I’ve thought and thought about it, and finally made the leap to tubeless fatbiking.
In the past, I’ve run Surly tubes, exclusively…with a multitude of tires, predominantly spending time with Big Fat Larrys and Husker Düs. Current setup is holey Rolling Darryl’s, the lightweight, high TPI Huskers, Surly tube, Surly rim strip. I’ve been pretty pleased…but I’m all about the reduction of rolling weight for the fatbike. (Really, for all bikes). So I decided to try tubeless.
There are 3 basic tubeless systems:
1) Taped Tubeless: Take a fatbike rim and use heavy duty tape (most use Gorilla tape) to make the rim airtight. Then, insert a tubeless valve stem (a Stans, if you can find it). Insert a couple cups of Stans sealant, and inflate. This is the favorite of many riders–including Matt Gersib, whose recommendations I trust a great deal. However, if you look on MTBR and other fatbike sites, you’ll see that most people who have problems with tubeless have problems with this setup. You’re trying to get a non-tubeless tire to seal perfectly on a non-tubeless bead. In my mind, while I understand the intrinsic appeal of this setup, I couldn’t bring myself to do it.
2) Gonzo Tubeless: I’m going to make this the category of all other tubeless. This includes guys who use glue or epoxy to bond holes in the rims shut, who weld valve stems in, etc. I’ll pass.
3) Ghetto Tubeless: Take a standard bike innertube, cut it lengthwise, stretch over rim, mount tire so that tube is between bead and tire, inflate. More details below. This is the option I went with, after much research and consideration.
Why Ghetto Instead of Taped?
Taped would save another 50-100 grams, no doubt. That said, in my mind, the Ghetto seems a bit more reliable. The rubber innertube helps ensure a better seal between tire and rim, and provides more friction at the tire/rim interface, hopefully preventing blowouts, burps, etc. I was also hopeful that it would be easier to mount up and inflate, and more burp-resistant.
I dismounted everything, except for the rim strip. I then procured some closed cell foam, to use under the tube. I got mine at Lowes…3.5″ wide and 50′ long. Should be enough to do 3-4 bikes. Here’s the exact product I used:
I cut a strip that was a little longer than I needed…
And then cut it down to width. I cut about 3/4″ off of the width–leaving a gap on both sides at the bead.
Again, this is closed-cell foam, so it shouldn’t absorb any water or crud. The hole you see is for the valve stem. With the scale ‘tare-d’ with a bead tool on it, I weighed the foam at 10 grams.
For tubes, I ended up settling on 24×2.1-2.3″ Qtubes with removable valve stems. Here is the exact part:
If you look at the tube, it has a seam that runs down the outside of the tube, opposite the valve stem. Take a pair of sharp scissors and cut down that seam, all the way around the tire. You’ll end up with this:
Insert the valve stem in the appropriate hole on the wheel, and stretch the tube around the rim.
The inside of the tube is powdered, so it doesn’t chafe/rub. Take a wet rag and wipe that powder off, so you can get a good seal.
You’ll end up with the tube hanging over a little less than 1/2″ on both sides of the rim.
(So it’s rim strip, foam, cut-tube).
Then, mount one side of the tire on the rim (should go on by hand). Dump some Stans in (I used 3 cups, but 2 should suffice). Mount the 2nd side of the tire on the rim. This was a little tight, but went on easily with a bead lever.
Make sure you have a nut on the valve stem before trying to inflate. This was the moment of truth. Since the valvestems are removeable, you could pull them out to get more air into the tire, more quickly. I’ve also seen many people use a ratchet strap or other device around the tire, to squeeze it down onto the bead more tightly. However, as I looked at hte tire on the rim, with the foam, the tire looked pretty snug. I decided to give it a go as-is. No lubricants, no soapy water, valve core in, no straps. The lovely Mrs. did the filming:
As you can see, no drama. The bead seated fully at 20psi. I pumped them up to 25 and left them sit. I then did the “Stans’ Shake, Rattle and Roll” routine to move the sealant all over inside the tire and get any bubbles or holes…to my surprise, there were none. It looks like the tire sealed fully without any sealant. No bubbling or squishing. It really was that easy. I think the foam helped a great deal (just one layer), as it pushed the tube-strip out against the tire and made seating the bead very easy.
The ‘after weight’?
My Surly tubes weighed in at 555 and 560 grams. The Q-tubes weighed in at about 180 grams. Even with the 10 grams of foam and some sealant, I dropped 350 grams, front and rear…or about 1.5 pounds of rotating mass. (And the q-tube is closer to the center of the wheel, as compared to an inflated Surly tube, which should exaggerate the weight savings effect based on the centripetal force–right BPaul?) I could drop a little more if I washed the mud off of my tires…
Even if there is no benefit in traction or inflation (and I’m guessing that there will be benefits in those departments, based on previous experience with Tubeless), the loss of 1.5 pounds of rolling weight is HUGE on a fatbike. HUGE.
When I cut the tubes down, I did not narrow them. I have not cut them down post-install, either. They do look a little ghetto:
But it makes it very, very easy to get the rim strip centered and get the tire on and off easily. I have absolute confidence that I could remount and seal one of these tires on a ride, with just a CO2 cartridge (and pump it up with a handpump), and the little flap of rubber makes me confident that I could do it with numb fingers, in the snow. Hopefully, I won’t have to…but that’s my logic in leaving the tube as-is, right now. You could probably drop another 10-20 grams/wheel if you did cut down the rubber.
Ride experience is limited to driveway time right now…but I’ll update in the coming weeks. They held air overnight, and didn’t lose a single PSI. I think this is about the best weight-reduction fatbike project around, right now…dollar for dollar, we’re talking about a $20 investment for a 1.5 pound weight reduction…in rolling weight.