What efficiency means on a bike
Efficiency is the share of your effort that ends up moving you forward. Not all of it does. Some is lost inside your own body as heat, some in the bike’s moving parts, some in squashing tyres against the road, and a large part in pushing air out of the way. Because the numbers differ for every rider and bike, it is more useful to understand the pattern than to chase exact percentages.
A bicycle is generally a very efficient machine compared with most ways of travelling, which is part of why it is so pleasant for everyday trips. The pieces that are left to improve are mostly small, and most of them are within a rider’s control.
The drivetrain
Your pedal force passes through the cranks, the chain, the sprockets and the rear hub before it reaches the tyre. Each of those steps loses a little to friction. In a clean, well-lubricated, correctly adjusted drivetrain, the loss is generally a small fraction of the power going in. A dirty, dry, rusty or badly aligned one can lose more and also wear out faster.
How you use the gears matters too. Running the chain at extreme angles, such as the big front ring with the biggest rear sprocket, adds friction and wear, which is why cross-chaining is worth avoiding where you can. Keeping the chain clean and lightly lubricated is also one of the easiest wins, and the basics of chain cleaning are quick to learn. Follow the lubricant maker’s instructions and see a bike shop for adjustments or worn parts.
Tyres and the road
Tyres lose energy as they flex against the surface. Soft, under-inflated tyres generally flex more and roll less freely. Tyres inflated far above what suits the surface can feel harsh and may bounce over bumps, which can waste energy too. The best pressure depends on the tyre, rim, load and surface, so use the range printed on the tyre and the manufacturer’s advice instead of a rule of thumb.
A quick tyre inspection before riding helps with both efficiency and safety, because cuts, embedded debris or low pressure all make the bike harder to ride. Choose tyres that suit where you actually ride. Smooth tyres suit pavement, while chunkier tread helps on loose ground but usually costs a little on smooth roads.
Air
At lower speeds air is a small cost. As speed rises, it takes over as the largest cost, because drag grows faster than speed does. That is why two riders going the same pace can feel very different if one is in a headwind or sitting bolt upright and the other is sheltered or lower. Body position, clothing and bike shape all play a part in that, but the efficiency view is simple: the faster you ride, the more of your effort goes into the air.
Habits that generally waste less energy
Efficiency is not only about equipment. Several riding habits tend to help:
- Ride steadily. Surges followed by braking spend effort and then throw the speed away as heat in the brakes. Looking ahead and easing off early often saves both.
- Choose a comfortable cadence. Very low cadence at high force, or very high cadence spinning with little resistance, both feel inefficient to many people. A moderate, comfortable pedalling cadence suits most riders, though the best rate differs between individuals.
- Shift early. Changing gear before a climb or stop, rather than in the middle of hard effort, is gentler on the drivetrain and on your legs.
- Pace your effort. Starting a long ride too hard usually costs more later, so pacing effort over the whole distance tends to give a better result than a fast start.
- Pedal smoothly. A smooth pedal stroke spreads the work evenly and avoids jerky loads.
- Stay relaxed. Gripping the bars tightly or holding tension in your shoulders wastes energy and tires you.
Weight and loads
Extra weight costs most on climbs and when starting from a stop. On flat roads at steady speed it matters much less, since rolling resistance rises only modestly with mass. A little less luggage can help, but removing safety equipment, such as lights, to save grams is not a good trade.
Realistic expectations
It is easy to spend money chasing small gains. In most cases the sensible steps are the cheap ones: keep the chain clean, keep the tyres in good shape, make sure the bike fits, and ride smoothly. Everyone’s body and bike are different, so results vary, and nobody should expect a guaranteed gain from any single change. If you have health concerns about physical effort, speak to a doctor before increasing how hard you ride.