How are they made? However you and I want to. I am experienced in many areas of composite manufacturing and thoroughly enjoy a challenge. Explore below for some ideas of how I have made some of my frames or check out some build reviews.
Tubes are the mainstay of conventional bicycle frame design, before getting into how they’re joined, they first need to be made.
Each build will have the method tailored, however the methods that I prefer are roll wrapping and two/multi part moulds.
I spent some time in a fishing rod and tubing manufacturer where I learnt the ins and outs of this technique.
Fundamentally, roll wrapping starts with a solid mandrel which will determine the internal dimensions of the tube, this then receives multiple layers of fabric which is applied via rolling with an even pressure. Compression can then be applied via high tension cellophane tape or heat shrink tape. Additional vacuum bags and other novel methods of compression can be employed.
Roll wrapping has many benefits both in simplicity, repeatability and resultant composite mechanical properties, however it has limitations in mandrel shapes due to requiring a taper to remove.
Perfect for – Seattubes, Bottom Bracket Shells, and Headtubes
Multi Part moulds:
The use of moulds is a production method which is more prevalent in general composites however in tube manufacturing it has it’s limitations. When complex tube shapes are required they come into their own however.
Their are many different ways to approach this however for my frames often use silicone bladders to provide compaction and allow for removal once cured.
Conversely to roll wrapping, moulds will provide the finished tube with a guaranteed outer dimension.
Perfect for – S-Bend Rear Stays, Unusually shaped downtubes and toptubes
Through intelligent selection of the methods available a tube set for a frame can be produced. Regardless of method the layup can be tuned throughout to provide reinforcement for bosses, holes and expected loads from the riding style.
Once the tube set is completed they need to be joined. Again, there are many different ways to do this, some of which I have tried and many of which I would love to explore!
Lugs are a staple in steel frame building and the entire history and evolution of them is something better left to a bike historian! I adore how lugged frames of all kinds look and some of my first builds were focused on the aesthetics of lugs. They add a lot of complexity to a custom build and will never create the lightest frame however they have a certain style which I think can’t be beat.
To produce lugs I have used various methods but I have refined it down to using multi part moulds and silicone bladders. Having lugs and tubes laid up separately then bonded together allows for a lot of tweaking and customising along the way as there are many areas where a crucial bit of fibre can be added or removed.
Perfect for – Style and future repair-ability
Tube to Tube:
This is a process used by a lot of composite frame builders. The tube set will be mitered together while in a jig then tacked with adhesive. Filleting and shaping is then carried out by hand to prepare for a vacuum bagged lay up to mechanically link the tubes.
This process has enormous flexibility as if a small change is required it can be put into place quickly and easily with a jig adjustment. Once the final geometry is checked the fibre can be laid up over the joints with scarfing and staggering to provide a proper transition through all the fibres. This lay up will then be vacuum bagged and cured. The finish straight from the vacuum bag is often less than desirable although I do enjoy the look some have managed to create from it, a matter of personal taste for sure. A light skim of filler smooths this out and prepares the frame for paint.
Perfect for – Quicker build times, fewer moulds (less material usage/waste), more ideal load transfer through fibres
For custom frame building the route I have explained above is the conventional method for a custom frame to be produced. However, most production frames will use a “semi-monocoque” design. Even with the quotation marks I still feel monocoque is marketing misnomer for some frames however it highlights the difference in design. The economy of scale allow large manufacturers to spend enormous amounts on aluminium or composite tooling for production run frames. Although this doesn’t mean these processes can’t be employed at a custom level, they will just take longer and be more expensive.
Full monocoque designs like some of the aero frames of the 90s and 00s are fantastic pieces of aerodynamic wizardry and I am more than capable of producing frames in these methods, it relates far more to a lot of my composites experience ironically! If this is the kind of build you have in mind then don’t hesitate to get in touch as I would relish the opportunity to build something akin to those historic UCI defying machines!
I hope this page gives a run down of the methods I employ to create frames and crucially hasn’t been too longwinded. If you have any questions or even just want to talk about crazy ideas then get in touch via email or on Instagram.