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Professional Review: Which Road Bike Tire Is the Fastest? (Part 3)

by Martin Yang 05 Dec 2024
Professional Review: Which Road Bike Tire Is the Fastest? (Part 3)

Professional Review: Which Road Bike Tire Is the Fastest? (Part 1)

Professional Review: Which Road Bike Tire Is the Fastest? (Part 2)

 

Speed and Time Issues

Up until now, I haven’t talked about saving time and increasing speed. In cycling, the faster you go, the greater the resistance you face, and this increases exponentially. At a given speed, it’s easier to maintain that pace and also easier to measure power. But when you try to quantify speed based on a given power, it gets more complicated.

Simply put, the faster you go, the smaller the differences between tires become. Air resistance has a bigger impact, and rolling resistance takes up a smaller portion of the total system. You can assume that the forces in the drivetrain are pretty much constant, and that the differences are negligible. The issue here is that while the tires help you go faster, increasing speed also increases air resistance, which ultimately reduces your gains. The math behind this is relatively complicated, but don’t worry—there are interactive calculators online where you can input different parameters to get the data you need. For example, Steve Gribble’s Bike Power and Speed Tool, recommended by Casper Von Folsach from the Uno-X Mobility team. By inputting our tester Josh’s current setup and improving the rolling resistance coefficient by 0.002, the result looks like this:

Hypothetical Situation Analysis

This is a purely hypothetical scenario, assuming a significant improvement in rolling resistance. Simply put, if air resistance remains unchanged, the stronger the rider, the harder it becomes to win every second.

In reality, there are many other factors at play that make predictions difficult using just a calculator. Road conditions, wind fluctuations, weight changes, and gradients all play a role. So, while you may want to know what you could achieve in an ideal world, it’s important to be cautious with the data. Moreover, all the predictions are based on actual tire rolling resistance measurements, and we can't solve all the problems through testing. These are just idealized forecasts.

Further Data Analysis

We’ve already determined which tires are the fastest and which are the slowest. If you’re trying to choose between two different tire setups, this information is definitely valuable. By analyzing trends, there may be opportunities to improve things, which is what I’m trying to do below.

Time Trial Tires vs Road Tires

The concept of time trial-specific tires is relatively new. The two leading brands used by WorldTour teams are Continental and Vittoria, both offering versions for road races and time trials. Schwalbe also has similar tires, and both Schwalbe and Continental now offer tires optimized for aerodynamics. Below, I’ve compared the data using 11m/s (which better represents time trial conditions), highlighting time trial tires to show their position.

 

Time Trial Tire Performance

From the results, it’s clear that time trial tires generally perform within the faster range. The only exception is the Corsa Pro Speed, which is slower than its road race version. Notably, the Continental GP5000 TT TR had the exact same test results as the standard GP5000 S TR, and it overlapped with the Schwalbe Pro One TT. So, on the test day, these three time trial-specific tires occupied the podium positions.

However, there is one notable outlier, the Continental Aero 111. While it’s optimized for aerodynamics, it doesn’t seem to be optimized for rolling resistance. According to our data, when riders mix the GP5000 TT TR for the rear wheel and Aero 111 for the front, the total rolling resistance is reduced by 3.8W. So, if Continental's claims about aerodynamics are accurate, the power saved by reducing air resistance should be enough to offset the increase in rolling resistance. But still, this remains an anomaly.

My guess is that to create deeper "vortex generator" grooves on the tire surface, the tread itself might be thicker than the standard GP5000 S TR, which leads to an increase in rolling resistance.

All-Season Tires vs Regular Tires

For most riders, the more practical choice might be whether to opt for race tires to gain some power benefits, or to choose more durable, grippier, or puncture-resistant "all-season" tires. To explore this, I’ve pulled out all the all-season models from the 9m/s chart (which better represents real-world all-season riding speeds) and highlighted them in pink to see what insights we can gather.

In this test, the two slowest tires were Vittoria and Pirelli’s all-season models, but the GP5000 AS TR performed quite well. Although it dropped a few positions at higher speeds, I personally think that 11m/s is more representative of race speeds and doesn't fully reflect the intended design speed of these tires.

If you’re a Continental fan, the trade-off with choosing the all-season version is that at 9m/s, the power loss for a pair of tires is 6.6W. For Vittoria enthusiasts, switching from the Corsa Pro to the Corsa Pro Control results in a power loss of 11.2W at 9m/s. Of course, this is mainly because the Corsa Pro itself is such a high-performing tire. Among all the all-season tires, the best performer is the S-Works Turbo Cotton Hell of the North, but it’s essentially just a wider version of the standard Turbo Cotton and requires a latex inner tube. We don’t consider this a true all-season tire, as most people now expect all-season tires to be tubeless.

Mid-Range vs High-End

All-season tires are not necessarily always mid-range or second-tier products. Some tires are quite expensive and are marketed with claims of better grip or similar features. So, how do mid-range tires perform compared to top-tier ones? Below, I’ve highlighted the mid-range tires in two charts (both at 9m/s).

We generally take a skeptical view of manufacturers' marketing claims, but it’s reassuring to see the mid-range and second-tier products ranked lower. However, the ranking for second-tier products shows a wider range of variation.

The Impact of Price

Let us now probe the pricing problem more closely. Although mid-range tires are usually slower than high-end ones, they are not always less expensive. A few premium products cost less than the mid-range offerings of rival companies. I have sorted the tires in the chart below by their recommended retail price in ascending order, or as near as feasible at the time of writing this post.

This is a little perplexing, then. The statistics do not show any obvious trend. Simply said, performance is not much affected by price. Given its performance is nearly on par with the GP5000 S TR but at a reduced price, one could contend that the Schwalbe Pro One TT provides the most value for money. I would be hesitant to suggest it as a daily choice, though, since it's a time trial tire and there is no data on its puncture resistance.

This chart would have varied even more if I had created it using real online costs rather than the recommended retail pricing from every brand. I can't make a dynamic chart since tires go on sale, and I can't locate a straight link between pricing and power loss.

Are Cotton Casing Tires Faster?

In recent years, brown/beige sidewalls have become quite popular, mostly for style reasons. Initially, a brown sidewall meant you were using a cotton casing tire, and people believed these tires were faster. Nowadays, brown sidewalls are usually just made of brown rubber. Of course, a few of the tires we've tested do have cotton sidewalls, so we can check the data to see if cotton casing tires are faster.

Overall, cotton casing tires are fast, but there’s also one that ranks second to last in terms of speed, with average speeds placed somewhere in the middle to the front. Cotton casing tires look cool, and from my experience, they do have a noticeable impact on the riding feel. However, there's no evidence to suggest that cotton casing tires are faster than rubber tires.

If you're just after a brown sidewall, it's better to choose a brown rubber tire rather than a cotton casing tire. Of course, this assumes that the brown sidewall version and the all-black rubber version have the same rolling resistance, but this may not always be the case, as different colored sidewalls might use different rubber compounds.

Tubeless vs. Tube Tires

Given that we now have testing equipment, it would be remiss not to dive into the tubeless vs. tube tire debate. This has been a hot topic among cyclists for a while, so we compared the power loss of the GP5000 S TR tubeless tire against tube tires with latex, TPU, and butyl inner tubes at the same pressure. The inner tubes used were the Vittoria Competition Latex, Pirelli Smartube, and Specialized lightweight butyl inner tube.

In the test, we used two different GP5000 S TR tires. One was the "wet" tire designed for tubeless use, and the other was the "dry" tire for installing inner tubes, to avoid any leftover sealant from interfering with the data of the tubeless tire previously tested.

The results showed that the latex inner tube was 0.4W faster than the tubeless tire at 9m/s, but 1W slower at 11m/s. Considering the margin of error in each test, we can confidently say that for our benchmark GP5000 S TR tire, the performance difference between using a latex inner tube and a tubeless sealant is quite small.

The TPU inner tube was slower, and the butyl inner tube was even slower than the tubeless tire. At a speed of 9m/s, switching from the butyl inner tube to the tubeless sealant provided an 8W power advantage, which is about the same difference as between the slowest tire and the fastest one in our data set.

The Impact of Tire Pressure

Alright, we've already established that switching from butyl inner tubes to tubeless tires can bring significant benefits. But what about tire pressure? There are plenty of tire pressure calculators on the market that can determine the optimal pressure based on factors like tire width, type, rim size, road surface, and speed.

To dive deeper into this, we tested the baseline GP5000 S TR at pressures of 90, 80, 70, 60, 50, 40, and 30 psi, and also gathered data for 73 psi. The bar chart below shows the results for each tire pressure.

First, let's look at the data for 11m/s, which includes pressures both above and below the ideal design pressure, as well as about 10 psi lower than the pressure typically used by testers.

We see a similar trend at slower speeds, but the data differences aren't as large, so we can vaguely notice a slight U-shape trend. Pressures above or below 70 psi result in power loss, but strangely, the resistance at 90 psi drops slightly, just below the maximum pressure allowed for this tire on hookless rims.

Looking at the trend, we can see that the loss from a tire being too soft is much greater than from it being too hard, but on the other hand, there's actually no benefit to having a tire too hard, aside from making the ride less comfortable. However, these tests don't account for the speed loss caused by having too low a pressure.

Perhaps the most valuable takeaway from this test is that as long as the tire pressure is within the correct range, you don't need to worry too much. Interestingly, tester Josh was able to use the GP5000 S TR at 30 psi and still outperform the Pirelli P-Zero 4 Season at 73 psi at 9m/s. Even when compared to race tires, his performance on the GP5000 S TR at 40 psi was better than the Cadex Race GC at 73 psi. So, tire construction is more important than tire pressure.

Key Points Summary

I know this can take a while to fully digest, and some of you may have skipped straight to this part, so here’s a quick summary of the key takeaways from our tests based on the questions we posed earlier. It’s definitely worth a look.

  1. How big are the differences between tires?

If you typically ride at around 40 km/h, swapping your worst tire set for the best could save you about 30W of power. And if you go from a butyl inner tube to a tubeless tire, you could save another 8W. For most people, a more intuitive example would be swapping from a standard tubeless tire to a top-tier racing tire at 30 km/h, which could give you a 22-23W power advantage.

This kind of difference is enough to noticeably affect your ride, either by increasing your overall speed or allowing you to maintain the same speed while using less power.

At WorldTour-level races, the difference between two commonly used tires, the GP5000 S TR and Corsa Pro, is only 10W per pair. In a sport where every fraction of a second counts, this difference can make a big impact.

To put it into perspective, for a 90-hour Tour de France, assuming all other factors are the same, that 10W difference would equate to 3,240,000 joules of energy. It sounds like a lot, but it’s actually the energy contained in just 430 grams of rice. This gives you an intuitive sense of the difference, even though the real-world situation is more complex.

  1. How does this tire gain compare to other upgrades, like wheels, frames, or helmets?

For comparison, we used 11m/s data, which is close to the wind tunnel testing speed. Switching from the slowest racing tires to the fastest could save you 21.8W of power, with a cost of around £160, or about ¥1,500.

This is similar to the power savings you’d get by upgrading from a 10-year-old Trek Emonda to a Factor Ostro VAM, with a frame upgrade costing around £10,000, or ¥90,000.

Swapping to the benchmark GP5000 S TR tires costs about the same as buying an aerodynamic helmet. While we don’t have helmet data, we know the power difference between the least and most aerodynamic helmets is 12W, and the difference between a non-aero helmet and an aero one could be even bigger. So, these two upgrades provide similar returns on investment in terms of cost versus power gain.

When upgrading from cheap low-profile aluminum wheels to higher-profile aerodynamic wheels, you gain about 5-6W, which is influenced by yaw angle, a complex factor we won’t dive into here. Aerodynamic wheels generally cost between £1,000 and £2,000, depending on specifications.

As mentioned in our previous tests, upgrading your tires and wheels gives you the best value for money. Start with the tires and helmet, and then consider other larger upgrades. Tires are especially important because they wear out over time, whereas helmets can wait until it's more cost-effective to replace them.

It’s also worth noting that the tire is the only upgrade in our investigation that’s directly related to the drivetrain. The faster you ride, the more important aerodynamic upgrades become due to air resistance, but at slower speeds, aerodynamics matter less.

  1. Do these benefits apply more to beginners or less experienced riders?

Cycling is a sport with diminishing returns, and tire upgrades fit this trend. The stronger you are or the faster you ride, the more important aerodynamics become, and the less significant rolling resistance is in terms of overcoming the total force required to maintain speed. We tested two speeds, which represent two reasonable situations, but due to the many variables involved, we can’t draw further conclusions.

  1. Can you choose tires based on ride feel, grip, or puncture resistance?

By switching to our test’s benchmark tire, you’ll clearly reduce rolling resistance, which will increase your speed. But tires aren’t just about minimizing rolling resistance. They are the only part of the bike that provides mechanical grip when cornering, which has a significant impact on the ride feel. You also need to ensure they offer acceptable puncture resistance and reasonable durability.

While rolling resistance affects speed, if your tire is too fast and you lose confidence in corners, that will also negatively impact your performance. We didn’t test grip, but based on personal experience, I can vouch for the GP5000 S TR’s excellent cornering performance, though I don’t have solid data to back it up.

In short, if you like a particular product but the test data today didn’t meet your expectations, don’t be discouraged, because today’s tests only represent a small but measurable part of a tire’s overall performance.

  1. Nothing is slower than a flat tire

We didn’t test grip, nor did we evaluate puncture resistance in this study. It might be tempting to install a Corsa Pro Speed tire for the best performance advantage, but if you’re not racing and just riding casually, I recommend being cautious. For everyday riding, puncture resistance is crucial. While tubeless tires have helped many avoid flats, nothing is slower or more frustrating than getting a flat and being stuck on the side of the road.

 

 Recommended Reading:

  • Professional Review: Which Road Bike Tire is the Fastest?
  • Professional Review: Which Road Bike Tire is the Fastest? Part 2
  • Wind Tunnel Showdown: Head-to-Head Comparison of 11 Super Bikes – Part 2
  • Wind Tunnel Showdown: 11 Super Cars Face-Off – Part 1
  • Beginner's Guide: A Complete Breakdown of Mainstream Road Bike Groupset Levels
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    Original Source: https://www.biketo.com/news/53743.html

     

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