I've come a long way with Mk4.

The plan was to do something similar to Mk3 and to not only include small improvements, but to use hemp bast fibre for aesthetic reasons. I have used some carbon tow underneath.

Here is the current look after the final lug was laid up and I have stripped off the tape and protective covering.


There is a LOT more work to do sanding and shaping the lugs, then I move on to the fixing of the various mounts and guides. The lugs will look good with a clear coat on them, but don't look great at the moment.

Not everything has been easy or worked properly:
- the hemp really doesn't wet out well. It's a real PITA to compress.
- I've had to do some touch up patches on the head tube and seat tube lugs to fill gaps (and I'll have to some on the bottom bracket too)
- the way that I tried to incorporate the FD cable path doesn't seem to be working well. There is a lot more work to do there.

Frame is noticeably heavier than Mk3, but I'll wait until I've sanded some more off these lugs before I throw it on the scales.

Two of the lugs have had a light coat of thinned epoxy and have come up rather well. Some more sanding, then the clear coat, and these will look great.

Still working on the BB lug. The cable path needed a tidy up and there was a deep groove from the layup that I wanted to fill/patch.

Not pictured, but I've bonded on the drink bottle mounts.

Tomorrow:
- file and sand shape to BB lug
- overall sanding and touchups with the file (a few areas look different now there is a clear coat on them)
- locate the FD mount
- locate and drill pilot holes for cable guides

Later:
- more sanding
- 2 pack polyurethane clear coat. Probably two coats on lugs, one on the tubes.
- screw and glue on cable guides etc
- take to LBS for headset install and BB thread chase

With any luck I'll be done by Monday and riding by the middle of next week.

nice. What do you usually use instead of hemp?

Previous bikes have all been carbon only layup. It is much easier to work with! Wets out well and smooths down.


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So the question that many want to know is if the carbon is easier to work with doesn't it produce a better or worse frame. Conversely is the harder to work with hemp plys make for a better bike? Andy.

Hard to say at the moment since I haven't ridden it, but here are some thoughts...

The carbon tow ribbon comes in much longer lengths and you might infer that this creates a stronger join as you wrap in patterns. The hemp is shorter (20-50cm) and you get less continuous wraps.

The new frame feels heavier, but I haven't weighed it yet. My third frame was just on 2kg, but I'm expecting the new 'hybrid' construction frame to be somewhere between 2.5 and 3kg.

Flax tow is becoming available in continuous non-twisted strand spools.

Looking great, I'm eagerly following your posts and progress. I'm finalizing the geometry for my first bamboo build this summer. I'm planning on using carbon tow and balsa lugs with a 1x9 drivetrain. What are you using for drink bottle mounts and cable stops/guides? Everything that I've read in my research says not to drill bamboo - something required by all commercially available parts that I've found. So I've been trying somewhat unsuccessfully to fabricate surface mounted ones out of hardwood. Any advice/suppliers would be much appreciated.

There are always clamp around the tube methods of attaching stuff. Hose clamps are pretty versatile. I've seen attachment points (bosses) made with a large and flat base which can be glued to the tube then additional tow wrapped around the base and tube. Andy.

Thanks, I personally despise the look of clamps. The amount of time and energy going into this build I want it to look right. I'd be interested in more info on the flat base mounts though.

That might make things better!

Also, more practice and perhaps the patience to set up some vacuum bagging.

I use commercially available aluminium cable stops like these from Nova:
NOVA CABLE STOP SINGLE - RIVET ON BLACK :: CABLE STOPS :: ALUMINUM SMALL PARTS :: BRAZON/SMALL PARTS :: Nova Cycles Supply Inc.

They are designed to be riveted, but I just screw them in.

I pre-drill the holes, then fit them with some epoxy (partly to go in the hole and partly to provide a 'bed'.

On an earlier frame I did drill on the bamboo:


But on the most recent ones I've drilled through the lug material:



Getting the front derailleur location correct is not easy, so the 1x9 drivetrain is a good idea. I'd seriously consider one of the new SRAM 1x11 drivetrains on a future build, but I had a cheap deal on a secondhand 2x10 Ultegra group for this one.

Drink bottles bosses use the standard cycling rivet in bosses inserted in disks of carbon fibre (cut from the shaft of a broken crew rowing oar - sculling, not sweep) and then bonded on. I went to my local bike shop and did this at the counter using their tool.

The colours really do come up nicely under the clear coat.

I'm sure it will look better in the daylight.

I put a lightweight wooden half round inside the tubes where the bottle mounts and FD will be. Then the tubes can be drilled and have an insert countersunk through with no danger of splitting.
I like to make diamond shaped overlays of either bamboo or homemade micarta in a colorful pattern that matches the lugs if they are finished that way.

A big thank you to everybody. Canaboo those overlays are unbelievable.

Mental note to copy this! The depth that I need to recess the FD mount is a bit of a worry at times.


One day I'll be this good! Practice...

You mentioned balsa lugs - did you get the HERO Bike kit?

Yes with some personal modifications. It seemed like the best place to start. I'm using BikeCAD for design; trying to mimick my Cannondale Synapse endurance geometry. I'm also using vertical dropouts from Paragon Machine Works. I am not a fan of horizontal dropouts. But everything else will come from their kit. I've watched their video so many times I think I've got the script memorized. I am impatient to start but it will be an outdoor project and its still winter here.

Pretty much the same here.

First thing to go from the kit is the dropouts - as you have done. I also got some Paragon ones and had some extra material welded on.


Their videos are good and the method works. It is all about practice and small improvements (and one day we'll have beautiful lugs like Canaboo!).

I was aiming for between 2.5kg and 3kg, but thought it would be closer to 3. Quite happy with this. About 30g of extra cable stops yet to be installed.

Second coat of clear is dry so I started to put on the small parts. Both derailleur hangers and the BB cable guide are on, but I ran out of the suitable s/s screws for the other cable stops. I had bought a small bag of counter sunk ones, but without the cable stop in hand when I bought them I couldn't test if they fit...and guess what, they don't fit. Grumble.




Next issue is the seat post insertion. I have a rather long 350mm seat post and a couple of cm below the end of the metal insert there is a node in the bamboo. So, despite a lot of filing and swearing, more filing, skinned knuckles and even more swearing, I can only get the seat post in about 13-14cm. This would be fine if the seat post was a 250mm version!

After consultation with my LBS mechanic the plan is to triple check measurements and then take to the seat post with a hacksaw. If I can get the saddle at the correct height with most of that 13cm inserted then I'll be fine as the minimum insertion on the uncut post is 9cm.

Tomorrow:
- pick up some suitable s/s screws and bond on cable stops.
- measure and cut seat post, then fit clamp.
- bolt on a few parts such as derailleurs and brakes.
- pack everything else (especially headset and bottom bracket) and go to LBS.

That is one sweet bike you are building. I love the idea of a bamboo bike. I have seen several nice ones in my area. I saw Craig Calfee build a couple at the Philly Bike Expo. He now uses fiberglass casting tape for the lugs. It has a big advantage that the polyurethane adhesive is sticky (Unlike epoxy) and it naturally compresses itself. He said the casting tape joints rival his carbon joints for strength when tested. They are easy to make, but need to be painted as they don't come out as nice as the artwork you are producing.

I watched several frames being wrapped and it was easy. Open the package of casting tape. Wet the tape and go to work. It sets in ~5 minutes. Much cleaner than epoxy and no need to compress the joints.

He has just started a kickstarter to sell kits with the jigs.
https://www.kickstarter.com/projects...o-bike-diy-kit

Ride Safe,

Joe

Its so nice being able to converse with somebody with real world experience with their kit. I could pick your brains for hours but I promise not to be a PITA until I get in trouble, but I've got a couple of questions and then I'll just sit back and watch your build for awhile. Great idea with the welded combo of Hero's dropouts and Paragon's. I'll have to find a stainless steel welder.

Like Hero's dropouts, I am not a fan of their rear brake bridge - functional but negative aesthetics. I was thinking of replacing it with one of Paragon's. My question is do you see any issues with going with ordinary steel vs stainless? I figure its going to end up encapsulated with carbon anyhow. So unless there's an issue with proper adhesion I'd like to spend the $ elsewhere.

I prefer as stiff a BB as I can get. Towards that end I was thinking of adding a couple of layers of carbon cloth as a sling/cradle along the bottom of the joints between the downtube, the BB shell and the chain stays. Carbon tow wraps will provide sufficient structural stability but I'm not sure how much stiffness. The cross weave of the cloth should help. Additionally I was going to add a tube (probably a hardwoodf dowel) between the chain stays just to the rear of the BB shell. It would probably have to be added after the BB has been completely wrapped - just because of the limited space; but it should stiffen up the structure. Any thoughts?

bmwjoe - The Calfee DIY kit looks interesting, but I am completely intimidated by mitered joints and his dropouts are also horizontal and even uglier than Hero's (if that's possible) Not having used either I think that Hero's is more user friendly for a beginner.

I love this bike! I have built several bikes using alternative materials, mainly hardwood and bamboo. I prefer the workability and look of carbon fiber over hemp for my lugs. Some people say hemp is more forgiving in regards to temperature expansion/contraction than carbon fiber as the bamboo and hemp do so at similar rates. I have no personal experience with any of that trouble. My question to you is where did you source the carbon seat stays and chain stays? They look very similar to what is on my Sette Durata, an Aluminum/Carbon hybrid frame. Did you use an existing frame, or did you find them on a frame builder supply site?

Send me a PM and we can chat via email. I have a metric truck load of step by step photos in galleries (no, I'm not OCD - it's a habit from when I was a Design Tech teacher) that I can point you to.


I had the same thought, so I fashioned one from a lump of carbon I got my hands on (a section of boom from a high end ocean racing yacht!).

If you can't get your hands on something like that, then order/buy a section of glass or carbon rod from somewhere (Rock West Composites?).


Good idea. I put a few patches of cloth in certain areas. The wrapping patterns for the carbon tow do leave some small triangular gaps in places (they do note this) so putting a bit of cloth down to start with helps.


Mitering is like anything. Easy with the right tools. That being said, the balsa lug method is very clever and you can get nice smooth shapes if you take the time and have a good eye.

Mk3 used the stays from a re-cycled carbon frame. I also re-used the head tube and fork from that frame.

This bike has a new unit that I purchased cheaply (odd ends of stock?) a couple of years back from a frame making supply shop (Ceeway in the UK).