How To Replace Your Mountain Bike Fork

Fitting a new fork to your bike is a fantastic upgrade and it can really improve the handling. It's actually a fairly simple process to do yourself at home, so I'm gonna demonstrate by fitting a new RockShox fork to my Nukeproof Scout. Really simple, this is how. As with any job working on your bike, you're gonna need some sort of tooling to do this. Now, if you're in a bike shop, there's a lot of specialist tools, such as this crown race puller, that you would actually need to do this job on a bike. But fear not, there's plenty of alternative ways. And although the correct tool is always the best tool for the job, you can actually do this with a fairly basic tool set. So you're gonna need some sort of Allen keys to remove the current forks from your bike. You're gonna need a hacksaw or a pipe cutter, some way of cutting the steerer tube down. And you're gonna need a file. And of course, the all-important tape measure so you can actually cut the correct length of your steerer tube. So this is how you do it. So first things first, you need to remove your existing fork from your bike. So obviously, putting your bike in a work stand is the easiest and the best way to do this. If you haven't got a work stand, then you definitely really do need someone to help you with this task by holding the front end of the bike up. So obviously, you're gonna need to take the wheel off first, because that's just gonna hinder things. Take your through axle or your quick release out of the bike there. Put your wheel aside for later, you won't be needing that till the end of the job. And next up, you wanna make sure you remove the brake caliper itself and the cable routing off your existing fork. And let that just dangle down. Obviously, you wanna make sure it doesn't hit anything. Next up is to just release the actual cable guide on the fork itself until that comes off the fork there. And just remove it. Make sure you don't lose the little bolt. So I'm actually gonna put that back on the fork so I don't lose that. Now, moving on up to the stem there, you're gonna loosen off your stem clamp bolts, but don't remove the top cap just yet, because that will, if you have that often at this stage, the fork could slide out onto the floor and you'll lose all your headset gubbins. So just loosen off the clamp bolts on either side there. This particular one is four millimeter Allen key bolts, but it's quite often a five and sometimes even a six. Right, so they are ready to come out now. Now, this is the bit you need to pay attention for. So I'm gonna slowly undo this top cap now and hold the fork at the same time so it can't go anywhere. I'm just gonna remove the top cap. Take note that the steerer tube here is about four millimeters below the top of the stem. You're gonna need to remember that for the step later on. So whilst grabbing the fork there, I'm just gonna slide the stem off the steerer tube there. I'm just gonna let this hang down. So I'm taking off my two spacers that are under the stem there, gonna put them on the side with the top cap next to them. Now, the next thing is this top plate of the headset. You wanna slide this up. So that is your top cap there. Then underneath that, you have a spacer of the compression ring there, which is a split ring that pushes into the top of the headset there. So make sure that stays in there as well. Then you have a washer and the top bearing race. Now, I'm just gonna let the fork slide out of the head tube there. Now, sometimes you might find that the lower bearing race sticks inside the head tube. So if that's the case, just keep your hand under that so it doesn't drop on the floor and get dirty. In this particular case, it's come out on the actual fork steerer. So just to show you that, that is the lower bearing race. Then there is a little spacer there or a seal. And then the actual crown race there is still part of the fork. Now, this is something we're gonna need to remove. But before we do that, we're just gonna give everything a bit of a clean. Whilst the fork is off the bike, just take this opportunity just to inspect the frame, make sure everything's sound, there's no rust, there's no damage or anything like that. So just take a look at the new fork and the old fork and see the differences. So the first one you're gonna notice is the steerer tube on this new fork is quite a lot longer than the old fork. So that's something we're gonna have to trim down to the correct length. Now, also, the crown race for the headset is still on the old fork. So you're gonna have to remove that. Now, there's two main types of crown races. There's the ones that push on and then there's those that have a split ring. This particular one has a split ring on it which means it's gonna be a lot easier to take off and you don't need specific tools for that. Now, also note that on mountain bike forks you often see this little recess here just underneath. That's really handy for getting in an old, flat, blunt screwdriver or a punch to loosen your crown race and get this off. Now, of course, that is not the correct method for doing it but it's one that I've been using for many years and as long as you take your time and use an old screwdriver, you never wanna use a good new screwdriver because you wanna keep them sharp for obvious reasons. It's absolutely acceptable to remove it like that. However, on certain forks, let's just say you've got a posh fork with a carbon crown or it's a very lightweight fork, you don't wanna be sitting there with a punch and hammering the actual crown race off. So that is a very specific tool for that job. Now, I'm well aware that most of you won't have access to a tool like this but I just wanted to show you this and show you why it's an important tool. So this is the Park Adjustable Crown Race Puller. So this actually goes upside down in a work stand and you've got these three blades here. The idea is you put your fork steerer tube into this and then you secure these blades underneath the actual crown race and then you simply turn the dial to pull the crown race off. You might question that this is a bit of an excessive tool for a job like this but actually, if you think that on road bikes, for example, you've got super lightweight and actually very delicate components on there like carbon fiber steerer tubes and that, the last thing you wanna do is use a punch and put a big gouge into that. So these are the best way and they're really, really good for removing the crown races but of course, fully aware that most people won't have them. I just wanted to make you aware that they do exist. So if you have a problem getting one off on your own bike, you can always just take your fork down to a local bike shop and maybe the packet biscuits and hopefully a mechanic will have one of these and it'll help you get your crown race off. So I'm literally doing a like for like fork swap here so I'm gonna measure the steerer tube with a trusty tape measure. Now make sure when you use a tape measure, you take into account that the bit on the end there can actually move up to two or three millimeters so make sure that is flush against the fork crown. So in millimeters here, so what am I? 174, 174. So that is the measurement I need to make my cut mark on the new fork. So let's get that measurement there, measure it up on the new fork there and then I've just got a fine flat screwdriver here to make a little score mark for reference. Now this is something before you cut, I can't emphasize enough, measure twice, cut once. You do not wanna mess this up and cut this too short. I've seen this happen a lot of times and it ends up being a very expensive thing to get around because to replace the steerer tube on any fork, it means replacing the crown and the upper legs as well and that of course will mean a full fork service to do so as well as the price of that component. So make sure before you cut, you've measured, you've checked it, you've measured again, you've checked again, the more times the better to be honest. Now if you're not doing a like for like fork swap and you actually wanna change the front end of your bike maybe by allowing the steerer tube to be longer and for more spaces, the best way to do this is to put the fork on the bike, so put the crown race on, assemble the stem on there, get it in a position that you like, then make a mark above the stem. Then from that mark, you need to allow for that three to four millimeters below that which is where you make your cut mark and the reason for that is when you tighten the stem preload cap on the top, it gives it enough room to actually pull that, pull everything together to preload that bearing correctly. If it's a flush fit, you're never gonna be able to tighten or adjust the bearing so there's no play and of course, if you ride a loose headset, after a while, you're gonna damage the bearings and you could damage your frame as well. Now when it comes to actually cutting the fork steerer, there's a few different options available to you. Now the classic or the good old fashioned way is by using a hacksaw. Make sure you've got a nice, fresh blade on there and it's tensioned correctly so it can't snap or actually go skew-iff so that is a good, solid way of doing it. Now if you use a hacksaw to do this, you're definitely gonna need a metal file afterwards to make sure there's no burrs and it's nice and smooth on both the inside and the outside. As for keeping the blade straight, there's a couple of different options for you here. Now you could get a dedicated fork steerer tube cutting guide like this one and the way this works is it's clamped into a vice, ideally, and basically you put the fork steerer tube through here and you line up your cut mark with the hole. Very simple, by eye, you then tighten this clamp up and then that is where you make your cut mark. That's a fairly foolproof way of doing it. It's the official way of really cutting down a steerer tube and not getting it wrong. You make a cut mark here, the small piece comes off, this is the piece you keep, job done. However, not everyone's gonna have access to these tools and of course, this is a bike shop spec tool. These are really good, this is actually my own personal one. Over the years, I've cut a lot of steerer tubes but you might not, you might only ever do this a couple of times, you might not be able to justify one of these. So something I do recommend keeping hold of is an old handlebar stem. Now you can use your old handlebar stem as a guide in a similar way. You could slide this onto your steerer tube and using your multi-tool, you can tighten it up in the relevant place, just like so. And then that is where my cut mark is. Make the cut mark there, it makes a nice saw guide. Because it's an old stem, I'm not too fussed if it gets any more damage but it's a good use of an old product. Now the final option available to you, and this is a really handy option if you don't have the luxury of having a workbench or a dedicated space to work on your bike, is by having one of these little fellas. This is a pipe cutter. So simply put, your steerer tube would go in here, you adjust the disc until it contacts it, and you rotate it around until you cut the steerer tube at your specified point. Gets a very accurate cut. They're not the cheapest items to kit but they're really useful. And like I said, if you don't have the luxury of having a space to work on your bike, that can be better than having to have a bench, a vice, a steerer tube guide, and a saw. Okay, so really the correct way of doing this is by using a vice, using a saw guide, and using a hacksaw. Now you can get away with doing the mark with a hacksaw, using some sort of guide, improvising by maybe leaning on it on a soft surface, you're not gonna damage it, but you won't beat this for an accurate and correct way of doing it. So just lining up that in the vice there. Now of course this vice isn't bench mounted here but it's mounted to a really heavy lump of wood and it's more than enough for this purpose. So the important thing is to make sure if you, for example, got some accidental other scratches on your steerer tube, you don't accidentally line one of those up. This is your moment of measure twice, cut once. Can't emphasize that enough. So that is the one, I've even made a little arrow by it this time so I know it's the one I wanna cut. So I'm just gonna slide this in and then by eye, I'm gonna line this up in here and then I'm good to make my cut mark. So this is the moment of truth. If I've got this wrong, it's not gonna fit my bike and I'm sure you probably wanna see that to be fair but I don't want that to happen. So make sure you hold everything nice and tight and nice and clean strokes on the hacksaw. Get it going, keep going until you're through basically and this is where having a nice sharp blade will be beneficial for you. So there we go, that is cut off there but while I've still got the vice here, just gonna slide it through a little bit more. We're gonna tidy it up as well. Just be careful because there could be some very sharp burrs around the edge there. You'll get your metal file and you just wanna make sure you just smooth off the edges. Now also, you just wanna use the rounded edge of your metal file and do the same on the inside of the steerer tube because you do need that to be smooth in order to fit your headset preloading star fangled nut. Now one very important thing to remember, when you cut your steerer tube down, you're gonna get all these metal swarf, metal filings, metal dust everywhere. You do not want this anywhere near the mechanical bits of your bike, especially bearings. So make sure you clean your fork completely before you put it back together and get it in the bike. If you're gonna blow this stuff on the floor, make sure you sweep it up and get it out of there. You don't want this stuff anywhere near the moving parts where it can interfere with that. Okay, so the fork steerer tube is now trimmed down. So the next thing is to reinstall the crown race. Now, as you noticed earlier on, this one has a split race, which means I have the luxury of literally sliding this on, pushing it in place. Doesn't need seating. However, if yours does need seating, then there's a couple of options open to you really. Now, the bodging version is to use a punch or a screwdriver to tap it into place. But really, you don't wanna be doing this unless you specifically know what you're doing because you can damage the surfaces that the bearing sits on. It won't sit flush. That means you'll get tight spots in the headset. Of course, the bearing will wear. It's not a good scenario. Now, the correct method is by using a crown race setting tool. Basically, a big, hard, toughened tube. You get different alloy inserts. They would sit over the actual race itself and you basically pick the one that sits the neatest on there. Slide this into position and then you would strike it with a mallet to actually set it completely straight. But of course, in this case, I don't need to do it. So, you're nearly ready to put your fork back in the bike but the last thing you need is to install one of these little fellas. So, this is a star fangled nut. And basically, it sits inside that steerer tube and it has a thread on the inside there for an M5 bolt. And the reason for that is your top cap with that bolt screw into that and they basically pull everything together so everything is aligned and taught with the bearing so the bearings are held. They're preloaded. There's no movement. Everything works correctly. So, this has to go to predetermined depth. Now, there's really a couple of ways of doing this. There is the bodge way of doing it which would be using an M5 bolt. I wouldn't recommend using the one that you're actually using for your bike. Use a spare one. And you're gonna have to hammer this into place. Now, you can do this but there's no guarantee that A, you're gonna get it to the correct depth or B, you're gonna get it in straight. So, that is, if you're comfortable with just using a mallet and not using the correct tool, you can do it. However, there are dedicated tools for actually setting this to the correct depth. There's a couple of options available. So, the older tool is like this one. You literally screw the star-fangled nut onto it. You line it up with the fork and you hammer it in with a mallet. The other option is one of these. Slightly more advanced version of that. The same thing. You screw the nut on. You align it over the steerer tube. Slide that down and then hit that home and again, it's the correct depth to set it inside. Okay, so now with the star-fangled nut installed into the steerer tube and the crown race in place there, I'm good to put the bike back together again. Now, although you don't need to have grease in there to actually lubricate the bearings as such, it makes a really good barrier against water getting in there. So, I do recommend putting some grease onto the actual crown race itself and then just around the cup on the inside of the frame here just where the bearing will sit. So, the seal and the lower race now. Gonna sit them straight onto here. Then taking care to make sure the cables are orientated correctly, just gonna put the steerer tube back into the head tube there slide it into place, locate that bearing at the bottom there and then put the headset back into the same place as it was before. So, firstly that bearing goes into place. Again, I'm just gonna put a smidge more grease just around the top there just to act as a waterproof barrier and then just make sure your steerer tube is fairly clean there and you're ready to start putting the other bits of the headset in. So, that split compression ring slides into place there. That's to make sure that the steerer tube can be pulled up nice and taut against those bearings and you've got that seal that sits in there. Make sure that's been given a wipe actually. Seal sits into place nicely there. That's the top cap of the actual headset goes on. Then there are my stem spacers and then it's a case of running that all the way back in again. Now, I've got my nice little gap at the top there. Just need to put the stem cap back on and then nip this up. I'm not gonna preload it too tight just yet. I just wanna make sure it's all on in the right place. Let's just make sure everything feels right and then it's time to get the brake back on. Now, something I definitely recommend doing, putting some fresh thread lock on those bolts. Okay, so there we go. It's successfully fitted the fork to the bike. The very last thing you need to do before doing a safety check is just make sure your headset bearings are preloaded properly. So, with the stem clamp bolts, that's the ones that hold the stem to the steerer tube. With those loose so you can turn the bars, line up your stem so it's in line with your front wheel. Good way of doing this is by standing over the front wheel and holding it between your legs. You get that nice line of sight lining up your top tube with the wheel and the stem and then tighten this bolt. You don't wanna be over-tightening this. This is literally until there's no movement but the handlebars can still move freely. As soon as there's any friction there, you've gone too far and you can actually damage the bearings. So, with that nice and snug now, just gonna tighten up my stem clamp bolts. Everything is in place. We're good. The wheel is safe. The front brake is safe. That means we're basically good to go and ride the trails. The last remaining thing would be to set the fork up and we're actually gonna look at that in the next essentials series on GMBN Tech. So, there we go. We successfully swapped a fork, trimmed it down and reinstalled it with a new one onto a bike. So, hopefully that's been a useful video for you. It's a really fun upgrade to do and definitely does improve the handling of your bike if you're gonna get a better fork on there. For a couple more great videos, click down here for our essentials playlist. So, that is all the basic stuff but it's really essential for everyone to know that stuff. And if you've got press fit bottom bracket issues, click down here. That is everything you need to know about maintaining it and making sure they don't creak. As always, click on the round globe to subscribe to GMBN Tech. We love having you here. Make sure you tell everyone about us too. If you like looking after your bike, give us a thumbs up.