Topeak’s Duo Fixer series is a clever saddle rail dual mounting system that can be used with a variety of tools, saddlebags and accessories. At the heart of the system is the Duo Fixer bracket which clamps onto alloy or carbon saddle rails and offers a lower QuickClick slot and an upper quick release tab mechanism. Utilizing a dual slot attachment design, the Duo Fixer provides a tool-free mounting to allow you to quickly install accessories or swap accessories between bikes. In this cyclists guide we’ll provide an overview of how the system works and an overview of the currently available accessories which includes everything from taillights, inner tubes, pumps to saddlebags. Currently there are no generic adapters for Garmin or GoPro accessories but we’re hopeful Topeak or third party companies will create them in the future.


The Topeak Duo Fixer series uses a simple plastic bracket that is designed to bolt onto the end of the flat section of your saddle rails. Circular cutouts on the bracket allow it to grip onto the saddle rails for a secure and rattle free setup. With its vertical bracket design the Duo FIxer mount is compatible with both alloy and carbon rails as both types have rounded top/bottom profiles (i.e. carbon rails have oval side profiles). The Duo Fixer bracket requires 15mm of flat saddle rail and 36mm spacing between the rails. This means the system is compatible with most saddles on the market except for spring-type or monorail saddles. The Duo Fixer bracket features an upper and lower slot to allow for various combinations of accessories. Note, to utilize the upper slot you need a minimum of 30mm height off the rear of the bracket to accommodate accessories.


On the upper edge of the Duo Fixer bracket you’ll find a slot cutout with a spring loaded release button on the left side. This allows you to slide accessories into the slot and have them lock in place automatically. Removing the accessories requires pushing down the quick release button and pulling the accessory out of the slot. Due to the position of the upper slot, accessories tuck underneath the saddle for a sleek semi-concealed appearance. Topeak currently offers three types of options for the upper slot: taillights, inflation kits and fenders. The taillights include the TailLux 40 DF or TailLux 26 DF where the Taillux 40 DF has a more focused beam than the wide COB style Taillux 26 DF. For inflation you can also carry CO2 canisters (e.g. Nanomaster DF) on the top slot or tubeless repair kits (e.g. TubiMaster GX DF). Finally, you can mount the FlashFender DF on the upper slot and protect yourself from the water and debris.


The lower slot utilizes Topeak’s existing QuickClick attachment design. It’s a basic slot design with a groove built into it to hold accessories in place. Pushing down on the release tab allows you to slide the accessory off the slot.  The lower slot is ideal for larger items such as tubes, saddlebags or pumps as there are no space limitations. Topeak has offered QuickClick saddlebags for quite a few years which means there are a variety of saddlebags to choose from including the SideKick Wedge Pack. For those who prefer to ditch their saddle bag for more minimalist look, Topeak offers a generic FreePack (i.e. dual strap design with tire levers) or the HybridMaster Mini (i.e. CO2 with a mini pump). You can also use the slot for fenders if you purchase the FlashFender DF Deluxe set.

Note you aren’t just limited to Topeak QuickClick compatible saddle bags. You can also use nearly any strap type saddle bag by attaching the strap mount included with the FlashFender DF Deluxe. Unfortunately, Topeak doesn’t offer the strap mount adapter separately so for the time being you have to purchase the full fender set to get your hands on one. The adapter slides into the QuickClick slots and then bolts into place by removing the bottom bolt on the Duo Fixer bracket and then reattaching it through the cutout on the strap mount. The bolt-on design goes against the quick-release nature of the Duo Fixer mounting design but is a more secure setup.


While most of the accessories are specifically designed for either the upper or lower slot, the FlashFenders offer the option to mount on either. Topeak offers the FlashFender DF Deluxe which includes two fenders, one pre-setup for the quick-release upper slot and one with the QuickClick bottom attachment. Currently, the adapter is not available separately so if you purchase the standard FlashFender DF you would be limited to only the upper slot. If Topeak were to offer the adapter separately, you would only need to remove a single bolt to swap the thin plastic fender between the adapters. Until the adapter is available separately, we’d recommend buying the FlashFender DF Deluxe if you’d prefer to mount the fender on the bottom slot.


With the variety of upper and lower slot accessories it can be a bit daunting to figure out which accessories to purchase. Based on the current Duo Fixer accessories here are some combinations we’d recommend:

The Minimalist

  • For riders looking to do more with less.
  • Upper / Lower: Taillight (TailLux 40 DF or TailLux 26 DF) / CO2 (HybridMaster Mini)

The Pro

  • Riders focused on speed and lightweight
  • Upper / Lower: CO2 Canisters (NanoMaster DF or TubiMaster GX DF) / Spare Tube (FreePack)

Long Distance Rider

  • For riders who need extra storage and tools
  • Upper / Lower: CO2 Canisters (NanoMaster DF or TubiMaster GX DF) / Saddlebag (QuickClick bag or strap bag + strap adapter)

The Commuter


Overall, we found the Topeak Duo Fixer mounting system offers a simple yet effective way to attach a variety of accessories onto your saddle rails. The dual slots allows you to tuck lights or CO2 underneath your saddle for a semi-concealed appearance along with saddlebags or large items directly beneath it. The quick-release style attachments make it quick and easy to swap accessories out for specific types or rides or swap between bikes. We particularly found it useful for swapping between bikes as you can install the base Duo Fixer bracket on multiple bikes and then simply move accessories between them. The main downsides of the Duo Fixer series is the lack of adapters and GoPro or Garmin adapter to allow you to use third-party taillights or radar systems. That said, if you’re looking for a flexible way to carry accessories on your bike then you should check out the Duo Fixer series.

Disclaimer: 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 or serve as a reference . The authors or the blog itself does not get any compensation from the product manufacturer or third-party websites/vendor links that are posted here.

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