THE USE OF A THIN LAYER OF FIBREGLASS INSIDE FORK STEERERS – THE INDUSTRY WIDE RATIONALE BEHIND THIS.  

 

BLUE: CARBON FIBRE ONLY RED: THIN LAYER OF FIBREGLASS

EXPANDED VIEW: FIBREGLASS USED TO PREVENT THE EXPANDED PLUG BONDING TO THE CARBON FIBRE

 

To provide further insight into why many major bike and frame manufacturers apply a thin layer of fibreglass inside fork steerers, we have created an illustration, and a more detailed explanation. This process, which is widely used, has two key purposes resulting in significant consumer gains with regards to maintenance and longevity of the products. The rationale is split below into two key areas.

1. Reaming of the inside of the fork steerer: The inside of the fork steerer needs to be reamed to ensure that it is perfectly round to accept the expander plug. Carbon fibre is too hard to be effectively reamed, so the thin layer of fibreglass allows the inside of the fork steerer to be correctly reamed for a perfect match to the expander plug. 2. Galvanic corrosion: Carbon fibre and metals such as aluminium have a habit of bonding together over time. Fibreglass does not have the same issue. The expander plug used on Elves Bikes, like most brands, is aluminium. To ensure that the expander plug does not corrode and bond to the inside of the fork steerer, the same thin layer of fibreglass is used to place a barrier between the aluminium expander plug and the carbon fork tube.

Manufacturers use different colours of fibreglass with various thickness levels. The most common colour used colour in bicycle frame production, which Elves Bikes have now also adopted, is black fibreglass. This is however the same colour as the carbon fibre making it difficult to distinguish between fibreglass and carbon fibre itself.  

In summary, the inclusion of this thin layer of fibreglass is specifically designed to enhance the customers experience and increase the quality of the product.