schwalbe jumbo jim fat bike mountain bike tire

It was back in May that we first saw how much variation there was in the rolling resistance from one fat bike tire to the next thanks to the great independent testing of Jarno Bierman and his Bicycle Rolling Resistance lab. The topic came up soon after of what impact converting to tubeless would have on the setup, being able to drop those big heavy butyl tubes.  So this time back Bierman picked the two tires with the lowest rolling resistance and one of the heaviest with the tallest knobs to put back on the drum and see what could be gained by dropping almost 400g of tube out of the mix…

Bicycle-Rolling-Resistance_schwalbe-jumbo-jim_testing-rig

Unsurprisingly the removal of the tube had a measurable impact on rolling resistance, and a side benefit was obviously a drop in weight too. Using a tubeless rim, the conversions in this test protocol dropped the (relatively light) 390g Schwalbe butyl inner tube and replaced it with a 10g tubeless valve and 60g of sealant for each tire, saving 320g per wheel. Dropping 25% off the weight of the tire/tube combo shouldn’t be underestimated for giving a better ride feel, but a quantifiable drop in rolling resistance was the goal here.

bicycle-rolling-resistance_average-fat-bike-tubeless-improvement

copyrighted graphics and data courtesy of Bicycle Rolling Resistance

The energy savings amounted to about 4-5 watts around 12-20psi, but since fat bikes run even lower than that Bierman took the test down to just 6psi. That’s where he noticed that the lower he went the bigger the savings. So while resistance does increase at those ultra-low pressures where the tire is getting more and more grip, the benefits of tubeless increase. The change wasn’t linear either, with a 17% reduction at 6psi vs. 14% reduction at 16 psi. That’s good news for fat bikers. Going tubeless has even more effect on reducing rolling resistance than it does on a regular mountain bike.

bicycle-rolling-resistance_schwalbe-jumbo-jim-liteskin bicycle-rolling-resistance_specialized-fast-trak-fat bicycle-rolling-resistance_45nrth-van-helga

Savings were pretty similar across all of the three tires tested, but the 4″ Schwalbe Jumbo Jim LiteSkin remains the fastest of the bunch. As Bierman puts it, “some smaller 29 x 2.25 MTB tires even have a higher rolling resistance than the tubeless Jumbo Jim LiteSkin which is just crazy.” The second place 4″ Specialized Fast Trak Fat comes in close behind, with even more of an improvement going tubeless. The more aggressive 45NRTH Van Helga had similar results, which Bierman says suggests that most other fat tires should improve as well.

bicycle-rolling-resistance_average-fat-bike-tubeless-improvement-data

The conclusion from the Bicycle Rolling Resistance lab:”tubeless is a necessity on fat bikes if you value speed.” They think that for most fat bikers running low pressures, you can easily earn back an extra 10% of your usable power output, just by ditching the tubes. That sounds like a no brainer for us to have more fun and longer adventures on the bike.

We’d like to thank people like Bicycle Rolling Resistance who are doing truly independent testing like this, and the companies who sponsor their work through ads, some even though they have nothing direct to gain from more efficient tires.

BicycleRollingResistance.com

16 comments

  1. Justin Wehner on

    It’s not the weight, though. The weight savings is great but the rolling resistance is better because you’re not having to deform as much rubber as the tire encounters the ground.

    Kudos to these guys for the testing! Nice to see real data.

    Reply
    • Ol Shel on

      Shhh. Weight weenies aren’t ready to hear this.

      Nor is the crowd that thinks 200psi means less rolling resistance out in the real world.

      Reply
  2. contrarian on

    Now all they’ve gotta do is modify this test rig with various types of sharp objects hitting the tread and sidewall at different angles and give some data on how the multitude of reinforced casings compare.

    Reply
  3. Fred on

    Is 60g of sealant enough for a 4″ fat bike tire? Maybe to make it air tight but is it enough to be effective puncture protection?

    Reply
        • Marin on

          Really??
          I use 80-100ml for tubeless ready 2.3-2.4 tire and after few days without punctures there’s barely 30-40ml left nexus because tire soaks up the rest and interior wall gets lined with it.

          If I were to use less, there would be insufficient amount of sealant to patch and puncture.

          Now, for a big ass fat tire, I’d reckon you need at least 3x as much.

          Reply
  4. Tim on

    60ml is enough. The size of the hole will likely be the same as for any other tyre. The liquid will still be transported to the hole by escaping air. That’s enough to plug the hole

    Reply
    • atlbikeshop on

      Not really, it is the added friction of the tube rubbing on the tire/ground from the inside of the tire. Latex tubes are super supple/pliable and create less friction than than butyl. no tube = least resistance because there is less materials rolling on the ground/tire.

      Reply
  5. don on

    Cool article and results aren’t surprising…however people who care about this stuff don’t run 400g tubes, they read everything out here in the wild west of the internet and know you can run standard Q-tube in the 2.4-2.7 size which weigh about 275. Boom, 150g of rotating weight gone… And agree with the 60g of sealant not being enough, that is one scoop, which check about 6 weeks later is almost completely gone/evaporated. Weight weenie your sealant is not a great idea. 2 scoops is about right. So now the weight difference is much smaller. Would like to see the test with these variables changed. If racing shorter course I go tubeless as the consequence of flatting aren’t bad. The rest of the time Q-tubes go in…two flats in really cold conditions a long way from home cured me quick.

    don

    Reply
  6. Graham Foot on

    This is a great test and goes to prove what we have known for some time. Almost every fatbike will sell is tubeless. I myself run 5psi and regularly commute. The tyres we fit tend to be Surly Nates as they offer the best all round performance.

    Reply

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