Road Bike Bottom Bracket Height

Most of this has to do with the evolution of cycling.

Road bike bottom bracket height. With 170 mm cranks a 10 inch bottom bracket height is a good starting point. When determining the geometry of my own frame i went with a relatively large bottom bracket drop of 70mm resulting in a bottom bracket height with 650b wheels and 2 6 inch tyres of just 290mm. If a rider is moving slowly they are sometimes vertical on a banked track so it is possible for the right pedal to hit the track surface. A 54cm specialized tarmac road bike has a 268mm bottom bracket height while a medium sized specialized hardtail expert mountain bike with front suspension only has a 309mm bottom bracket height and a medium specialized epic expert carbon with both front and rear suspension has a bottom bracket height of 332mm.

This is the distance from the ground up to the center of the bottom bracket. This is also surprisingly close to the bottom bracket height of a lot of mountain bikes despite the requirement of the latter to accommodate cranks and pedals. This measurement has phased away and you will notice that bottom bracket drop bb drop is what it has been replaced with. A road bike typically has a bottom bracket drop of approximately 70 74mm.

Road racing will require a slightly higher bottom bracket due to the need to pedal through some turns. 10 inch bottom bracket height is a good starting point if you are using 170 mm cranks. For years brands and all the content around bicycles referred to bottom bracket height. Frames built specifically for very steep tracks can run as high as 11 inches.