The major aero/weight savings that can be made on a TT/tri bike have been discussed ad infinitum (aero helmet, tighter fitting suit, BTA bottle, disc wheel, clean cabling, etc). However, what are the thoughts of the ST bunch to making other marginal refinements, for example, aero/Ti skewers, aero pedals, sleek minimalist saddles? I confess that I do have more than a passing academic interest in the question as I’ve managed to misplace a skewer and considering whether or not to spend more than bottom dollar on a blinging set of Ti (claimed aero) skewers…
These are my “bling” aero skewers. Not very bling, but probably pretty aero (compared to the Mavics I had on there before). Aero is sometimes as much about intelligent decision making as it is about $$$$.
I was very happy to not buy the Ti versions, who gives a monkeys about weight anyway…
http://www.wiggle.co.uk/lifeline-crmo-quick-release-skewer-set/
Maybe aero skewers, or fancy derailleur pulleys.
I am sure all of those have been discussed, I seem to remember a multipage thread about proper foot position when feet are stationary going down a hill. I believe it was discussed the drive side foot needed to be in the 7:00 position to best shield the rear derailer from creating drag.
I am sure that the difference is measurable but I cover the valve hole on my disc wheel with duct tape. Mostly for aesthetic reasons for me though.
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I would think you quickly get into trivial gain territory when chasing after friction and drive chain loss. Beyond having a clean drive train the cost for ceramic bearings and other improvements is massive versus the potential gain.
Trimming your cables just a little shorter.
Positioning the release lever on your brakes so that it’s fairs the bolt behind it a little more.
Bending the extra cable sticking out of the front der. backwards.
Staying mentally engaged to constantly check you head position and make sure your helmet tail is almost touching your back.
Replacing a tire with only 300 miles on it because it’s marginally less aero.
Flattening cable crimps streamwise.
But that’s free, so I do it on my own bikes. 
Tape over exposed bolts. Mostly to prevent water/seat from pooling, but super marginal aero gain.
Racket grip tape (GammaGrip 2) on the basebar instead of bike handlebar tape. Thinner profile for better aerodynamics when you’re in aero, and they are sticking out in the wind.
Aero brake levers (3T). Frontal nosecone shape and small, bladed levers.
https://www.3tcycling.com/road/wp-content/uploads/SH-AERO-BRAKE-LEVER-03.jpg
Leverless skewers (keep an allen key in my flat kit).
http://www.tredz.co.uk/prodimg/29491_1_Zoom.jpg
Aluminum bottle cage mounting bolts (hey, a gram is a gram).
You didn’t ask about swimming, but you are overlooking switching to low profile goggles and the second you could save over a 2.4 mile swim.
I confess that I do have more than a passing academic interest in the question as I’ve managed to misplace a skewer and considering whether or not to spend more than bottom dollar on a blinging set of Ti (claimed aero) skewers…
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