How to determine chain lengh?

[Christian Schneider]

Switching from 53X39 chainrings to compact 50X36, do I shorten the chain? How does one go about determining the best chain lengh for a particular gearing?

 

[James Huang]

http://www.parktool.com/repair/readhowto.asp?id=26

The Park Tool web site is quite helpful for a wide range of repair questions.

 

[pharaonic]

Parktool site

The parktool site is indeed a great reference for fixing/maintaining your bike.

Interesting to note though that the "rigorous" equation at the bottom of the chain length page is not exact. The approximation used leads to an insignificant error in practice but (as a mathematician) I couldn't help noticing it!