Step 6: Fiberglass the Lugs & Carbon-Wrap the Dropouts

Step 5: Shape Lugs | Step 7: Reassemble Jig

8 Steps, ~1 hour

Goal: Strengthen the Lugs and Wrap the Dropouts, in preparation for re-assembling the Jig.

Materials: • 4 Fiberglass Packets • Mini Pump • Epoxy Resin • Epoxy Hardener • Plastic Cups • Gloves • Safety Sleeves • Carbon Spools • Compression Tape • Push Razor • Scissors


6.1 Fiberglass the Lugs | Introduction

• This step uses epoxy resin. Make sure you have adequate ventilation: open your windows, and if you have a fan turn it on. Put on your gloves, sleeves, apron and mask. Make sure the temperature in your space stays above 70 F (21 C).
• Put on your gloves, sleeves, apron and mask.
• Push two pumps of clear epoxy and two pumps of red hardener into a plastic cup.
• Mix until uniform color – about 30 seconds of sustained mixing. No streaks!
• This will take 30 minutes to begin to cure. As the resin sets it will get hot. Take care not to burn yourself – once it gets warm, rinse out the resin with water and mix up a new batch.


6.2 Fiberglass the Lugs | Prepare Fiberglass


6.3 Fiberglass the Lugs | Fiberglass Head Lug

How do I fiberglass my Head Lug?


6.4 Fiberglass the Lugs | Compress Head Lug

• Wait 15 minutes.

• Now begin to compress with the compression tape, adhesive side UP.

• It’s very important that you pull the tape as tense as possible. Push the compression tape to its limit.

• Keep the tape flat. If the tape cuts into the Lug, this will induce a stress concentrator which will later need to be removed with excessive filing, removing too much carbon.

• Wrap as tight as you can without wrinkling the compression tape.

• Wipe off any excess resin with a rag.

• Leave this tape on for 2.5 hours.


6.5 Fiberglass the Lugs | Fiberglass & Compress Seat Lug

• Wet out the Seat Lug with Epoxy

• Take 1 piece of the Side Support fiberglass and wet it out completely.
• Wrap the fiberglass along the side of the Seat Lug, so that it covers 2/3 of the roughed bamboo, the side of the Seat Lug, and wrap it over and around the back of the Seat Stay. Half the width of the fiberglass should cover the roughed bamboo on the Seat Stay, and the other half should cover the balsa Lug.
• Repeat on the opposite side of the Seat Lug with another piece of Side Support Fiberglass.

• Take 1 piece of Small Loop fiberglass and wet it out completely.
• Wrap it around the Seat Stay, over the Side Support fiberglass you just wrapped.
• Half of the width of the Small Loop fiberglass should cover the roughed bamboo, and the other half should cover the balsa lug.
• Repeat on the opposite Seat Stay with another piece of Small Loop fiberglass.

• Take 1 Main Loop of fiberglass and wet it out completely.
• Wrap it around the Top Tube, over the Side Support fiberglass you just wrapped.
• Half the width of the Main Loop fiberglass should cover the roughed bamboo, and the other half should cover the balsa Lug.

• Press all the air out of the fiberglass

• After 15 minutes, compress the Seat Lug using the same method described above.


6.6 Fiberglass the Lugs | Fiberglass & Compress Bottom Lug

• Wet out the Bottom Lug with Epoxy

• Take 1 piece of the Side Support fiberglass and wet it out completely.
• Wrap the fiberglass along the side of the Bottom Lug, so that it covers 2/3 of the roughed bamboo, the side of the Bottom Lug, and wrap it underneath and around the Chain Stay. Half the width of the fiberglass should cover the roughed bamboo on the Chain Stay, and the other half should cover the balsa Lug.
• Repeat on the opposite side of the Bottom Lug with another piece of Side Support Fiberglass.

• Take 1 piece of Small Loop fiberglass and wet it out completely.
• Wrap it around the Chain Stay, over the Side Support fiberglass you just wrapped.
• Half of the width of the Small Loop fiberglass should cover the roughed bamboo, and the other half should cover the balsa Lug.
• Repeat on the opposite Chain Stay with another piece of Small Loop fiberglass.

• Take 1 Main Loop of fiberglass and wet it out completely.
• Wrap it around the Down Tube, over the Side Support fiberglass you just wrapped.
• Half the width of the Main Loop fiberglass should cover the roughed bamboo, and the other half should cover the balsa Lug.

• Take 1 Main Loop of fiberglass and wet it out completely.
• Wrap it around the Seat Tube.
• Half the width of the Main Loop fiberglass should cover the roughed bamboo, and the other half should cover the balsa Lug.
• Press all the air out of the fiberglass

• After 15 minutes, compress the Bottom Lug using the same method described above.


6.7 Fiberglass the Lugs | Carbon-Wrap & Compress Dropouts

• Pick up a small spool of carbon fiber.
• Unravel a five inch section of the carbon fiber and dunk it in the resin. There are 24, 000 strands in the carbon fiber: you’re trying to get every strand wet.
• Run it between your fingers to get rid of the extra resin.

• To start the wrap on your first Dropout, cross the fiber over itself in an X over the roughed bamboo. Do not simply spiral the fiber around the bamboo. This is called locking off the carbon. You want your first wrap to anchor the carbon to the bamboo.
• Continue to wrap, crossing the carbon fiber and wrapping over the Dropout teeth.
• Keep wrapping the Dropout until it is fully covered, always keeping in mind the Four Laws of Wrapping. (see below)
• Once you have completed your first Dropout, repeat these steps with the other three Dropouts, using a small spool of carbon fiber for each Dropout.

• The Four Laws of Wrapping:
1. Always completely wet the carbon fiber in epoxy.
2. Always lay the carbon wide and flat: avoid it twisting.
3. Always wrap the carbon fiber tight: wrapping it loosely will make your bike weak.
4. Cross the carbon over itself: do not simply spiral it around the bamboo.

Note:
• Throughout the wrapping it’s common for the carbon fiber to get clumpy. When this happens, work the resin into the fiber, and try to remove the clumping strands.
• If your carbon fibers get knotted, cut the carbon fiber and start your wrapping again, remembering to lock off with your new strand.
• Some people find it easier to wrap if a short amount of carbon fiber is unraveled – if the carbon fiber is too long, it’s harder to keep the strand tight at all times.

• Compress the Dropouts using the same method described above.


Bike Making FAQ
Step 5: Shape Lugs | Step 7: Reassemble Jig