I have played around with different fatbike fender designs, but I was still getting that stripe up my back when riding in wet and muddy conditions. So far I have made a front fender (rigid and Bluto), frame fender and rear fender . . . but I needed something more. I wanted something that I could mount directly to the seat with and was sturdy . . . I wanted the Ultimate DIY Fatbike Seat Fender.
Downloadable PDF at the bottom of article.
In order to attach something to the seat and be effective, the fender would have to be longer than a traditional fatbike fender. However, the longer the material the more flexible and less sturdy it will be. I thought about adding braces, but decided on putting bends in the material instead.
Next was to figure out how to mount it to the seat/seatpost. I tried wrapping it around the seatpost and using zipties, but it would spin and slide with very little effort. Upon closer inspection I discovered the empty space between the bottom of the seat and the top of the seatpost clamp. A little trimming and this is what the prototype looked like.
And for material . . . crazy carpets. This is my stock of carpets that I pulled together over the last couple of years, however recent ones I have seen in stores have been less stiff and more foam like. Flexible cutting boards and binders may also work.
The final version ended up being a little longer than the prototype. It took a little time (and scrap material) to determine exactly how it would attach under the seat. I found that a four point mounting system, zipped to the rails, worked the best.
And here it is installed. Several runs in wet conditions confirmed that the design significantly reduced the amount of flying water and mud. While the bends do increase the stability/rigidity of the fender it does tend to dance around when the conditions get rough.
So if you want to give it a try, click here for a two-page downloadable PDF.