FFC composite builds

Hello everyone

I’m new to the forum and thought I’d share some of my recent projects and what I’m currently working on.

My brother and I built a lot of different stuff over the years, but mostly kiteboards, skis and snowboards, but also some kitchen knifes, a plane for the redbull Flugtag, …

I work a lot with composite materials, which I believe is awesome for the home builder. There are relatively few tools required to get started and one can make really high quality, structural parts in a garage.

So far I only built one bike:

It was made in a tube-to-tube process. all the tubing was manufactured in vacuum infusion on 3D printed mandrels. those tubes were then cut, mitered, bonded and all the joints overwrapped with prepreg. I built this thing 3 years ago and it held up beautifully since then.

And shortly after, being a mountain biker at heart, I started building a high pivot enduro bike. Some pictures from the process so far:

front triangle machined on a CNC router I mostly built to make the bike…

the rocker link and all axles were outsourced

seat stay mould off of a printed plug

machining of the shock mount. There are so many components on a full suspension bike, but I don’t need to tell you guys…

laminating the front triangle mould

tooling done

laminating one of the seat stays

both seat stays done

laminating the front triangle

a bladder on the inside popped when pressurized, leaving me with an expensive piece of trash…

And this is where I’m at right now! back to square now with the front triangle…


Impressive stuff! I’ll need to have a good look later.

Nice work @Lester
I can’t wait to see this thing come together.

Impressive stuff!
Subscribed to this thread.

Looking forward to updates on the enduro build.

Do you think tube-to-tube construction would be up the the task for a simpler dual sus MTB?

Also more info on the skis! I’m just wrapping a ski trip and the depression is already starting to set in…

Wow! this is super impressive! Where did you and your brother acquire so much knowledge on composites?

Also, let me see if I can understand your workflow.

  1. CNC MDF male mold
  2. create carbon fiber female mold (wet layup + vacuum bag?)
  3. layup carbon frame (prepreg + bladders?)
  4. autoclave?
  5. profit? (joke)

I can’t seem to figure out what that white thing is. Is it to help you lay up the prepreg?

Super cool stuff, you make it look so easy, but I bet it’s not!

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Great work and craftmaship! I have seen you on pinbike already. Could you share your hints for tube to tube builds? I have put some questions here in this forum.
And from another point…how you are making slide side of ski?

yes i cannot see a reason why a tube to tube construction wouldn’t work for a mtb. Depending on the design you might need a moulded downtube that is not just straight to give you room for a shock, and if you do this i would probably directly mould the shock mount.
Honestly if I had to start over with the project this actually might be what I’d do :smiley:

I build a lot of skis and snowboards - and unlike with building bikes i kinda know what I’m doing there. I have a very systematic approach for this and calculate the exact core profile i need to get the stiffness I want with a given core material and layup.
freeride ski build on youtube
this is an old video, the last pairs are CNC machined and pressed in a pneumatic press.
If you want to give a ski build a go then hit me up, I’m happy to help with the flex, layup, material choices, …

If you tinker with it for long enough you pick up a lot of bits of information from here and there, and by now I work in the composite industry-ish. Not directly with composite materials anymore really, but in the development of machinery of a company working in the composite industry. So I’m constantly in contact with the topic.

The male mould is machined from a PU tooling board, not MDF, but same idea.
the negative mould is made on that with carbon fibre, but with vacuum infusion instead of a wet layup.
the prepregs are laid into the moulds, with bladders on the inside
originally the plan was to inflate the bladders and cure it in an oven, but by now i luckily have access to an autoclave.
the fiberglass mould you highlighted is a helper to shape the overlap that sticks out over the split line of the tool during debulking.

with thick laminates in complex shapes it is best to do a debulk every couple of layers, where you put the whole thing in a vacuum bag to consolidate all the layers. This tool helps to have the overlap properly shaped which really helped to close the two moulds and you can have a pretty high level of confidence, that there are no wrinkles in the overlap. I’ve never seen that being done anywhere, so I don’t know if there is a better/easier solution to do the same, but it worked great.

you can get the ski base, edges and everything you need in shops like skibaumarkt.de


Nice to have you here @Lester !
Btw, I got all the infusion stuff to try a top sheet with glass like you explained to me once a few years ago but I haven’t tried yet.

Machined the seat stays last weekend, and managed to cast the chain slap protector during the week. It is weirdly satisfying to drop this floppy piece of PU in place :smile:


Super cool stuff.

How did you machine the SS? Did you make a fixture for your CNC router? Or was it done manually in the mill?

Looks great!

How did you machine it and hold the stay?

my usual process with a 3d printed jig, bolted down into a machined pocket on the cnc router to position it within the work coordinates.

works for me, but I’m sure this is not the way it’s done…


Awesome! Nice work.

Seriously impressive stuff! Excited to see this come together

I’m back at it! little unorthodox but I decided to make two half shells first, that then will be bonded together with more prepreg strips on the inside. Should help me with process reliability and hoefully make something rideable this time :smiley:

So far so good and the two sides look pretty much perfect! Super stoked on it


The industrial design on this is next level. Are you using Fusion for it? Or some other software?

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Yes all done in Fusion. Was a big learning curve and I spent way too much time on the design, but I am stoked every time i see the transition between top tube into the seat tube down to the main pivot :joy:

So guess it was worth it

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Inspirational stuff!
Definitely following this thread from now on…

This is a pretty epic project! Daniel is right, the industrial design of this thing is incredible. You should definitely be proud of what you created here.

Do you have any tricks to get such a crisp sharp edge on the TT-ST-main pivot line? That’s not a trivial feature to pull off. What material are you using for the BB and pivot inserts?

Also, what was the deciding factor in going with the clamshell/dual cure process? More control over fiber placement on the outer control surfaces?