Originally Posted by
ftwelder
Here ya go. You mount the caliper on a bracket that goes directly to the axle and can rotate on the axle on a bearing (bushing). Near where the caliper mounts to the bracket, there is another small bushing. This is called a lower stay rod bushing. The upper stay rod bushing bolts to the fork crown.
When the bike is moving and you apply the brake, the caliper pulls down on the stay rod causing the brake force to move upward directly toward the upper stay rod bolt where it belongs, in a nice thick chunk of metal.
Welding a gusset on a skinny tapered blade is so very bad. There is nothing about a tapered fork blade that should be near a disk brake caliper unless it is very large, thick and straight. Torch brazing on the fork blade will jeopardize the condition of the material in a critical area. ending the gusset at the drilled hole is so wrong it's not even funny.
road-brake by
frankthewelder, on Flickr
Frank -
I remember the early 70's Proteus Framebuilding book (it had a yellow/tan cover) had a similar design for making a strong fork when heavy duty blades were lacking. That design placed a flexible plate under the top headset bolt with two holes in the outer end of it. Then a pair of seat stays ran from the front dropouts up to the flex plate where a 6mm bolt through the flex plate and into a plug brazed into the head of the stay. Don't remember any mention of effects on brakes (of course this was pre-disk era). Don't remember ever building one and about this time I got access to forged Cinelli full sloping crowns which solved the problem well enough and looked great.
Here is a quick sketch from memory of the Proteus design recommendation;
