UNDERSTANDING GEAR RATIOS


All those round things with teeth around the outside are commonly known as “sprockets”. (Yes, I know for those who insist on being technical … they are cassettes/cogs on the back and chainrings on the front.) These sprockets are several different diameters and this is for a reason. All those different diameters provide a different gear ratio when the chain goes from one to the other. When the chain is on the smallest sprocket in the front and the largest sprocket on the back it is the lowest gear ratio. And when the chain is on the largest sprocket in the front and the smallest sprocket in the back it is the highest gear ratio. Knowing these gear ratios, lowest to highest, helps us to determine the performance capability as well as the hill climbing ability and effort needed. As to the fastest speed we can ride we can only pedal so fast. Once we reach the maximum rpm we are capable of pedaling we reach the maximum speed we can go. The only way we can go any faster is to have a higher gear ratio. And even then we reach the point of “practicalness” as sooner or later we find too much resistance in our pedaling.

There are other contributing and limiting factors involved in determining the gear ratios such as wheel size and tire choices, but I am not addressing any of that here.

HERE is a well written article on the subject of understanding gear ratios.

large sprocket on tadpole trike

As you can see in the picture above an oversize sprocket has been installed on this tadpole trike. It looks mighty impressive, but the truth is probably not many of us could pedal it to its potential top speed as we just don’t have what it takes. Most of our trikes come equipped from the manufacturer with a 52 tooth sprocket as the largest. The picture above is real, but the one below is fake … a little photo editing fun I had sometime back.

130 tooth chainring on Catrike 700

Mind you there are bikes and trikes with oversize sprockets which have been ridden to accomplish setting new land speed records for human powered vehicles. Usually they have some sort of streamlined bodies on them so they can cut thru the air and not deal with the resistance you and I do with our plain ol’ trikes. Here is a picture of one such vehicle which broke the world record. I haven’t kept up with who currently holds the distinction so this may not be the current record holder.

world record holder

It takes more than gearing to accomplish such a feat. One must be a very top athlete to reach these speeds with just human power. But you can bet there is not 52 tooth sprocket installed here.

Some of us need help with gear ratios as what we currently have isn’t “getting it”. It can get a bit on the expensive side when one starts changing all the sprockets to accomplish such a change in gear ratios. Obviously the best time to do it is when the original sprockets are wore out and in need of changing. And we can only accomplish that by …

KEEPING ON TRIKIN’

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About Steve Newbauer

I have a few current blogs (tadpolerider1, navysight, and truthtoponder) so I am keeping busy. I hope you the reader will find these blogs interesting and enjoy your time here. Feel free to email me at stevenewbauer at outlook.com

Posted on June 15, 2016, in components, options, tadpole trikes, upgrades and tagged . Bookmark the permalink. Comments Off on UNDERSTANDING GEAR RATIOS.

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