The one job I can't do despite reading this a hundred times
Changing tyres is about the most common of jobs when working on the modern motocross bike; it’s right up there with changing the air filter and dumping the oil, though actually changing the tyres is one of the trickiest of all jobs, it’s really hard to describe within the pages of a magazine how to physically do this – but if anyone can tell us it’s our resident tech guru Leeroy.
A good tyre changer can switch rubber in about five minutes though this takes a lot of experience; the best thing is to take your time as there’s nothing more infuriating then pinching a tube and having to do it all again, so to save your sanity make sure the wheel is clean and warm, believe me it’s way easier than changing these things cold, they’re really stiff then. So then, over to Leeroy.
First off try to get the wheel off the ground and at a good working height, it really saves your back when you’re scrambling around on the floor; also you need to get an old oil drum or a car wheel rim to get the sprocket or disc suspended, so you can work on the actual rim of the wheel as opposed to having the thing wobbling about when you’re trying to get a good purchase on the thing, after all even with the best technique it can be a physical job.
With the wheel ready to work on you need to remove the valve; just letting it down isn’t enough, there’s still too much air in there to remove the tube properly, also with the valve removed you can unscrew the valve stem retainer nut and loosen the rim lock nuts – don’t take the rim lock nuts off the rim locks completely, just have them at the end of the thread, that way you don’t wreck the thread.
With the air out of the tube you can break the bead; it’s not too hard you need to lay the wheel on the floor and step on the sidewall of the tyre, once it’s dropped into the well of the rim (the lower section of the rim where the actual heads of the nipples sit) it will all go down easily. Then spray some penetrating oil into the inside of the tyre to give it some lubrication to come off a little easier.
Now with the wheel back at working height you can start to remove the tyre, with the rim lock furthest away from you, you have to leave the tyre to drop into the rim as much as possible and away from the rim lock or valve so you need to start near the rim lock and the valve, push the tyre downwards into the well nearest your body then put a couple of tyre levers under the rim of the tyre and lever them up, only taking small ‘bites’ though.
Then as soon as you start to get round the rim it starts to get a little easier so you can take bigger bites, do this all the way round until the one side is all the way off, now grab the valve and pull it out of the inside of the tyre.
Now you flip the wheel over and get a lever under the rim and pull the rim out from inside the tyre.
You may need to give the rim and the tube good clean as there’s always a bunch of crap on there, it’s amazing how dirty you get doing this job but don’t stress, you’re half way through it. The next job is to get some talcum powder and get the tube nicely covered in the white stuff, this really helps when putting the tyre back on as it lubricates and stops the tube from sticking in place inside the tyre causing problems. It’s way easier to put the tube inside a bin liner and throw a bunch of powder in there then give it a good shake up.
You also need to give the actual tyre a good coating internally, so throw some in there and spin the tyre about to get a good even coating inside; now making sure the tyre is nice and warm and it’s ready to go on.
Now opposite to actually taking the tyre off, or in fact the last stage of replacing the thing, you need to start with the rim lock to make sure it’s all in place properly; so with the nut all the way on the end of the thread to give yourself the most amount to play with push the tyre down over the rim lock and into the bead, you won’t get it all the way in as the rim lock thread will stop it, but start to work getting the one bead over the rim, it’s easier to work from one side as opposed to both sides of the rim lock, if you get my drift, it actually goes on pretty easily and you can often do this without any levers though sometimes it helps. Now with the bead over one side of the rim you can re-fit the tube, starting with the valve, I know it’s a bastard getting your hands in there but this really is about the hardest part of the job; get the threaded part of the valve in the hole then put the thin nut on the valve, just enough to get the air chuck on when you’re done.
With the tube all nice and tucked in place you can start to get the last part of the tyre on the rim, starting with the rim lock and valve furthest away you get the levers in; start with the levers a couple of inches apart holding the tyre down as you go, Motionpro make a bead buddy tool which locks in place over the spokes and stops you chasing the bead round-though this is a great help don’t stress as you can do it without, its just a bit trickier.
The trick here is to make sure the bead of the tyre is always in the well of the rim, this is essential to getting the last part over the rim, it simply won’t go over without you doing this so be vigilant in this part of the job; so making sure it’s all the way down (this is why you leave the rim lock till last) you can work your way round levering the tyre over and in place in nice little ‘bites’. As you get to the last section where the rim lock is you must be really careful not to pinch the rim when you’re on this last part of the tyre, also make sure you push the rim lock inside the tyre to make sure the bead isn’t sitting on it. Providing you keep the bead inside the well of the rim it will go over easily, if it’s a struggle you have to go back and make sure that it’s in as deep as it will go.
Now put the valve core back into the valve stem and blow the tyre up, popping it back on the bead; you really shouldn’t go over about 50psi to do this, after all you have all that talc in there to help it go on nicely. If there’s a section that won’t come up you need to deflate the tyre, break the bead again then re-inflate the tyre until it’s all out on the rim properly – it can make a hell of a ‘popping’ noise but that is perfectly normal.
Then all that left to do is to refill the tyre with the correct pressure; between 12 and 15psi depending on the conditions of the track, then the final job is to tighten down the rim lock, not crazy tight but just nice and snug.