Continental's new GP5000 tyre has unsurprisingly come out faster than the GP4000 tyre it replaces in testing by UK coaching and cycling tech brand AeroCoach.
But surprisingly, the tubeless GP5000 TL variant was outperformed in certain tests by the non-tubeless clincher version of the same tyre.
The GP5000 is a replacement for the much-loved GP4000, the all-round racing tyre which has lasted 14 years at the top of Conti's range.
AeroCoach's tests saw a range of tyres put through their paces, including various widths of the GP5000s, the older GP4000s, and the fast-rolling GP TT clinchers. The tyres were tested for both aeroydnamic speed and rolling reistance – in the wind tunnel and on rollers.
AeroCoach kept a rider on a Cervélo P2 with a shallow section front aluminium wheel and AeroCoach’s rear AEOX tubeless disc as the constants.
In the wind tunnel
First up was the wind tunnel test, which comprised riding at a speed of 45kmh at various angles of yaw – the angle at which the wind hits the rider and bike.
At low yaw angles, the performance of the three tyres was close enough to be within the margin of error. But increase the angle and the differences become more pronounced.
All three tyres were tested in their 23mm width, though the measured width varied quite a bit on each tyre.
The GP5000 came out as winner of the aero test, significantly outperforming the GP TT from five to ten degrees of yaw, and beating the GP4000 over 10 degrees.
In the end, the GP5000 was 0.3 watts more aerodynamic than the GP4000, and enjoyed a 1.7 watts advantage over the GP TT.
It’s certainly an interesting result, as one might assume that time trial-specific tyres would have an aero advantage, but that’s not the case for Continental's latest GP range, at least.
On the rollers
For the rolling resistance test, the experts at AeroCoach monitored power output, speed, atmospheric conditions and bike/rider weight, swapping between tyres on the rollers.
The coefficient of rolling resistance (Crr) models power output required to travel on a real road, with a lower score meaning a better result.
This test saw the 23mm GP5000 perform significantly better than its predecessor of the same width, with 28.4 watts required to overcome rolling resistance at 45kmh on a flat, smooth road.
The GP4000’s figure was 33.7 watts, while the GP TT unsurprisingly came out the best at 26.6 watts.
Probably the main reason for this result is the GP TT’s unidirectional tread and smooth central raised section along the tyre’s tread. For this reason, it’s a tyre best-suited for time trialling, rather than an all-round racing tyre like the other tyres tested.
Tubeless vs clincher
AeroCoach also pitted a set of 25mm GP5000 clinchers against the 25mm GP5000 TL (tubeless). Comparing the two – the results are pretty surprising.
Running under the same conditions as the test described above, the clincher with a latex inner tube comfortably beat the tubeless tyre, with only 27.2 watts required to overcome rolling resistance at 45kmh.
The 23mm clinchers, however, performed worse than the 25mm tubeless option, with 26.6 watts required at 45kmh.
Explaining the results of the tubeless rolling resistance test, AeroCoach’s Xavier Disley said, ‘I think it’s the tyre carcass, it’s just so thick on the tubeless version of the tyre.’
It’s worth noting that Continental’s own testing suggested that the GP5000 TL was faster than a clincher version with an inner tube.
However, Disley has suggested that the use of a butyl inner tube instead of a latex inner tube may explain the discrepancy.
The final verdict
The GP5000 is certainly an improvement over the GP4000, as one might expect. Aerodynamically it just had the edge, while the improvement in rolling resistance was more apparent.
Meanwhile, the GP TT was the worst performer in the wind tunnel, but top of the class on the rollers.
Combining the savings, however, and the GP TT comes out winner, thanks to its large rolling resistance advantage. It’s a close-run thing though, beating out the GP5000’s by 1.4 watts in the combined ranking.
The GP4000, meanwhile, lags behind, 4.3 watts down on Continental’s new rubber, while the 25mm clincher version of the GP5000 happily finished best of the rest behind the TT-specific tyres.
The GP TT doesn’t come in a tubeless option. That means that while losing out on speed, the GP5000 tubeless tyres offer superior puncture protection – where sealant can seal small cuts and punctures.
For some, though, the test may disprove the old mantra that tubeless tyres unilaterally offer lower rolling resistance.
However, it's worth noting that this study was done using latex inner tubes, where most riders will opt for butyl inner tubes which will likely result in higher rolling resistance for the clincher tyre.
For us, though, despite the interesting results we’re confident that sealant and airtight rubber is the future.