Fair enough. And good points all around. I guess I'm just a bit frustrated. I'm only an engineering student so I'm far from an authority on the subject of bicycle design, but I get really frustrated when I see engineering designs that are a potential safety problem. Since I started engineering school they've been pounding into our heads how things we will eventually design can kill people and every effort should be taken to protect against that.
In the context of disc brakes, I'm disappointed that bike engineers haven't altered what several people in this thread have already identified as a more robust design. Well designed safety systems should be passive and redundant in nature. This current system instead naturally wants to eject the wheel. The job of preventing this falls on the "lawyer lips" and the skewer's clamping force. A properly engineered system should work with undesirable reaction forces and convert them into an asset. Moving the caliper as you guys have mentioned here would play on the existing strengths of a fork.
Regardless, I'm not trying to argue and I'm sure you're right about the industry being responsive to alternative ideas. I'm more just venting about an otherwise great bike being spoiled by such a basic oversight. Though to be fair, the current disc placement is an ISO standard. Perhaps the case should be made to the International Standards Organization to re-evaluate this standard.
Originally Posted by
FBinNY
While I characterize it as a poor choice (back mount vs. front), I wouldn't go so far as consider it a defect. The existing systems do a decent jon holding wheels on despite the issue, and there's zero movement with decent axle faces and skewers.
I'm not a big fan of disc brakes, except for the classic ones where the wheel itself is the disc (IMO, all bikes have disc brakes, except those with hub brakes), but experience has shown that existing designs work OK, and wheel ejection is extremely rare -- if it happens at all.
I might point out that while the reaction force from the disc is pushing the axle down, the weight shift from braking is forcing the fork down onto the axle, which mitigates the effect. There may also be other good reasons for rear of fork mount, such as better shedding of dirt from a rising disc, vs. a falling one which would pile dirt atop the brake.
The industry is pretty responsive to problems, and has never been slow to try alternatives. If wheel ejection were even on the radar, you can rest assured that a change to solve the problem would have been by now.