Successful compromise between stiffness, weight and comfort
The requirement list of our customer was a light, comfortable Rohloff, Gates bicycle with a disc brake. Besides that certainly taking certainly her small height and custom geometry into consideration. As said the comfort had a high priority. Therefore I designed the frame around the new Ergon CF3 seat post. The CF3 follows a novel approach by two parallel leaf springs with a floating head. Thanks to the perfect function principle thrust of the force transmission and the compression direction act physically together perfectly. The “suspension” seatpost combined with tires of a width of 25C on a wide rim (Notubes Iron Cross ) provide unique comfort and lower rolling resistance. Maximum tire width of the 28C fits into this frame. Starting position for the mass geometry was the old bike. Because of rather shorter inseam the top tube was slightly bended to adjust to a lower stand-over height requirement. To keep the rear triangle flexible , we have used 16×0.9mm thin seat stays, which gives a positive influence on comfort. The drive side seat stay has a neat frame lock incorporated. This is needed to introduce the Gates Carbon Drive CDX belt into the triangle. Stiffness and rigidity was of course also important. Drive influenced optimized tubes and Chris King Inset head set gives the stiffness where needed. Premiere in this Rohloff bike is the adjustable chainstay length. We replaced the sliding Paragon brezzer dropout by this new one. No detailed images can be given Also new is the non-drive side Rohloff dropout. This really saves a lot of weight and offers a clean dropout. The Tune Momentum and Tune Rohloff Rolf shifter is a must have, especially the colored alloy version which brings the bike to a final weight of 8.0kg . With a little more effort 7.5kg could have been possible. But who can offer such a fast 8kg Rohloff speed bike with that comfort? Let us know if you know of any which is also so beautiful.