↑These are photos from February 2024, taken just before the summit on the Osaka side of Takenouchi Pass.
The rain had stopped, but the road was still wet, and water spray was kicking up as I rode.


The screen of the wrist-mounted heart rate monitor attached to my handlebar is covered with water droplets,
but this wasn't from the rain itself.
Water spray coming up through the gap between the fork and front wheel
gets kicked backward as I ride,
and it hits not just the cycle computer and lights
but my face too.


I hit pause.
On the pause screen the background becomes white, so the fine sand in the water droplets becomes visible.
I wiped the screen clean after the rain stopped, and this is how it looks after riding for a while from a completely dry state.

It's my own fault for not wearing eyewear,
but when this spray hits my face, my eyes sometimes start to itch.


This is a Niner gravel bike, the RLT 9 Steel,
with a head tube length of 125mm,
or 129mm if you include the thickness of the bearing cup flange on the headset.
At first glance this doesn't seem that long
—it seems like you could get decent handlebar drop by using a steep stem angle—
but in reality...


...the fork's shoulder-to-dropout measurement is actually quite long, so you can't get much drop at all.

The frameset is designed for 25–50mm tire widths,
but except for a brief period when I ran 28C tires,
I've only ever used 25C tires
(the tires in the photo above are also 25C),
so there's a large gap between the tire's highest point and the fork crown.

When riding in the rain,
the water spray coming through this gap is enormous,
and as speed increases, the amount of spray bouncing backward increases too.

So I made a fender that blocks just this water spray:

↑This is it.


I took an AssaSavers
"plastic fender for MTB front suspension lower leg arch that mounts with zip ties"
and cut it down,


then positioned it so the only contact point with anything is the mounting hole on the fork crown.

The mounting is incredibly solid—
if you grab the support arm and try to wiggle it, it doesn't move at all.


↑Viewed straight-on at the fender, it looks like this


↑From roughly the horizontal angle, it looks like this.
A full fender that's wider than the tire and extends down to just below the rear edge of the wheel
would create tremendous air resistance,
but this fender creates no noticeable aerodynamic drag
(at least, I can't feel any difference).

The effectiveness is amazing—the water spray hitting my face and bike computer has been dramatically reduced!
Since installation requires tools, once it's on I often leave it on rather than deal with removing it.


↑It could be angled a bit more horizontal.
The "installation conditions" mentioned in the title refers to the fact that this is only needed
when running significantly narrower tires relative to the fork's shoulder-to-dropout measurement.

That said, the problematic water spray only occurs
when running significantly narrower tires relative to the fork's shoulder-to-dropout measurement anyway.

I'm currently running 25C tires,
and based on the arm bend and bracket angle, it should work fine up to about 30C.




↑This isn't a shot taken while riding—
I lifted the wheel and spun it while spraying water from a hose,
but the large water droplets dripping backward from the left and right edges of the fender's rear end
matches what happens during actual riding.




↑This is a frame capture from video shot on a rainy night.
The water spray is illuminated by the light, creating the appearance of white sparks.
The fender has redirected the forward spray to travel lower but further out.
If there were a rider ahead and I was following slightly offset to the right,
the spray would probably hit their right leg—that's how far forward it's traveling.

The spray is narrower in width and reduced in volume overall.
The water spray that was bouncing back toward me is what was problematic,
but now that the rebound point is farther away and the volume has dropped dramatically,
the spray hitting my face has been reduced to a barely noticeable level.


↑The fender by itself.
The main components are
an AssaSavers fender,
a universal bracket from Reckmont,
and a center fork bracket from Cateye.



↑This is the Cateye center fork bracket.
It's a support arm with a bracket for mounting a front light to the fork crown bolt holes.
For lights like the G VOLT series that mount upside-down,
you can also reverse the orientation of the light's mounting bracket.


↑On a tangent,
I converted that support arm into a rear light bracket.
Since the light is lightweight,
I made it a cantilever-style mount.
The original bracket had M6 bolt slots, which I bent to accommodate M5 bolts instead.



I was lucky to find a light in a color matching the frame (totally joking).


The square raised section on the underside of the Reckmont bracket is


because I've inserted an FRP backing plate like this.


The back of the fender still has the instructions from the original product on it,
but we don't need to worry about that.


My attention to detail here is using black-finished stainless steel M4 nuts.


The FRP plate I'm using as a backing is from Tamiya's Mini 4WD parts,



↑and I also use it as the backing plate for the pump bracket when mounting a short portable pump on the back of my saddle bag.