Originally Posted by
Jaytron
Brings me to my next question, I know finding a new big ring must be harder than just picking one that has the same number of teeth, etc. What other measurements do I need to be aware of?
What are you trying to achive by going to a double from triple?
The standard double combinations are 53/39 or compact 50/34, if you want anything different, it will normally add to the cost as you will need to buy the regular cranks, and then additional chainings.
Also there is the cassette, there are many different combinations for this, dependant on what you go for, a longer chain may be needed.