Originally Posted by
AndreyT
I will use my authority in such matters to put an end to his discussion, if you can call it "discussion":
Firstly, by now the facts are well-known: through-axles were introduced purely as a marketing ploy. TAs were introduced exclusively as means to forcefully trigger another "renewal" of the bicycle fleet in circulation. They do not have a pre-mediatated technical reason to exist. Nobody ever bothered to design TAs to offer any mechanical benefits. Any technical benefits that might be provided by TAs (if they even exist) are post-discovered, they come as a surprise.
Secondly, regarding what these post-discovered benefits are... All that talk about "increasing stiffness" or "better safety" and some such is pure nonsense, disseminated either by paid shills or by gullible audience duped by said shills. There's no "increased stiffness" or anything like that. At this point there's only one potentially viable benefit of TAs, with some anecdotal accounts to back it up: for bicycles equipped with disc brakes TAs seem to result in marginally better consistency of disk rotor alignment in wheel replacement scenarios (both same-wheel removal/install scenarios and different wheels replacement scenarios). However, on the other hands, this seems to hold water only when compared to the classic cone-bearing QR wheels. Modern cartridge-bearing QR wheels appear to be as consistent as TA setups in this regard.
No other benefits of TA have been discovered so far in any serious sense.
Respectfully...
Thru axles are more self-aligning than a quick-release; The width across the fork ends and the relatively close fit at both ends with respect to the thread diameter, means the thru axle pilots right the first time, not just once clamped in place, but also prevents cross threading.
If thru axles were only a marketing ploy and served no function, than I would expect they would have been a) introduced before disc brakes on rim brake bikes, and b) introduced on rim brake bikes even after they were introduced on disc brake bikes. Neither (a) nor (b) is true.
Thru axles were intoduced to solve a specific problem, that being, the rare but existing events of axle pullout under severe disc-braking loads. It only takes a couple or even a single case of this on a properly installed quick-release to cost a bike company a lot of money in liability, most especially, if there is evidence that the company knew of the danger beforehand, that is what really runs up settlement dollars, plus the cost of class actions and forced recalls of bikes which then become very expensive scrap. Simple engineering calculations, and measured tests, have both easily confirmed the pullout scenario. Bike makers would have lost huge in court.
Yes, thru axles do have additional "bonus" features, that weren't the initial drivers, and hey, that's great. For me, I see such bonus on the two-piece hollow-spindle crank designs, introduced to save weight, but I also experience much greater bearing life due to large bearing diameter and easy preload adjustability, and easier crank removal. But I know the driver was weight savings. Plus, the first cranks like this were backwardly compatible into current or ancient BSA BB shells, a true feat. The only way thru axles could have been better would be to achieve that; Trek's Thru-Skew comes close, by closing off the dropout into a hole and using standard QR skewers as a thru-axle, and they did this on their later 520 touring bikes. But the larger diameter, fine threaded thru axles are superior in adding stiffness to the fork/hub assembly, and so ruled the day on their more highly-stressed bike models.
Contest. Show your work.