SRAM Red TT Chainring
SRAM's TT Chainrings are stamped from 7075 aluminum for low weight and excellent strength. The teeth are ramped and pinned for precision shifting, too.
To choose the correct chainring, 1) determine the number of teeth (they're usually marked, or simply count them), 2) determine how many bolt holes there are (usually 4 or 5), and 3) determine the Bolt Circle Diameter (BCD; see diagram).
Common BCDs include:
130mm (Shimano Road)
135mm (Campagnolo Road)
110mm (Compact Road)
104mm, 94mm, and 64mm (Mountain)
Finding the number of teeth and bolts holes is easy. If you don't know your chainring's BCD, measuring it is tricky. So, instead, measure the exact distance (center to center) between 2 adjacent bolt holes. Then find that number on the correct chart below to determine the BCD for your chainring.
|BCD Chart for 5-bolt Chainrings|
|Bolt to Bolt (measure center to center)||Bolt Circle Diameter (BCD)|
|BCD Chart for 4-bolt Chainring|
|Bolt to Bolt (measure center to center)
||Bolt Circle Diameter (BCD)|
If you have any questions concerning chainring compatibility, please contact us.