Bicycle geometry and fitting

When buying a bicycle it is extremely important to choose right geometry. It may not be felt at first but in the long rides when parts of the body are subjected to constant stress, seven small maladjustments can appear in really painful form. Most common of these is the back pain that can be felt when the back is overstretched or over-bent. The back should not be straight but bent in a little arch so when a bike hits a bump it can bend a little and absorb the shock. If it were straight, the shock would cause it to bend out of the straight position, which is not a problem for a few bumps. But can cause strong pain after 2 hours the constant stress. The similar thing is when the back is bent too much.

There are more situations like these but most of the problems can be countered in start by choosing a good geometry, and later by adjusting seat position, steam length and other things. Choosing a good geometry is not an easy thing. Even if you try a bike for a spin before buying it you won’t be 100% sure that it’s right for you until you have spent some time on it. So here is one site i found recently that can help with choosing a geometry.

It is called ¬†“fit calculator” and is available online¬†at “competitive cyclist”. As input it requires 8 measures from a cyclist’s body (like body height, inseam length and such) and in the end it produces the lengths and measures of a bike geometry that would most likely fit for that person. It provides both road and mountain bike calculations, with 3 different versions of each. I would say it is a great starting point for getting a good geometry with, of course, the next step being actually riding that geometry and testing if it really fits.

For me it provided some useful info. I recently drove a route with 40km climb, first long ride with my current bike. And in the last 10km i experienced back pain, and it was getting worse the more i rode. When i got home, i did a bit searching online, found that calculator and decided to give it a try. It produced interesting results. All my bike geometry was perfect except that the seat was 5cm too much back which caused my back to be overstretched which proved as painful. Now, I’ve set it as it should be, although i’ll feel it only in next long ride.

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