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How to make a Carbon Mountain Bike

So how do you make a carbon mountain bike?

If you're at On-One, it's easy. You copy your sister company - Planet X. OK, so there may be a little more to it than that. It's a question I put to On-One designer, Stevo Olsen.

Carbon frame manufacturing techniques and technology has come a long way since Trek introduced it OCLV Frames in the 90's. The OCLV method was a radical departure from of producing carbon tube and aluminium lugged frames. OCLV was a method of using Carbon lugs and Carbon tubes. Planet X has had a lot of experience using carbon in its bike range and we decided that On-One needed more than one carbon frame in its range. On-One is uses a monocoque front triangle which we then bond the rear stays. All On-One Frames use 30-40 tonne high modulus carbon and high-grade epoxy resins.

 How do we make an On-One carbon mountain bike?

Well, we just follow these steps:

  1. Brief:

  2. The initial designs are discussed with the factories technical team to ensure the best methods are engineered into the design of the frame.  This ensures the frames make full use of carbon as a frame material.

  3. Design:

  4. 2D & 3D Drawings get finalised between On-One and the factory before the steel tools are cut.

  5. R&D:

  6. This is the most critical stage to keep the weight down, stiffness just right and feel balanced.  CAD FEA and lay-up software is used, however this is very technical and needs to be varified by real world and laboratory testing. The lab results are recorded and matched to each lay-up pattern, so that whether to add or remove a layer can be determined to "tune" how the bike feels.  Richard Ussher is riding the 29er to fine tune its "feel" for the race circuit.

  7. QC:

  8. R&D will then document the patterns and layer make-up for each part of the frame.

  9. Material Preparation:

  10. Most 30-40T HM Carbon comes in from suppliers pre-pregnated with high-grade epoxy resins. Pre-preg Carbon needs to be kept at a stable temperature to ensure shelf life. Carbon is refrigerated and handled in air-conditioned rooms, where it is guillotined into specific pattern profiles and weave orientation.

  11. Manufacture:

  12. Production is then down to following the QC document for the carbon lay-up of each part of the frame.  Carbon is wrapped around mandrels and shapes with the longest "tube" sections containing a polyester tube that is inflated inside. QC inspections at each stage keeps the production failures low and ensure that problems are quickly identified.

  13. Curing:

  14. The whole frame is now put into a steel mould and put in to the curing rack ovens.  These rack ovens are set to 160-180°C and compress the tool together to melt the epoxy. The PE bags are then inflated to compress the carbon against the mould, squeeze out any air bubbles and excess epoxy.

  15. Bonding:

  16. The front triangle, seat stays and chain stays are then bonded and cured together.  Any aluminium bosses, bottom bracket and headset shells are also bonded into place.

  17. Inspection:

  18. The Frames get a final inspection and are documented for critical measurements before sanding and painting. Frames from each day's production are also tested to the CEN standard to ensure the same lay-ups and frame stiffness.

Photos of the testing phase:

Drop testing

Teseting the seat post

Testing the seat post

Testing the bottom bracket

Some do not make it!

29 May 2010