How to Change a Frame Size

The size of your bicycle frame is as important to safety and performance as a proper fitting pair of shoes. A bicycle frame that is too large leads to crotch injury and makes the bicycle unwieldy. A bicycle frame that is too small leads to knee injury and shoulder problems. Changing your bicycle frame is possible, because the components are designed to fit on any adult-sized frame. This allows you to size up a new frame for your body and then use the old frame's parts.

Things You'll Need

  • Measuring tape
  • Fully stocked bicycle workshop with work stand
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Instructions

    • 1

      Go to a bicycle shop with a large selection of bicycle sizes. Ask a shop employee to assist you with a proper sizing.

    • 2

      Sit on a variety of bicycle sizes. Have the shop employee hold the front of the bicycle while you spin the pedals and cranks. As you turn the pedals, look to see if your knees are extended all the way down and locked or if there is a slight bend under the knee. A proper fit has the knees slightly bent during the turning. Avoid a frame where the knees extend fully and lock.

    • 3

      Hold the handlebars and sit as you would during a ride. Check your elbows to make sure there is a slight bent. Next, stand over the down tube on the bicycle. The down tube extends from the front of the bicycle to the seat stem. Place three fingers under your crotch and check that they can fit between the crotch and down tube. If not, the frame is too big, if there is too much space, the frame is too small.

    • 4

      Purchase the right frame after the sizing procedure. In your workshop, place the old bicycle frame with the parts onto the work stand and strip the bicycle frame of the components. Start by removing the wheels, then the cranks, chain, derailleurs, brakes, handlebar stem, front fork/suspension and bottom bracket.

    • 5

      Place the seat stem from the old bike into the receiving hole on the new frame and place the unit into the work stand and assemble the bicycle with the old frame's component group.