On another thread, there was a question on how a tire can be changed so fast, and if you need special tools. However, I believe it is more technique than tools, so I sat down and wrote my procedures. In racing, you have to be able to make tire changes quickly, especially in the ISDE events, as minutes can mean penalty points. Here are my thoughts:
All you need is 3 big tire irons, a 14 inch car wheel (I use one from a 1967 Chevy I used to have), and soapy water or WD-40. Once you have the wheel off the bike, here is the process:
1. Place the car wheel on the bench, with the deepest side facing up.
2. Place the MX wheel on the car wheel. Since it is only 14 inches, it supports the spokes just inside the aluminum rim. Make sure you put the sprocket side down, as you don?t want any skinned knuckles.
3. Pull the valve core and let the air out of the tube.
4. Take the nut off the tube, and push it in a little just in case it has gotten crusty.
5. Loosen the nut on the rim lock, but leave it on the shaft, just at the end. Some folks take it off, but I?ve never found it unnecessary.
6. You now need to break the bead. Depending upon how long the tire has been in place, it may be a little tough. Use the flat end of the tire iron between the tire bead and the rim to push the bead into the rim trough. If it won?t budge (which is often the case), use a rubber mallet to get it started. Break the bead all the way around so the bead will drop into the rim trough during removal.
7. Start straight across from the rim lock and put all 3 tire irons in place and ready to pull on the bead using the curved end to hook the bead. Place them about 2 inches apart. While pulling on the center tire iron, push the rim lock into the tire with the other hand by pushing on the stud as the bead crests the edge of the rim. This is the toughest part, as you need the bead to drop into the trough at its most distant point from the iron, at the rim lock. If the tire is really stubborn, and will not move on the rim to drop into the trough, use a little soapy water to help the bead move into the trough.
8. Once the center tire iron has been pulled up by the rotor, grab one of the other irons with your free hand, and pull it to the rotor while holding the center iron close to the rotor. Hold both of these at the rotor, and pull the third tire iron into the same position as the other two. You now have about five inches of the bead off the rim, and you can easily remove the center tire iron. Leave the other two in place, as they will come out easily later.
9. Using the rubber mallet, gently hit the tire on the sidewall to help the bead drop into the trough. Place the free tire iron you just removed about two inches from one of the other tire irons (stay with the curved end for the duration of removal), and pull it to the rotor. Maker sure you use the free hand to hold the other two irons at the rotor, or they will pop back and hit you in the jaw, causing great frustration and pain. You will notice that another iron (the one in the middle) has now popped free, as there is no longer any pressure from the bead. In some cases, it sneaks under the bead too far, and you have to wiggle it free, but don?t require a lot of effort.
10. Take the free iron and place it about two inches from the iron still in its original position, and pull it to the rotor. Repeat this process a couple more times, and the bead will be completely on top of the rim. Should take about 30 seconds.
11. At this point, if you are just replacing the tube, the process is different from that used to replace both tire and tube.
Tube replacement only:
1. While lifting the bead away from the rim with your fingers at the valve stem, push the stem through the rim hole (not very easy, but you?ll get better with practice), pull the old tube out (a friend can be of great use at this time). If you are replacing with a heavy duty tube, it?s almost easier to take the tire off the rim and follow those directions, but it is possible with only one bead broken loose, just more difficult.
2. If you have any baby powder, pull the rim away from the bead with your fingers, and squirt some into the tire. Roll the tire around on the ground a few times to move the powder around inside the tire, and then put it back in place on the bench.
3. Take the new tube at the valve, and put this section of the tube into the tire with the stem in about the right spot to go through the hole. You will need to work the stem into the hole far enough to put on the nut a few turns. On tires with short sidewalls, it?s tough, but be patient.
4. With the stem through the hole, and the nut on a few turns, begin to put the remainder of the tube into the tire, moving into the direction of the rim lock. Since the tube goes on top of the rim lock, you want this section of the tube in place before you finish putting the entire tube into the tire. Be careful that the tube does not fall under the edge of the rim lock. This is not uncommon with standard tubes, as will result in a pinched tube during assembly.
5. Continue around the tire until the entire tube is in the tire.
6. With your fingers, screw the nut onto the stem far enough to allow you to put air into the tube. This step is critical, and often ignored, which results in punctured tubes.
7. With the stem sticking out of the rim, put air in the tube. Inflate the tube quite a bit, as this will eliminate any wrinkles and twists, and gets the tube to lie inside the tire properly. Remove the valve core, and let all of the air out of the tube. Leave the core out for now.
8. Lubricate the bead with either WD-40 or better yet, soapy water. Don?t use too much, as you don?t want to turn your baby powder to paste. You just need enough to help the bead slide in place.
9. Start at the rim lock, and push it up into the tire by pressing on the stud. Here is why I leave the nut on a little, as you don?t want to push the rim lock so far into the tire that you will have to fish it out again. The nut stops it from going into the tire, but allows it to go in far enough to clear the bead.
10. While holding the rim lock inside the tire, take the curved end of a tire iron (never use the straight end while installing a tire), and put that section of bead on the rim. The idea here is to get the bead started down into the trough right at the rim lock. Also, just hook the rim; don?t go inside the tire with the iron, as you may catch the tube.
11. Continue around the rim, working from one side of the rim lock to the other side while continuing to press the bead into the rim trough, and periodically pushing the rim lock up into the tire. The idea here is to have the last section of the tire to be popped in place be directly across from the rim lock. Remember, you?re trying to make sure the bead drops into the trough as you put more of the bead under the edge of the rim. If the bead does not go into the trough all of the way, you might actually break the cable inside the bead. Sound impossible? I?ve seen it done. Ruined a brand new tire! Also, use all three irons. After you begin, you will always have two irons in the tire, with the free one being used to put in the next section of bead, which frees an iron previously used. Just keep trading off with the iron that?s freed with your latest action.
12. The last 7 inches are the most difficult, but just take small bites with the iron, and you?ll be fine. Continue to make sure the entire bead has dropped into the trough. You can use a rubber mallet on the sidewall, as well as on the last 4 inches or so, and it will pop right into place.
13. Now grab the air hose. Put about 35 pounds of air into the tube. Three things are going to happen. First, you will seat the bead. Second, you will push the rim lock against the bead on the inside of the tire. Third, you will push the tube stem all the way out of the rim.
14. If the bead did not seat, release the air, relube the bead, and put in 35 pounds. Since you did not break the bead on the other side, it should have remained in place.
15. Once the bead is seated, and with the air still in the tube, tighten the rim lock and stem nut. If you let the air out before you tighten the rim lock, you risk pinching the tube, so leave the air in for now.
16. Once both nuts are tight, set the air pressure in front at 15 ?, and the rear at 14 ?. After practice, this will take just over a minute.
Taking the tire off the rim
1. If you are at this section, you have decided to take the tire off of the rim. Really not a tough job if done right.
2. First things first. Leave the tube in the tire. No reason to take it out, as it will come off with the tire.
3. I will assume you have the rotor side of the tire off, and the bead is over the edge of the rim, and the tube stem has been pushed into the tire cavity.
4. Flip the whole assembly over, and grab the rubber mallet. Gently hit the sidewall, and the bead on the sprocket side will come loose, and drop to the center of the rim. If you have a heavy duty tube, you will need to push on the tire to get the tube to pop over the edge of the rim on the rotor side.
5. There are two ways to remove the tire, either with the tire standing up or laying on the rim. It?s easier if you stand the tire up between your legs, and grab the tire irons. Lube the bead on the inside of the tire. Using either end, stuff the irons under the bead (about 2 inches apart) that is still on the rim, from the sprocket side. Make sure your irons are 180 degrees from the rim lock, or you will be working too hard. The idea here is to reach in under the bead, and hook the rim with the center tire iron. Pull on the iron as if you are trying to wrench the tire off in one move. Hold it in place, and grab one of the other irons and pull into the same position as the first iron. Hold the two in place, and pull on the third iron. If you have lubed the bead properly, the tire is going to pop off the rim. Might have to take one more bite, but about 7 inches usually does the trick.
Putting the tire back on with the tube in place.
1. Well, at this point, you?ve got the tire off the rim, and are ready to install a new tire, or the old tire with a new tube. With the superior instructions received here on greatest forum, you?re only about 2 minutes into the tire change, so have lots of time before the last commercial break is over on your favorite TV show.
2. Put your now tireless wheel on the car rim, sprocket side down. Put the tube inside the tire (if it is a standard tube, air it up and let the pressure out. This will eliminate any wrinkles, and help the tube lay flat). I assume that you have put powder in the tire prior to inserting the tube, but if not, do so now, I?ll wait.
3. Place the tire/tube combination on the top of the rim. Slide the tire off the rim just over the valve stem hole in the rim. Grab the stem, and push it through the hole, and spin the nut on a couple of turns. (this method does not work unless your rim lock and air pressure stem are close to each other. Some bikes have the valve stem and rim lock 180 degrees apart, in which case you have to install the bottom tire bead first, and then the tube. Another option would be to relocate the stem closer to the rim lock)
4. Push the tire next to the rim, right at the rim lock, and push the stud on the rim lock so that the rim lock goes inside the tire. The object is to get the bottom bead to drop under the rim lock first thing, as getting the bead under the rim lock later does not work.
5. Using your irons, push the bottom bead in the rim trough, alternating from side to side, with the rim lock in the center. Let the top bead protrude over the edge of the rim so the tire carcass will flex. If you leave the top bead under the edge of the rim, you will be very unhappy as you try and put the last little section of the tire under the rim. Be careful not to pinch the tube if you are using a standard tube. If you have a heavy duty tube, it will stay in place right inside the tire.
6. The last little part of the bead will go on a little hard, so take your time, and take small bites. Once the bottom bead pops in place check the direction of the valve stem to see if it is at an angle. If it is, use the rubber mallet to hit the knobs of the tire while holding the spokes in place. Not hard, just enough to turn the tire slightly so the stem will line up straight.
7. If you?re using a heavy duty tube, push on the tire to pop the tube into the rim. You?ll know you are there when the inside of the top bead is lying on the rim. The beautiful thing about installing the tube in the tire first is that you don?t have to try and hold the bead up with one hand while trying to hit the stem hole in the rim with the other hand.
8. The installation of the top bead in next. Lubricate the bead with either WD-40 or better yet, soapy water. Don?t use too much, as you don?t want to turn your baby powder to paste. You just need enough to help the bead slide in place.
9. Start at the rim lock, and push it up into the tire by pressing on the stud. Here is why I leave the nut on a little, as you don?t want to push the rim lock so far into the tire that you will have to fish it out again. The nut stops it from going into the tire, but allows it to go in far enough to clear the bead.
10. While holding the rim lock inside the tire, take the curved end of a tire iron (never use the straight end while installing a tire), and put that section of bead on the rim. The idea here is to get the bead started down into the trough right at the rim lock. Also, just hook the rim; don?t go inside the tire with the iron, as you may catch the tube.
11. Continue around the rim, working from one side of the rim lock to the other side while continuing to press the bead into the rim trough, and periodically pushing the rim lock up into the tire. The idea here is to have the last section of the tire to be popped in place be directly across from the rim lock. Remember, you?re trying to make sure the bead drops into the trough as you put more of the bead under the edge of the rim. If the bead does not go into the trough all of the way, you might actually break the cable inside the bead. Sound impossible? I?ve seen it done. Ruined a brand new tire! Also, use all three irons. After you begin, you will always have two irons in the tire, with the free one being used to put in the next section of bead, which frees an iron previously used. Just keep trading off with the iron that?s freed with your latest action.
12. The last 7 inches are the most difficult, but just take small bites with the iron, and you?ll be fine. Continue to make sure the entire bead has dropped into the trough. You can use a rubber mallet on the sidewall, as well as on the last 4 inches or so, and it will pop right into place.
13. Now grab the air hose. Put about 35 pounds of air into the tube. Three things are going to happen. First, you will seat the bead. Second, you will push the rim lock against the bead on the inside of the tire. Third, you will push the tube stem all the way out of the rim.
14. If the bead did not seat, release the air, relube the bead, and put in 35 pounds. Since you did not break the bead on the other side, it should have remained in place.
15. Once the bead is seated, and with the air still in the tube, tighten the rim lock and stem nut. If you let the air out before you tighten the rim lock, you risk pinching the tube, so leave the air in for now.
16. Once both nuts are tight, set the air pressure in front at 15 ?, and the rear at 14 ?.
After practice, this will take just a few minutes.
