Introduction 

The carbon fiber Mistress is my second homebuilt recumbent.  My first was "Woodie."  The above image shows  what "Woodie"  looked like shortly after it first became roadworthy.  Woodie's frame was made using five layers of birch plywood- three core layers of 3/4 inch (13 ply) and two skin layers of 1/4" (5 ply).  To minimize the weight  I cut a channel down the center of each of the three core layers before gluing the five layers togehter.   The result was a hollow rectangular wooden tube.  For strength, I made the frame solid (i.e. no lightening channels) in the region of the bottom bracket, head tube, and swingarm attachment. 

The swingarm (i.e rear chainstays) came from a dual suspension child's (20") mountain bike.  I bought the donor bike new from Walmart specifically for the swingarm.  I felt a bit funny about it at the time, since it was just before Christmas and the bike was about the right size for my son.  But this little  bike was not for him, it was for me!  In retrospect, I should have bought one for each of us.  By now he would have long outgrown the bike, and I would have a spare swingarm.  If I could find another one now I would buy it.  The bike was called a "Flexor" or something similar, if you see one let me know.

Though it's hard to see in the image above, Woodie had rear suspension. The suspension unit was hidden by the seat.  This pic below shows the frame with the seat removed.

 

Before getting started on the Mistress, I made lots of changes to Woodie.  By the time I went to the 2004 Bentride, it looked like this: (Photos by Vic Gedris, thanks Vic!)

Gotta love the point on the front end (for aerodynamics of course). 

Some of the changes included a sleek new aluminum fork from Bill Cook at Barcroft,  a rear brake, a smaller rear wheel (26 inch vs 700c),  lightening holes in the seat frame and seatback, and a new idler.  I had also added nylon wheelcovers on the back.  I made wheelcovers for the front wheel also (you can see the clips on the front rim), but I ditched those after the first ride on a windy day.

Overall, I was pretty pleased with how Woodie turned out, especially since this was my first attempt at bike building.  But there were a few areas for improvement. Of course, I thought I could reduce the weight.  And I wanted the seat to be lower.  Also, it was a bit crude looking and just a little too obviously "homebuilt". 

I had read on the web about other homebuilt carbon fiber bikes (both bent and upright) and wanted to try my hand at it.  I thought using carbon fiber would help reduce the weight and look cool too. Most of the bikes I came across used a foam core, but I decided to try something different.  My idea was to make a hollow wood core  (like Woodie's frame only with thinner walls)  and reinforce it with carbon fiber composite.

Of course, the main drawback to the wood core, compared to foam, was that it would be heavier.  On the other hand, the wood core would contribute significantly to the strength and stiffness of the overall structure, so less carbon would be needed.  Also, the wood core would provide a solid place to attach other main components such as the bottom bracket and head tube.  In addition, the wood core would eliminate the need for a jig, since it would be stiff enough to be self supporting and its flat sides could be used as reference surfaces for ensuring that the holes for attaching the head tube, bottom bracket, and swingarm were correctly oriented. 

I considered trying to construct the whole frame this time, including the rear end (chainstays/seatstays/dropouts).  However, the donated swingarm worked so well for Woodie that I decided to use it again on the new bike.  Basically, I decided to make a carbon reinforced version of Woodie, rather jump straight to a fully carbon fiber frame.

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