Reparto Corse

The legendary Bianchi Reparto Corse… Race Department in English… is where the future of cycling technology is explored, and where for over a century meticulous craftsmen have been working with elite racers to extend the technical performance of their, and ultimately your, bicycle.

Bianchi’s Reparto Corse has once again applied that century of experience to the hottest new materials and production technologies to push bicycle performance to a level never achieved before: the XL Evolution EV4. Here’s what goes into creating this masterpiece:

EV4 HYPERALLOY

The base material of the EV4 frame is an aluminum alloy with zinc and magnesium optimized to provide characteristics previously unheard of with aluminum bicycle tubing. The alloy is enriched with particular elements present in crucial proportions that contribute to the frame’s ultimate tensile strength reaching a value between 600-650 N/mm2 – an improvement of approximately 25% over the best 7000 series tubes currently available. The theory here is that the higher the inherent strength of the tubing material (the ultimate tensile strength), the thinner the walls of the resultant tubes can be drawn. The thinner the tube walls, the less material and the less weight.

One-pass TIG welding, with a bead no wider than 6mm starting and finishing at the tube’s neutral axis, in a way that minimizes interruption to the welding flow.

EXCLUSIVE REPARTO CORSE TUBING DESIGN

After the tubes have been cut to exact tolerances, they are assembled in the welding jig with a maximum gap at any tube juncture of just 0.1mm. The welding itself is performed in one single pass not wider than 6mm, starting and finishing at the tube’s neutral axis, in a way that minimizes interruption to the welding flow.

TIG welding is performed in an atmosphere of inert gas (argon) which protects the welded elements from the damaging effects of oxidation. The localized argon atmosphere is not confined to the outside surface of the tube joint, but also flows inside the tubes to ensure that the entire environment is completely protected. As a further measure, the welding rods used are checked for quality and purity. In order to avoid any unnecessary heat damage to the frame, all cable guides are brazed at a temperature 30 degrees lower than the fusion temperature of the aluminum.

NATURAL STATE WELDS

Like all Reparto Corse lightweight aluminum frames, the welding beads on the EV4 frame are left in their natural state rather than being manipulated. Bianchi’s research has shown that the technical disadvantages of smooth welds outweigh the small aesthetic advantage.

There are two ways to achieve the aesthetics of a smooth weld. One is to use a double weld pass. This produces an excess of weld material that can then be filed smooth. However, the double weld pass greatly increases the heat-affected area. Also, the butted section of each tube must be thicker (heavier) to withstand the added thermal stresses. The other option is to perform one weld pass and then smooth over the weld area with a synthetic filler material (really a hi-tech type of putty). This gives a nice finish and doesn’t weaken the structure of the frame, but it adds up to 100 extra grams of cosmetic weight, defeating the objective of tube profiles carefully engineered to reduce excess weight.

1 1/8" COMPACT STEERING SYSTEM

The Bianchi Compact Steering System has already been proven in its 1" variant. The 11/8" steering system offers a notable increase in rigidity with a negligible weight penalty. The increase in front-end stability is particularly noticeable during sharp deceleration on long, winding descents. In the past, ultra-light frames have often been associated with a lack of stability when descending, but with the 11/8" Compact Steering System and Bianchi’s well established sloping frame geometry, the EV4 frame is as competitive in terms of stability as it is in terms of weight.

An enlarged headtube diameter also offers benefits in the frame construction process. The increased surface area between the headtube and the toptube and downtube makes a more solid juncture, which in turn results in a frame that comes out of the welding process with its alignment already very close to true. Stress-inducing post-welding manipulation is therefore kept to a minimum.

CNC REAR DROPOUTS

The EV4 frame utilises the new CNC rear dropouts specifically developed for the EV2 frame in 2001. These dropouts are of an exclusive Reparto Corse design and are produced using CNC machining rather than conventional forging. These dedicated frame components provide three advant-ages over the standard rear dropouts:

• Increased welding contact surface between chainstays/seatstays and the dropouts.
• Increase in rigidity and power transfer in rear triangle of frame due to the increased welding contact surface.
• Improved shifting performance of rear derailleur due to increased thickness of the replaceable derailleur hanger.

STRUCTURAL FOAM INJECTION

Once again existing EV2 technology is applied to maximise the advantages of the EV4 frame. Structural Foam Injection, originally developed for thin-wall tubing applications, is fully compatible with the EV4 design philosophy. The bi-composite, non-toxic foam, developed by Henkel and then patented by Bianchi for specific bicycle tubing reinforcement applications, produces an increase in rigidity of 15% at the bottom bracket area and an increase in the frame’s resistance to fatigue of 100%.

The bi-composite foam also has the function of absorbing load forces rather than dispersing them. Because of this important characteristic, accumulated fatigue in the welded area around the bottom bracket is significantly reduced. The structural foam weighs less than 20 grams.

POST-WELDING TREATMENTS

Two types of post-welding treatments are used: solution treatment and artificial ageing. Both involve heat.

The heating phase of the solution treatment requires a significant number of hours and is a delicate operation due to the upper temperature threshold of the solid solution. A careful control of the temperature must therefore be maintained throughout the operation in order to avoid burning, the result of the upper temperature limit being exceeded.

Salt-solution baths are used for this treatment. The bath is electrically heated to the required final temperature and is then scrupulously controlled to avoid potentially explosive situations due to the nitrate constituents of the solution.

The cooling process takes place in water at room temperature.

The solution treatment gives the material a more solidified structure that has increased resistance both to dynamic stresses (pedaling force) and to accumulated fatigue stresses.

Ageing occurs naturally in about 3 days, or it can be artificially speeded up, to 12 to 24 hours if the temperature is increased to 100-250 degrees C. The process increases both the material’s hardness and its tensile strength.

After the heat treatments, the frame undergoes a chromo-phosphorization anti-corrosion treatment.

CARBON FIBER FABRICATION

Bianchi has developed a Computer Evaluated Selective Material Reinforcement (CESMR) program to analyze potentially critical zones of the component or frame so that carbon fiber material is specifically concentrated in the areas subjected to the highest stresses. We use a new high modulus, high strength carbon fiber compound that is 47% stronger than standard and 6% stronger than High Strength carbon fiber, and is 27% stiffer than either. A 3K carbon weave final surface treatment increases reliability and durability with no significant weight penalties.