Tech Tips - Changing a CushCore Tire Insert

CushCore was designed to improve the ride feel of modern higher volume tires by taking up volume inside the tire and removing the bouncy ride quality, much like a volume spacer inside a fork. They also have the added benefit of being dense enough to ward off rim dents from rock impacts and thanks to the snug fit around the rim, they can also can help lock your tire onto the rim, preventing air burping out under hard cornering or other trail events. Fitting and removing CushCore or any other tire insert is one of those tasks that people tend to dread, unnecessarily so, in our opinion. Being able to remove your tire on-trail to repair a puncture is vitally important, especially if you find yourself off the beaten track. However, with the right tools and more importantly the right technique, CushCore can be relatively easy to fit and remove. It's all in the thumbs! We would also recommend checking out the official CushCore installation video below: https://www.youtube.com/watch?v=_8oz7YIk0gg We'll go through removing the CushCore first, and then re-fitting, since we had a wheel with a CushCore already installed, but obviously removal and fitting and completely independent of one another.

Removing the CushCore

Step 1:

Remove air. Simply unthread your valve and let the air out just as you would with any other tire. 

Step 2:

Grab a tire lever - something solid and sturdy is best. We really like the Pedros tire levers because they're super strong and have a nice hook to them, the CushCore Bead Dropper also works great. Metal tire levers work if you're really struggling but they're best avoided if possible so as to avoid damaging your rims. 

Step 3:

Grab a garbage can - round is best but square will do. If you're trailside you're unlikely to have a garbage can to hand, so just put the wheel on the grouns - you just need something to put your weight on. 

Step 4:

Break the bead. The is the most important step, and is where most people go wrong. Holding one edge of the rim down with your knee, grab your tire lever, and push the tire down where it meets the rim on the opposite side of the wheel to your knee so that it unseats and drops into the center of the rim. Chase the tire all the way around the rim so that the tire is fully unseated all the way around. Incidentally this is also good practice on any tubeless tire, insert or not, and is the reason many people struggle to change tires. 

Step 5:

Now the bead is fully unseated all the way around the tire, you can use the hook on the tire lever to remove the tire, just as you would a normal tire. Pop one edge of the tire off, then work your way around. If you're struggling it's worth checking that the bead is definitely fully unseated all the way around, or you can use two tire levers at the same time if you just have a really tricky tire. Once enough of the tire is off, you should be able to just run the lever around the edge of the tire and it'll simply peel off the rim. 

Step 6:

Pull the CushCore out. You should be able to reach inside the tire at this point, grab the CushCore and pull it out. It might be a little tight but manageable. Once the CushCore is out the tire should come off like any other tire. You may want to use a rag to soak up any sealant inside the tire.

 Here we can see the CushCore has saved the rim and tire from a number of impacts

 

Fitting the CushCore

Step 1:

Fit the special CushCore valve to the rim. CushCore needs a different valve because the insert will cover the valve opening inside the tire on a regular presta valve, meaning it's impossible to check your tire pressure or deflate the tire without removing the valve core and sticking a long 2mm allen key down there. The official CushCore valves get around this by being drilled through the sides so the insert cannot plug the holes. 

Step 2:

Let's pretend we're fitting a brand new CushCore. Because they're quite a tight fit, it's a good idea to stretch the CushCore out to help it fit onto the rim. Put your foot inside and hold it down while pulling up as hard as possible to stretch it out. Don't worry, it's not going to break. 

Step 3:

Fit the CushCore around the rim first - the center of the CushCore should fit inside the well in the rim. If it's really tough to get on, you may need to stretch it out a little more. I use a technique much like mounting a tire - place it around most of the rim then I roll the last little bit on with my thumbs. 

Step 4:

Fit the tire over the CushCore - it doesn't need to be on the rim at this point, just over the CushCore. Sometimes it can be useful to use a long tire lever or similar to lever the last bit of tire over the CushCore. Pay attention to the rotation direction here - you don't want to fit the tire backwards and have to correct it later. 

Step 5:

Now we can start fitting the tire to the rim. With the wheel on your garbage can or the ground, starting at the valve use your thumbs to roll the tire over the rim and under the CushCore to seat nicely on the rim. Work your way as far around the rim as you can before it becomes too tough. Don't forget to line your tire logo up with the valve for extra mechanic points. 

Step 6:

Here's the important part, to make it easier to get that last bit of tire on grab your tire lever and push down on the parts of the tire you already fitted over the rim. Push down on the tire right next to the rim to unseat it and push it down into the center of the rim and work your way all the way around. 

Step 7:

There should now be enough slack in the tire to fit the last bit of the tire over the rim. This is often do-able by hand but depending on your tire/rim combo you may need to use a tire lever, being careful not to pierce the rim tape. This is much the same as fitting any other tire, though a little tighter. 

Step 8:

Once you've gotten the one side of the tire fitted, flip the wheel over and get started on the other side using the same process. 

Step 9:

Now the tire is fully fitted, it's time to inflate it. It's a good idea to do this to fully seat the tire before injecting sealant just to avoid making a mess. The tire should in theory fully seal without the use of sealant, so during this step we can make sure the rim tape isn't punctured anywhere, that the valve is tight etc. before adding sealant. The tire should fully seat all the way around, and thanks to the CushCore helping to push the tire onto the rim, this is usually achievable without a compressor, one benefit of CushCore to the home mechanic. 

Step 10:

Time to add sealant - deflate the tire and remove the valve core. Use either a sealant injector - here we're using the Stan's injector. We also use a two ounce sealant bottle - it's cheap and simple. I use the same amount of sealant as if I weren't using an insert - about 4oz per tire. 

Step 11:

Reinstall the valve core and reinflate the tire. Give it a spin to ensure the sealant fully coats the tire and if the air stays inside, then you're done. Congratulate yourself, refit the wheel to your bike and go ride!