The Continental Grand Prix Force (24C) is meant to be used as a rear tire together with the slightly smaller Grand Prix Attack (22C) (read review) on the front. Continental calls this the "Tire Positioning System" and they claim this gives an aerodynamic advantage because of the smaller front tire while the bigger rear tire provides more comfort and grip. Both the GP Force II and GP Attack II are very closely related to the popular GP 4000S II and GP TT that both use the same 3/330 TPI casing and Black Chili Compound.
Personally, I'm not sure if the 22C on the front and 24C on the rear is the right way to go. To gain an aerodynamic advantage, it's critical you pick tires that fit your rims/wheels well. It could be possible the 22C tire on the front increases aerodynamic drag if your wheels are designed to be used with 24C/25C tires. If you really want the aerodynamic advantage of the 22C tire on the front, you would have to use it with a rim/wheel that was designed to be used with the smaller tires.
|Model||Grand Prix Force II|
|Tire Type||Tubetype (clincher)|
|Supplied By||Bought in store|
|New or Used||New|
|Specified Weight||195 grams|
|Available Sizes||24-622 (700x24C)|
Size and Weight Measurements
|Size and Weight Measurements (Bike Wheel: 622x17C, Pressure: 100 psi / 6.9 bar)|
|Specified Weight||195 grams|
|Measured Weight||196 grams|
|Measured Width||26 mm|
|Measured Height||23 mm|
|Total Tire Thickness Center||2.3 mm|
|Total Tire Thickness Sidewall||0.5 mm|
My sample of the Grand Prix Force 24-622 comes in at 196 grams which is pretty much spot on to the specified weight of 195 grams. The measured width on a 17C rim, at an air pressure of 100 psi is 26 mm. Measured height is 23 mm. The 24-622 rating seems to make sense as both the 25-622 Grand Prix 4000S II and 25-622 Grand Prix TT came in at a maximum width of 27 mm and a height of 24/25 mm.
I always look forward to the thickness measurements as this tells us a lot about the intended purpose of the tires. With a measured thickness of 2.3 mm at the center of the tire, the Grand Prix Force II slots right in between the Grand Prix 4000S II which came in at 2.9 mm thickness and the Grand Prix TT which came in at a thin 1.9 mm. The sidewalls have a thickness of 0.5 mm which is pretty much spot on to the other 3/330 TPI Conti's.
Rolling Resistance Test Results
|Rolling Resistance Test Results (Speed: 29 kmh / 18 mph / 8 m/s, Load: 42.5 kg / 417 N)|
|Inner Tube||Conti Race28 (100gr butyl)|
|Rolling Resistance 140 psi / 9.7 Bar||
CRR: Not Tested
|Rolling Resistance 120 psi / 8.3 Bar||
|Rolling Resistance 100 PSI / 6.9 Bar||
|Rolling Resistance 80 PSI / 5.5 Bar||
|Rolling Resistance 60 PSI / 4.1 Bar||
|Use the formula: RR (watts) = CRR * speed (m/s) * load (N) to calculate rolling resistance at a given speed and load|
As I already suspected from the tread thickness measurements, the Grand Prix Force (11.0 watts) fits in right between the Grand Prix TT (9.9 watts) (read review) and Grand Prix 4000S II (12.2 watts) (read review) in the rolling resistance test at the higher air pressures. At lower air pressures, rolling resistance rises a bit faster when compared to the 25-622 tires. At the very low air pressure of 60 psi / 4.1 bars, the Grand Prix Force even gets outperformed by the Grand Prix 4000S II.
Puncture Resistance Test Results
|Puncture Resistance Test Results (higher is better)|
|Puncture Resistance Tread||9|
|Puncture Resistance Sidewall||4|
In the puncture resistance tests, the Grand Prix Force performs as expected as well. With a score of 9 points in the tread test, it outperforms the Grand Prix TT (8 pts) by 1 point, and it gets beaten by the Grand Prix 4000S II (11 pts) by 2 points. These results seem to be very closely related to the total tread thickness. It looks like the Vectran Breaker used in these tires is of the same thickness, and the increased amount of rubber makes it harder to penetrate the tire.
With a score of 4 points in the sidewall puncture test, it scores in-line with the other 3/330 Conti's that all seem to come in at 4/5 points.
If you can't make up your mind on whether to go with the Grand Prix 4000S II (read review) or Grand Prix TT (read review), the Grand Prix Force II might be a good compromise between those tires as tread thickness, rolling resistance, and puncture resistance all fit in right between those tires. Whether you should use this tire as a rear tire with the smaller Grand Prix Attack on the front is a tough decision. I would only suggest doing this if you have a smaller rim/wheel on the front that fits the 22C tire well.
I'm going to rate this tire 4 out of 5 because rolling resistance at lower air pressures seems to collapse somewhat and rolling resistance is very close to the Grand Prix 4000S II which offers much better tread thickness and puncture resistance. If you want a smaller tire on the front, it would be just as easy to go with a 23C/25C front/rear Grand Prix 4000S II combo.
TEST VERDICT: Recommended