Over the past few months SRAM President Stan Day has personally delivered updates regarding the recall and re-release of the new road hydraulic brakes. In this latest installment, Stan has explained what caused the original brakes to fail, and what improvements have been made to the new model which is set to launch in late April.
According to the clip, the failure was caused due to two mechanical issues, which proved to be beyond the capabilities of the seal that was originally spec’d. The first mechanical issue resulted from a cylinder bore that was not cylindrical enough. In extreme cold, the seals stiffened and became less compliant, so the oval shape of the cylinder bore was beyond what the seal was capable of handling.
The second problem resulted from excessive negative pressure in the brake fluid reservoir, which was again outside of the seals ability to compensate, which resulted in air ingested into the system. These two issues and normal variances during manufacturing lead to failure in cold temperatures and could have also allowed the brakes to fail even in warmer clients.
As a result, SRAM went back to drawing board and the new product that will be released next month has been through more rigorous testing standards and will see a number of mechanical enhancements. The new 2015 model will have a completely new lever body design that is lighter and has better ergonomics, ensures better sealing on all critical surfaces, and improves shifter cable routing. In addition to that there is a new bleed port design with an easier interface. The new design has also undergone a battery of both in house and real life testing in temperatures ranging from -20C (-4 F) to 46 C (115 F).