What is a road bike? The basics explained

The anatomy of a road bicycle

What is a road bike?

Road bikes are bicycles designed to take you as far and as fast as your legs can manage. The road bike gets its name from the terrain it is designed to be used on – the road.

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At first glance, the road bike hasn’t changed a great deal over the years. Compared to a complex full-suspension mountain bike, it’s a traditional bicycle with a near identical silhouette to those raced 50 years ago.

Of course, there’s nothing traditional about the carbon fibre frames and electronic 24-speed drivetrains we see now on high-end machines. Modern bikes are faster, more comfortable and more technologically sophisticated than ever before.

While the tech has improved, the most important thing is still how the bike fits you. If you get that right at the start, everything else will be simple.

Read on for a full rundown of the fundamental components that make up a road bike.

Frame and fork

Road bike frame
The vast majority of road bike frames use the traditional two-triangle design.
Matthew Loveridge / Immediate Media

The frame is the heart of any bike, and road bike frames are usually aluminium or carbon, with steel and titanium used in more niche models.

Traditional road frames use a flat top-tube and a shorter seatpost, but compact geometry is now most common, with a sloping top tube to make a smaller, lighter frame and also improve the standover height. It’s very important that you buy the right size and shape frame for you and the type of riding you’ll be doing.

The forks on more expensive bikes are typically made from carbon, while cheaper models may use a combination of carbon and aluminium, aluminium only or steel.

Wheels and tyres

Front wheel
A low-profile rim brake road front wheel.
Matthew Loveridge / Immediate Media

Road bike wheels don’t have to be as robust as those of mountain bikes, so they tend to have fewer spokes and lighter rims. Aerodynamics are important, so the rims are sometimes deeper (depth refers to the height of the rim cross-section).

Traditionally, road rims were very narrow, but in recent years they’ve been getting wider as research shows this is more aerodynamic, increases tyre volume for a smoother ride and potentially leads to fewer flats.

Road bike tyres are also skinny, but not as skinny as they used to be because wider tyres are comfier and often faster in the real world.

25mm is a typical width for race-focused bikes, while more endurance-oriented machines might come with 28mm or 30mm tyres. In the past, 23s were common and some riders went as narrow as 18mm.

To minimise rolling resistance, road tyres usually have a slick or near-slick tread and run at high pressures of around 4.8 to 8 bar / 70 to 120psi.

Crankset (or chainset)

Ultegra crank and Di2 derailleur on blue road bike.
The crankset is the unit comprising pedal arms and chainrings.
Matthew Loveridge / Immediate Media

Road bikes usually use two chainrings, with most bikes coming equipped with ‘compact’ 50/34t cranks or ‘semi-compact’ 52/36t gearing where “t” is the number of teeth. The traditional ‘standard double’ had 53/39t rings, but that’s becoming less and less common.

Bikes with SRAM’s latest 12-speed AXS groupsets get 50/37t, 48/35t and 46/33t options to match the brand’s cassettes that start with a 10t cog rather than the more common 11t. (Remember: the gear gets harder as you increase the number of chainring teeth or decrease the number of cassette teeth.)

Triple (i.e. three-chainring) chainsets are still fitted to some cheaper bikes and give lots of range. These are becoming less common, with the lighter and simpler compact taking over and, thanks to the explosion in popularity of gravel and adventure bikes, there are now various ‘super-compact’ crank options on the market, with lower ratios such as 46/30t and 48/31t.

A further option is the simple 1× (pronounced “one-by”) crank with a single chainring.

These are relatively rare on pure road bikes, but are a much more practical option than they used to be thanks to the ever-wider-range cassettes offered by component manufacturers.

Cassette

Rear view of Force eTap AXS cassette and derailleur
The cassette is the assembly of sprockets mounted to the rear wheel.
Matthew Loveridge / Immediate Media

Road bikes use gears that are more tightly packed together to help you pedal at the ideal speed (pedal revolutions-per-minute is referred to as cadence).

Mid-range and high-end road bikes typically have 11 or 12 sprockets (referred to as 11- or 12-speed) while more affordable ones might have eight, nine or 10. The range of sprockets on a road cassette is typically something like 11-28t or 11-30t.

Derailleurs

Rear derailleur
The rear derailleur is mounted at the rear dropout of the frame.
Matthew Loveridge / Immediate Media

Derailleurs are the mechanisms that change gear, pushing the chain across the cassette sprockets and from one chainring to the other, controlled by the shifters.

Apart from those unusual road bikes with 1× gearing, most have front and rear derailleurs. The vast majority are moved via physical cables connected to the shifters, but electronic derailleurs are also available, with the major component makers (Shimano, SRAM and Campagnolo) all offering their own systems.

Shimano 105 R7000 groupset review, front derailleur
The front derailleur shifts the chain from one chainring to the other.
Jack Luke / Immediate Media

Handlebars and levers

Side view of Shimano R8070 levers.
Road levers combine shifting and braking into one, and are designed to fit drop bars only.
Matthew Loveridge / Immediate Media

Drop handlebars mark out a road bike, and offer a number of positions. The tops, with your hands either side of the stem, are used for steep climbs or cruising.

The hoods are the brake lever covers, and these provide a comfortable cruising position and good leverage for climbing out of the saddle.

The drops are the lower parts of the bar, used for a lower position at speed and greater control when descending.

Various bar widths and shapes are available to suit different tastes. The handlebar is attached to the top section of the fork (the steerer) by the stem.

Road levers combine shifting and braking controls into a single unit. While brake levers all operate on more or less the same principle (pull the lever, bike stops), shifting arrangements differ between component manufacturers.

Saddle and seatpost

Saddle and seatpost
The seatpost is raised or lowered to suit different rider leg lengths.
Matthew Loveridge / Immediate Media

As you would expect, these parts have a big impact on the comfort of your ride. For road bikes especially, comfort is more dependent on correct setup than it is on having lots of padding.

Road saddles are generally narrow and sparsely padded. They look very uncomfortable, and do take some getting used to, but are actually better than soft saddles for long rides because they support you where you need it most, and don’t compress nerves and delicate soft tissues.

Saddles come in a variety of shapes, with no single design working for everyone. Some models are available in multiple widths to suit a range of sit bone widths.

Brakes

Rim brake
Rim brakes are still widely used on road bikes and can provide excellent performance.
Matthew Loveridge / Immediate Media

Road bikes use either rim brakes (dual-pivot calipers) that clamp the wheel rims themselves, or disc brakes that grab disc rotors mounted to the hubs.

Disc brakes are generally considered superior, particularly in wet weather, but a good set of rim brakes is perfectly adequate for most riding.

Rear SRAM road disc brake
Disc brakes offer more consistent performance in wet weather, but are heavier and more expensive.
Matthew Loveridge / Immediate Media

I want a road bike, so what now?

Cyclist riding Giant Defy Advanced Pro 2 through Spanish mountains
Road bikes are enormous fun to ride – you’re in for a treat if you’ve never tried one before.
Russell Burton

A decent entry-level road bike is a joy to ride and need not be eye-wateringly expensive.

Head over to our road bike buyer’s guide for everything you need to know when it comes to choosing your first road bike, and if you want to geek out about components, our complete guide to road bike groupsets is the place to be.

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If you already have an idea what you’re looking for, check out the best cheap road bikes and the best road bikes under £1,000.