Essential Press Fit Bottom Bracket Maintenance
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Essential Press Fit Bottom Bracket Maintenance

November 6, 2019


– 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. AS always, click on that round globe to subscribe to GMBN tech. We love having you here. And of course, if you
like fixing your bike, give us thumbs up!

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