CX/Gravel Inner Tubes Vs Tubeless

Published: 2022-06-16 by Jarno Bierman
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CX/Gravel Tubeless Vs Inner Tubes

One of the key advantages of tubeless bike tires has always been the reduction in rolling resistance that the elimination of the inner tube brings. We've already done many tests where we compared tires with inner tubes and the same tires set up tubeless. This time, we're going to look into gravel bike tires to see how many watts can be saved by going tubeless.


If you're interested in more comparisons of inner tubes and tubeless set ups, we recommend the following articles on our site:



This time we've tested 8 gravel bike tires with and without the standard Continental Cross28 butyl inner tube that we use for the standard tests. As usual, the averaged data of those 8 tires is available free for everyone and Pro Members can dig into the individual tire data.


The averaged results will give a good representation of what to expect when going tubeless. We did find some differences between the 8 tires, but none of the tires went outside the margin of error of the test, which means we can't be 100% sure there is a difference between the tires.


Test Set up and Conditions


We've performed all tests on the same day to get the data as accurate as possible. The speed during all tests was our standard speed of 28.8 km/h / 18 mph.


All tires were tested with the same Continental Cross28 butyl inner tube. We added 30 ml of sealant for the tubeless run as all tires are tubeless-ready and require sealant to seal fully.


We used the following tires:


  • Continental Terra Speed TR 35-622
  • Schwalbe G-One R 40-622
  • Tufo Gravel Thundero 40-622
  • Challenge Strada Bianca Pro HTLR 36-622
  • Panaracer GravelKing Plus 35-622
  • Rene Herse Snoqualmie Pass Extralight 44-622
  • Pirelli Gravel H 40-622
  • Specialized S-Works Pathfinder 42-622

Test Conditions


  • Speed of 8 m/s, 28.8 km/h, 18 mph
  • 700 x 17.8 mm wheel
  • Temperature between 21.5-22.5 °C / 71-72 °F
  • Diamond plate drum surface
  • 77 cm drum diameter

Test Results - Average Results of 8 Tires


Inner Tube RR
XLow
Pressure
RR
Low
Pressure
RR
Medium
Pressure
RR
High
Pressure
Watts Watts Watts Watts
Tubeless 22.6 19.3 17.6 16.6
Continental Cross28 27.7 23.2 20.8 19.4
Tubeless Advantage 5.1 3.9 3.2 2.8
Average RR of 6 gravel bike tires.

When we look at the averaged results of the 8 gravel bike tires, we see similar results to what we've seen in our other inner tube vs tubeless tests. The tubeless set up is superior when it comes to rolling resistance, and the tubeless advantage gets bigger at lower air pressures.


When we compare the gravel bike results to the same tests done with smaller road bike tires. We see the tubeless advantage is larger for the gravel bike tires. We attribute this to the lower air pressure used in gravel bike tires, and the bigger butyl inner tubes required for the bigger tire sizes (155 grams vs 100 grams).


As these are the average results of the 8 tires we tested, we feel this will give the best indication of what to expect when going tubeless with gravel bike tires. There were some differences between the different tires, but they didn't go outside the margin of error of the tests, which means we can't be 100% sure the difference is real or the result of a measurement error.


A short summary of the individual results is that the maximum tubeless advantage at the "extra low air pressure" was 6.2 watts, and the smallest tubeless advantage was 3.8 watts (average = 5.1 watts). At the "high air pressure" the maximum tubeless advantage was 3.2 watts, and the minimum advantage was 2.1 watts (average = 2.8 watts).


Test Results - Individual Rolling Resistance Data (Pro Members)


The next section is only accessible by our highly valued Pro Members. This section includes all test data of the 8 individual tires used for the tests.


Conclusion


When comparing butyl inner tubes and tubeless set ups, we feel our tests' averaged results will give a very good indication of what to expect when going tubeless. We did find some differences between the individual tires, but they might be the result of the margin of error of the tests or other external factors.


At the lowest air pressure, we found a minimum tubeless advantage of 3.8 watts and a maximum tubeless advantage of 6.2 watts, while the average value of all 8 tires was 5.1 watts at this air pressure. Using the averaged values would mean the maximum error would be 1.3 watts which we consider insignificant when we consider some, or all of that, can be attributed to the margin of error of the tests.


What's become 100% clear from our tests is that going tubeless with gravel bike tires will give an excellent gain in (free) speed as it can save more than 10 watts of rolling resistance for a pair of tires over standard butyl inner tubes.


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