SEACOAST BY BIKE

Back in the good old days bikes had two different sized wheels. Then came the two wheeler connected by a chain. Shifting is like changing the size of the wheel to optimize effort and maximize speed. But when and how to shift? The more you know about the process, the Great Balkini says, the shiftier you get. On a bike, that's a good thing.

ABOUT the Great Balkini

When to shift a bike is a function of terrain and how well the motor feels at any given moment. Specific advice is therefore impossible, but some basic facts will help sort it all out. A road bike has anywhere between 10 and 30 gear ratios romantically known as speeds. The speed is you.

For the developing rider just three or four speeds are useful and the rest either overlap, or are so close it does not matter. Don’t feel cheated. The bike has a thousand other parts, and an extra sprocket or two that provide a few more speeds are developed for elite athletes. For the rest of us it is about marketing.

In theory the big "chainring" to the smallest rear sprocket is a bike’s top speed, but it is impossible for anyone but a superbly conditioned cyclist to turn enough rpms (revolutions per minute) to come anywhere near that promise. The average rider using big gears does not have enough leg speed to stay with riders spinning lower gears at higher rpms.

In everyday riding, forget about the big chainring unless you are compelled to keep up with someone faster, then it is the only way. In that case you are better off finding others to ride with, or know your own way home. My solo rides are exclusively on a 39 tooth chainring. The 53 is reserved for riding in a go-fast group.

Forget about the front and you have less to think about. The rear works more smoothly as the sprockets are closer together in tooth count. Properly adjusted, there is a "feel" to each flick of the lever. Learn them. On a flat stretch run the chain up and down the rear cluster and search out comfortable ratios. Everyone has rhythm on a bike and finding yours is not elusive. If it feels good and it’s more than 60 rpms and the bike is moving along you’re on your way to success. As the grade changes, shift the bike up or down one or two sprockets while trying to maintain the same leg speed. Think first -- and it works every time.

Changing gear ratios affords astounding leverage over the terrain especially when the rider knows what’s up the road. Uphill it is crucial to shift before the pedals become hard to turn as, under strain, the attempted change is never smooth. The resulting racket does not harm the bike, but destroys momentum that is the bicycle’s unparalleled performance gift. It is also vital to know how long the climb is. Using a lot of energy and momentum to crest a hill, only to find it is still going up, stops even strong riders dead in their tracks. When that happens and recovery isn’t in the offing, it becomes an unnecessarily painful slog to the top, or worse, a walk.

Not surprisingly, going downhill is the place to rest and learn. Use your legs to get your butt off the seat just enough to relieve pressure and cool off. A little of that makes a big difference. With gravity’s help, the pedal speed increases beyond the ability of most riders to keep up. Try to resist shifting into the big chainring to power down. Try an "aero tuck" that always results in a faster speed than pedaling.

Let the pedal speed exceed your ability until you can keep up by shifting down to eventually gain some resistance. Coast until everything slows as all too quickly wind resistance and gravity kick in, and the pedals will become manageable. Increased leg speed is the welcome result, and it amazes most at how long the faster leg speed can be maintained. Combined with momentum, this is what allows skilled riders to roll over hills as if they were flatlands.

Many riders that look as if they know what they’re doing are not performing close to their potential. I see this often while riding. It is apparent when some pass me in a big gear while I am spinning lower gears. More often than not, I don’t have to shift to the big ring to stay with them -- and that means they are doing something wrong.

Finally, for those who are curious, a little history. In the early days of cycling, direct drive and a big wheel were the only way to make a bike go faster; hence the "penny farthing" or big wheel. Mankind’s constant quest for speed led to bikes with 8 foot wheels and larger, that were risky to ride. Most roads of the day were not paved and falling off one of those things was common. So was serious injury, even death.

In the early 1900’s along came the safety bicycle featuring two equal wheels driven by a chain connected to a front chainring and a single rear sprocket. This became the bike we know and love today. Other than space age materials, the major advance in road cycling was multiple sprockets, providing the ability to change the size of the wheels from small to large at the flick of a lever. That’s what you are doing when you shift.

A 53 front x 11 rear is the highest standard gear on a road racing bike. That translates to a 130 inch or 11-foot diameter wheel, one that is virtually impossible to turn with any worthwhile leg speed. Pro sprinters, after motoring up to the finish at 40 mph, kick that in for the last 200 meters. Using big gears to go as fast as possible is part time work riders at all levels and a waste for the everyday cyclist.

Now let’s get technical. Those who are interested can figure out all available ratios on their bikes in wheel size equivalents. Divide the number of rear teeth into the number of front teeth and then multiplying by 27 inches. That’s the non-metric size of a standard full-sized rear wheel. The smallest gear on my bike is a 39 x 27 or the equivalent of a 39-inch wheel. 53 x 12 is the largest and that is equal to a 119-inch or 10-foot diameter wheel. My 10-speed cluster is 12,13,14,15,16,17,19,21,24,27. What’s yours?

One tooth in the rear makes a big difference. In order are the wheel choice sizes without ever using the big ring. 39 x 12 equals 88 inches, the equivalent of a 7-foot wheel the size of the biggest penny farthing I ever rode when I played around on early bicycles. Being that high off the ground with marginal brakes was a fun, scary experience, but not a good machine for exercise.

The rest of the small cluster wheel size equivalents in inches are: 81, 75, 70, 66, 62, 55,50, 43, 39. The ratios in the 53 are: 119, 110, 102, 95, 89, 84, 75, 68, 59, 53. Only the top four speeds are greater than what is available on the smaller chainring. Count your teeth and do the math. This knowledge really can help you ride better.

Copyright (c) 2005 by David Balkon, All rights reserved.

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