Aero testing race tyres - which is fastest?

We’ve previously tested a range of race tyre options and seen that the difference in aerodynamic performance can be significant.  So as manufacturers start to release “aerodynamically-optimised” tyres, we wanted to look into these claims so we can give the best possible advice to our riders on tyre choice.   As before, we have also included rolling resistance figures taken from Bicycle Rolling Resistance to give an idea of the overall fastest option.

AERODYNAMIC COMPARISON

• All tyres tested in 28mm (stated) width except Aero111 as a 29mm

• All tyres tested on a Chrono (68mm) front wheel

• All tyres inflated to 72psi

• All tyres measured between 28-29mm on the test wheel, other than the Pirelli which measured 29.3mm

• Testing conducted at 48kph

Looking at the data, it is clear that the aero performance can be split into two categories:

Low yaw: (0-10 degrees, representing ~89% of ride time per Parcours’ yaw data)

• All tyres test within just over 2W of each other
• Pirelli P Zero Race TLR RS is slightly slower than other tyres on test, potentially due to the slightly greater width when mounted (0.5mm wider than other tyres tested)
• Aero benefit of the Aero111 tyre limited to approximately 1W over other tyres tested

High yaw: (10+ degrees, representing ~11% of ride time per Parcours’ yaw data)

• Significant differences seen as stall conditions are approached and passed
• Almost 17W difference between the best (Aero111) & worst (Corsa Pro Speed) performing tyres
• Differences between tyres remain broadly consistent up to the point at which the wheel & tyre stall.  The aero-optimised tyres outperform the others by delaying stall  

OVERALL RANKING

We then combined the yaw weighted average aerodynamic drag (see details here) with the rolling resistance to give an overall performance figure for each tyre.

• Aero drag shown as a front wheel yaw weighted average at 48kph

• Rolling resistance shown at 72psi, adjusted to 48kph

KEY TAKEAWAYS

The majority of interest in this data is likely to focus on the top 3 ranked tyres:

Vittoria Corsa Pro Speed:

• Whilst the fastest rolling in BRR testing, the new casing construction on the Corsa Pro Speed does not appear to have completely solved the comparatively low stall angle seen on the older Corsa Speed tyre
• Above 7.5-10 degrees of yaw, there is a significant increase in aero drag as the wheel system stalls

Continental GP5000 TT:

• Ranked #2 in rolling resistance & a close #3 in aero performance
• In our view this remains the go-to choice in many conditions

Continental Aero 111:

• The headline result is that the high yaw performance lives up to the manufacturer claims.  Absolute savings (in W) will vary depending on the test wheel used (& stall performance of the rim), as well as test protocol factors like airspeed, yaw weightings etc.  However, the benefit is clear
• Real-world testing supports the wind tunnel data in showing that delayed stall has a far more significant impact on ride handling than it does on pure aerodynamics  

Others:  

• Schwalbe Pro One Aero tyre performs well in the wind tunnel, however it does not delay stall as long as the newer Continental Aero 111.  The bigger issue remains the rolling resistance versus its competitors
• Pirelli P Zero TLR RS measured up slightly wider than the other tyres (including the stated 29mm width Aero111) which likely had an impact on aero performance.  Combined with higher rolling resistance than pure race tyres hindered its ranking, however Bicycle Rolling Resistance testing suggested it is better compared to an all-round option in other respects (puncture resistance, grip etc.)  

So which tyre is the best option come race day?  As ever, the answer will have to remain “it depends”.  In our testing and rankings we have not attempted to include factors such as puncture resistance, durability, ease of fitting or price.  

However, we can suggest the following:  

• For low-yaw conditions the exceptional rolling resistance of the Vittoria Corsa Pro Speed offsets the relatively poor aero performance
• In higher-yaw conditions the Continental Aero111 is head and shoulders above the competition.  Not only does it offer incredible aero performance but the massively enhanced handling stability may also allow you to run a deeper front wheel and further reduce drag
• As an all-round option, the Continental GP5000 TT is within a small margin of the Corsa Pro Speed for rolling resistance and a similar difference to the Aero111 for aero performance