cgates66 |
08-07-2020 09:57 AM |
Quote:
Originally Posted by Caballero
(Post 2772005)
well, I came across the first 2021 SL7 to bite the dust at 5:30am. Rider was supposedly on the maiden voyage when during a downhill section braked and heard an all mighty snap followed by a series of other disturbing sounds.
guessed the rear disc caliper hadnt been torqued down properly and had pulled out of the mount under hard braking with the rear caliper and part of the chain stay in the spokes, lightweight disc rear wheel spokes snapped, super record eps rear mech caught up.
the owner was surprisingly calm about it, though Id hate to be the mechanic that put it together !
|
That is rather shocking. The failure mode you describe, though, doesn't make sense: the rotor is rotating in a way that would force the caliper down under braking, not lift it up. Further, the caliper is "clamped" onto the rotor under braking by pads, meaning that it literally can't twist (e.g., if only one bolt came off) or slide to one side or the other. And on Shimano, the bolts themselves are clipped after install, so even if loose, the worst thing that can happen is that the caliper rattles a bit - but only when the brakes are "off". The design is pretty robust. I'd be surprised if Campy was much a much different design.
For this to have happened as described:
1) both bolts would have to come off of the caliper somehow, meaning both under-torqued and unclipped;
2) while the brake pads were clamped hard on the rear disc, the caliper would have had to miraculously slide forward off of the disc, and then twist into the wheel;
3) hydraulic brake hoses aren't noodles, so the slide forward part would take some force, and it would need to come forward ~1.5" or more, which is a lot.
This is a very strange accident and I'd love to see pictures, and learn what the actual failure mode was (as a disc brake user!).
I wonder if there wasn't a frame defect or damage and something broke in the vicinity of the caliper. That makes a lot more sense than the caliper coming loose under braking, which I don't think (as described above) can physically happen.
|