Michael Hanslip Coaching

If you want to go faster, you have to pedal harder

How long do knicks last?

That seems like a pretty simple question, but it proves to have a very complex answer.
I've been considering the answer for some time now. And I feel no more prepared to answer the question than when I began.
 
By the time the fabric is thin and see-through, they are long past their use-by date. On some of my older bibs the end came when the straps stopped being so stretchy - if they can't stay up then they aren't fit to wear. On others, it was the gripper elastic around the leg opening that perished first. My newest shorts were purchased for commuting to work and now have approximately 125 trips through the washing machine on each one. My race shorts from the same brand have the same pad in them, and worn back to back the less worn race pair either seem a little firmer in the padding, or no difference (I think it depends on the day more than which particular shorts that are being compared). The back-to-back wearing thing is what I do with my cycling shoes to decide when they are worn, as long as the current shoe feels similar to the unused new shoe, they can keep going. It seems easy with shoes and hard with shorts.
I don't believe the end comes strictly from numbers of wash cycles - time in the saddle also contributes. And in the case of my commuting shorts, they've had comparatively few miles. At 30ish km per day and 125 days, that's approaching 4000 km. Where I could find a mileage for top quality shorts, it was around double that. But neither is it just mileage - each washing is also contributing to the demise. If I did 100 km per outing, then I'd have no quandary around saying "worn out". Because 12,000 km is on the far side of everyone's line. If 50 km is typical and 8000 km is worn, then that's 160 washing cycles.
By neither distance nor washing can I definitively state that these shorts are worn out. I don't want to drag them past their end, that doesn't look, feel or perform best. Neither do I want to abandon them before they are ready to be abandoned. That's wasteful and expensive.
Like I wrote at the beginning, I still don't know the answer.