Fitting a Bike to Your Body
A bicycle is a personal thing: here's how to make it fit you.
Here are some tips on adjusting your bike to suit your body:
Frame Size
- There should be at least an inch between your crotch and the top tube when you're straddling the bike. (Of course, a "girl's bike" has no top tube.)
- The frame size is the length from the seat to the bottom bracket (where the pedals connect to the frame).
- Calculate the correct height measurement for your frame by multiplying the length of your inseam (crotch to floor) by 67, then dividing by 100. Subtract about ten centimetres (four inches) for a mountain bike.
Seat Position
- A common error is to keep the seat too low, which can be very tiring. When you're riding, the leg on the lowest pedal should be fully extended, but not locked. You should be able to keep your foot almost parallel to the ground; you shouldn't have to stretch to reach the pedal.
- The seat should be at the same level as – even a little higher than – the handlebars, depending on the bike and your body.
- The seat can usually be moved back and forth on rails. When your elbow touches the front of the seat, your fingers should be within a centimetre (about half an inch) of the handlebars.
- Also, read what feature writer Jon Sparks says about saddle height here.
Handlebar Position
Women and, less frequently, men are prone to straining their backs if they have to stretch too much to reach the handlebars. Some solutions to this problem:
- Modify the handlebar position
- Attach brake levers that curve in closer
- Consider riding a more upright style of bicycle
Also, your hands on the grips should naturally fall about shoulder width. (Feature writer Jon Sparks has more to say about handlebar position here.)
Pedals
- Normally, the ball of your foot should sit over the centre of the pedal spindle. (Don't get in the habit of pushing with the arch of your foot, which can give you sore feet over time.)
- Cleats, if you wear them, should sit under the ball of your foot. Adjust the cleats so the toe-in, toe-out position is the same as your stannding or walking position.
Gearing Ratio
You may never need to know this, but as you get used to riding, you may like to know that you can change the way your bike behaves by changing the sizes of your front and back sprockets. Different gears change the ease with which you can turn the pedals. You will want easy gears for climbing hills and harder gears to take advantage of tailwinds. Most 18- to 21-speed bikes have a range of gears that will meet the needs of a city commuter, but sports cyclists will enjoy experimenting with more radical configurations.
In my next piece, I'll discuss bike storage.
