Find valid triples for a sorted list of integers (part 2)
(I won't comment on the actual algorithm, just on the coding style.)

Overall, this feels pretty ok and standard Python style.

Some remarks:


remove commented-out code before going "live" (live here meaning, submitting to CR).
make sure your lines don't exceed 80 characters.
That will have the added convenience that there'll likely be no horizontal scrollbar for the code block here, making things overall easier to read.
I like the from __future__ import division, especially since the only division in the code is actually integer divison, and now is explicit with //.
Bonus: add from __future__ import print_function, add parentheses to yourprint` statement at the bottom and your code will be "generic" Python, not major version 2 or 3 specific.
(My preferred approach is to code Python 3, and then if necessary, refactor things to be Python 2 compatible. Start from the future, not from the past.)
the lower-first-CamelCase style is not Pythonic. CamelCase is used for classes, but functions and variable names are usually all lower case, with underscores as deemed necessary for readability.
(NB: you probably want to use the word "triangles", with an "n" in there, instead of "triagles". Or use e.g. find_triplets, since that's in your doc-string description.)
the quadruple nesting in findTriagles is about the limit of nesting (for-loop within an if-statement within a for-loop within a for-loop), but since the function is really short, it's probably ok. When there's a lot more code in any of these indented parts, consider moving a part to a separate function.
There is no general document doc-string (describing the purpose of the code), and the doc-string for findTriagles is missing its initial line/sentence: it jumps straight into the parameter description. findSum does this better.
findSum is an odd name: I don't see any sum calculation there. find_max_index or similar might be better.
for consistency: add space around the equal sign in upperBoundIndex=min(i+2, len(numbers)-1).