Hondo6

Several problems with this comment.

First: the fact that your frame has lasted 15 years or so is irrelevant. Your model frame may or may not have been designed for a long service life. The fact that it has lasted this long argues that it was - but that's no guarantee; you might simply have been lucky to date. It also tells you nothing about the typical TdF frame - which was doubtless designed by a different designer using different design criteria than yours.

Second: the UCI weight limit is around 20 years old. When it was first imposed, it arguably made sense in terms of safety; carbon construction was then not as well-established as it is today, and there was a plausible concern that the "race to the bottom" in terms of weight would cause designers to go too far in terms of weight reduction. However, it no longer makes sense due to materials advances since 2001. Numerous complete bikes are being sold today to consumers that are lighter than the UCI limit. They have zero safety issues. In fact, for some TdF riders teams actually have to add weight to existing bikes in order to meet UCI criteria, particularly for mountain stages.

Yes, the UCI limit must be followed. That doesn't mean it's still relevant or technically appropriate, other than the fact that it's a rule to be followed.

Third, you don't seem to understand the concept of a fatigue limit and it's impact on design. For materials with a fatigue limit, best data indicates that there is a threshold below which repeated stress can never cause fatigue failure. Steel and titanium are two such materials (though there is some thought to the contrary about titanium, it's still generally accepted to have a fatigue limit). Design structures made from them to be strong enough, and barring a flaw in fabrication or a design error they will not fail from fatigue stress falling within design limits. Ever.

In contrast, both AL and CF have no fatigue limit. This means that repeated stresses from normal use - even small ones, like road bumps - will eventually cause structures made from them to fail. (The exact number of repeated stresses of a given magnitude that will cause failure cannot be predicted exactly, but can be roughly estimated.) That's true even for normal use causing only stresses falling within design limits (anything can be damaged by stresses outside design limits).

Designers using these materials get around this by overbuilding the structure - e.g. ,they make it far stronger than absolutely necessary. How much stronger? That depends on the intended life span and the safety margin desired. No way around that; it's the nature of the material. But CF and AL have very low density, so it's feasible to use more material than the minimum necessary to make them stronger (and thus last longer in routine use) while still getting a light structure. How long the structure can be expected to last in routine use thus depends at least in part on how much extra material over and above the minimum necessary is used.

Fourth: can't speak to current pro team practices. But I'd guess any TdF team would gladly buy a TdF winner a new frame in exchange for a TdF win. And pro athletes are hugely willing to accept risk when it comes to winning - just look at the number of pro athletes (all sports, not just cycling) who still test positive for PED use today. The psychology of the pro athlete (faster/higher/stronger/I'm invincible!) all but guarantees that. So I'm guessing many if not most pro riders would willingly take huge risks if they thought those risks gave them a competitive edge. That would include using a frame that cut safety margins rather close. My understanding is that concern is a big part of what led to the UCI weight limit for bikes in the first place.

Finally: even when adhering to the UCI weight limit, saving weight in the frame gives the total system (bike) designer more flexibility. Weight saved in that area can be used elsewhere - e.g., electronic shifting, beefier and better brakes, etc . . . ). Design flexibility is always a good thing; it almost always leads to a better overall system.

Hey, I'm glad your frame - which I'd bet is CF - has lasted 15 years. But I stand by what I said: a TdF frame has different necessary design criteria than consumer frames, in part because it does not need to last as long. If it lasts a year, that's 3-4 times longer than it actually needs to last. And with CF (and other materials without a fatigue limit), intended normal lifetime impacts the design. Due to the nature of the material, there's no way around it.