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March 2019

About acceleration – pick up speed quickly when you need to

by John Allen

Bicyclists don’t accelerate as fast as most motor vehicles, but many bicyclists could do better. Smooth, quick acceleration is not only for racers. It offers a safety advantage – for example, to get across an intersection in a short gap in the cross traffic, to pass a double-parked car before traffic from behind catches up, or to outrun a chasing dog.

And now I'll bet I've got you thinking: "oh no, can see the next line coming: Thighs of Steel --Ten Helpful Hints!, just like in That Magazine…

Relax, I'm not one for bodybuilding pep talks. Despite my rather advanced age, and training which is which more fitful than fitness-oriented, I regularly outpace younger bicyclists for the first 100 feet or so when cross traffic clears. I owe this moderate success to riding technique and bicycle setup. I’m going to tell you how I do it, so you can accelerate quicker than I do.

Fitness determines cruising speed, but acceleration requires only a short burst of power, not a major, sustained effort. Short of a Herculean effort that involves pulling up on the handlebars, your weight, standing on the pedals, gets you started from a stop. (If you ride a recumbent bicycle, you must start in a lower gear and spin up from a stop, but it's still only a short sprint.)

All too often, I see cyclists struggling to accelerate in a high gear. The bicycle may not have low gears – typical of many road-racing bicycles -- or the cyclist may not be using the gears well.

At the start of a ride, or when you didn’t have time to shift down before stopping, it is possible to lift the rear end of the bicycle with one hand, shift down with the other hand, and spin the cranks with one foot -- as long as you have clipless pedals or toe clips and straps, and there isn't heavy baggage on the rear of the bicycle. Usually, you want the foot on the ground to be the right foot and the shifting hand to be your right hand, so you are shifting the rear derailleur. But preferably, downshift before stopping.

Your starting gear should be just low enough that your strongest pedal thrust, standing out of the saddle, barely hops the front wheel off the road. Lower gears than that are useful for long climbs, but they won’t get you going any faster from a stop. It is important that your bike shift easily and quickly, and if it doesn't, get it adjusted.

A good starting gear is about 35 to 40 gear inches (3 to 6 meters development). If this gear uses the largest rear sprocket, you can shift the rear derailleur to the end of its travel entirely by feel. Using the large-large combination is heresy due to chain angle, but you won’t be in that gear for more than a few pedal strokes, and it helps to find that starting gear easily when shifting down. 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. This combination uses a “mountain bike” cassette and rear derailleur -- also entirely possible on a road bike – check mine out -- but you can also get a starting gear in the same range with a 38- to 40 tooth chainwheel and 28-tooth sprocket. You will in that case probably benefit from a triple crankset, and then this is the middle chainwheel.

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.

To start from a foot-on-the-ground 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. If you don’t, then wait to clip in until you have reached cruising speed. 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.

You won’t always be accelerating from a complete stop. A red traffic signal may change to green before you reach the intersection. Or, the traffic situation ahead of you might open up. So, as you slow down, keep the pedals turning, and shift down repeatedly so you are always in the gear which would work best for acceleration. 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.

Is there a law that requires 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, ready to restart: skill at a "slow race" can help you be faster! If you still have to come to a complete stop, stop a few feet short of the intersection so you can get both feet on the pedals when you see that the light is about to change, and creep forward, ready to sprint.

Stop signs are more difficult, because you are required by law to come to a complete stop, whether or not this is actually necessary. It is fairly easy to come to a full stop and immediately restart without placing a foot down – 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 like bar-end shifters – quick to shift down through multiple gears at once. Their position will inform you whether the rear derailleur is nearing the high or low end of the cassette, and which chainwheel you are using. Grip shifters, dual-trigger shifters and brake-lever shifters tell you what gear the bicycle is in only at the extremes ends of their range.

The advice so far has assumed that your bicycle has derailleur gears, but for nimbleness in urban traffic, an internally-geared hub is better. It has a bit more power loss, and generally wider steps, but importantly, it can shift when the bicycle is stopped or moving very slowly, so you need never get stuck in the wrong gear. Hubs with 5 or fewer speeds should be set up so the starting gear is their lowest gear. If a hub has more than 5 speeds, the starting gear might be second gear or higher, with lower gears for steep climbs. Often, internally-geared bicycles are overgeared, and so it may be to your advantage to install a larger rear sprocket or smaller chainring. Information on setting up internal-gear hubs is at https://sheldonbrown.com/internal-gears.html

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

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