Not sure what size bike you need? Our cycling blogger takes you through the essential information you will need to know when choosing your new bike.
Finding the correct-sized bike is a minefield. There are simply far too many variables and far too much deviation amongst bike manufacturers. The first tip, then, is to make sure you try the bike properly before buying; internet purchases are not the way to go.
Bicycles are usually sized according to the length of the seat tube, but this can mean from the centre of the bottom bracket to either the top of the seat tube, the centre of horizontal extension of the top tube, or anything in between! What’s more, the bottom bracket is not always the same height above the ground, so even two bikes of the same size, measured in the same way, might not both be a good fit.
A good guide is to take your inside leg measurement, and compare that to the ‘stand-over’ height of the bike (i.e. from the ground to the top of the top tube), since this takes into account the length of the seat tube as well as its height above the ground. Ideally, you should have around a 1 inch gap above the top tube (for road bikes).
The stand-over height is important to get right because it cannot be adjusted once you have purchased the bike. But the other bike dimensions are also vital to finding the best riding position.
Although cycling is generally gentle on the body compared with other sports (assuming you remain upright!), many hours in the saddle can accentuate even small tensions in the body and cause injuries. Needless to say, this is devastating for the professional or club rider, but can also remove the joy of cycling for keen amateurs and occasional cyclists.
Nothing beats a professional bike fitting, but if you are looking for a rough guide, your body should incline forwards around 45 degrees, your legs should be 35 degrees off straight when fully extended, and your arms just 15 degrees. Pro riders will maintain a lower, more aerodynamic position, and the measurements will differ for different body types.
The default setup of your bike is unlikely to fit your required dimensions, but you can make adjustments to create your ideal riding position. Your body and arm position can be adjusted by changing the length of the stem. Most bikes come with a stem of around 10cm, but an adjustment of even a few centimetres can make a huge difference.
Your leg position can be varied by adjusting the saddle (both the height and the forward/backward position). Many inexperienced cyclists have their saddle far too low, making their riding much less efficient. But raising the saddle too far can also be hazardous; knee injuries commonly arise from overextension due to a high saddle height.
Albeit not an injury-risk, another factor that can make a huge difference to the enjoyment (and the speed) of your ride is tyre pressure. To avoid the frustration of a heavy-legged slog, be sure to make pumping up your tyres to the correct pressure a central part of your pre-ride routine.
Why does tyre pressure matter so much? In a nutshell, lower tyre pressure increases rolling resistance. This is because tyres at lower pressure deform more, creating a greater contact area between the tyre and the road, which means more friction and therefore more wasted energy. So keep those tyres pumped up!