Carbon Frame Tech Explained

Ribble have been synonymous with producing high-quality, performance carbon road bikes since they first hit the UK market back in the early noughties. Each and every frame is designed in house, by our R&D team based in Lancashire and is custom made for us and us alone.

Cutting-Edge Technology

All of our frames exceed the relevant safety standards. However,  we go above and beyond these by developing frames with the latest cutting-edge design features. Before any frame leaves the factory it is subjected to the most stringent of quality control tests. 

Our flagship model, the Endurance SL R is undoubtedly the most advanced carbon frame we have produced to date. Here we take a look at the SL R and its sibling Endurance SL to outline the latest manufacturing innovations and technology that make up the DNA of any premium carbon frame.

What is a Monocoque?

You may have seen frames referred to as being monocoque and could be forgiven for wondering just what this means and why it should matter? Let us explain;

Monocoque carbon frames are formed by weaving separate strands of carbon fibres together to create one single integral construct of carbon. This helps to distribute dynamic stress over a wider portion of the tubing. The best way to avoid weak spots, especially at the joints, is to have no joints at all. This one-piece construction is superior to that of separate pieces of carbon that are bonded together.

A partially completed Endurance SL Monocoque frame, the eagle-eyed may spot the plastic at the top of shot, this forms part of the EPS mold process

As well as being a monocoque construction, the Endurance SL R and SL series framesets also benefit from an advanced manufacturing process known as Full EPS Inner Core (expanded polystyrene system).

EPS is a process whereby an expanded polystyrene internal mould is covered in latex. Carbon fibres are then ‘layered up’ over this internal construct. The whole mould is then heated to 130 degrees, inflated and then cured.  When the latex is removed it produces a perfectly smooth finish with no excess material inside the frame.  But what difference does this EPS core make to the construction of a frame?

  • Unlike other methods of manufacturing, the EPS process results in a frame with no excess carbon on the inside of the tubing. why should this matter we hear you ask? Well, not only is the inside of the frame smoother, but it also eliminates any imperfections for enhanced structural integrity of each fibre.
  • It enables the frame to be constructed as one piece, a monocoque frame is stronger, lighter and stiffer than a comparable bonded frame.
  • It eliminates the imperfections in the carbon layup that earlier production methods were susceptible to.

Using the highest quality carbon tubing is essential to achieving the holy grail of strength, durability and weight. To achieve this we have chosen a bespoke mixture of Toray T1000/T800 carbon fibres.


Comparisons of the tubing profiles effects on drag, The right hand image is a truncated aerofoil.

Aerodynamics played a key part in the development of the Endurance SL R and SL framesets. In point of fact, each offers a significant drag reduction of up to approximately 28.5% over the previous generation. Much of this can be attributed to the inclusion of modern wind-cheating features and sculpted tube profiles.

  • Truncated aerofoil tube profiles – Earlier aero frames featured teardrop tubes which were extremely aero but offered less stability in crosswinds. The truncated aerofoil reduces these effects whilst providing beneficial aero drag savings.
  • Enhanced lateral stiffness – When you put the power down through the pedals a frame with reduced lateral stiffness will ‘flex’. Thereby reducing the amount of power generated being transferred to forward motion. This is less efficient so a frame with a high degree of lateral stiffness is advantageous.
  • It’s lighter as there is less material – A monocoque frame can be manufactured to be lighter for the same amount of strength
  • Provides better vertical compliance. The dropped seat stay design of the frame and profile of the tubes work mutually to absorb vibration transmitted through the frame.
  • Internal cable routing– Cables create drag as well as looking untidy. Routing the cables through the frame removes the drag effects of the cables whilst giving the bike a super clean look.
  • Internal wedge seat clamp– Instead of an external seat clamp, there is now an internal wedge mounted within the junction of seat tube/top tube.
The SL range of bikes are designed with cutting-edge features like the aero efficient integrated seat tube wedge.

Comfort and handling

The Endurance ranges distinctive dropped seat stays provide more vertical compliance for more comfort through vibration absorption and enhanced power transfer.

Each frame incorporates a number of design features to make them as fast, light and comfortable as possible.

  • Precision steering– Oversize fork steerer, headtube and blades stiffen up the front end for those out of the saddle efforts..
  • Dropped seat stays– These filter vibrations to help reduce ‘road buzz’.
  • Boxed section chainstays- They ensure that the bike remains stiff for better power transfer.
Combining an oversize headtube with tapered fork steerer creates a stiffer and lighter front-end for improved steering precision and control.

Tyre clearance

Our current range of high-performance carbon road disc bikes has more than ample clearance to fit tyres better suited to the rigours and demands of today’s road surfaces.

Tyre clearance has undergone somewhat of a revolution over the past few years and consequently, most bikes now have larger clearances to enhance, comfort, speed and grip. The Endurance SL and Endurance SL R Series are a prime example. The caliper versions now offer clearance for tyres up to 28mm or 25mm with mudguards. The disc versions are compatible with 32mm tyres and 28mm with mudguards.

The caliper brake models have clearance for tyres up to 28mm to be fitted for more comfort and traction.

There is also a very neat innovation exclusive to these 2 frames in terms of the fitment of mudguards. Not only are there concealed eyelets for fitting these guards but there is also a detachable bridge available for the disc version. Without mudguards and the removable bridge fitted you would be hard-pressed to know that the frame is compatible with mudguards. But with this neat innovation in place, there is the option to fit full-length guards when the weather is inclement.

The removable mudguard bridge, a neat solution to the lack of brake bridge on disc brake equipped models. .

Bottom Bracket Tech

The Endurance SL R Series frames the lightest frame that we offer by some 300g over the SL at 850g. A major part of this weight difference is the oversize press-fit BB on the Endurance SL R. This means that it is compatible with oversize BB86 chainsets for maximum power transfer. This also ensures that each watt generated is transferred into forward momentum and no effort is wasted.

The Endurance SL, on the other hand, utilizes the traditional threaded bottom bracket system which requires an alloy insert in the frame shell to accept the threaded BB. This insert accounts for a significant part of the weight difference. The advantage of a threaded BB system is it is less susceptible to creaking but it does not accept oversize BB30 style systems.

In Summary

In summary, we can say that the Endurance SL and SL R series are manufactured from the best carbon that money can buy.  Not only are they light and stiff but they also absorb more of the vibration from the road than any other carbon frame that we have ever produced.  In practical terms this means that you feel less fatigue when riding them over longer distances and rougher surfaces. Plus they can be built up to a UCI weight busting specification.

  1. Interesting article – can fully understand the structural advantages of rectangular section chain stays – taper head tubes – aerodynamic sections, dropped seat stays, and lack of weight from a carbon frame, but in couple of years there will be improvements and cutting edge becomes yesterday’s technology. So am not chasing latest innovations and sticking with steel lugged – look so classy next to a carbon frame any way!

  2. Been pushing pedals for years and after all the articles i have read about bike carbon technology yours is by far the most informative and interesting.
    Thank you!

  3. So does that mean my Ribble R872 Silverversion from last year is 28.5% less efficient than this new model?

    I’ll have to be 28.5% more efficient.

    Still a great bike.

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