-Originally posted in 2013-
A couple weeks ago Anand came in wanting his fat bike tires converted to tubeless. He wanted to lighten up his wheels and increase flat resistance. Neither his tires nor his rims are specifically made to be run tubeless (there aren't many rims that are, and even less tires that are) -- [edit, there are now]. I had some ideas of how I thought it should be done, but decided to look around the interwebz to see how others have done it. I found a couple of different ways people had done it, but none that I liked. They either didn't lighten the wheels at all, or we're nearly impossible to install (especially in your garage... and don't even *think* about doing it trail-side).
We're dealing with Surly Rolling Darryl rims and 45NRTH Hüsker Dü tires, for the record.
So here's what I did:
The first thing I needed to do was raise the bed of the rim so it would seal better against the bead of the tire. This is what makes inflating it possible. On most rims (Rolling Darryls included) the center of the rim in deeper than where the bead sits when it's inflated. This makes it easier to install the tire onto the rim, but makes it impossible to inflate without a tube because all the air rushes out of the tire between the bead and the rim.
I picked up some foam from the local hardware store that is intended to sit below a window sill or between a concrete foundation and the bottom of a wall frame. Basically what you need to know is that it's foam and it's about 3/16" thick.
I measured and cut (using a straight edge!) two different strips of the foam that were just long enough to go all the way around the rim and meet end-to-end, but not overlap.
For Rolling Darryl rims I cut the first foam strip 1-1/2" wide...
..and laid it in the center of the rim and secured the two ends together with a short strip of packing tape.
The second strip of foam was 2-1/4" wide.
Then I laid that one on top of the other, and secured the two ends like the first layer.
While I was at the store getting the foam, I picked up a roll of downspout tape. It feels just like electrical tape, but it's 2" wide. [edit, Whisky and lots of other have wide tubeless specific rim tape available now]
I laid down a layer of that on one side of the rim, making sure to pull it tight the whole time.
It's really important to make sure the edge of the tape rolls up the side of the rim. It's also really important to make sure the foam stays centered the whole time you're installing the tape. Pulling the tape tight will make the foam want to wander to one side or the other. Keep it in the center!
Next, I laid down a second layer of tape on the other side. The tape is wide enough to overlap in the middle about 1/2". Press that overlap and along each bead (where the tape meets the metal or the rim) down really well to make sure it's sealed.
Find the valve hole and poke a hole through.
I used Stan's valves because I like them. If you're super cheap you can cut the valve off an old tube. Make sure it has a removable core, though, so you can add more sealant later.
Pull the valve through the hole and tighten the lock ring as you push the base of the valve to compress the foam.
I like Orange Seal. You might, too. You should try it. You have and don't like it? Use Stan's, then.
Install one bead of the tire, dump in sealant, and finish installing the other side of the tire. I used a full 8oz bottle per tire. You could probably get away with 6oz if you're really trying to save weight, but I wanted to be safe.
Note: I left the rigid rim strip installed. You don't really need it anymore. It added some weight, but it matched the bike better than pink foam.
Inflate. I used a compressor because I had one. If you have a pump that pushes a ton of air, you might be able to use that. It won't be very much fun, though.
Shake it up, roll it around, go ride!
I was able to save him 3oz per wheel by ditching the Surly tube going tubeless. Not bad. Like I said throughout, there were other places to save even more weight, but I didn't want to sacrifice anything (aesthetics, flat resistance, reliability, etc.).
Now you can convert your fat bike to tubeless. Come buy your parts from Pedal & Spoke, Ltd. If you're not feeling up to doing it yourself, but want to take advantage of a tubeless setup, bring your bike by the shop and we can do it for you.