JonnyHK 

Yes. They are using some sort of fibrous bark.

Many folks use hemp fibre, but I understand it is a total pain to wet out and then you really have to compress it well. If I had to go to hemp I would spend more time trying to get the vacuum bagging working around the complex tube shapes.

mambo1

Thanks. Aren't you worried that the frame will fail then? I vaguely remember reading that Calfee had to take a load of returns because of this issue. I would like to build my own bamboo frame just for fun, but don't like the carbon wrap for aesthetic reasons (regardless of the technical ones) does anybody offer the hemp warp finish?

JonnyHK 

Plenty of folks haven't had problems with carbon lugged bamboo bikes. Calfee is doing it for a living and also offering a very high level of service/warranty - people also have a very high expectation of their products, so even if the 'failures' aren't really that bad (i.e. not failing, but just loosening up a bit or cosmetic problems) they still have to act on it.

There are some kits that come with hemp fibre and you can buy it as is.

I'm chasing down a friend in the bamboo biz (home wares, fabrics) to see if they can source some bamboo fibre roving/rope for me.

mambo1

Great. Thanks for the info.

Canaboo

I'm pretty sure Calfee's problems were from bamboo that wasn't thoroughly dried rather than the different coefficient of thermal expansion of the two materials.
Bamboo and wood both shrink as they dry and continue to do so for many cycles of gaining and losing moisture. The best solution is a prolonged period of unstable climate in order to force this process to happen.
James Wolf has a system of pumping moisture into an enclosed environment and then dropping the humidity repeatedly to ensure this happens.
I think Calfee was just speed drying and then smoking the bamboo which likely didn't allow it to reach its final minimum dimensions until it is already built into a frame.

I have used Manila rope that has been untwisted, washed/dried and separated into manageable hanks of material. Manila hemp(banana leaf) is very strong and looks very natural. Coconut fiber is another good one that is often available from garden centers.
Here's a view of the bb lug of my first frame using Manila.

JonnyHK 

Canaboo - how did you compress those fibres when the epoxy was curing? How much material to you sand/file off later to get the finished smooth shape?

Canaboo

Strips of old inner tube cut into varying widths offers the easiest compression wrap solution. You can really crank up the tension and force the lug into shape so that less sanding required.
A good tips is to wrap with fiber and then compress the matrix with tubing strips and then place the frame in the sun. The heat will increase the viscosity of the epoxy(especially if it has started to harden while you are wrapping) and allow it to flow and fill any voids.
That gives a bit of a shortcut to achieving a nicely shaped final lug.
If you think your matrix is a bit light on epoxy you can wrap the lug and then use a syringe to inject more epoxy in after everything is contained. The pressure will force the excess out.
You can also strategically add pressure to low spots where fibers may just be bridging a hollow where you would like them to lie in the curve.
I usually save my discarded rubber gloves and roll them up in a wad and place them on top of these areas and wrap the rubber strips on top of them. Wrapping over the area twice with the wadded up glove between layers of wrap so the glove doesn't get embedded in the matrix.

JonnyHK 

I had thought that one key fault with this kit (and the 'how to' videos) was how narrow the electrical tape is. It works great for compression, but it is very easy to have bunch up and create sharp or deep ripples in the cured lug.

My original thought was to find some wider tape, but your inner tube method seems so much better. A road tube would give a 2.5" wide strip. The packing of the gloves would be good for the tight areas around the chain/seat stays.

I'll be sure to try this one on my Mk2 bike.

Canaboo

That just takes practice to lay the tape on smoothly. Builders do get a bit aggressive with the pressure rather than applying the tape smoothly.
The inner tube strips are definitely more versatile and user friendly.
There is a happy medium for the width of the strips but it helps to have a variety of widths on hand.

alex jb

Great info guys.
going on a build course as I was a bit chicken to do it at home with a kit, maybe as I rebuild my other N+1 stable

JonnyHK 

At the bike shop to have the various technical bits done that I don't have tools for - threads chased, bottom bracket faced, head set installed.

JonnyHK 

Just back from LBS with headset, fork and a few details done (threads of BB chased).

With wheels it is actually starting to look good.

triathloner

you have to give us a ride report, and curious what you will have into the frame only when it's done.

JonnyHK 

Small update...

I was away for almost two months touring around the UK in a camper van, but I'm back and things are happening.

Decision was made to build it up as a geared road bike, so with the help of the nice folks at Nova Cycles Supply I got a set of cable stops and other 'braze on' parts. Obviously I'm using a 'glue and screw' method to fix these!

Front derailleur
STI stops on the down tube
Cable stop on the chain stay




I've installed a bottom bracket and now all I need to do is source the final few parts. Have done well with gifted parts and some cheap second hand, but the last couple of things are proving hard to get so I might just have to pony up some real money and buy new ones.

Missing:
- front derailleur
- shift/brake levers

JonnyHK 

Crapola!!!

The 53/39 crank I was gifted rubs on the chain stay. Only a little (inner chain ring obviously not perfectly straight), but it will certainly be worse when I'm riding and things start flexing around.

Need to see what I can find in a 50/34. This will be 1cm smaller in radius, so should have plenty of clearance. I hope...

Canaboo

Is it rubbing on the carbon wrapping or the actual bamboo?

Scooper

Can you move the chainrings outboard a bit with a longer BB spindle without screwing up the chainline?

JonnyHK 

Canaboo - it is rubbing on the carbon. You can see the uneven surface there so I think I have enough material to file some off - but I'd rather not monkey about with that and re-varnishing it etc.

Scooper - I'm pretty sure I can add a small washer to move things slightly out, but possibly only 1mm. It is a Hollowtech type crank (Dura Ace 7800).

It is only just touching, but once I put my 95kg and a few watts down it will rub a bit more!

Hopefully swapping to a compact solves the issue, but if not I'm sure I'll be fine with a washer and also filing off some material. Plenty of options - just looking for the easiest!

JonnyHK 

Just rolled it down to the LBS where we tested a compact 50/34t crank - plenty of clearance.

JonnyHK 

And we are done!




It rides well - nothing strange so far. Will take it on a longer ride in the next couple of days.

Few small things NQR:
- front derailleur hanger mounted too high. I think my measurement was marked as a centre point, but I've fixed it on as if that was the base line. Shifts OK, but not correct.
- need to take a file or grinder to the inside of the bolt on the dropout. It is running very close to the 11t cog.

Bottom bracket seems very stiff. Pushed it around a bit and I've seen more movement on production bikes!

Those new 105 shifters are very nice.

Full album of construction photos:
https://www.facebook.com/jonny.cantw...e=3&uploaded=5

JonnyHK 

Bamboo bike had its first real ride yesterday: up The Peak on HK Island twice and also Mt Butler.

It rides well - straight and no wobbles - so I have managed to get the key parts of the geometry right. Descending was fine with my only real issue being the new brake pads and the quality of the rubber (it's got cheaper tyres than my regular ride).

Very smooth and quiet. Presumably the damping effect of the bamboo tubing and long chain stays.

Strong - nothing broke and there was no obvious movement in the frame under power.

I think I may have achieved the universally desired 'laterally stiff, yet vertically compliant' balance in this frame.


Only problem is that I don't have a drink cage. I'll have to work on a set of mounts for one or use one of those back of seat triathlon abominations.

Johnny Mullet

Awesome project!

Gaetan7TB4

Hi all,

congrats JohnnyHK ! I am taking a lot of advices from your "how to" to build my own ! Unfortunately all the small parts from Nova Cycles are so expensive for me to be sent in France

But anyway your bike looks awesome !

busdriver1959

Have you checked into Ceeway? They're in the UK so shipping might be a lot more reasonable.

Gaetan7TB4

hi Busdriver,

thanks for the advice ! Only problem is that they don't put the prices on the website so it's quite a pain to compare... plus the shipping is 19£ which is not so less than Nova Cycles.

Anyway I will check both and see which one is cheaper and also has all the parts I would need !