Q&A - BB height

You often read in tests that a bike has a low or high bottom bracket, but what measurement does that refer to


Q. You often read in tests that a bike has a low or high bottom bracket, but what measurement does that refer to and what difference does it make?

Jeffery Andies, St Leonards on Sea

A. Bottom bracket height is the distance to the ground from the centre of the BB axle. The ideal bottom bracket height varies quite a lot, depending on bike purpose and how much travel it has. Anything near or below 13in on full suspension bikes definitely reduces pedal clearance on rocky or rutted terrain but adds stability at high speeds. In contrast, 14in or above bottom brackets mean you can pedal through more stuff (rocks, corners, etc.) but they tend to feel more wobbly and nervous at slow speeds.

Guy Kesteven

Freelance Writer, UK
Guy started filling his brain with cycle stats and steaming up bike shop windows back in 1980. He worked the other side of those windows from '89 while getting a degree in “describing broken things covered in mud" (archaeology). Dug historical holes in the ground through the early '90s, then became a pro bike tester in '97. Guy has ridden thousands of bikes and even more components the world over since then and can remember them all in vivid, haunting detail. Can't remember where the car keys are, though.
  • Discipline: Strict sadomasochist
  • Preferred Terrain: Technical off-piste singletrack and twisted back roads. Up, down, along — so long as it's faster tfhan the last time he did it he's happy.
  • Current Bikes: An ever changing herd of test machines from Tri bikes to fat bikes and everything in between.
  • Dream Bike: His Nicolai Helius AM custom tandem
  • Beer of Choice: Theakston's Old Peculier (not Peculiar)
  • Location: Yorkshire, UK
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