South Salem Cycleworks: Salem, Oregon
(503) 480-2001
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118mm Bolt Circle Diameter, 5-Bolt chainrings

118mm Bolt Circle Diameter (BCD), 5-Bolt chainrings on this page:
40-tooth | 52-tooth

Back to master list of available chainrings

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Bolt Circle Diameter is the diameter of the circle formed by the centers of the chainring fixing bolts. With 4-bolt cranksets, this is easy to measure. 5-bolt cranks are more difficult.

If you are unsure about what size chainring you need, Wolf Tooth Components has an excellent guide to measuring your rings.

SR Apex-5 40-tooth 118 BCD chainring. Used, $30.00/each

SR Apex 40-tooth chainring

Works on several 1980s Campagnolo cranksets

SR Apex 40-tooth chainring

Here's the other side of the ring

SR Apex-5 52-tooth 118 BCD chainring. Used, $45.00/each

This ring is drilled and tapped for an SR alloy chainguard. That's what those five small threaded holes on the ring's perimeter are for.

SR Apex 52-tooth chainring

Front side

SR chainring

The back side

SR Apex chairing

Close-up showing that it is an Apex-5 ring as well as the amount of wear on the teeth.