|Distance between fixing holes||PCD|
Chainrings are sold by number of bolts and PCD or BCD, which is the same thing and stands for Pitch Circle Diameter or Bolt Circle Diameter. Easier than diameter to measure is the centre-to-centre distance between two adjacent bolts. That can then be multiplied by the appropriate geometrical factor to get the PCD: in the case of 4 bolts x1.414 or 5 bolts x1.701.
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01 June 2016 (Wednesday): CC Breckland 25-mile time trial (East District Champs)
07 June 2016 (Tuesday): Godric CC 10-mile time trial
11 June 2016 (Saturday): EDCA 10-mile time trial (district champs)
15 June 2016 (Wednesday): CC Breckland 10-mile time trial
19 June 2016 (Sunday): EDCA 25-mile time trial (district champs)