I was just bought a new fine ultegra chain for 10 speed road race bike. This is actually the first new chain for this not so old bike. I am a fan of statistics, measuring power with a power unit on my time trial bike, and so on.
Let's focus on this worn chain.
It ran for about 1000km, so worn you nearly can do a 270-360 degree bow with it. How much effect are you losing between a completely new chain and a worn but (which is the point of comparison) accurately cleaned and re-oiled chain?
I mean, look at a cleaned oiled chain, fitting well with the current sprockets and not skipping cogs. Where is the power going away against a new firm, chain?
How do I measure?
Can I proof any other important winnings?
And (which I may have to point out) together with which kind of use.. I mean, the differences in a low-efficient 200km tour may be negligible compared to a 30km Time Trial where one may average 350 watt in 40 minutes.