Installing The Most Challenging Insert - Cushcore eMTB
Unless you've had some experience (and a lot of experience is better) installing tubeless tires can be a colossal butt ache. Once you add an insert to the equation it can seem impossible. Even the first steps can have you cursing and spitting without a little guidance. All is not lost however and once you get to know the process, virtually anyone can do it.
Inserts make this task nastier because they fill up the bed inside of the rim, making it more difficult to push the tire bead into the inner channel of the rim during installation, an essential part of the process. It's also something extra to install and wrestle with.
What makes these particular noodles a little more difficult is their girth and volume. Cushcore's eMTB inserts extend out from the rim slightly more than Cushcore Pro meaning there is more to grapple with. But again, fear not brave rider! If I can do it, you can do it.
Knowing your sequence of actions in advance can be helpful, so you know what to do once you reach each milestone.
Most of these apply to any tubeless install but they are even more important on challenging combinations.
Gloves protect your hands but also allow you to apply more force and have better grip. I use riding gloves that are worn or have been taken out of regular service for any reason, but anything that isn't too thick will work. This makes a big difference when you are grappling your bead into place.
Patience is a Virgin*
Progress can be slow and tricky to notice, especially when you are pushing the bead from the end that is already seated toward the open end. It often feels like nothing is happening because the movement is small. Sticking with the plan, and performing certain actions several times, will get you over the line.
*points to anyone who knows where that quote is from
Having a clean and tidy work area is helpful. Or at least that's what I've heard since mine has been a disaster until recently On the rare occasions when things are sorted, every task goes more smoothly.
Using a garbage can as a stand to push against apparently makes the job much easier. I have a buddy who keeps one on hand just for this purpose. I don't do that because my shop is already overstuffed with crap but he tells me it works great.
Bead Dropper and Bead Bro
Cushcore's Bead Dropper tool is the most effective tire lever I've used and it doubles to do its primary function; dropping the bead into the rim channel to ease installation or removal. I keep two on hand but one is enough in most situations. Unfortunately they aren't practical to carry around with you on a ride for most people because of their large (dual purpose!) handle. Their other innovative tool is the Bead Bro. At the final stage of any tubeless install you will find a short section of tire bead that is reluctant to mount. It usually takes two hands on one side to get the force to get it into position, or maybe even a tire lever. Unfortunately, while you are working on one side, the other one often slips off. The Bead Bro locks the other end of the bead in place giving you a third hand. You can pick up both tools together for 30 USD and they are great even if you don't use inserts.
There are some specific bead lubes you can buy, but I find that tire sealant (particularly those that make some effort to be non toxic) works just fine. This can be used on the insert, to help place it on the rim and to help the tire slide over, and applied to both the tire bead and the inside of the sidewall of the rim for the final steps. If you don't wear gloves, you'll need to try to keep your hands clean because any sort of bead lube could compromise your grip.
Remove the existing tire (with or without insert)
The key to removing a tire is to break the bead all the way around the tire. The aforementioned Bead Dropper works great for this. I get the best results when I turn the tool backwards, so the hook is facing away from the rim. Starting across from the valve, and with the wheel on the floor or on a garbage can, push firmly into the edge of the bead with the tool. This may take a couple of tries if your bead is particularly locked with sealant. Keep moving around in the same area until it eventually drops or try a different spot if it's stubborn.
Once you have it off in one spot move away from that position in one direction and then the other, pushing the bead off a couple more times all the way around the rim. Or, if the tire isn't very tight, once you've broken 10 or 12 cm off you may already be able to slide the tool in under the bead and sweep the rest of the bead off. Otherwise drop the entire bead and you may even need to push it again into the channel of the rim for more slack. At this point it should come off easily using any decent tire levers.
I've heard it's helpful to leave your tire out in the sun to soften it up for 5 or 10 minutes but I was installing on a rainy day so that wasn't an option. Just opening it up from the folded position for as long as possible helps ease the tire into its final shape to help the install.
Inspect Valve and Rim Tape
Always have a careful look at your rim tape at this point, after cleaning off the old sealant and any other debris you find. There are few things more devastating to a home mechanic than to have installed and aired up your tire and added sealant, only to discover that your rim tape is shit. Make sure there are no bubbles, gaps, or tears and that the tape extends across the entire rim bed. If you have regular valves you'll want to either modify them or use CushCore valves, which allow air to flow horizontally. Most valves will be plugged by the insert because their port is in the bottom. I've had success by using a hacksaw and cutting a cross in the bottom of inserts with aluminum bases. I've also had moderate success with rubber-based valves, but the air flow is never perfect in those cases.
Also - valves can get so gummed up with sealant that they need to be tossed. Most can be saved but discovering this earlier is vastly better than once you've got everything back together.
Every Cushcore I have ever installed has benefitted from a stretch before you wrestle it over the rim. On subsequent installs this likely won't be the case but when they are new, you can't stretch them too much (as long as you don't break them?). I do this by pinning the bottom of the insert to the floor with my foot against a hammer and then pulling up with my arms and pushing with my legs. You can also extend your bent knees into the gap so the top end is over your thighs and then extend your legs gently. I do this several times in each position and then rotate five or six times. This makes life much easier.
Install the Cushcore
With Cushcore Pro or Trail or XC, it's possible to install the tire first, inflate to seat the beads, and then remove one side before pushing in the insert. I tried this with Cush eMTB but the size of the insert made that seem close to impossible so I went to the Cushcore first, tire second technique.
Cushcore eMTB has two recesses to give your valve some space, although I haven't noticed any issues without this in the past. This did came in handy installing it on a bike with Tyrewiz however.
After stretching, it's a bit like getting the first bead of a tire onto your rim, only you are just placing the insert into the bed of the rim so it is evenly positioned. As mentioned, I stand on a hammer with a rubber handle to pin the rim to the ground, once the bottom section is in place, so you can pull up on the insert to get it aligned. Work it from the bottom up, easing it into place. You might want to use a lever here but be careful not to damage the insert or the rim tape. It's not too hard to do it with your (gloved) hands though so I'd try to stick with that. With a little patience you'll get there.
It feels like you've been in the middle of a small explosion when this happens. Because you have.
Slip your Tire over your Cushcore
With my first wheel, which I installed beforehand as a trial, this went on pretty smoothly. I'm not sure what sort of magic I conjured but it just sort of slipped on. Maybe because it was a much warmer day? This time it took some massaging to make it happen but I got there eventually.
I also do this with the rim placed vertically facing me, after I have the bottom section installed. If the last section is sticky, I turn the wheel over and push the section that is in place down toward the last bit to gain some slack. It may feel like nothing is moving, but you'll be surprised how effective this is.
I think next time I might try to roll the pre-installed Cushcore part way off the rim, in one short section, to meet the tire and then push them on together.
Install the Tire
This is likely a task that many people list in the challenging column, but again, it's not that bad if you have a plan and you are patient. I wouldn't apply any bead lube yet because you want the first section of the tire bead to stay between the Cushcore and the rim.
I again perform this task with the wheel standing vertically, facing me and I usually sit on a chair.
This is the point where you should double check that you've got the tire going the right way and you've aligned the tires logos and lettering to your satisfaction. On the top of the wheel, you want the ramps on the knobs facing toward the front of the bike. Alternatively you can look for that one tiny embossed arrow.
Now that that's sorted, with the valve at the bottom and lettering aligned, start at the top of the tire with the side that is furthest from you. Push the tire away from you and down so the tire bead is below the rim and the Cushcore. Then, with two gloved hands on the tire and your finger tips along the bead, pull up towards you, raising the edge of the insert, and roll the bead underneath.
Then, ideally in the same motion, push that first section into the rim bed with both hands. This may take a couple of tries before it stays. Once the first section is in, move your hands a little further apart and repeat this process. Now is good time to apply the bead lube of your choice. After you have about 30cm (12") of bead in place, you can use both hands on one side at a time, alternating left and right, using the same technique. After the first section it will get easier. Until the last section that is.
Once I've got a long stretch in place on either side and it's starting to get tight, I lay the wheel on the ground and drop the entire bead that is in place. It's important to get the bead right into the rim's channel here. Once that's done, I stand the wheel up again and push the entire tire toward the unseated section. Sometimes it's best to push on both sides at the same time but other times it seems effective to alternate pressure side to side, keeping firm on the side that you aren't pushing on.
Go back to pushing the bead under the insert and into the rim with two hands per side at this point. Once you get stuck go back and press the tire toward the unseated section several times and push it in a little more until the last section will seat.
The second side follows the same procedure exactly but everything will be a little tighter and more challenging. You'll want to be even more diligent about dropping the bead on the last section, applying lube (after the first section is on) and pushing the tire toward the open section once things get tight.
For the last section, particularly on the second side, you've got some decisions to make. If you are impatient, and confident you won't damage your rim strip, you can use a tire lever to lift the last section into place. This was a terrible idea in the age of tubes, because they invariably pinched, but less so now. Cushcore's levers are great here as well because the ends are rounded and the edges aren't sharp. Don't try to lift a long section into place in one go. Instead push a little bit at a time until there's only a small section when you can put the lever in the middle and snap it all into place.
Towards the end, if one end slides off as you seat the other, Cushcore's Bead Bro is a nice third hand, locking that last section into place. If heard of people using toe straps for this purpose as well. Barring that, stick with pushing the tire toward the open section as many times as you need to. This is working even when it feels like it's not. If you are stuck, do it again. Repeat as many times as necessary.
Inflation and Seating
A proviso here is that I have twice blown tires off at this point while using a compressor. Once I destroyed a carbon rim (a very early ENVE) and shot the presta adapter into the ceiling drywall. Both times I was left temporarily deaf and in mild shock, and sealant was dotted all over me and my entire workshop. It feels like you've been in the middle of a small explosion when this happens. Because you have. Be careful if you are using a compressor.
Whatever you are using to seat the tire, the bead lube you used earlier will ease this process. Some people like to inflate until they've heard at least three pops. I find that tire models and brands, as well as rims, are all a little different, so I take it slow, hoping to prevent another explosion. And I wince every time I hear the tire announcing that it's slipping into place.
A couple of years ago I stumbled upon a very useful hack. The worst thing about presta valves is that the volume of airflow they permit is pitiful. One day I tried using my compressor's Schrader attachment on my presta valve once the core had been removed. Surprisingly, despite noting seeming to be in place to depress the valve, his works perfectly, and allows what seems like 5X the airflow. You'll be amazed by the difference this makes.
This will also work with floor pumps using their Schrader setting, although some tire and rim combos will still require a compressor or a dual stage floor pump. If you aren't sure if your tire has seated properly, hold it up in front of you and spin it to see if it wobbles or not. If it does you may want to wait a day and try the process again. Otherwise you can let the air out and give it another go. The tire will stretch a little every time you inflate it. Others swear by bouncing the inflated tire, banging it against the floor, or just massaging the tire into place.
Put Sealant into That Sucker
Until recently, I always poured sealant into the tire before I closed the final section. It works okay but it's messy. I've used some syringe systems but they always seem to gum up. Lately I've been using an old Avid bleed syringe and a section of medical tubing. It works great but it takes about 4 applications to get enough volume in there. If you have small bottles of sealant, and you cut the nozzle perfectly, you can squeeze them in directly, but I always end up with goo everywhere when I do it this way.
Whichever method you choose, I recommend positioning the valve at about 8 o'clock so gravity pulls the sealant away to create space for more. If you are going through the valve, it pays to create some negative pressure. I push the bottom of the tire into the floor and use my free forearm to apply pressure to the top, and then release as the sealant goes in, creating some helpful suction.
What if it's still Leaking?
If your tire still has a slow leak is, keep inflating the tire to pressure and leave it over night if possible. The bouncing and banging techniques can also be helpful here and you can try a little more sealant. I find that sometimes the whole system benefits from a ride; just make sure you bring a pump and only trust this if the leak is slow. If it's a big leak that you can't find, or you notice air coming out at the spoke holes or the valve, once it's been tightened with your hand, your problem is with the rim strip, and the bad news is that you're probably going to have to do it all again.
Is that it?
There are all sorts of combos of tires and rims and some work great, while others are nasty. I find Bontrager rims with their stock plastic rims strips are some of the worst. As far as tires go, heavier casings are worse than lighter ones. Asymmetrical rims are another curveball, particularly if they, like some recent WTB rims, have narrow and shallow channels.
The good news is this all gets easier with practice and eventually the process gets to be relatively stress-free and quick.
Andrew Major and I will both be riding these inserts and giving our verdict in the coming weeks.
Cushcore eMTB sells for 160 USD a set (with valves) or 80 USD each