It takes practice to become a perfect pedaler. One pedaling drill you can do on any ride with downhills is spinning the pedals as quickly as possible as you accelerate down slopes. To do this correctly, leave the bike in a gear that's too easy, one that forces you to fan the pedals to keep up with the speed of the bike. Your goal is to rev your legs as quickly as you can while remaining seated. At first, you'll probably bounce a lot on the seat. But, with practice, you should be able to stay in the seat and maintain a calm upper body even though your legs are spinning at supersonic speed. If you do this drill a lot, your pedaling speed and efficiency will quickly improve.
If you're willing to purchase a handy piece of cycling equipment, a great way to smooth your spin is to train indoors on rollers. Rollers consist of a frame with three spinning drums (one for the front wheel, two for the rear), with a rubber belt connecting the front drum to one of the rear drums. You put your bike on the rollers and start to pedal and you can balance and ride just like you do spinning down the road outside. Most rollers have optional equipment that allows increasing resistance because there isn't much drag from just the roller unit itself.
Develop A Winning Spin
Rollers require above-average balance and exaggerate any pedaling flaws. With enough practice, you naturally eliminate pedaling problems because they're so noticeable. And, when that happens, you ride faster with the same effort because your pedaling becomes more efficient and more of your energy goes into driving the bike.
Think they're just for roadies? Actually, the concentration and spin improvement builds confidence and the ability to ride tight singletrack, maintain your balance in slick mud and skirt narrow ledges high in the mountains, too.
A classic cycling trick to improve pedaling technique is riding a fixed-gear bike in the winter. Constant pedaling is required because you can't coast. And you must accelerate pedal speed on downhills because you can't shift. These factors combine to smooth your pedal stroke and force you to spin complete circles. Pick ride routes that avoid steep climbs and descents. You don't need to buy a new bike to pull this one off, either. A threaded-hub wheel, a track cog, a BMX chain and a few axle spacing tricks can turn your regular bike into a fixed-gear rig. We can help with the conversion.
Try The Track
If you're one of the privileged few who can ride a track bike at a velodrome (a circular, banked track for cycling), you'll reap the same benefits as training on a fixed-gear bike. Never ride a track bike on the road, though. Brakes are a must on the street, and track bikes don't have them.