Given the choice between riding on a warm sunny day versus a wet day, most cyclists would undoubtedly choose the former. Nevertheless, while we cannot command the weather one way, we can choose the right gear for wet weather to make the most out of it. Whether you’re commuting to work or doing a long training ride, one essential wet weather accessory is the bicycle fender. However, except for those who live in wet weather climates most cyclists install and uninstall fenders for the occasional rainy day or only portions of the year. Typical fenders are bulky and can require special fender mounts to properly install. Today, we’ll be looking at the Topeak D-Flash S which is a lightweight and simple saddle rail mounted fender.

The Topeak D-Flash S is a lightweight fender that is thin enough to fit in a backpack or jersey pocket to keep your back dry on wet days.

The D-Flash S is part of Topeak’s new expanded fender line that includes the D-Flash DT (down tube mounted), D-Flash ST (seat tube) and D-Flash FS (front fork or seatstays). These fenders are flat-printed, origami inspired polypropylene fenders that are designed to be lightweight, stylish and easy to mount. With the D-Flash S, you don’t need any hardware or fender mounts on your bike. You simply push the fender under the rails and use a velcro strap to secure it. The fender has an interesting reflective pattern for nighttime visibility and some style. With a low retail price and weight, the D-Flash S is a tempting option. 

CategoryBicycle Fender
Retail Price$9.95
Measured Weight (in g)22
Likes+ Lightweight and Compact
+ Nighttime visibility with reflective graphics
+ Doesn’t require fender mounts
Dislikes– Velcro attachment
– Gets in the way of saddlebags
– Installing requires some patience and force
Where to Buy (US) Topeak


Topeak packages the D-Flash S on a plastic sheet with their iconic yellow graphics. Perforations along the fender outline make it easy to pop the fender off the sheet to install on your bike.

In the box you’ll find:

  • D-Flash S
  • Velcro attachment strap


Unlike traditional fenders that are large and bulky or require fender mounts, the D-Flash S is a simple paper thin fender. Extending only a few inches from the back of the saddle, the D-Flash S is designed to protect your backside from the spray from your wheels. Topeak claims the fender is inspired by origami, resulting in a fender that requires only a few simple folds to assemble. After bending the sides of the fender down, pushing out the four vent holes and opening the strap insertion points, the fender is ready to go.

Topeak D-Flash S - form factor
The flat-printed fenders are compact and lightweight

Built from polypropylene, the D-Flash S is a thin fender that also holds its form well. This fender is quite similar to others on the market such as the Ass Saver, and utilizes the simple construction and minimal mounting design to keep the retail price low. The fender has a minimalist and modern style with an interesting pattern which is also reflective to help with night time safety. Compared to larger fenders, such as Topeak’s Defender line, the D-Flash S is something we’d categorize as a ‘personal’ fender. Riders behind you will still get sprayed, so if you are riding with others they better avoid drafting behind you.

Topeak D-Flash S fender- comparison
The saddle mount allows the D-Flash fender to be more compact than traditional fenders


One of the advantages of the D-Flash S compared to traditional fender is the portability. As such, Topeak uses a simple Velcro strap that wraps around the saddle rails to make installation and removal of the fender quick. Grooves on the outer portion of the fender press against the portion of the saddle rails that curve out which keeps the fender firmly in place. While the design is simple and secure, we worry that the Velcro strap can be difficult to clean especially if you ride through clay or mud. Also we found that installing and removing the fender to be frustrating. For flatter saddles with less area above the seat rails, positioning the D-Flash S required a significant amount of force to bend under the saddle. For some of our road bikes we weren’t even able to install the D-Flash S as there wasn’t enough space to property position it.

Topeak D-Flash S - installation
The fender requires some force to install between the saddle rails.


Overall, we found that the Topeak D-Flash S is an affordable and clever fender solution to keep your backside dry. Inspired by origami, the fender is paper thin and simply folds into place. The fender isn’t a substitute for full wheel fenders but is a great option for those who are looking for a lightweight fender that doesn’t require tools or hardware for the occasional wet day. Although the mounting design is simple and only requires positioning the fender on the seatrails and Velcro strap, we found it required a lot of force and patience particularly with flatter saddles. As a positive, you don’t need fender mounts or special brackets, meaning the D-Flash S is compatible with everything from commuter bikes to racing bikes. Whether you are a fair weather rider or just looking for a minimal wet weather fender, at $10 the D-Flash S is a fender to consider.

Disclaimer: The product for this review was provided by Topeak. The views expressed on this website are solely those of the authors and are here to help people make an informed choice before a purchase. The authors or the blog itself does not get any monetary compensation from the product manufacturer or third-party websites/vendor links that are posted here.

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