When are Alu bars worn out? Maybe an answer-->

[Steve in SLO]

In recent threads there were lots of opinions and ideas tossed out, but not one seemed individualized to the bars themselves.
In 'Tales from the Toolbox' by Scott Parr, an ex-Team Motorola mechanic, his take was that as bars wore, they 'drooped'. He said to measure the width between barends. If your bars were 42c c-c when new, and they measured 40.5 c-c, it was time to think about replacing them.

[Blue Jays]

Components that can unexpectedly break (that will likely result in a nasty crash) are candidates for periodic replacement.
A few years for bars, stems, and saddles (for example) and then they're destined for low-speed commuting bikes and similar duty.

[Charles M]

I look for the white dust that notes corrosion, but looking at bar sag would certainly be a sign at the degree suggested above. Past that I wouldnt run a bar for more than 3 years steady use (though I have bikes with bars a lot older that didnt have much use).

I would guess that once you have any measurable difference at all in a modern Alu bar it would be time to go...

[Steve in SLO]

Pez uses 3 year rule on steady use, but 'steady use' differs greatly from someone riding randonneur style vs a racer, etc.
The suggestion in the book uses an objective measure of a single component's condition, not the condition of 'all components like this after x time of use'. This makes more sense to me.
It sounds reasonable, as Pez states, that a modern alu bar should probably be replaced when any downward deflection is noted. Scott Parr wrote the book in the 90s, during a changeover in bar manufacturing processes. To ride bars that have drooped inward 1.5cm seems a bit sketchy, although I think he was just using those numbers to illustrate a point, not as a firm guide.
Cheers.

[Volant]

"When are Alu bars worn out?" Just before your collarbone is. ;)

[Steve in SLO]

I just measured my 40cm o-o Cinelli Mod 63 bars from back in the day. I bought them used with indeterminate mileage, trained/raced them for 4 seasons with lots of out of saddle sprints and climbing. They probably have about 25K miles from me. Their current o-o distance? 39.9cm. I guess they're barely getting broken in.