[Music] today we're going to be looking how to replace a threaded bottom bracket on your mountain bike so that's the bearing that your cranks revolve around and of course this is a consumable part so it's going to naturally wear out as you ride so therefore it's a great skill to learn how to do this okay so before we get started with actually swapping the bottom bracket out on this bike let's just talk a little bit about the types of bottom bracket of which there are two major styles you're threaded and you get press fit threaded as you imagine involves bottom bracket cups that actually screw into your frame a pretty simple approach and we're going to deal with that in a minute the other option available on the market are press fit now we also have a video on that the link for it is going to be in the description underneath so you've got both styles covered between this video and the other one now the difference of press fit bomb brackets are you still have a bearing that supports the axle of your crank the difference being those bearings the way they fit into the frame itself so don't screw in now this is quite cool concept because of the fact that the frame manufacturer only has to produce the frame with a fairly simple shell and a certain tolerance on that shell but where did the press fit concept come from then well manufacturers essentially tried to streamline the system with a different approach and i thought wouldn't it be cool if you could just put the bearings directly into the frame and then the axle of the crank just go straight into that which was a great concept except to do that you had to machine bearing surfaces directly or is it basically cups essentially into the frame design which meant a lot of additional labor a lot of time and very precise tolerances so therefore we moved away from that to the press-fit style system now like i said press fits are very good but only when they're installed correctly and maintaining them is also a good idea to make sure they can't move around at all in that bottom bracket shell because any movement will come across as creaking which can drive even the most sane cyclist completely crazy threaded system though is brilliant so let's have a closer look at it okay so what about bottom bracket width then it's going to be different on different mounted bikes right well there's 68 and 73 options available which are fairly standard for road bikes and mountain bikes there's 68 for road bikes some mountain bikes and 73 is a bit more common and then of course you get the slightly wider option so you get the 83 which is pretty much a downhill bike for that bit extra stability and then you get fat bikes which can use those but more commonly tend to use up to 120 mil width between the actual bottom bracket bearings there so pretty wide and of course that is to accommodate the width needed for the wider drivetrain spacing to accommodate that bigger rear tyre now when buying a threaded bottom bracket you will find that they usually come with a number of spacers this is so you can space out the chain line on the bike and of course to make sure it fits correctly if it's a wider spacing for example than it needs to be for a 68mm shell now let's talk about the direction in which the threads work on a bottom bracket which you do need to notice so with your pedals on your bike they essentially both tighten your right and your left pedal they tighten towards the front of the bike and the bottom bracket they both both cups tighten towards the rear of the bike so if your drive side that is anti-clockwise and for your none drive side that is clockwise now you might think that's a bit strange actual pedaling is going to undo the bottom bracket but not so it's actually quite cool so think about what happens on a bearing so the outer surface actually rotates in a different orientation to the inner surface so technically the bearing itself as it's rotating is slightly tightening the cup and preventing it coming loose and the reason that we have the bottom bracket cups tightened towards the rear of the bike rather than the front is because if you get a seized bearing and it was the other way around you're essentially going to tighten those cups into the frame so much you may never get them out again so the concept is if you get seized bearing we'll actually try and undo the cup slightly so that's the theory anyway but it works and both cups remember tighten towards the rear of the bike that's all you need to remember and then of course there's the actual bottom bracket itself now there's loads of different orientations out there now you will need to make sure you get the correct one to suit the axle size the brand of crank you have and of course the frame so this one will suit 68 or 73 mil shelves is for a shimano crank which of course i've got on the bike behind me here is a slightly different bottom bracket but it will accept the crank no problem and uh these are the parts so you've got the right and left cup or drive side and none drive side cups complete with the bearing in there and you've got a bearing cover you've got the spacers and you have the plastic shell that sits on the middle it helps keep the water away from those bearings now the plastic shell will differ on different bottom brackets essentially you'll have a wider version of these on the downhill style bottom brackets otherwise you'd think the cups sit far apart and it actually wouldn't be doing its job now yes you can run without these they're not essential but they will make your bottom bracket last much longer so it's advisable to use these okay and then we're on to the tools that you're going to need for the job so firstly you're going to need some sort of grease just a generic bicycle grease is fine unless you've got like an exotic frame for example if you're putting alloy cups into a titanium frame you might want to use some anti-seize compound rather than having an actual grease but grease will do the trick as long as you keep an eye on it you're going to need something to get the cups in now you can use a more traditional style bottom bracket tool spanner i'm going to be using the socket variety here because the fact there's so many different options available on the market we've got loads of different sockets to suit you can quite happily have one of these and just buy bottom brackets to suit the socket you have i'm going to be using a torque wrench it's not essential but it is a good idea to know how tight you're tightening these things and because i'm using a shimano crank i'm going to need allen keys to remove the cranks but also this little tool here now this is to essentially remove the pre-load cap that's on the left hand crank that just pre-loads everything together to make sure there's no play in the system but your bike might not need that you might just need an eight millimeter allen key to remove your cranks okay so now it's time to get the bike prepared so i've got my bike in a work stand but you don't have to do this as long as you've got somewhere to lean up if you've got a friend to help that would be beneficial for you so first up we want to get the old bottom bracket off so there's a few steps to this process if you have a shimano rear derailleur you want to turn the clutch off if you have a sram rear derailleur you want to put the cage lock on in this case i've got the clutch on a shimano mac so i'm going to turn this one off and then i just need to remove my chain guide here just to allow the chain to get out of harm's way i'm going to lift the chain off at this stage of the process right now next up is to undo the pinch bolts on the left hand crank and then slowly just start with this tool just start undoing that preload cap and then remove it from the bike completely and i like to use the crank to help me so spin the crank backwards keep the tool in place now in the case of this bike which has shimano cranks on you need to remove this none drive side crank first in order to get the drive side off uh might be different with your crank you might need to remove the drive side first i'm just giving this a wiggle you might need to tap yours with a mallet but i can see this is coming off nicely and you get a bit of grass foliage behind the crank there give it a bit of working sometimes you need to there we go so sometimes you need to use a mallet just to get those off now it's important at this stage to make sure you give the back of your crank a good clean that's pretty pretty grotty in the back of there but we put this on the workbench and we'll get to that in a minute now when it comes to this side sometimes you'll need to tap this with a mallet something like a soft ended mallet like this just to free it a little tap just to loosen it and slide on out there we go as with all mechanical processes you should sort of lay down the equipment in the order you remove it ready to sort of do the reverse when you reassemble then it's a case of making sure everything is nice and clean at the same time give those cranks a quick wipe down on the back there it doesn't always get exposure when you're cleaning the bike and whilst you're at it just observe what's going on with them have a look at the condition of the chain means check the crank for any sort of bad things could be cracks or any damage in the paintwork there and just take note of it and if you need to replace anything this is the stage you would do that and now it's time to remove the old cups from the frame now depending how long they've been in there they could well be quite stuck and depending how they were installed the grease could have dried up perhaps they were installed dry so just assume at this part of the process they could be stuck so take a little bit of care here so very carefully take into account the fact that the drive side of your bike so that's where your transmission is that will loosen to the front of the bike which means a clockwise action and the opposite for the nut drive side so that loosens counter clockwise which is towards the front of the bike now make sure whichever method you're using whether using a socket like i am or if you're using the pressed steel style tool you use all of your body weight to remove this but make sure if it slips you can't hurt yourself and of course you want to make sure the tool doesn't stand a chance of slipping in the first part of the process here so just take care you want to loosen this and then bit by bit you'll find that the cups will start removing from the frame and just unscrew them by hand at this point when the tension is taken off and they're nice and loose now when doing the opposite side of the bike you need to make sure that you get yourself in a position where you're not going to slip so i'm actually leaning over the bike with the bike in the work stand here just to do the none drive side cup there we go now as i'm removing the drive side cup here note that there is one spacer here i'm going to need to replace a single spacer at the same point here when i'm putting the fresh one back in and note on the nun drive size there are no spacers so it might be different on your bike so just if everything worked correctly then basically mirror exactly as it was if things weren't quite right then you want to refer to the guide that comes with the bottom bracket of choice and it will make recommendations depending on your bottom bracket width how many spaces you should have right left if at all now with the old bottom bracket out of the bike it's time to give the frame a bit of a clean up in this area take advantage of the fact there's nothing down here because it can be quite tricky especially on a suspension bike like this one sort of clean all the workings around the sort of swing arm and the pivots and stuff so just give it a bit of love while you're down there now to get in here i'm just using a bit of this brake cleaner you could use pretty much anything you want to use anything as abrasive as a degreaser down here i don't think there's much need give these threads a good going over and then apply a small amount of fresh grease to the threads on the bottom bracket shell like i said earlier if you're using for example a titanium frame and you're putting in a different material bottom bracket you might want to use anti-seize instead of grease at this point now i have the fresh bottom bracket here and note it does tell you the orientation of them it says on their right cup or left cup the right cup will be drive side sometimes it will say drive side on the cup itself otherwise it will just say right so just take care when you're looking at this but if confused you can use the orientation of where it says titan to identify which one is which note that they're both tightened towards the rear of the bike so i know therefore even without the right marking on this one i can see by the orientation of the arrow that this one is the drive side cup and this one is the none drive side cup now if you look on the threads here you can see there's some kind of thread lock compound already on there but i'd still put a small amount of grease on here just to be sure to make sure it goes into the frame nicely now just before i install the cups i just want to double check that the threads are in good condition on the edge of the cup so the leading threads there and the same on the bottom bracket shell now just before you turn them into the frame it's a good idea just to doubly check that everything lines up because they're very fine threads and when you're using a heavy duty tool like a socket set or the big traditional bottom bracket tools it can be very easy to slip at this point and not screw it in correctly which would mean you could be in danger of damaging the threads in your frame and then you're going to need to have your frame tapped again so at this point do take extra special care to make sure the threads line up properly now something i like to do with most threaded parts like this is to actually screw it the opposite way just a couple of turns first just to make sure that the threads are back out of themselves and then they can locate in place so note here i'm just going to screw it to the front of the bike just slightly for this drive side cup and then i'm going to screw it towards the back of the bike and yes that feels great i can feel that engage in there so now i'm free just to screw this in as far as i can by hand you'll find when it gets to the compound that's on the threads it will naturally get harder and you'll start wanting to use the tool at this point now bit by bit work that cup into the frame using the tool of choice you have here until it feels nearly tight and then if using a torque wrench like i am here at this point you want to apply the correct amount of torque now this will differ depending on the bottom bracket in question it can be between 30 and 55 newton meters so this is something you will need to check if you're going to use a torque wrench now bottom brackets do need to be tight but they don't need to be ridiculously tight so don't go hanging off the tools and risking your tooling slipping on the actual bottom bracket which will round off the bit where it actually gets traction and of course you don't want to damage any threads so just use a bit of common sense at this point now it's time to repeat with the opposite cup at this point you might notice on the opposite cup i have the little plastic spacer in place here so i'm going to thread this in exactly as i did before i'm actually going to back it out first slightly just to make sure it lines up and the same process just very carefully just thread it in by hand until there's that natural resistance of whatever sort of compound there is on the threads and then i'm going to use the tooling to just get that bottom bracket screwed into place there and again in this case i'm using a torque wrench just to be doubly sure but you don't have to it's just advisable if you do have one it's a good idea to check this but of course you're only gonna be able to do this if you're using a socket set like i am if you don't have one of those just exercise caution you want it tight but not crazy and now it's time to get your cranks back on the bike so you want to reverse the process in which you remove them to start this process so just give them a bit of a clean and put a bit of grease just on the axle itself nothing to go crazy just to help it slide into place neatly there now just guide it all the way in until it starts appearing at the other side and then you want to make sure you line up your cranks correctly now depending on where the splines are uh usually it's fairly easy but we have seen people get this wrong and you have the cranks not quite line up so just take care here when you're putting the crank on now if like me you're using a shimano crank you're going to need to use this preload tool just to wind up and make sure there's no movement in the system before adjusting those pinch bolts and making sure that they are nipped up nice and tight now shimano recommend these pinch bolts be between 12 and 14 newton meters and of course just like anything with a twin or a triple bolt set up make sure they're tightened equally so don't just tighten one and then the other just bit by bit on both of them until they feel like they're about in the right area there like i said 12 to 14 newton meters most important thing at this stage is to make sure they're all in and nice and flush together making sure there's a good amount of axle in the actual crank arm itself if there's not then you may need to remove a spacer here at this stage but provided your bike was set up like this in the first place it should be fine a bit of a running check now then we want to get the chain back in place get that chain guide tightened back in and make sure it's all aligned correctly and then switch the clutch back on and then we're good to essentially pretty much go and hit the trails but there we go it's a pretty simple process replacing a threaded bottom bracket on a bike but like i said just take care with those threads it's the most important bit to make sure you get that right if there's any other videos you'd like to see us make get in touch in the comments underneath and we'll see you in the next one see you later