Monday, May 21, 2007

Shifting gears



Not long ago I visited a local bike store and looked at a Trek Lime, similar to the one in the photo above.

Besides the iPodesque design, what makes the 3-speed bike unique is its “automatic transmission.” You never have to change gears because somehow the bike figures out what gear you should be in.

I don’t understand the technology, nor do I understand what’s so difficult about changing gears yourself – especially when you only have three of them.

But apparently the bicycle industry views gear shifting as something that a segment of the population finds difficult.

This isn’t a new phenomena. In fact, I recently discovered that my two old Schwinn Suburbans both feature a unique technology that – back in the 1970s or early 1980s – was viewed as a way to make gear shifting easier for the masses.

It’s called a Front Freewheel.

I was so unfamiliar with the concept that at first I thought my bikes had a mechanical problem. I figured the rear freewheels were somehow frozen due to rust. I used up a can of WD-40 on them and banged on them with a mallet, to no avail. I figured I would eventually replace them as soon as some old parts showed up at the recycling center. But why did the front chainrings spin, along with the chain, when I was coasting? That was certainly by design, not by accident. Why?

It was puzzling.

Eventually I brought up the topic in another blog and someone was kind enough to explain what I had.

The Front Freewheel simply moves the freewheel component of your bicycle from the rear cog to the front chainrings. When you’re coasting (not pedalling) the chainrings continue to spin and the chain keeps going around and around.

But why?

Because with the chain in motion, you can shift gears even though you’re not pedaling.


1982 Shimano Catalog - Front Freewheel

“Smooth FF System shifting can be done while coasting, back-pedaling, even with your feet off the pedals,” states this page from the 1982 Shimano catalog, which I downloaded from the Schwinn website.

Today I took one of my Suburbans out for my usual Tuesday route and put the Front Freewheel to the test. Everytime I shifted gears, I tried to remember not to pedal – which is the opposite of what you usually do before changing gears.

It worked just as advertised. As long as the bike is in motion, the chain jumps up and down the rear cog as you shift gears.

Wouldn’t it be easier to just make sure you’re pedalling when you shift gears?

No, that would be too complicated for some.

“Both young and old enjoy the convenience of multi-speeds, but many new riders have difficulty shifting correctly,” according to the Shimano catalog.

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