filament

The tubes have been cut and bonded together so we now have the overall shape of the tandem frame. We've opted for no lateral tube this time and 724mm BB centres for a belt drive. The stoker's BB shell has a threaded titanium BSA insert. Disc brakes with through axle and an internally routed hose.
The transitions between the tubes are made with a blend of a structural epoxy adhesive. The smooth curves provide a nice surface on which to apply the carbon prepreg wraps. That's the next step.
IMG_4413 by Filament, on Flickr
IMG_4418 by Filament, on Flickr
IMG_4417 by Filament, on Flickr

mtseymour

Is this frame designed for fast century rides or touring? How much does team weight affect the choice of tubing and layup? Is the internal routing for Di2 and hydraulic rear brake? Will the frame use the common I.S. standard or Shimano's new flat mount for the rear brake?

filament

There are no rack mounts for touring and the geometry is well balanced to tackle most road terrain, speeds and distances. The tube and joint laminates are designed to suit the team weight. The hydro brake hose runs internally and this frame will have wireless eTap so there's no need for internal wires, but it is an option. This frame takes a flat mount caliper but I have also done mounts for ISO on other disc frames.
I'm currently doing the junction wraps and will post a photo to show how it looks before cure.

chojn1

Looks awesome! Thank you so much for sharing the build process.

Is your headtube aluminum core or pure carbon tube? Any problem with the tapered headset?

Also, I thought having a separate tube for the stoker's stem apart from the captain's seatpost was a brilliant idea. Why did you not think it was useful in this application?

Thanks,
CJ

filament

Thanks for the kind words CJ. The head tube is carbon fibre and designed to take a Onepointfive format headset with a tapered steerer fork.
The stoker stem tower was essential on the TT frame but not required on this one. It's an option.
Cheers

Bad1

The carbon frame exhibited is awesome looking at this stage, the attention to detail & build is top notch, a totally modern frame with internal routing, flat mount disc brakes, thru axle and with Etap,the wave of the future, no junction boxes, wires, internal battery's rattling around. Looking forward to seeing the finished frame, also could you provide the weight of frame.
Thx.

twocicle

Nice looking frame. Would be interesting to hear back on the long term if the head tube and EBB shell last without any serious reinforcement or if they interact at all with metal components.

FWIW, installation of Di2 components is a piece of cake if you have some mechanical sense and a little bit of foam or zip ties to wrap obvious rattle points. Otherwise pretty much bullet proof for us so far.

filament

The head tube and BB shell are very reinforced. The carbon in these locations has a very thick laminate of high strength fibres at the correct angles. The surfaces are also insulated against electron exchange with the aluminium headset and EBB.

filament

The joints have now been wrapped with prepreg carbon fibre. This process involves placing many layers of carbon by hand at specific angles in a sequence. The next step is to cure the joints under pressure and heat in the oven.
You can see how thick the BB shell laminate is here. It's incredibly strong.
I hope you find the process interesting.
Wrapped BB joint by Filament, on Flickr

Wrapped tandem frame by Filament, on Flickr

geoffs

Well I'm finding what you're posting really interesting and am enjoying watching the build process.
We might be after a new frame next year looking at a similar component set with eTap etc., although we will most probably buy a Seven as I can buy wholesale. We need the frame to be coupled as well for travel

EthanBixby

Great projects! You might look into North Sails Thin Ply Technology, which was developed for carbon fiber sails. It is used in carbon masts, planes, skis, and many other items. More info is here: North Thin Ply Technology - Lightweight Prepreg And Spread Tow Technology It seems to me the next step in the development of Carbon bike frames.
Keep on pushing the envelope!
Ethan

filament

I could bond couplers into the tubes before assembling the frame. No problem.

filament

Here's the recent custom carbon tandem now painted. The frame weight is 2.4Kg.
RoadTandem1 by Filament, on Flickr

twocicle

Looks sharp. Nice weight.

Which make/model fork did you go with?

geoffs

Wow. The finished frame just looks stunning. I'm in lust

PMK

Spread tow has been used by many companies already. Often they use is as a visible layer, but regardless it is a structural ply also.

Downside is when I do a repair, it becomes difficult to match the spread tow appearance.

mtseymour

Very nice frame! is it designed for flat-mount disc brake? Is it rated for 180 or 203mm rotor?

Bad1

Hi Richard, I see you have posted a picture of my now completed tandem frame which is now on its way to me by early next week. I must say to all you tandem enthusiast out there, Richard is a true professional to work with, from his CAD design drawings of the frame design, to working with you to change the smallest of detail. Also responding to any questions or doubts very promptly in a professional manner! I am very pleased with the whole inter-action with Filament Cycles.

MRacing

Beautiful work. Thanks for sharing and patiently answering questions about the builds. Bleeding edge technology is nothing without the well earned experience needed to create a functional masterpiece, I hope everyone appreciates the lifetime of knowledge it takes to chase perfection. There's quite a bit more going on here than simply gluing some plastic sticks together!

geoffs

Looking forward to seeing the details and some photos of the completed bike