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Old 01-17-20 | 10:09 AM
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Wilfred Laurier
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No. Linear pull brakes have a noodle or roller that allows the main brake cable to pull directly sideways, so 1mm of cable travel = 1mm of travel of the arms at the anchor points. This is not true of centre-pull cantilevers.
When the straddle cable is straight across (lowest possible position), the arms move very little for any given movement of the lever. On old cantilever systems I liked to set them up super low like that when possible, but this resulted in very tight rim/brake pad clearance and mushy lever feel.
Think of a clothesline - it is nominally straight across from the back of my house to the garage, but you can move the centre of the clothesline up and down significantly without pulling my house and garage closer together - the tension in the cable is enough that it causes deformation in the system (the line stretches and the sheaves might flex or deform, but no movement at the ends.

Because cables can only act in tension in a straight line, the main brake cable pulling straight up on the middle of a straddle cable straight across can create (theoretically) infinite tension in the straddle cable - the straddle cable will have a 'lateral' component to its movement and a 'vertical' component to its movement, and since there is very little of the vertical direction in a very short straddle cable, the tension needs to go very high to counter the tension in the 100% vertical main brake cable. It's a basic trig equation.

Further,
In general, if a machine (linkage, gear, or lever system) increases force, it decreases movement, and vise versa - if a machine increases movement it decreases force/ just like the low gears on your bike that allow you to ride up steep hills but at the cost of distance travelled per pedal revolution vs. high gears that allow you to cruise at high speed with slower pedal movement, but has the cost of needing more force at the pedals to go up hills. You don't get something for nothing.
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