12-JAN-2013
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The kit contents all laid out on the custom frame plan. Nearly everything needed is included, save for some wrenches, gloves, power drill etc.
19-JAN-2013
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Day 1: jig setup on a 2'x4' flat board (fiberboard from local hardware store). Balsa blocks mounted to jig points using epoxy to become frame lug cores. Bamboo cut to length, then roughed according the BBS's video instructions. Bamboo is then tacked inplace on the balsa core lugs, again using an epoxy adhesive. Seat post sleeve is also permanently epoxied into the pre-bored bamboo seat post. I used a high quality West Sytstem G-Flex epoxy with high density filler rather than the JB Weld included in the kit.
19-JAN-2013
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Day 2:
Head tube balsa lug core after shaping. Goal is to make smooth transitions from the bamboo tubes to the steel head tube. Fiberglass will first be applied to these joints before the frame can be lifted from the jig, remounted vertically prior to carbon wrapping. Note the roughed bamboo end...with lots of exposed fibers to enhance bonding strength. There is a definite technique needed with the pull saw to achieve this...I practised on a spare section of bamboo. According to BBS website, you should aim to complete epoxy bonding within 48 hours of perfoming this roughing to reduce drying out of the fibers...which reduces bonding strength.
19-JAN-2013
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Bottom bracket balsa lug core prior to shaping with the included file. The frame tubes are tacked to the core "landing pads" and marker lines indicate the first areas to file down...forming 1 cm rasied pads filed circular & flush with the bamboo ends.
19-JAN-2013
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Seat lug core nears completion of filing...still needs area between the seat stays faired out.
19-JAN-2013
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Rear dropout brackets supported at the maximum 130mm spacing of the jig. Bamboo Seat Stays & Chain Stays epoxied to the dropout connection points. Note the Wheel Clearance Checker arm between the stays.
19-JAN-2013
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Bottom Bracket lug core from below prior to fairing. Marks indicate landing pad fairing zone (1cm deep circular & flush to each stay). A mark is also indicating approximate centerline of bottom bracket.
I used a high quality G-Flex epoxy (4-7 hrs set time) thickened with a high density adhesive filler...although kit comes with 5-minute JB Kwik for this work. In hindsight I would go with a faster curing epoxy next time...as I basically lost most of a day waiting for it to set. None of these bonds (except seat post sleeve) are structural at this point...all strength comes from glass & carbon work later.
19-JAN-2013
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View of the rear triangle area. Note the wheel clearance checker now positioned between chain stays.
20-JAN-2013
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Day 3:
Bottom Bracket faired & glassed, ready for carbon wrapping. I followed the BBS instructional video recommended glassing steps for all the lugs. It worked out pretty well.
20-JAN-2013
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Head tube lug core faired & glassed.
20-JAN-2013
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Seat lug core faired & glassed.
20-JAN-2013
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Bottom Bracket faired & glassed. After all the glass work is completed, the frame is strong enough to support its own weight and is removed from the jig. After re-configuring the jig, the frame is mounted vertically, spupported from the bottom bracket and rear dropout. This allows for better access for rough filing/sanding the glass work and then for the carbon wrapping phase.
21-JAN-2013
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Day 4: Carbon Wrapping Completed
Head tube lug after initial filing/sanding. Recommend a power detail sander for this work. Knocking down the ridges is important to reduce stress risers that can lead to cracks. Though the surface now looks grey, it will go dark black after a finish coat of polyurethane is applied.
I followed the BBS recommend carbon wrapping procedure as best I could, but it was my first experience using carbon tow and hand layup. The wrapping sequence is fairly complex so take notes while watching the videos and draw diagrams if needed. I would switch to the slower setting West System epoxy hardener to give more working time...I found I was hurrying too much while doing this work.
21-JAN-2013
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Seat Lug carbon wrapped and intial sanding completed.
21-JAN-2013
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Bottom Bracket lug carbon wrapped and initial sanding underway.
21-JAN-2013
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Rear view of frame. The rear jig allows up to 130 mm clearance between dropouts. My Alfine 11 speed internal gear hub requires 135 mm clearance. After discussing with BBS, the recommendation was to add 5 mm spacer (extras in kit) between drops in the jig AFTER re-configuring the jib for vertical mounting. This allows both dropouts to move away centerline 2.5mm...if this spacer is added while the frame is still mounted horizontally, the upper (driveside) dropout will lift up 5 mm away from centerline. Thus the dropouts will no longer be equal distance from centerline.
21-JAN-2013
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Side view of bottom bracket showing carbon build up around bottom bracket shell.
21-JAN-2013
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Another view of bottom bracket.
21-JAN-2013
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Rear dropout (non-drive side) showing the disc brake mount points. I will need to figure out how best to add a fitting for a rear bike rack mount & rear fender mount.
21-JAN-2013
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Rear Dropout, drive side. With horizontal dropouts, chain or belt tensioning is done by moving the axle fore/aft in the slots. Note that with a belt drive bike, you need a way to open the rear triangle on the drive side to install/remove the belt (no way to remove a link like on a standard chain). The bolt seen here releases the seat stay end from the dropout, so using a belt becomes possible.
21-JAN-2013
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Underside of bottom bracket showing the carbon wraps. I'll fill the voids with thickened epoxy and fair it down for better asthetics.
28-JAN-2013
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Day 5: Overall frame ready for finishing.
28-JAN-2013
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Bottom Bracket ready for finishing.
28-JAN-2013
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Seat Lug ready for finishing.
28-JAN-2013
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View of bottom bracket lug showing some filled epoxy added to fill in some voids.
28-JAN-2013
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Head tube lub ready for finishing.
28-JAN-2013
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Day 6 & 7: Finishing of Lugs & Bamboo Surfaces
First a thin layer of slow-set epoxy was brushed on all carbon areas to create a smooth, hard surface. After thorough curing overnight, surface was lightly scuff sanded to remove any stiple bumps, then a coat of polyurethane was applied to provide UV protection to the epoxy (which will degrade without it). A full 5 coats was applied over a few days to achieve a high-gloss, protective layer.
The bamboo was scuffed with steel wool and then treated with Teak Oil, which is basically a varnish that penetrates into hard wood before curing to water & UV resistant, natural looking finish.
01-FEB-2013
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Here the 68mm English Threaded Shimano bottom bracket is installed.
01-FEB-2013
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Heatset bearing cups installed. This was done using the 2 large aluminum bottom bracket jig plugs as washers with a threaded rod & nuts to compress the bearing cups into the headset. Shown taped off to keep clean until fork is installed.
01-FEB-2013
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Frame now ready for rest of components.
03-FEB-2013
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Frame being weighed at about 3 Kg. This compared very closely to my all aluminum Spot Acme frame at 3.5 Kg (with rear pannier rack & fender still installed).
02-FEB-2013
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Rear wheel seated in dropouts showing integrated brake disc and disc caliper mounting points. Note the white No Turn washer under the axle nut. This is a specific Shimano part for mounting the internal gear hub in horizontal dropouts. Drive-side uses a chrome coloured No Turn washer.
02-FEB-2013
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Detail showing rear disc clearance from chainstay. This was a lingering concern during the build process and I was glad to see no mods were needed to clear the stay.
02-FEB-2013
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Rear Internal Gear Hub with belt drive cog wheel (24T, for CenterTrak Carbon Belt system)
02-FEB-2013
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Side view of rear hub. Note that the 113T belt off my Spot Brand Acme bike did not fit as this frame has a slightly longer wheel base. After confirming the new frame dimensions, a 118T belt was ordered. Note the chrome No Turn washer. The Seat Stay attachment bolt will need to be undone when fitting the new belt into the frame.
02-FEB-2013
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Detail view of front crank showing plenty of clearance between crank cog and chainstay. The bottom bracket axle is actually a fair bit longer than the Spot Brand Acme bike, which had quite a bit less clearance to the frame chainstay.
02-FEB-2013
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Underside view of bottom bracket showing crank & wheel clearances.
02-FEB-2013
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Seat Stay top end detail showing wheel clearance. Plenty of room for a fender and rear rack...just need to work out where to place attachment points.
02-FEB-2013
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Complete bike awaiting new drive belt and a rear brake caliper adaptor plate.