WikiPedalia is not endorsed or affiliated with the Wikimedia Foundation.
Compact Frame
Traditional "road" frames have been built with level top tubes since the early 1900s. The influence of mountain and BMX bike design has led to the increasing popularity of frames with sloping top tubes, higher at the front.
"Compact" road frames have sloping top tubes, and are intended to be used with a long seatpost. Compact frames are a little bit lighter than traditional ones, but this is partially offset by the weight of the longer seatpost. Some riders believe these frames are stiffer.
When lines extending forward from the down tube and top tube intersect directly above the front axle, as is usual with a road frame, weight loading only tensions the down tube and compresses the top tube. When the intersection is behind the axle, he frame is better at resisting braking loads. When the intersection is ahead of the axle, the bending loads on these tubes require the front end of the frame to be of stronger construction.
Manufacturers like compact frames because they are more versatile in terms of fit. Usually 3 or 4 sizes are enough to fit 98% of customers. This saves a lot of money for a manufacturer who doesn't need to deal with so many different sizes.
