Having a well-fitting bicycle is vital for two reasons. Firstly, to fully enjoy your time in the saddle without creating injuries or falling into any bad cycling habits. And secondly, to maximise your power output. Setting your position does take a little bit of time, but it will provide a solid basis from which you can adjust things as your riding develops.
Before even buying a road bike, though, it’s crucial to have some idea about what size you’ll need. That’s not quite as easy as it sounds, because different road bike brands can use different ways to measure their bikes. Some use the traditional method of seat tube length: where a ‘57cm’ frame would refer to the distance between centre of bottom bracket and top of seat tube. Others use effective horizontal top tube length: where a ‘57cm’ frame would refer to the distance between centre of seat tube cross-section and centre of head tube cross-section. Others use strange hybrid systems.
Once you know what effective horizontal top tube length you need, it’s probably best you use that as your reference size and consult the geometry charts you’ll find on bike manufacturers’ websites to choose the model that suits you most closely. Then, to get your bike to fit you absolutely perfectly will require a process of subtle tweaking. However, follow the pointers below and you will quickly come close to having a well-fitting bike.
Comfort on a road bike, especially when it comes to long rides, is all about reach. There’s a very simple way to see if you are too stretched or too hunched up: get on the bike, take hold of the bottom of the drop handlebars and look down. If the bars are set correctly, you shouldn’t be able to see the front wheel hub because the bars will be in the way. If you can see the hub in front of the handlebars, you’ll need a longer stem; if the hub’s behind the bars, you’ll need a shorter stem.
Handlebar height is a much more personal preference. If you’re new to drop-handlebar road bikes you may feel more comfortable being slightly higher, whereas experienced riders might appreciate the added speed that comes with being lower. In any case, handlebar height is an easy thing to adjust by altering the position of stem and spaces on the steerer tube.
Having the correct saddle height is often seen as the most important thing on a new bike — setting it correctly will fully utilise all the power generated by your legs and prevent injury. According to triple Tour de France winner Greg LeMond, one way to do that is to measure your inside leg from crotch to floor when not wearing shoes, then multiply this by 0.883. The resulting figure provides a rough idea of your ideal measurement from the centre of the bottom bracket to the top of the saddle.
Once you’ve set your saddle height using the ‘0.883 of inside leg’ formula, you can hone its position further. Ask a helper to watch from the side while you pedal on a turbo-trainer (or pedal backwards while stationary). Ideally, with your foot at the bottom of its stroke you want to have a very slight bend at the knee — it must not be locked straight. Then ask your helper to watch from behind. If your hips are rocking from side to side, the saddle is too high — ideally you want your hips stay nice and level — however, having the saddle a fraction too high is better than having it too low.
Ultimately, though, great bike fit is about personal comfort, so do experiment a little. Adjust things only by very small increments each time and see what works for you.