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I would think the IS mounts would need to be significantly stronger if the calipers were on the front, bc the force from the rotor during braking would push the caliper away from the fork, instead of into the back side of the fork.

That is an interesting article though, I had not thought much about that!
 

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I agree that the caliper is on the back to get some protection provided by the fork. If you're using cable actuated discs and they were mounted on the front, then you could hit a stick at an inopportune time and have the front wheel lock up, sending you sailing.
 

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I read that article too and wonder just how many riders have really had the wheels fall off cause of disk brakes? I'm actually a little suspecious of the arguement put forth on that website. And why not the same arguement for the rear brakes? Not only do you have the braking force, but also the drivetrain acting against the QR to some degree.:confused:
 

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Cast aluminium and magnesium are much stronger in compression than tension, if the caliper was on the front, braking forces would try to tear the caliper off the front of the fork. Post mounts would be sturdier than IS in that application, but you'd still tear the threads out of the post mount eventually, or the caliper would just perpetually loosen up as the bolts tried to stretch out of the posts..

The better question may be why all disc brake forks don't just use 20mm thru axles which would eliminate the QR & disc brake reliability issues. They could even make light weight QR 20mm axles for XC racing applications where you didn't need the thump and crunch survivability.
 

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The cast mounts on an aluminim fork, or welded mounts on a steel fork would be under tension if the mounts were on the front taking all of the strain. On the rear, they are compressed into the lower fork leg spreading the load. also, being behind, they are out of the way of oncoming brush, trees, rocks, animals, hikers.... that you may encounter on the trail. The down side is that the tangential braking force on the rear edge of the rotor of a forward rotating wheel works to push the wheel out of the dropout. If they were on the front, the force would serve to push the axle into the dropout which would be better. so, keep your lawyer lips on, and keep your Q/R tight. On the rear of the bike (with vertical dropout), the compression, and direction of the torque are both in your favor.
 

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i would have to say if it was on the front of the fork the mounts and the lowers would have to be incredibly stronger. with the mount on the back the fork is backing it up pretty much
also
ok sure threads like on the inside of a nut are pretty strong
but if you weight 150 pounds and are on a 30 pound bike thats a 180 pounds that is relying on to set of threads
i would say after like a month or two of braking would just tear out the threads and then you would ave to replace the lowers
doing that every 2 months could be really expensive
 

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The caliper on the front of the fork is a better idea. When applying the brakes it would push the wheel into the dropouts on the fork. The threads...same tension/compression (at a quick glance) assuming the front mount is 180 degrees offset from the rear mount.

The reason I don't think it is on the front is because there is a good chance you will catch the brake wire/hose on something more often than if the wire/hose was behind the fork.
 

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You are right about the brake pushing the wheel into the dropouts if the brake was on the front, but you have to consider that those small threaded eyelets cast into the fork would then be the weak link (being pulleded down and away from the fork leg, rather then pushed up and into it). Those are more likely to break under repeated stress than would be pushing the wheel put of the dropouts of a properly tightened Q/R or nutted axle. thru-axle wheels have no issue at all. thru axles in my opinion are the best axle for a suspension fork anyway (mortorcycles have used them for how long?) but they don't have the convenience of a single lever QR. The protection the fork leg provides to the hose/cable and caliper are also important considerations.

I mostly ride BMX though. My front brake=my shoe jammed between my tire and fork crown. It's the lightest set-up i've ever run!
 
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