As you might guess, geometry refers to the angles and lengths of tubing that make up a bike frame. Some key factors that determine how the bike rides and fits are reach, fork rake, head angle and stack height.
Taking all of these factors into account, most road bikes can be classified as either ‘race bikes’ or ‘endurance bikes’ with the latter also known as sportive or Gran Fondo bikes.
Typically, race bikes will feature long reach and short stack height. These are the kind of geometries that you’ll see in the Tour de France and other pro road races.
The race designation doesn’t necessarily mean the bike must be light and expensive, but the frames will be built for stiffness to maximise pedalling efficiency, and the geometry will allow you to flatten your back for a more aerodynamic position.
On the other hand, for a relatively casual rider wanting to cover long distances, endurance bikes typically prioritise comfort over speed.
The material construction is optimised to absorb vibrations from the road — they are compliant, in cycling vernacular — and the geometry will usually allow the rider to sit a bit more upright than they would on a race bike. It’s a slower position, but one you’ll be comfortable in for hours and hours.
Both main types of road bike typically come with handlebars featuring distinctively hooked ‘drops’. These give the rider three options for hand position:
On the tops — sitting upright and opening the chest for easier breathing on steep climbs
On the hoods — a comfortable position that still lets you control the brakes and gears
On the drops — a fast position that gets you out of the wind and gives the best control over the brakes.
Speaking of brakes and gears, you won’t get far into your bike-buying experience before someone starts talking at you about groupsets.
These are collections of compatible components grouped together under a single name at a roughly comparable price point, ranging from very reasonable to horrifyingly expensive.
They include the brakes, shifters, chainrings, cranks, cassette, rear derailleur and front derailleur. If that last bit just sounded like a list of familiar sounding words that make no sense to you in a bike context, allow us to explain:
Shifters are the combined brake and gear levers mounted to the handlebars.
Chainrings are the big sprockets that drive the chain, and the cranks are the arms that drive the chainrings. Collectively, rings and cranks are known as a chainset, or crankset.
Cassette and derailleurs
The cassette is a collection of sprockets at the rear of the bike, and the derailleurs are the mechanisms — sometimes known as ‘mechs’ — that change gear by shifting the chain between the sprockets at front and rear.
There’s a very clearly defined hierarchy among groupsets, with the most common Shimano sets starting at the bottom with Claris, then moving up to Sora, Tiagra, 105, Ultegra and finally the pro-level Dura-Ace.
Campagnolo and SRAM also make groupsets, but they’re currently somewhat of a rarity on entry-level bikes.
Aside from some incremental refinements, the major differences between high- and low-end groupsets are the number of speeds, a little bit of weight and a LOT of cost.
Honestly, compared with equivalent kit from just a few years ago, Shimano’s lower end groupsets are all really, really good, and Tiagra and above are better described as ‘amazing’.
By ‘Speeds’ we mean the number of sprockets at the rear of the bike rather than total number of gears on the bike. In recent years, component manufacturers have been trending towards increasing this number as much as possible while using only two chainrings at the front.
Many respectable very-low-budget bikes still use a triple chainset and eight speeds, but a double paired with a 9-, 10- or 11-speed cassette is generally a much better option.
Modern rear derailleurs can handle a huge range of sprocket sizes within a single cassette, so a double chainset and big, wide 11 to 32 or even 34 tooth cassette will give you all the range you need, and be much easier to maintain and use than a triple!
Rim vs. disc brakes
That’s the complicated bit over, now onto the controversial stuff! Disc brakes are becoming more and more commonplace on road bikes, and they’re starting to creep into the lower price brackets.
While a conventional ‘rim brake’ uses levers and cables to squeeze the wheel itself, disc brakes press on a dedicated rotor fixed to the wheel hub, like on a car. Cheaper disc brakes use cable actuation, but the really good stuff happens when you bring hydraulics into the mix!
Hydraulic disc brakes turn a very small effort from a single finger into a brutally effective amount of stopping power. You still need to be careful to avoid locking up your wheels and skidding, but it’s a lot easier to push your braking as far as possible before that happens.
They’re also much more consistent and predictable in the wet than rim brakes.
Some established riders — including many professionals — argue that you don’t need disc brakes on a road bike, and they’re technically right.
They’re more expensive and heavier than traditional brakes, and slightly harder to look after. Budget-conscious riders may still be better off with rim brakes, though if performance was the only consideration we’d pick discs every time, especially if we were going to be riding in urban areas or in the wet.
Carbon and alloy
The vast majority of road bike frames are built from carbon fibre or some variation of aluminium alloy. Carbon is relatively affordable these days — with prices for a complete bike starting at around £800 — and is often considered to be more compliant and lighter than alloy.
That said, many of today’s alloy frames are more than a match for the lowest-cost carbon frames when it comes to ride quality. They’re also more durable and crash-proof than their plasticky cousins, and often not much heavier.
Alloy frames are usually cheaper to produce, which means you can expect a nicer spec than on a similarly priced carbon bike.
Bikes are usually measured from the middle of the chainset up to the top of the seat tube, so your inside leg measurement is usually the most important factor in correct sizing. People come in all shapes and sizes though, so if you’re an anatomical anomaly then you might need to consult with an expert.
Most brands classify sizes in letters from XS to XL, or numerically in centimetres. A ‘medium’ frame would typically correspond to a 54cm, but there is quite a bit of variation between manufacturers.
Once you’ve picked your bike and found the right size, you’re going to want to do a fit. Very distinct from sizing, this process involves adjusting the saddle, pedals and handlebars — collectively known as your ‘contact points’ — so that you’ll be as comfortable and efficient as possible when riding.
Most bricks and mortar bike shops will sort you out with a basic fit as part of your purchase, or you can arrange one separately. They’re highly recommended for all riders, and are absolutely essential if you’ve ever had a back, neck or knee injury.
A very frequent source of confusion, the ironically named ‘clipless pedals’ are pedals you clip your shoes into!
The name originates from the days when buckle-up toe-clips were in popular use among enthusiasts and racers, and the new clipless pedals did away with these.
We strongly recommend clipless for anyone who’ll be riding for more than a few miles at a time. Most riders find them to be far more efficient than flat pedals — because they allow you to pedal in smooth, circular strokes — and are far easier and safer to use than toe-clips.
Most new bikes are sold with terrible flat pedals, sometimes with toe clips, so you should budget for a set of clipless and compatible shoes at the same time as buying your new bike.