KR-515 use the innovated tubing forming technology SPF to shape most the tube on the frame.
The front part of the SPF chain stay was enlarged to join the BB i/o heavy & expensive cold
forged yoke, it makes the BB area become much stiffer, other than the stiffness,
it also creates the one piece looking normally was found on full carbon frame

The new SPF down tube was designed to match the shape of the top tube,
it makes the whole frame look more unique,also thanks to SPF,
the whole frame still keep light weight as usual.

By using SPF process to shape the complicate TT/DT/ST aluminum pipe at butted condition,
the whole frame wilL look more close to the full carbon frame ,
but the price is much cheaper.
It is the good choice for the rider if you consider the performance more than the name
of the frame material.