the shell is made of 2 layers of 3 cm (1.18") styrofoam (the kind they use for building isolation).
It can be cut and sanded easily (too easily in fact, so this job must be done carefully).
For the sanding, both halves are stuck together with double sided tape. It can be removed
easily afterwards.
These 2 pics show the 2 cuts I made in the shell ment to allow the rear wheel to "penetrate"
the shell when the suspension is pushed in heavily (yes, we have some beautiful holes in
our Belgian roads...). This turned out to be unnecessary however, since I backed up the
rear stays a little. (see built up pics)
I applied a first layer of Carbon (all 200g/m2) + epoxy on the 2 seperate halves with a simple cheap "one use" paintbrush.
To hold everything in place, I used common "kitchen" plastic food wrap (I don't own the equipment for vacuum bagging remember.)
This foil offers some advantages:
-the foil doesn't stick to epoxy due to the very thin greasy layer on it.
warning: results may vary with the brand! make a small test part first!
-it is stretchable. You can stretch it carefully around curved surfaces without wrinckles
-it provides a very smooth mirror-like finish
Both halves are taped together. Let the epoxy cure for 12 to 24 hrs. after that, remove the wrap.
Thes pics show the strenghtening layers (up to 6) I applied on the critical areas (bracket, headset and rear connection).
The 2 halves will be separated again by cutting the headset strenghtening layers when cured.
The seprated halves with the removed "wheel penetration area". As previously mentioned, this
turned out to be unnecessary...
some pieces of foam were double taped on the bottom of the 2 halves to allow the plastic foil to be
wrapped around without having to bend the CF at 90° around the edges of the bottom of the halves.
(CF bends back when the bending angle becomes to sharp)
A kevlar layer (impact strenght) is applied and wrapped in the same way as before.
Kevlar is a real pain when it comes to cutting or machining it. Remember to buy a brand new pair of
very sharp scissors and even then, beware of blisters on your fingers ;-)
The basic shape of the seat made of 1mm balsa boards.
The balsa seat covered prevoiously with a Kevlar layer is epoxied to the frame.
After curing, the seat wil be cut in the middle to separate the 2 halves again.
2 additional layers of CF are applied (more than 2 at a time gets tricky due to the shape)
the plastic wrap provides a smooth surface. You still see the waves of the fibers though but this is not important at this time.
little wrinckles...of no consequence at this time since 1 more final layer will be added (no pics of that).
Don't you love CF?!
The excess of CF is removed after the last layer. We are ready to remove the foam.
The styrofoam is removed at this time since it is of no use anymore. On the contrary, it hase no strenght and it weighs about 300g.
It was roughly removed with a cutter first and with aceton for the remaining parts. (sticky, stinking job. Do it outside the house!)
I applied up to 5 more strenghtening layers at the inside at the critical points and 1 cf + 1 glass fiber layer from
the front to approximatively the low section of the seat.
Aluminium tubes are added for the cables to pass through.
The 2 halves epoxied together.
First junction strap applied
Second junction strap applied + plastic wrap stretched over it to hold everything in place.
Result after first light wet sanding job.
A thin layer of epoxy was applied before wet sanding again. I repeated this several times until I obtained a satisfactory result.
Allow the epoxy to cure at least 48 hrs before sanding.
16 layers of CF + 1 kevlar, jigsawed after curing. More than strong enough, but stiffness could be improved by using a plywood mid-section to get a thicker result. Nnext time better...
The rough balsa shapes for the rear stays. I used 2 layers of 8mm (3.14") and 2 layers of 5mm (0.20")
A little setup with a "B&D Workmate" to keep everything straight. The balsa shapes are sanded.
For the rear fixation of the rear stays to the frame, I use a front wheel hub which will be modified.
Though I didn't encounter problems with the hub so far, it might be better to consider the use off bronze bearings. Ball bearings don't like just small angle variations.
Result after some CF (6 layers)
A balsa mold was made for the "pyramid" that will be used for the lower attachment of the suspension.
The mold covered with tape, to prevent sticking with the epoxy.
A 12 layer CF junction plate is epoxied between the 2 stays.
The "pyramid" in place. strenghtening will be added later due to a lack of stiffness.
The modified front wheel hub for the rear stays attachment to the frame.
Thickness at the hole=5mm.
The bracket: rough cuts were made in it to make shure the epoxy sticks well to it.
The sanded rear stays in place. Finishing epoxy will be added later.
This allmost looks like a bike yet.
A hole was made in the seat to be able to apply extra epoxy to the rear attachment.
Same thing for the bracket.
The headset tube previously wrapped in cf.
Headset tube in place. I used a mix of epoxy and cf to strenghten the junction.
The holes at the bottom of the boom are filled.
Strenghtening of the fixation points.
Now it looks like a recumbent...
The tiller is semi home-made. The attachments are home made, but I bought the carbon tube.
Notice that the hydrolic front brake is in place. Tim Biesemans (www.tim.be) did the job
Finaly: the bike is ready for a first test drive...
The rear brake comes from a race bike. Not allways possible depending on the size of the tyre. No problem with my schwalbe stelvio.
A blury detail of the tiller attachment.
A little pic of the flanders fields where I live.
Don't forget your shades ;-)
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