For those who use power meters:
A clean bike definately feels faster.
Anybody with a power meter willing to estimate the benefit, either in watts or MPH?
I believe most of us probably have no idea because we tend to focus our energy in other areas. If you’re anal enough to use a PM then you’re going to be anal enough to ride a clean bike when racing. In addition, we’re probably smart enough to not make these types of estimates. 
Sorry I couldn’t be more help…
Thanks, Chris
at least 50-100W at speeds over 750mph 
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so its only noticeable on descents?
I have no doubt at all that a clean chain is VERY tangible in the effort of a ride. Maybe it is a placebo or what ever - but I think that it is for real.
3 watts. no joke
Not aware of any university studies per se BUT I recall reading an article out of the old Triathlon Times where Jeff Devlin was being interviewed about pre-race activities. He told a story about how he and Kenny Souza roomed together at a race. The drivetrain on Kenny’s Nishiki was filthy whereas Jeff’s Merlin was pristine. Jeff said he only beat Kenny by a couple of seconds that day even though both of Kenny’s run splits were faster.
Jeff attributed his win to his clean drivetrain…no joke. His comment was basically that Kenny’s dirty drivetrain didn’t allow him to go as fast as he would have on clean equipment. Call it placebo but how can a piece of moving machinery operate better when the lubrication is full of dirt/grit/grime etc? Hasn’t there been a study about dirty pulleys and how it robs you of watts (just a little) over a 40K tt?
There was an impromptu study by AFM (I think) on BTR last week on old vs new chain…the difference was substantial. Best performance was with a clean but broken-in chain (100ish miles). Look it up, interesting stuff!
about 5 watts I have heard (pro cycling team)…