Carbon Frame Tech Explained

Ribble have been synonymous with producing high quality, performance carbon road bikes since they first hit the UK market. Each and every frame is designed in house here in Lancashire and is custom made for us and us alone.

All of our frames exceed the relevant safety standards. However,  we go above and beyond these by developing frames with the latest cutting-edge features. Before they leave the factory they are subjected to the most stringent of quality control tests. 

Here we take a look at the Endurance SL and SL R and the latest manufacturing innovations and technology that they utilize.

What is a Monocoque frame?

Monocoque carbon frames are formed as a single integral piece which distributes 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. And this 1 piece construction is superior to separate pieces of carbon that are bonded together.

A partially completed Endurance SL Monocoque frame, note the plastic which forms part of the EPS inner core process which produces a smooth internal finish for enhanced structural consistency.

The Endurance SL R series and SL frames also feature an advanced manufacturing process which is known as Full EPS (expanded polystyrene system).

EPS is a process whereby an expanded polystyrene internal mould is covered in latex , carbon is then ‘layed up’ over the top of 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 and leaves no excess material within the frame.  What are the benefits of this EPS construction?

  • The frame is as smooth on the inside as it is on the outside, so it is free of debris which other methods of construction leave within the frame.
  • It enables the frame to be constructed as one piece, this reduces weight and increases stiffness.
  • It eliminates the imperfections in the carbon lay up that earlier production methods were susceptible to.

Using the  highest quality carbon tubing is essential to achieving the  right balance between strength, durability and weight. We have chosen a mixture of Toray T800/T1000  carbon which offers the very best blend of carbon to achieve these goals.


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

Offering approximately 28.5% less drag than previous award winning R872. Much of this can be accounted for by the profile of the tubing. Many of the tubes feature a truncated aerofoil profile for maximum drag efficiency. This tube profile offers numerous benefits of which some are listed below. Also included in the bullet points are other drag reduction features.

  • Earlier aero frames with teardrop tubes were less stable in crosswinds, the smaller cross section of a truncated tube means the bike is more stable when subjected to crosswinds.
  • Enhanced lateral stiffness. By this we mean that when you apply force to the pedals the frame does not twist out of alignment due to the side to side stresses applied. This allows more power generated to be transferred directly into forward motion.
  • It’s lighter as there is less material.
  • Provides better vertical compliance. The design of the frame and profile of the tubes work together to absorb vibration transmitted up through the frame from the road.
  • Internal cable routing- cables within the tube reduce drag and protect the cables from the elements.
  • Internal wedge seat clamp- instead of an external seat clamp there is now a wedge mounted in the 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- due to the oversize fork steerer and headtube.
  • Dropped seatstays- these filter vibration 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 offer better grip and enhanced comfort. 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 whopping 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 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

So, in summary the new 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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