cycling – Zacksunsang

Winters in Korea are harsh. Snow and slush, ice salts, and sub-zero temperatures that constantly leave extremities on the verge of going numb. With all the muck and debris, fenders save the day. They help keep the splatter at bay.

While on a weekend country-road gravel ride outside of Seoul, the rear fender experienced a ductile fatigue failure, splitting cleanly at the bolt mount on the underside of the seat stay bridge. I tried to salvage the broken section since it had the mounting bar and bracket attached. But over the course of the ride it became too cumbersome and was ditched in a garbage can. The half fender was born.

The half fender is easier to mount than a full fender since it only requires two 5mm bolts, one at the chain stay and one at the seat stay bridge. It helps keep the frame cleaner around the bottom bracket and seat tube. Without a fender, this area can easily get dirty with it being so close to the rear wheel. This section is also more difficult to clean with all the small voids around the front derailleur (FD) and if there is a FD clamp.

The half fender doesn’t do a lot in terms of protecting the rider from poopoo splatter and debris, but it does keep the bike cleaner and maintenance down.

Unlike the SKS fender, the gold fender doesn’t have the same cross section to help contain flying debris. The gold fender is just a flat piece of aluminum. This was a repurposed aluminum strip that was originally a doorway seam binder. It is thin and easy to cut and bend, also, gold.

For future or alternative designs, I would consider extending the bottom section of the fender below the seat stay bridge to offer more protection around the bottom bracket.

The HB017 is a carbon fiber aero frame and fork. The lines and design of the frame and seatpost are clean; there are no awkward bends or curves. It is what one might think a straight-forward modern aero frame would be. As with other modern aero framesets, the assembly is fully integrated, meaning the cables are all hidden inside the frame and this can easily lead to assembly issues, particularly when building a non-brand bike.

With internally routed aero bikes, the cables from the levers run inside the frame as do the cables from the derailleurs. The one-piece handlebar and stem component that is compatible with the frame was purchased separately. However, it did not fit my geometry nor was it at an aesthetically pleasing angle. The angle of the stem was 6 degrees, and I was going for a zero degree stem. The aftermarket for building integrated bikes is limited. Bike companies like specialized, Willier, Cannondale, and any other commercial brands have their own designs that are not cross-compatible. There are after-market options but these are often hundreds of dollars, far more than I was willing to spend.

With the limited availability of compatible parts, I decided that the BMC integrated stem would work, as it is available in different sizes and for a reasonable price. The details of this build are described below.

The Frameset

The frameset was purchased from Aliexpress. The geometry was acceptable. The frameset included all parts, including seatpost, stem, and handlebars.

Aero Cockpit

I intended to build an aero bike with the fully integrated handlebars and ordered the handlebars that were compatible with the frame.

The stem angle of these bars was higher than I wanted. Something visually unpleasing and less aero. Due to the nature of the internal routing through the headset, using a different stem is simplified if the headset hardware, including the spacers could still be reused. Fortunately, I found out the BMC stem has a similar cross section at the steerer as the existing headset. The BMC stem also has a better stem angle, 12.5 degrees. This matches the slope of the top tube which is aesthetically pleasing.

There are additional benefits of having a separate stem and handlebar: handlebar mounting accessories for round cross-sections, adjustable handlebar pitch, and the option of changing the stem. I used a generic carbon road handlebar and routed the cables from the outside of the bar, under the stem, and through the spacers, into the frame.

The Complete Bike

Tag: cycling

Half Fender. Fender Power

Aero Integrated Stem for HB017