any degreaser near them,
because that will basically dissolve the grease
from the inside,
and like I said in this particular case,
they feel really good.
There's no reason to change them.
So I'm happy with those.
So just give it a clean on both sides there.
And clean all the parts of the bottom bracket.
Clean those seals.
Make sure there's no sort of damage to them.
Make sure they sit home properly as well,
because if they're not doing their job at sealing stuff out
then obviously your bottom bracket
is gonna deteriorate quicker.
Now for carbon fiber frames,
I recommend using a press fit retaining compound.
It's specially formulated
to basically lock those cups in place.
Now in order to do that you do need to use a primer first
because it's quite powerful stuff,
and if you don't use the primer,
when you later go to knock out those cups,
you can damage the frame 'cause it's quite powerful stuff.
So just make sure that you do that.
It's not that dear to buy and it's gonna go a long way
'cause it's liquid basically.
Now as you can see, it comes in a bottle like this.
You don't need a lot to just coat the inside of your frame.
Now something that is important to say though,
it takes between 10 and 30 minutes to dry.
So a good idea is to paint this on now,
which I'm gonna do,
and then I'm gonna continue the rest of the job
so by time I go to fit the bottom bracket
it's ready for the press fit retaining compound.
Now there are styles of press fit bottom bracket.
If you've got ones with aluminum cups,
you might want to use a little bit of grease.
You only want a tiny bit of grease
because there's still a chance,
even though the fit on those,
the tolerance, is a bit better,
they can still move around
and of course that will cause creaking.
In which case, you're probably better off
using an assembly compound,
which has those particles suspended in it
to stop that moving around.
So just make sure you use the right stuff
for your particular setup
and hopefully you will be creak free.
Now direct mount chain rings are really, really stiff,
however you can still get minute movement
which can translate into creaking.
And as you can see, having removed this one,
there's quite a lot of grime stuck in there,
in those little splines.
So it's really good idea to clean that up fresh,
and then you're gonna reduce the chance
of any creaking coming back.
Now although it's not completely necessary,
I like to put a little bit of assembly compound
just on the splines on a chain ring.
I'll clean up afterward so there can't be any chance
of grease getting in there,
but it does mean if anything does come loose,
there's less chance of any sort
of movement and creaking occurring.
I wanna put those bolts back into place.
I'm just gonna put a little fresh drop
of threadlocker on those as well,
just to make sure there's nothing that can creak.
So slide that back into place.
Locate that onto the crank.
Just give it a quick wipe down
with a fresh bit of shop towel.
Make sure there's no chance of any sort
of dirt and grime can stick to that,
at least don't make it easy for it.
And then, as you can see,
there's one, two, three bolts to replace.
So literally the case of putting a tiny bit
of threadlocker on those bolts.
I like to use medium strength,
I don't like too hard with threadlock
because it can make taking the bolts out harder
and more likelihood of random hits to the bolt out,
which creates problems later on.
Now I'm aware that a lot of people won't have access
to a torque wrench but I can't recommend them enough.
They're really, really good,
especially for something like this in a high load area.
Now in this particular one, the SRAM chain ring,
it say T25 tighten to eight to nine newton meters.
So I've got a torque wrench here ready,
I've set this between seven and nine there
so it sits on eight nicely,
and I'm just gonna make sure that these are tightened up.
Now actually it turned out I guessed that pretty good.
And after awhile of tightening bolts on bikes,
you do become familiar with roughly what is tight.
But there is no substitute for actually knowing
when it's tight and when it's not.
Of course, if you can get ahold of one, great,
if you can't then just be careful.
Okay, so now it's time to put the bottom bracket
back in the frame.
Now with press fit bottom brackets,
it's absolutely crucial that you get those cups
completely aligned when they go back into the frame.
If they're even a tiniest bit off,
and they're not in straight,
soon or later something will creak as they move around
in there as you're pedaling.
Now, for that reason, the best tool for the job,
I mean the best tool for the job anyway
is the correct tool for the job,
but you really can't beat
using a dedicated bottom bracket press.
It's essentially a miniature version of a headset press
which you can also use.
So I do recommend trying to borrow one from a friend
if you've not got one or see if you
can borrow a headset press
and do it that way.
However, the thing that's a little different with these,
than using just a standard press to push them in,
is they come with a adapters that are crucial
because they sit into those bearings,
so take the stress off the bearings
and just push the cups in place.
They'll make sure everything is aligned correctly.
Really, in this case, you can't beat this tool.
It's the best tool for the job.
However, we all know that someone out there
is gonna be doing this with a block of wood and a mallet,
and if you do this,
just make sure you're incredibly thorough
because you don't really get a chance
to make sure it's straight
and then it's gonna drive you batty when it starts creaking.
So if you have to use the block of wood and a mallet method,
just make sure you take your time.
Okay, so now is the time we wanna put
our press fit retaining compound
onto the actual BB sleeve to slide in.
Now obviously you just wanna double check that
that primer has set in place nicely,
'cause it forms a barrier so this stuff
won't damage your BB.
Okay, so, I'm just gonna slide this into place
and then I wanna insert the tool through there,
ready to put it in.
And we get the other cup, do the same thing,
apply some retaining compound to that.
It's quite viscous stuff so it's not gonna drip everywhere.
Slide this into place here.
Click the tool in place.
And then, fit this bottom bracket back into the frame.
(clicking)
And there we go.
That is proudly in place.
So my press fit bottom bracket
is back in place in the frame.
It's in there with the retaining compound
so I know it's not gonna walk around
or give me any problems.
Now you just need to reverse the process
of putting the bottom bracket back on,
making sure those nice seals are in place.
Slide the axle back into the frame there.
(axle pops)
Make sure that's sent home.
Retain the axle on the other side,
and then just tighten back to manufacture spec.
So same thing as before, just tighten up that crank bolt.
In this case, it's the 8 millimeter bolt
on the SRAM crank here.
And then hopefully that will be the end
of my creaking bottom bracket.
Everything is in working order.
It's been cleaned.
It's been lubed,
and it's been put back in with press fit retaining compound.
Just put the chain back on.
Put the chain guide back in place,
and go and hit the trails.
So there we go, that is the basic essentials
of taking out your press fit bottom bracket,
putting it back together again,
and hopefully removing any chance of creaking.
For a couple more videos,
click up here if you want to see Blake's manual machine.
This is one of those homemade wooden contraptions
so you can practice your manuals in your back garden.
And Blake swears this thing is amazing,
so well worth checking that one out.
And click down here for five traveling mistakes
to make when taking your bike places with you.
We've all done 'em,
I know I've done a few of these ones.
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