Sunday, December 19, 2021


The Art of the Seal

(…or How to set up tubeless wheels so they actually hold air!)

Setting up your wheels as tubeless can be a hit or miss proposition many times. The process is pretty straight forward, but there are a few things that can go wrong and inevitably do, leaving you with tires that don’t hold air overnight or even for the duration of your ride. We’ve outlined the process below and discussed some of the issues you might encounter. Using the correct combination of rim, tubeless tape, sealant, valve and tires can greatly reduce any issues but finding that perfect combination can take a lot of research and trial and error. We’ve designed the new Module tubeless tapes to adhere to your rim bed better and seal the rim faster than other tapes, but you may still experience some air loss if everything is not perfect!

  1. Clean your rims
  2. Tape your rims
  3. Insert the valve
  4. Seat the bead
  5. Add sealant to the tire
  6. Inflate the tire
  7. Check for air loss

Measure your rims and choose the correct width tape for your rim bed: Consult the rim manufacturer for specified width or measure with calipers or tape from side to side where the rim bed meets the sidewall. If the rim bed is fairly flat you can go with a tape which is close to being exactly the same width. If your rim has a deep channel, we recommend that you step up to the next width of tape to allow for the tape to settle in the channel. Many people use duct tape instead of tubeless specific tape. Duct tape does seal the rim, but can cause a real mess if you need to remove it at some point, which is almost always the case. For that reason, we highly recommend that you don’t use duct tape to seal your rims!

Clean your rims: This is especially important if your wheels were previously set up for tubeless. Remove any old tape material and/or dried sealant as well as possible, paying close attention to the sidewall area. Dry out or remove any liquid sealant with an air compressor nozzle or towel as needed. Wipe the rim down with 99% isopropyl alcohol to prep for tape. If the rims were previously taped with Gorilla Tape or some other duct tape, you may have to spend more time removing the gummy rubber adhesive and stuck tape material.

Tape the rim: The starting point for tubeless tape can be an emotional subject as some people like to start at the rim so that you have at least a double layer of tape over the valve hole while others insist you should start at the opposite side of the valve hole to decrease weight in that area. I’ve seen multiple videos that state you should start at one point or the other but nobody ever says WHY you should start there! I’ve done both but prefer to start at the valve hole, or actually, about 2”-3” to the opposite side so you have about 4”-6” of tape overlap. Either way, make sure to pull the tape tightly but not stretching it too much as you apply it. It’s always best to work with adhesive products such as rim tape in warmer temperatures. If your wheel is cold because it’s been sitting in the garage, leave it inside for a couple hours to warm up. If you don’t have a couple hours, you can warm the rim with a heat gun or hair dryer, and at the very least, warm the starting point of the tape so it adheres well. If you are applying our Purple Tubeless Tape System, apply the red tape first and then apply the blue tape over top. Try and make sure not to create any major air bubbles and if you do, just peel the section back and start again. I do start the second layer of tape opposite of the valve hole and overlap about 4”-6” as you did with the first layer. Use a clean towel and work your way around the rim pressing the tape into the curves of the rim bed. 

Insert the valve: Use an awl or a small Philips screw driver to poke a hole through the tape. If the tape is transparent, you can do this from the outside of the rim bed, but if the tape is not, poke it from the spoke side creating a small hole. Before inserting a valve, try and make sure that you have a good fit between the rubber seal on the valve and the rim bed. This can be a source of problems if it causes the valve not to sit cleanly in the rim bed. Once you have identified the best valve base shape and selected a valve, insert the valve carefully or screw into the tape so as not to accidentally tear the tape. Put the rubber grommet on the valve stem and screw the knurled nut on until it’s hand tight. Make sure not to over tighten or use tools!

Seat the bead: Do this BEFORE adding sealant! First, visually inspect the bead to make sure it’s not sitting too far in the middle of the rim. Also, make sure that the beads are on opposite sides of the valve! Next, place a presta adaptor on the valve and blast some air from the compressor into the tire. Usually, this will do the trick to seat the beads on the rim but in some cases it won’t work. If the tire is filling with air, wait until the bead makes a loud pop (usually it will make two or three pops) as it seats on the rim. Continue to inflate the tire to about 40psi. If the beads don’t seat and the tire is not holding air, then take the following steps: remove the valve stem and change out the Schrader tire filler fitting (also called a “ball chuck”) on the compressor hose to a standard air nozzle. Fit the end of the air nozzle into the open end of the presta valve and give it a blast until the tire starts to fill and the beads seat onto the rim. This will work a majority of the time. If you are attempting this with a pump, make sure you have a good high volume pump and a six pack of good beer on hand since it may take you a while!!

Add sealant to the tire: Now that you’ve done all this work to seat the beads of the tire, remove the valve stem core again and let all the air out, or if you previously removed it, then just leave it out. No. I’m not kidding! Now that the beads are seated they will stay that way! Some might argue that you should add the sealant directly into the tire BEFORE seating the beads, but I personally prefer to inject it into the valve stem with a syringe and have never had issues with this! PLUS, this method will also prevent a messy and embarrassing accidental sealant explosion if the bead fails to catch the rim when inflating the tire!! Add the amount of sealant recommended by the sealant manufacturer by injecting into the valve stem with syringe. Replace valve stem core and tighten. Inflate tire.

Inflate the tire and check for leaks: Inflate the tire to no more than the maximum recommended air pressure listed on the side of the tire. Check the air pressure in about 10-15 minutes to make sure the tire is holding air. If the tire has lost air, which can be typical unfortunately, you’ll need to locate where it’s leaking. Sometimes it’s obvious and you may see the sealant bubbles, or hear the air coming out. But sometimes it’s not obvious. If it’s a slow leak just air up the tire a few times and try to get the sealant to seal the leak. This works a majority of the time. If the tire is still losing air, fill up a bathtub or large tub with water and submerse the tire and wheel in the water. You will see bubbles where the air is leaking. Most times, this will be at the valve, and it’s just a matter of tightening the valve stem nut, turning the valve a bit in the rim to seat better, or waiting for the sealant to do it’s job. If air is leaking through a spoke hole then it may be coming from a opening in the rim tape or leaking through from the valve. The best fix for this is to let tire sit over several hours and adding air when it starts getting too low. At some point the sealant should do it’s job to seal the leak and this can sometimes take minutes, sometimes hours, and sometimes more! If your tires are bleeding down very slowly, sometimes a good ride will do the trick to help distribute the sealant throughout the tire. It’s important to understand where the air is going though since you could damage your rim by adding too much air if that air is pressurizing the inside of your rims. This happens when there is a leak in the seal of the rim, either in the tape, or through the valve stem. If your tire is not reaching the desired pressure and you don’t see air bubbles when testing for leaks in water, this could be the case. In this case you should relieve the pressure in the rim by loosening the valve stem nut and then try and stop the internal leak to the rim. WARNING: not taking this precaution could lead to a damaged rim!

That’s it – GO RIDE! Now that you’ve successfully setup your tubeless wheels, go ride! Don’t forget to check your air pressure before each ride and inflate to the desired pressure for optimal traction and cornering performance. If your tires go completely or almost flat overnight, then your rims have not sealed correctly and you may have to pull everything apart and start over if the tricks above or adding extra sealant don’t work.

Visit our website at WWW.MODULEBIKE.COM to see all the Module bike products! 

About the author: Kenny Roberts is the owner of Module and has worked in the Bike Industry for over 25 years with many companies including DT Swiss, Intense, Syntace and Cush Core among others. Kenny was at the forefront of working with tubeless technology at DT Swiss as early as 2004. 

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  The Art of the Seal (…or How to set up tubeless wheels so they actually hold air!) Setting up your wheels as tubeless can be a hit or ...