About Acceleration

John Allen

Smooth, quick acceleration offers a safety advantage – to get across an intersection before cross traffic arrives, and in many other situations.

Acceleration requires only a short burst of power. Your weight, standing on the pedals, gets you started from a stop. The action is like that of climbing stairs, and if you are strong enough to climb stairs, you can accelerate briskly. There’s no need to be in peak form to accomplish this.

Brisk acceleration is needed most frequently in stop-and-go urban riding, but it is useful whenever you cross a road in a gap in traffic, or pick up speed as you crest a hill.

How you slow down has a major effect on how you speed up. All too often, I see cyclists struggling to accelerate in a too-high gear. Keep your cadence up, downshifting repeatedly as you slow down. Then you will always be in the right gear to pick up speed when that becomes possible, whether or not you come to a complete stop.

Does the law require you to come to a complete stop at a traffic light? No, the law requires only that you not cross the stop line before the intersection. If you slow to a crawl before reaching the intersection, you can keep both feet on the pedals: skill at a "slow race" can help you be faster! If you do have to come to a complete stop, stop a few feet short of the intersection so you can start pedaling when you see that the light is about to change, and creep forward, ready to sprint. Photo by Keri Caffrey.

An important advantage of an internal-gear hub is that you can downshift at a stop, so an unexpected quick slowdown or stop doesn’t get you stuck in a high gear. This advantage comes with the disadvantage of fewer drive ratios – except with a couple of very high-end products – but even with these, weight is somewhat higher and efficiency lower; also, wheel removal and replacement are more complicated than with derailleurs. All in all, I prefer an internal-gear hub with 5 to 8 speeds on a bicycle I ride in the city, derailleurs elsewhere.

Still, with derailleurs, as long as you have clipless pedals or toe clips and straps, and you are not carrying heavy baggage on the rear of the bicycle, you can lift the rear wheel with one hand on the back of the saddle, shift down with the other hand, and spin the cranks with one foot. Usually, you want the shifting hand to be your right hand, so you are shifting the rear derailleur. But this is only for when you are stuck in a high gear. Preferably, downshift before stopping.

Downshifting is easiest with shifters on the handlebar, as has been usual for decades now. (Older bicycles can be retrofitted too). With twist shifters or bar-end shifters, a single sweep will take you from the highest to the lowest gear, so you can shift the rear derailleur or hub gear with the right hand while signaling or braking lightly with the left hand. Combination brake-lever-shifter assemblies let you brake with both hands while shifting, but they downshift only one or two steps at a time.

In the best gear to start from a stop, a pedal thrust, standing out of the saddle, will barely hop the front wheel off the road. Lower gears are useful for long climbs, but won’t get you going any faster from a stop. It helps for the starting gear to be easy to find. I like to have it use the largest rear sprocket, so I know that I have reached it when the rear derailleur won’t shift down any further.  

A good starting gear is about 35 to 40 gear inches (2.8 to 3.2 meters development). A 50-tooth chainwheel and 34-tooth largest rear sprocket will give you a 35 to 40-inch starting gear on a bicycle with the usual wheel size. Using the large-large combination is heresy due to chain angle, but you won’t be in that gear for long, and it helps to find that starting gear easily when shifting down. You can get a starting gear in the same range with a 38-tooth chainwheel and 28-tooth sprocket, give or take. This combination typically uses the middle chainwheel and largest sprocket on a “mountain bike triple” setup, but there is no law against installing one on a road bike.

As you ride, you have plenty of opportunities to get used to your shifters and practice handlebar coordination and gear choice.

Relatively wide ratios in the lower gears (larger sprockets) work best, so you don't have to shift every couple of pedal strokes at low speeds. These days, the “more is better” syndrome has increased the number of rear sprockets to the extent that you may have to skip over gears because the steps are too small. And with one of the new 1x systems that has a single chainwheel and a pie-plate sized largest sprocket, your cadence as you soft-pedal provides the only clue that you are in the best gear for acceleration.

I don’t have to tell most CRW members this, but to start from a foot-down stop, you stand over the bicycle in front of the saddle with one foot on the ground and the other foot already on its pedal, forward and high. Your first pedal stroke will get you into a standing position to pedal. Practice till it’s second nature to get the second foot clipped in quickly. After your first few stomps, as the cadence rises, you transition to seated pedaling and then shift up through the gears to maintain a high cadence. Work is force times distance, and so faster pedaling accelerates you quicker, as long as it isn’t so fast that your feet can’t keep up.

At a stop sign, you are required by law to come to a complete stop, whether or not this is actually necessary. What is important is to be able to stop, and for your actions to communicate to drivers in cross traffic that you are yielding right of way. This often requires a full stop. To meet the letter of the law, though, it is fairly easy to come to a full stop and immediately restart without placing a foot down, by shifting your weight forward, then backward. – I’ve heard this called the “genuflection stop.” With practice, some cyclists learn to stay balanced at a full stop – a track stand – though on a freewheeling bicycle only if the front wheel is turned uphill. I’ll look the other way if you only slow to a crawl.

I hope this is helpful, but I will decline invitations to drag races.

John Allen is the CRW Safety Coordinator.