Well I didn't know that could happen (bottle cages)

[Gravity Aided]

Quite true. Cumulative effect.

 

[ColinJ]

All of the flexing occurs at that point, as well. Doomed to failure, due to metal fatigue. Different sized bottles exacerbate the problem. Steel may be heavier, but will flex before failure.

Yes - I only use 750 mL bottles, which are nearly 50% heavier than standard bottles when full.

 

[Gravity Aided]

They used to make bottles of different sizes, but all with the same diameter, but now it seems like Molly Bar the Door when producing water bottles.

 

[fossyant]

That's my Cage of choice. No issues in 5 years on my fixed.