Today, a new technical topic where I tackle the
efficiency of inner tubes. Following my last article on the
23 mm vs. 25 mm tire section, I had bought the market magazines discussing these
subjects. In one of them, a
summary table, given by Specialized on tire efficiency, had Butyl vs. Latex bis caught my attention. It showed that the same
tire could gain 2 watts just by changing a butyl inner tube for
latex.
So I wanted to check. In 2012, I had already made a buy bulk sms service start at a comparison, but
Butyl vs. Latex
reference or methodology compared to all my recent tests. I had nevertheless
put forward the hypothesis that Latex could save a good watt.
So I started with the wheels from the previous tire test, RAR Alu on a tubeless base equipped with GP4000s and
Hutchinson light 77g butyl inner tube. Identical conditions for the test,
Salbert, no wind, sun, 20 degrees. I again chose to adjust the
water bottle to leave with 70kg of total mass. First climb and result
STRICTLY identical to the last tests 15 days earlier, 11’49 for 270w.
Quite disturbing but it must be recognized that under identical test conditions the
SRM does not drift by a nail. The 5 other measurements on the tires had
also given this time around 11’47 / 11’49 for 70 kg rising to 269 / 270w.
2nd climb, I put my Edge carbon 38 mm tire now that we have clarified some for the rear still in GP400S
and butyl.
The wheel is 50 g heavier on the periphery
At the front I keep the RAR aluminum (I will explain why later). No surprise at 0.5 watts ready it is
the same result. Then I change and put a Michelin Latex 22/23 inner tube
in the rear Edge. I keep the RAR butyl at the front. I do 2 climbs in a
row and there good surprise, the gain compared to book your list the butyl is about 3 watts!
Given the repeatability of the previous measurements, I do not doubt these.