A gravel bike is not a road bike or a mountain bike, and although at first glance it can be confusing, it is not even a cyclocross bike. So what is a gravel bike then? Here we list some of the main features.
Although the term itself can be self explanatory, in the mind of a seasoned cyclist or even someone just starting to explore the pleasures of the two-wheeled world, we need to elaborate a little more than just this simple term.
Gravel can be said to be synonymous with open roads, rolling countryside away from traffic, immersed in nature.
And yet we can even say that there is a connection to historic, heroic cycling. Cycling made of dust, mud and climbs that had little to do with the asphalt roads of today. To give you some idea of how hard things were, as French cyclist Octave Lapize crossed the finish line after having conquered the legendary Tourmalet climb for the first time in the 1910 Tour de France, he cursed the race organiser with a legendary cry of "You are murderers! Yes, murderers!"
To Octave a decent gravel bike would have come in very very handy. Let's take a look, and find out why.
At the soul of every bike is the frame. Gravel bikes can be said to have more than one type, even to the point that every cyclist - regardless of fitness level or experience - can find his perfect match. Frames can be constructed out of steel or aluminum, in carbon up to the finest titanium. The choice of material in some cases can be a question of survival. If we are planning on leaving from home to go on a solo adventure ride or to explore places that seemingly have little to do with bicycles and the riding of them, steel can be a precious ally that is easily repaired in the unthinkable event of a breakage.
Carbon, on the other hand, should be the first choice if we place weight and the desire to ride a versatile gravel bike as a priority. Typically these frames are used on gravel bikes that are found in the backroad or all road segment of gravel bikes. Frames that provide a less adventure style of riding, and are more orientated towards a endurance/granfondo road bike.
Beyond the type of material used, it is the geometry of the gravel bike that makes the real difference. The stack is greater at the expense of a more contained reach compared to a road or cyclocross bike. This allows a higher position of the rider, giving a more relaxed comfortable ride for those long rides. A set-up that allows you to adopt a higher head tube and a bottom bracket shell with a lower center of gravity, which translates into a greater BB drop, a characteristic of the mountain bike world.
The frame and fork of a gravel bike also permit the fitting of accessories such as an additional bottle cage, front and rear bags, frame and saddle bags, a handlebar bag, etc.
Many years have passed since the International Cycling Union (UCI) decided to place a maximum tyre width rule of 33mm to be used during their cyclocross races. This new rule annoyed many riders who were used to racing with 34mm or 35mm tyres depending on the race conditions. However, every cloud has a silver lining, as this rule, combined with the growth of long-distance gravel racing in the United States in the early 2000s, had a undeniable contribution towards the development of bikes capable of fitting a wide range of tyre widths. Frames were able to utilise from 28mm to 45mm tyres and beyond. These multiple choices permitted bike riders to easily tackle tarmac roads and technical tracks with the same bike. A versatility that became even more impressive when we add the possibility of using a 28'' wheel or alternatively a 27,5 wheel.
Disc brakes and wheel hubs handed down from the cyclocross and Mountain Bike XC world allow for strong performance braking even in the most adverse of weather conditions with wet and muddy surfaces. The use of hubs with thru-axles also contributes to greater structural wheel strength and stiffness.
The tubeless tyre setup also arrives courtesy of the Mountain Bike world. The wheels can be used without an inner tube by fitting a correct width tubeless rim tape, a tubeless specific tyre and rim. With the addition of an anti-punture liquid specific for tubeless tyres, any small leaks or holes are filled by the liquid thus repairing and limiting air leakages in the event of a puncture. When done correctly this setup guarantees a watertight wheel. The advantages translate into riding comfort, due to the lower tyre pressures, and less chance of "pinching" as if we were using an inner tube. In some cases, you only notice that you have punctured when you lean the bike against the wall and notice bubbles of tyre liquid.
The handlebar is another key component for the gravel bike. Here, too, the possibility of choice is impressive. We go from carbon or aluminum handlebars that follow the similar form of the classic road bike handlebar up to the bell-shaped or cow horn handlebars that have open drop angles of up to 25°. A solution that improves handling on bumpy slippery road conditions. These bars also permit the brake levers to be mounted with the hoods pointing inwards. This set-up allows you to grip the levers with a perfect alignment of the forearm with respect to the axis of the hand.
A curious side-note: search for a picture that shows what type of handlebar Octave Lapize used on his bike at the 1910 Tour de France…