The Best Cycling Tires Are Like A Three Legged Stool
Which bike tires are best? What are the fastest bike tires?
Over the years we’ve done a lot of work with tires. I’ve learned that there are three key elements that make the best and fastest tires for cyclists, which I compare to a three legged stool. The three legs together provide support and stability, but if you remove one or two, you are left with an unstable stool.
The Three Legs
The three key elements of a great tire are:
- Rolling Resistance
I’ve seen many tires that have incredible rolling resistance, but are terrible aerodynamically and have the durability of rice paper. I’ve also seen incredibly durable tires that have great aerodynamics, but have such terrible rolling resistance the other two elements are irrelevant.
Let’s look at each leg in more detail.
Leg 1 – Aerodynamics
We’ve studied numerous tires in the wind tunnel. An aerodynamically great tire:
Is aero in a yaw angle range that cyclists experience. In 2015, we collected more than 100,000 data points and found the yaw angles cyclists undergo while riding. You want a tire to be aero in this range. If it’s aero outside of this range, it really doesn’t matter. For example, at 90 degrees, the tire is extremely aero but since a rider rarely experiences 90 degrees of yaw, there is no aerodynamic benefit.
Allows air flow to reattach quickly after the air flow detaches and becomes turbulent. This is a bit complex. When air hits a tire straight on, the yaw angle is considered to be 0 degrees. If air flow hits a tire directly from the side, the yaw angle is considered 90 degrees.
To test in a wind tunnel, a tire is swept over a range of yaw angles, generally -20 to +20 degrees of yaw, since these are generally the angles a cyclist experiences on the road. When you do this the air starts detached, and is turbulent. Turbulence is not a good thing for aerodynamics because it rapidly increases the drag, thus slowing you down. At a certain yaw angle, the air reattaches to the tire and becomes laminar, or travels smoothly again. Laminar flow is a good thing for aerodynamics because it reduces the drag, making you faster. This is an extremely simplified explanation of air flow but meant to give you a general idea for understanding the implication for tires.
At 0 degrees during the sweep, the angle is closed and then you begin opening the angle again. This means the air will detach again at some point. You may guess it would detach at the same point it reattached but that is not the case. Generally, it is easier to keep air attached than it is to reattach. The air actually detaches at a greater yaw than when it reattaches. The difference in these angles is key. Many tires hold air flow well once attached, but are terrible at reattaching. This is important because in the real world, air attaches and detaches often. Therefore, you want a tire that is “sticky” and will allow air to be laminar most of the time.
Leg 2 – Rolling Resistance
Rolling resistance is the amount of energy that is consumed by a tire as it rolls. If getting faster is the goal, increasing your watt-output efficiency is key. With high rolling resistance, the watts that you put into the pedals are absorbed by the tire rather than moving you forward. When you lower your rolling resistance, the watts you put in are used to propel you forward, making you faster. If you set up your tires and tire pressure correctly, rolling resistance generally has a constant value, so a tire with low rolling resistance allows you to maximize your output to move you forward. For more on managing tire pressure and why it’s important, check out our article on tire pressure.
Leg 3 – Durability
Cyclists seem to be in one of two camps when it comes to durability—it’s either very important or not even considered. Many cyclists are set on riding a tire that “doesn’t flat,” and others focus solely on the aerodynamics. While not flatting sounds good, it’s often accompanied by poor rolling resistance. Our general recommendation when it comes to durability is this:
Durability needs to be in the middle. Rubber, tread, casing construction, and a possible protection layer create the durability of a tire. Tire engineers are the ones that construct the balance within all the elements to determine how durable a tire is. You can have extremely durable tires made of really hard rubber that will not even think about flatting when you hit a rock, or tires made from silk that have extremely low rolling resistance that flat when they see a pebble in the distance (an exaggeration, but you get the picture). We look for a tire that is in the middle—one that can withstand bumps in the road and has a lower rolling resistance.
Our Pick For The Best Road Bike Tires Money Can Buy
Hands down, our recommendation for “stable stool” tires are the Continental GP 5000 and the Continental GP 5000 S TR. Continental has struck gold with these tires and their predecessor, the Continental GP 4000 S II. Yes, there are tires with lower rolling resistance like the Vittoria Corsa Speed G+ 2.0 (TLR), but the aerodynamics and durability are poor. You can also find a bomb-proof tire like the Continental Gator Skin that has surprisingly good aerodynamics, but the rolling resistance is so bad it kills the tire’s performance. Based on our research, our advice is to choose a Continental GP 5000 (tubes) or the Continental GP 5000 S TR (tubeless), set your pressure using our tire pressure charts, then forget about it. Following this advice can save you more than 100 watts, or 10+ minutes on an Ironman or Century.