Wednesday, March 23, 2016

Stock Parts....

....Blockhead.  I needed some fork ends that would take a way oversize piece of straight gauge as a fork blade and a 10mm axle.  The yarder is running a rear hub for a front hub.  Nothing really seemed to fit the bill so I machined these little pieces out of some 4130 plate.  Quite simple really.  8 corners, 90 degree angles.  They line up the blade with ample room for the disc rotor and there's enough space left over in the miter to manipulate the spread of the crown a bit.  Brass is sweat both inside and outside the fork blade and the rest is capped.  I'll get a good picture of the finished product before its all gone, but have neglected to so far.

One Paragon item I never thought I'd use is their tapered steerer (MS2009).  It is a beautifully machined piece of 4130 with relief internally to match the transfer of stress loads of a fork flexing from bump and brake into the steerer and headset and on into the main triangle.  In my mind it has seemed excessive in most rigid bike applications versus a straight steerer.  I find a straight 1.125" steerer, or for increased braking demands a externally tapered steerer for a 1.125" headset (MS2026 or my own made) more appropriate for brazing a unicrown or segment crown fork for most bicycles (meaning up to a 29" tire and 3" width or less).  Increased leverage from added length of the fork blades on the 36er coupled with a 200mm disc rotor creates a need for extra strength in the fork crown and the tapered steerer is up for the task.  The crown tubing pieces wrap the fork blades and in this case approach the size of the steerer base.  Tube diameter and wall thickness are a crescendo of sorts, growing thicker towards the top.  All told the 9 inches of steerer tube stack will most likely remain its full length when the build is complete.