Originally Posted by
79pmooney
If that hole was for an axle stop to prevent the wheel being pulled forward by a strong rider - well they got it all backwards. Strong riders need strong track ends and tightly secured hub nuts first and foremost.
That’s not what the screw is for. The Parallax is an aluminum frame, 7075, I believe. I bought one in 2018 as well (but might be a different model year from the OP’s).
The track end itself could be a different alloy from the tubes, but it’s aluminum. To make it tougher, they put in a stainless steel insert, held by three screws. That’s why the track end is milled or forged a little thinner in the area surrounding the axle slot. Presumably, that insert was removed for pictures after the crack appeared.
FWIW, my bike has had no issues, structural or otherwise. But it’s been treated gently. I rode it quite a bit in 2018, only about five times in ‘19, twice in ‘20, and a little so far this year. It goes out in good weather, on mostly smooth roads. 780 miles on it, give or take a few.
It’s troubling to see a failure like this, and the kind of thing that will not be cheap to repair—because 7075 will need to be TIG welded, whereas a steel dropout could be fixed with MIG or even a gas torch.
Since the frame’s history is not really known, it’s hard to say what’s the most likely cause. Also, I’d never heard of the suspicion that indoor trainers can cause this, but it seems plausible.