Tubeless Conversion for a WTB Rim with a Drop Channel

Proof of concept devised, tested, and documented by Travis (aka illcomm33 on MTBR.com). You can read the MTBR.com forum discussion on WTB drop channel rims, for which Travis created the following how to...

Travis also created video demonstrations for us!

watch Part 1 (Steps 1-6)

watch Part 2 (Steps 7-10)

Step 1 - Gather a Few Needed Items

• Heavy Duty Caffélatex Conversion Kit

• WTB Rim (WTB LaserDisc Trail 29er used)

• Weather Seal Gray 3/8 inch wide X 3/16 inch thick X 17’ roll ($2.50 at Lowe’s)

• Rubbing alcohol (blue spray bottle)

• 12mm Stan’s Yellow Tape

Step 2 - Prepare the Wheel

Prepare the wheel, removing the original rim-tape and cleaning the rim-bed with alcohol and a rag. A touch of sand paper is a good idea if there are any sharp burrs at the spoke-holes. Dry the rim-bed with a paper towel or micro fiber towel.

Step 3 - Apply Stan’s 12 MM Yellow Tape

To install Stan’s 12mm Yellow Tape, start 2 inches (5 cm) from the valve hole.  Wrap two complete times around the wheel and stop 2 inches (5 cm) after the valve hole. As Stan notes on his install video (notubes.com) the tape is flexible and won’t necessarily tear so pull it down while pulling hard on it.

Step 4 - Apply Foam Weather Seal

Lightly pull the Weather Seal 3/8 inch wide X 3/16 foam  around the rim.  Do not remove the white paper backing at this point.  I had success starting halfway around the rim directly ACROSS from the valve hole.

Note: It may not matter where you start the Weather Seal. I chose my starting location directly across from the valve hole so that there would be a complete circle of foam coving the valve hole.

Step 5: Install Caffé Tape

Spray rubbing alcohol onto a clean cloth and carefully re-clean the inside of the rim area, especially on the shoulder of the rectangular drop channel (where the caffelatex tape will adhere); this is very important. This will remove any oil residue left from the previous 2 steps. Now proceed with installing the Caffé tape as outlined below.

First, remove the white paper backing of the Weather Seal.  Be careful to avoiding touching the inside of the rim surface.

Using the red Caffélatex tape, start 2 inches (5 cm) from the valve hole and stop 2 inches (5 cm) after the valve hole. This will result in 4 inches (10 cm) overlap.  The Caffélatex tape only needs to be wrapped one time around the rim. The tape is flexible but won't stretch, so put it down while pulling hard on it to avoid wrinkles or air bubbles. If the tape doesn't stick well, stop and clean the rim with a paper towel or micro fiber towel. The tape has a good adhesive base; if it doesn't stick there's something wrong with the rim surface.

Make a round hole using a small screwdriver.  The smaller the puncture created for the valve hole, the easier it will be to ensure an air-tight seal when installing the valve.

Step 6 - Use Tube for Perfect Tape Adhesion

This step is often optional; however with a WTB rim, this step is very important for a sucessful tubeless setup. DO NOT SKIP THIS!

To ensure perfect tape adhesion and easier tire inflation, mount a tire with an inner-tube on the wheel and keep it at 50-60 psi for several hours. I let my wheels sit for 20 hours. Then, remove the tube.

Note: The images below were taken after the wheel sat with the tube for 20 hours. As you can see there was little adhesion of the tape to the actual weatherseal but the shoulder connection is tight.

Step 7 - Insert the Valve

As stated in Step 5, the smaller the puncture for the valve hole, more likely the tire will be air tight. Make sure the rubber valve base is pressed firmly against the tape. Thread the lock nut onto the valve and secure it against the rim.

Note: I used a Mavic O-Ring that comes with the UST valve on the outside of the rim, underneath the lock nut (you should be able to get a small o-ring at any home improvement store). This stopped the few air bubbles coming from the valve.

Step 8 – Mount the Tire

You will need a compressor and soapy water to mount the tire. Inflate the tire just to be sure the tire will hold pressure. This can be very easy to very difficult depending on the tire brand, model, and materials.

A liberal use of soapy water and a good compressor can do wonders with inflating the tire; using the soapy water on the rims and beads rims and beads can lower friction and reduce the force needed to push the tire over the edge. Next, deflate the tire and remove the valve core from the valve using the valve key supplied in the Conversion Kit.

Step 9 - Inject Caffélatex

Add the sealant! I used the Caffélatex injector to measure out the sealant and then injected it through the valve.

I didn't use any adapter on the injector tube, it's faster without one. If you chose to leave the valve core in, then the adpater will be necessary.

Step 10 - Inflate, Shake, and Roll

Insert the valve core back into the valve. Inflate, shake, and roll: it's done. Caffélatex will seal any porous areas in tire casing or the bead.  Use soapy water on any area that needs sealing. Shake, flip, let the wheel rest (on a bucket) and repeat if necessary.

Note: The tire pictured is a Maxxis Igniter 29 X 2.1, which is a non-UST, TNT, TLR, or 2bliss tire. This is probably the main reason this seeping occurred. The tire was used for test purposes only and is being replaced by a 2Bliss style model as suggested in the Effetto Mariposa instruction manual.

You will need to adjust the pressure a couple of times (depending on how porous the tire is). Then the system will stabilize and you'll be ready to go!

Troubleshooting

• Caffélatex Around the Eyelets - A few eyelets showed moisture (Caffélatex) right after the conversion. I am assuming the liquid seeped underneath the valve stem. This cleared up within a day and the has not been an issue and both wheels have continued to hold air just fine.

• Weather Seal - Perhaps starting the Weather Seal right at the valve hole instead of covering it might allow the valve stem to seat lower in the channel and possibly prevent the moisture around the eyelets.  This approach would allow for the user to really press the tape against the actual rim cavity (around the valve hole) and may work better.