Saturday, July 23, 2011

True blue

   Wow, I really wish I had finished all of the painting before this heat wave hit, then all this sitting around would have provided a good amount of drying time prior to applying the decals. It's not like I'm facing a deadline or anything, just anxious to see the job completed.

   In the meantime I can tell you about one of my homemade tools in my workshop. Back in the spring of 2008 I was hit by a car during a ride. I was fortunate not to be seriously hurt, but my 1989 Cannondale was not so lucky. While the damage wasn't very obvious, the frame was knocked out of alignment about 1½ inches, making it dangerous to ride. I took very good care of the bike, and I really didn't want to just toss my old friend on the scrap heap. The bright blue, nearly scratchless frame deserved a better fate!
   After taking a mechanic's course at Bikesport, where a segment on wheel truing was included, I came upon the idea of using my damaged frame as a wheel truing stand. While I'm sure the complex and expensive-looking stand at Bikesport would give a super accurate gauge for the perfectly straight wheel, I was hoping to avoid having to dish out serious bucks and yet create something that could do a reasonable job.
   Since front and back wheels have different axle lengths, I planned on making two separate stands from the frame. After completely disassembling the bike, I hacksawed the frame near the seat tube at the end of the top and down tubes, leaving the rear triangle intact. I used a couple of leftover step boards from a porch repair project as bases for my truing stands.
   To provide stability for the mounting post, as well as additional wheel clearance height for the rear wheel platform, I planned on adding a raised block on which to attach the rear triangle.  I screwed the two pieces of board together and drilled a hole the diameter of my old seat post. I then glued in a dowel with the same diameter and mounted the triangle upside down on the dowel, securing it with the existing seat post clamp.
   The front truing stand was made in a similar manner, but in lieu of a wooden dowel, I cut off the fork's steerer tube to the appropriate length. I made sure to drill a hole the diameter of the steerer tube in another riser block and attached it to the second platform with screws. The fork was then secured to the platform simply with an eye hook and a bolt through the brake mounting holes.

   For my truing "gauges" I mounted zip ties with the free ends cut to a point on each side of the fork and on the seat stays. I can slide them to the location needed for the rim size, and a simple twist adjusts the distance from the tips to the rim surface. During a truing job, I install a wheel in the appropriate stand, and set the zip ties exactly opposite each other at the rim height and twist them towards each other until they are just barely out of contact with the rim. As I slowly rotate the wheel, I listen for the scratch of a tip on the rim and locate the warp. I then tighten the spoke nipples on the side opposite the spot where the tip scratches in order to pull the rim away from that contact point. When I spin the wheel and hear no more scratches, it means the wheel is straight.

   Although I get a twinge of sadness when I see the still flawless blue paint, I'm so glad I found a way to re-use the old bike instead of just making it a memory.


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