For size medium and large: 7.875"x 2.0" (200x50mm)
For size extra small and small: 6.5"x1.5" (165x38mm)
Front mounting hardware is 22mm wide with an 8mm through hole
Rear mounting hardware is 18mm wide with a 9.53mm (3/8") through hole.
We designed the Blur XC specifically for modern 100mm forks. Anything less will handle a bit too quickly for most tastes. Anything longer than 105mm will have too much leverage over the light weight tubing, and will void your warranty.
1 1/8"
34.9mm (supplied with frame)
A Shimano 34.9 top swing/ top pull. Anything but saint should do the job.
The Blur XC uses a 68mm bottom bracket shell, and a 50-51mm chainline. Pretty much any of the newer external bottom bracket cranks will mount up without issue. The Truvativ stylo and shimano Deore XT are our favorites. If you are using an ISIS setup, you need a 68x113mm bottom bracket.
The bike is designed for 1.95"-2.1" tires. You may be able to squeeze some 2.2" or 2.3" tires in there depending on brand, but it will certainly be tight.
140-160mm.
Any standard 135x10mm hub will do the trick.