Tubeless Fatbike Conversion

Update! (05-31-2014)

Fatbikes are a lot of fun. If you get a lot of them together, they are a blast!. What’s not fun are flats on a fatbike. Flats are never fun, but add in big wheels and the possibility of working in cold temps during the winter, and you have the recipe for less than smiles.

Tubeless is nothing new now a days. Tubeless wheels (typically) have fewer flats from punctures, and ride smoother. It’s pretty easy to understand why I wanted to convert my fatbike to tubeless. The problem?. There isn’t a great fatbike tubeless solution. There are no systems, no dedicated tubeless wheels (a big dollar idea), no tubeless tires, etc.

I decided to try to set up my wheels tubeless, even though it’s not supposed to work.

The Popular Options:
It seems like there a few schools of thought on the early fatbike tubeless methods.

  1. Ghetto Tubeless – Using a normal tube after slicing it open length wise thus creating a make shift rim strip with a built-in valve stem,. add sealant, inflate, and trim the excess tube if desired.
  2. Traditional – Add tape, install valve, add sealant, inflate.

I choose to attempt a traditional approach as it has the least weight and is the least complex. Some people build up the center of the wheel cavity with non porous foam to help seat the tire, I choose to skip this step because after the tire seats, it serves no benefit.

The Materials:
I used Gorilla Tape (both wide and standard widths), Stans valve stems, Stans sealant, Surly Holly Rolling Darryls, Surly Knard 120 TPI for the rear, Surly Big Fat Larry 120 TPI for the front, Surly rim strips, Stans injector, air compressor, floor pump, and a five gallon bucket.

IMG_0462sHow I Did It:
I cleaned the wheel thoroughly including the sides of the rim (1). I added a Surly rim strip (2). I added one layer of the wide Gorilla tape down the center of the rim carefully covering the entire rim strip, and then afterwards using the standard width Gorilla tape to cover both the left and right sides individually, carefully placing the tape all the way to the edge of the rim. I also used a pick tool to poke a small hole for the valve stem. It is important to make the valve hole smaller than the diameter of the valve (3).

rimPrepsI installed a tube into the tire, and mounted the tire as normally done.

IMG_0475sI then inflated the tire to 30 PSI to ensure the bead seats on both sides of the wheel. Once the beads seated I carefully deflated the tire and broke the seated tire free on only one side of the wheel. I then removed the tube and then installed the Stans valve stem.

IMG_0476sI remounted the open side of the tire to the wheel (it is most likely loose, and that is alright at this time).

I then wrapped the tube previously removed around the outside of the tire. This helps push the tire to the edge of the rim, helping seat the tire when you inflate it.

IMG_0478sI then used an air compressor to inflate the tire. If you hear any air leaking out, press on that area with your hand.
IMG_0480sOnce the tire starts to inflate, I stopped inflating with the air compressor and used a floor pump to inflate the tire to 30 PSI to ensure the bead was seated thoroughly. Once the bead is seated I carefully deflated the tire and removed the valve stem core. Using the Stans injector, I injected six ounces of Stans sealant into the wheel through the valve stem. I then re-inflated the tire with an air compressor initially. After the tire takes some air and begins to fill, I switched to inflating it with a floor pump to ensure I filled it to 30 PSI.

I then did the “Stans” shake to seal any leaks. If you don’t know what that is, there is a video detailing what I am referencing here.
IMG_0483sAfter shaking the sealant onto the sidewall all the way around the wheel, I sat the wheel down on a bucket for about three minutes to allow the sealant to work its magic on the sidewalls of the tire.
IMG_0481sI repeated the shake and bucket work at least three times per side of the wheel, rotating which side of the wheel is pointed down each time. If you are still leaking sealant and or air out of the sidewall, repeat this step until the leaks seal completely.

I then deflated the tires to about 12 PSI (my desired riding PSI), and repeated the shake and bucket trick two more times to be sure everything was sealed all the way.

The Outcome?

It worked!. The Big Fat Larry tire was a real pain to get seated. The Knard seated without any real effort. I believe this was because the Big Fat Larry is a 4.8″ tire and the Knard is a 3.8″ tire and on the 82mm rim the 3.8″ tire has less tire per mm in width to displace. I think an air compressor is a must for mounting a Big Fat Larry tire on a 82mm wheel. The conversion lost about a pound or so in weight. They still ride wheelies just fine :) I’ll provide updates as I spend more time riding on them, but so far, I couldn’t be happier!


IMG_0485sUpdate! (05-31-2014)

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39 thoughts on “Tubeless Fatbike Conversion

  1. Nice work. Are you considering going to a single chain ring drive train? Check out the Wolftooth chain rings. Sounds like a good idea.

    • Thanks! I like the idea and weight savings that a single chain ring would provide, but I worry about having the legs to push one on steep hills or in deep snow. I really like the looks and reviews from Wolftooth chain rings, I think they would be my first choice!

  2. I just did this on my BFLs & Clownshoes using two 4″ strips of Gorilla tape, each pulled to the side. Worked like a charm. Thanks!

  3. Does the tape go up and over the rim lip (where the bead seats?) I know on the ghetto meathod, the tube sticks out the side of the rim and wondered if the tape does as well?

    • We taped the rim to the edge of the wall where the rim goes from horizontal to vertical. There is no tape sticking out of the rim.

  4. Ant reason to use Gorilla tape over the wide Stans tape? I’ve got a whole roll of this tape and it’s at least half the weight of Gorilla tape.


  5. I did exactly as u said except when I set up the beads after installing the Stan’s valve stem. I couldn’t get the tube to sit on the outside of the tire, so I put the wheel on the five gallon bucket, with the loose bead down, let gravity help set up the loose side. It worked great! (Also I let the tires sit with the tube inflated overnight).

    • I’m glad to hear you had success with the tubeless conversion! I too think letting the tires sit with an overinflated tube before beginning the tubeless conversion process helps tremendously by making the tire wider and have a uniform bead shape.

  6. I wonder if having Tubeless on a fat tire be a risk. Considering the low pressure that has to be used on fat tires, is there the concrete risk that the tire come out from the rim?

    • I can’t speak in certainties, but I can say that when I deflate the tires after setting them up tubeless they are a choir to get off the rim at 0 PSI. They want to stay beaded.

  7. I used the conversion with a surly knard on the rear and a 45 north Husker Du on the front. The knard is doing great, but the Husker Du is oozing black goo out of some spots on the side wall, and tread area. My buddy is having the same issue with his 45 north Dillinger. The tires hold air, the just leak black goo. Anyone out there with similar issues?

      • I took the bike on a couple rides and it seems to be fine now. The knard is a 27 tpi, the Husker du a 120 tpi, I don’t know if that makes a difference. My buddy was concerned the black goo was from the tire, and that the stans and 45 north tire could be reacting. I kinda think the dye from the gorilla tape may just be turning the stans black and the leaking is just part of the process. One LBS guy recommended:, another LBS guy said he’s used them both and hasn’t noticed a difference. If my tire desolves into nothing I’ll post again…..

        • So after a few more rides and talking to some smart folks, the tire no longer leaks at all, no could really explain why the leakage was black (I still think I was the gorilla tape) but both tires hold air and I’m looking forward to a long season of snowy fat biking!!

          • So so locals and myself are struggling with bead leaks with PSI < 10, my 27 tpi knard is rolling strong but my 120 tpi Husker du giving me fits! It will hold 40 psi over night no problem, but slow leaks at the lower pressures. Maybe a take the tire off clean the rim etc? Open to suggestions…..

          • I have a few more thoughts after setting a handful of tubeless fat bike wheels and after of a winter of running tubeless. One of the thoughts I have are that tires become “better” tubeless wheels the longer they are used. I had a few issues with low pressures early in winter, but am able to run pretty ridiculously low pressures now (roughly 3 psi and up). I think that over-inflating a tire with a fat bike tube for a few nights before the conversion helps extend the beads evenly and wider making them a more uniform shape for the tubeless conversion. Sorry to hear about the troubles! I hope you have more success in the future! Until we have ready made reasonably priced tubeless options (eg. Stans), I think this may be as good of option as any.

          • I had the same problem. Did the gorrilla tape tubless method, held air for a month in the basement, finally took it out for a ride in the cold and they flatted. Filled them with air and they seemed to hold it again, until I rode at around zero. Made a half a lap and they flatted again. Seemed to just lose air out the bead, and I ran them at around 8# to start. Some suggested putting tape thru the bead area. I haven’t tried that yet. Any thoughts? (Husker dus, used over a year).

    • I’m glad to hear the rear Knard setup is doing great, but bummed to hear the 45Nrth setup isn’t working. I was unsure if the 45Nrth tires would be different. I am a little suppressed as 45Nrth and Surly are both owned by the same parent company and I assumed they were constructed the same way. It sounds like I can’t add any clarity to the 45Nrth tubeless setup, but I have seen the blog Riding Against The Grain set up these tires. Take a look:

  8. Do you still need the surly rim strip if you’re going to put a different color tape showing up in the holes? So in other words, would it be, colored tape, surly rim strip, the Stan’s tape and the rest of the procedure ?

    • I prefer the Surly rim strip over colored tape personally. I can’t speak to the effectiveness of using colored tape instead of a Surly rim strip. I have read of others doing this in the past. One word of caution about skipping the Surly rim strip, I have read about cases where the tape used throughout the setup was not liquid resistant, and the Stans sealant seeps through the tape after some time. I played it safe with my setup and went with the Surly rim strips. If you do go with tape instead of the rim strips, please let me know how it goes both short term and long term as I am curious. Good luck!

      • Well, I dove in today and did the tubeless. I sanded down the inside of the rim, used a surly rim strip (oh, I’m doing 29+ wheels, rabbit holes). then over the rim strip, 2 full layers of nylon packing tape like someone recommenced. I taped on the horizontal part of the rim, up to where the rim goes vertical to the bead. Does that seem right? Put tire on, inflated with tube. sat overnight. Pulled tube, put stands stem in. Pulled core and inflated and got a good bead. Inserted Stans goop, 4 oz, installed stem valve and shook. Shook and flipped a bunch. Added air several times. Seemed I had a lot of leakage around edge of the rim. Common? Let it sit a few hours. Tire was flat. Inflated again and added soapy water. SOme leakage was from rim edge, some from odd spoke holes. I wondered if maybe the tape had come off inside and it was leaking around it some how. I kept inflating and shaking problem spots and checking with soapy water. It seems to be sealing up now and will check again. Not sure it was so easy, and hop they hold air.

        • I have not used that tape so I can not speak to it’s attributes until I try it. I would recommend mixing up some soapy water in a spray bottle and spraying all the beads and holes and shaking the wheel to slosh the sealant until you see all soapy air bubbles stop coming out. If you stop before all bubbles stop, you have a leak and eventually, the tire will deflate. Let me know how it goes moving forward. I wish you the best of luck!

          • I decided to start over, so I peeled everything off the rim. Surprisingly, the strapping tape did not come off the edge of the rim, but rather somehow, leaked between layers. Not sure-maybe the tape itself wasn’t good. Stand had made it thru to between the layers of tape and on top of the rim strip. I’ll try gorilla tape today- 2″ wide should fit well.

  9. Gorilla tape fit pefectly on the RH rims-like it was built for it. Used 2 layers over the rim strip. Mounted the tire, pulled the cores from the stems, blasted air in and it popped onto the rims perfectly. Added 4 oz of Stans and inflated. Not-one-speck of leakage!!!! Held air right off the bat. I did the shake rattle and roll and after a week-it’s holding pressure!!!! I read somewhere that someone used 2 layers of gorilla tape-wonder if one layer would be enough? Maybe for protection in the holes of the RH rim?

  10. Is there someone having trouble with Tubeless on a fat tire? Considering the low pressure that has to be used on fat tires, is there the concrete risk that the tire come out from the rim?

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  12. I had my tires set up tubeless over the past week. (two attempts). Holding air fine, but there are a couple of bulges in the rim strips in the cutouts. Something to be concerned about? There doesn’t appear to be any Stans that has gotten between the tape (Scotch Tough Transparent) and the rim strip. Just air.

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