The man behind the frame is Robert Barr, owner of one of a new wave of high-class, limited availability bike companies that are much, much more than the give-it-a go garage creators which although admirable never quite have the drive to make a brand not just a reality but flourish. We have seen the studious and methodical rise of Unno bikes, there will be more, created not just out of curiosity or dissatisfaction of what’s available but through a desire to make something truly unique, special. There are many interpretations of boutique bikes, people sometimes fooled by the paintwork hiding bikes that are often quite ordinary and certainly two a penny. In ARBR you are getting the exclusivity that has often been incorrectly attributed to bikes that have long since lost the undivided attentions of their owners.
It’s in the garage that might well lie the superiority. Barr and his team are no strangers to the pit lane and behind this brand you will find an incredible pool of skill and knowledge gained through many years working in Formula One, Moto GP and Superbike racing. Obviously there are quite different ways to achieve top performance between engined sports and pedal power, so its not a given that they'd succeed. However when you mix mountainbike fanaticism with knowledge of the processes there’s a good chance you’ll be in the mix.
But has Barr and his team had a touch too much benzene in their heads or is this a really serious new British company? We recently tested the bike. In three days time they launch. You’ll see that they mean it. Here’s an exclusive on an exclusive with Robert Barr, founder of Arbr Limited.
Words and Images by Steven Jones
Is this another case of stronger, stiffer, lighter? What exactly is your aim with the Saker?
The Saker has been developed with a focus on descending at speed across demanding technical terrain. The aim was to produce a frame that allowed riders to push limits.
As such our focus was on ensuring strength targets were met rather than achieving a target weight as a primary objective. Our aim was to maximise the strength to weight ratio and achieve a stiffness that would maintain some compliance and feel in the frame.
It’s a great size for most people, an amazing balance front and rear, would you make different sizes for other people and re-proportion the frames?
We make two sizes and the balance and proportions for both are good, keeping the rider centred. If I were to deviate significantly from those sizes I would consider compensating by adjusting the chain stay length. I would also consider laminate revisions. For the time being we will keep with two sizes but that could change with demand.
The material chosen – largely cloth rather than Unidirectional (UD) – why?
We have used a high proportion of cloth as it has better inter-laminar properties and fracture toughness when compared to UD. By alternating the orientation of the cloth plies you can get an incredibly strong frame, more resistant to impacts, delamination and the multitude of load cases that a mountain bike is exposed to.
The UD enhances the strength for certain load cases and is used to fine tune stiffness characteristics. We use a lot of continuous UD around our lugs in the form of hoop plies and boot laces.
“I could not get the manufacturing process benefits or control by going off shore to Asia"
It’s the shapes rather than the materials that counts right?
The shape of the frame dictates the structural efficiency. The material provides the ultimate strength and robustness, and the carbon can be laminated, orientated and staggered to put the strength where it is needed. The type of carbon used is very important as is the resin system.
If you start with an inefficient shape and structure it becomes difficult to compensate for the loss of strength by adding material.
What reasons did you choose UK manufacture?
I wanted to use a certain manufacturing technique and have complete control over the process. There is a large skill base in the UK when it comes to carbon fibre manufacture, much of it as a result of the Motorsport Industry. I wanted to tap into that capability and produce a uniquely crafted frame using all my experience and contacts. It’s been fantastic to work and develop the frame with skilled passionate people. I could not get the manufacturing process benefits or control by going off shore to Asia.
Carbon fiber - better than steel or ali - or just different?
I wanted to achieve a high strength to weight ratio for which carbon has significant advantages. The use of carbon does depend on the application, it is a great material but there are limitations that need to be respected and for some components other materials can be better suited.
Give me some reasons why (if) you believe carbon fiber performs better on mountainbikes than other materials? Are you claiming any performance advantage?
As mentioned previously a lot of the benefits come from the strength to weight ratio that can be achieved using carbon fibre, this results in a lighter more robust product. Carbon fibre is very versatile and you can use the various weaves and fibre types to tune the stiffness and feel of the frame. In our frame the benefits are maximised through the combination of a controlled manufacturing process, the grade of fibres used, and the sequence and placement of plies.
There is a team of highly skilled and experienced people behind the development this frame. A lot of motorsport and aerospace technology has been integrated much of which you cannot see from the outside.
Talk us through the suspension details….
The frame runs a high single pivot with rocker activated shock. Combined with an idler this produces a frame with close to 100% squat in the lower gears, a rearwards axle path and the removal of chain feedback.
The suspension kinematics were designed to give a progressive shock rate, keeping the bike supple to find grip early in the stroke before ramping up to provide mid travel support and bottom out resistance against large impacts. I wanted to remove the requirement to pack shocks with volume spacers so damping ratios can be maintained.
All of the features were designed to work in unison. Combining our suspension characteristics with our geometry produces a responsive bike with huge stability and grip. It’s a lot of fun to ride.
How many prototypes of each bike have you made? How can you tailor ‘feel’ within a frame? How does the R&D work with that?
There was a lot of FE development completed on the frame, to define the shape and optimise the laminate. The target stiffness was achieved by adjusting the frame surfaces, and then by adjusting ply placement.
We worked through the theoretical numbers, tested the stiffness of the first components and evolved from there. A number of frames and swing arms have been lab tested and we have been riding three frames over the last 18 months, proving them out across all conditions, using and living with them as our customers will.
“You can’t start and finish on a screen, it’s only part of the process"
Controlled flex and traction, surely everything cannot be learned from behind a screen?
It is critical to understand where performance comes from based on rider feedback, measurements and analysis. You start with a benchmark from which you identify a philosophy and a series of targets to improve performance. You can’t start and finish on a screen, it’s only part of the process.
We worked through the numbers to make the best choices in order to hit our targets. Of course it doesn’t mean anything if the finished product fails to inspire confidence and deliver on its promises. The time we spent up front meant the benefits were realized.
If the improvements aren’t there you need to rethink and understand the interactions. It’s an evolutionary process of learning and implementing beneficial changes.
Do you believe reach should reach vary between bike type?
For the core mountain bike disciplines I think reach should be close between bikes. Weight distribution is very important for each discipline and that is something we focused on, there a lot of other factors that need balancing.
How many people are involved before an ARBR bike hits the lay up and assembly line?
The team comprises of up to 4 people across the following areas: Mould preparation, kit cutting, laminating, bonding, finishing and paint.
Ultimately, the question arises, what are you paying for in one of the worlds most expensive mountainbikes?
The level of engineering has been stepped up for this frame and they are built from the best materials using the best manufacturing process possible. It has been developed in house to our demanding standards with a focus on performance and quality, they are built to a level of detail and craftsmanship like no other.
The performance of the bike matches the level of quality and craftsmanship. We combined a series of design features to produce the best performing bike possible, and that is evident on the trails.
This is not a mass produced product and our finishing options mean frames can be individual to each owner. You are paying for a unique high performing product.
We will launch very soon and there will be a lot of detail covering the bike and company on our website.