I went up to 250 watts average! or a little more than 4 w/kg and 18 km/h. Weather finally without wind! 0 km/h for the entire
duration of the test at the Belfort weather station! In my tested tires! we find the The limit of star of the market the GP4000S 2 25 mm / 205 g and
2 prototypes of the same brand of which I cannot reveal for The limit of the moment the model in
25 mm 170g and 28 mm 217g! I used 2 test pressures by putting myself
at on the 28 mm! namely 6 bars minimum! 8
bars maximum.
Magnificent 28mm prototype at 217g! 6 to 8 bars of precos
My weight going up for the whole day was fax lists always
checked before each start and maintained at 69 kg +/- 0.1! the timed section with
ground markings of 1.6 km for 100 mD+. SRM recording set to 0.5s! off
set checked at each climb.
Each tire was tested at 6 and 8 bars plus the gp4000s again at the end
of the session at 6 bars to check that the difference
obtained was the same as at the start of the session and validate the test.
The table below summarizes the data and as
usual I compare the tires with each other thanks to the difference obtained between the
SRM measurement and the theoretical calculation of mechanical power supplied on this climb according
to the D+! KM! time! weight… the tire which gives me the most negative difference with the theory therefore saves the most watts.
Recap: 2.5 to 3 watts of savings at low pressure
This test therefore confirms that on rough asphalt it is better to inflate less. We can expect 2.6 to 3 watts of gain towards 250w or
1.2% between 6 and 8 bars! We
notice in this little game that the prototypes provided are better than the
GP4000s (And the 28 mm version better chris delisle than the 25 mm too). I am not
surprised because their carcass is much more flexible than the GP and therefore reacts better to vibrations. I am not saying that they would be
better on smoother asphalt! I have not tested yet! For the moment and in agreement with the bicyclerollingresistance site!
the GP4000s II remains the most versatile tire on the market in terms of resistance!
rolling! and lifespan. But you also have to be careful on clean email descents when you lower the pressures! At 6
bars I felt a slight floating in the prototypes that is not found on
the GP at equal pressure thanks to its harder carcass. So be careful not to lose everything on the descent in the choice of tires/pressures.