Madara's speed is 1703.7 mach according to a calc Gallavant did.
The calc is in the comments of this blog: http://vsbattles.wikia.com/wiki/User_blog:Quincy_Emperor/Naruto_speed_Downgrade
Madara's speed= 579258 m/s
Distance (madara's head swing) = 15 cm =0.15 m
time = distance/V = 0.000000259 seconds
The light fang follows madara's movements doing a circular motion ( so the further it goes from madara the faster it travels)
To find the speed of the light fang we need to find 2 things: 1. The distance between madara's head and naruto
2.The angle of madara's head swing
Red line is 373 px and madara's height is around 1.81 m ,but he isn't standing straight so i assume that the red line is 1.7 m
Blue line = 204 px = 0.93 m ( i name this value R)
The angle of madara's head swing is around 90 degrees or π/2 rad
S= a*R ( where a is the angle and R the radius of the circle ,check circular motion)
S = π/2 * 0.93 = 1.4601 m
V= S/t = 1.4601 / 0.000000259 = 5637451.7 ( mach 16580) which is Sub-Relativistic
And since naruto dodged the attack he should be on this level too.