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The Bicycle FenderBag: An innovative on the bike storage solution for mountain bikes.
The Bicycle FenderBag: An innovative on the bike storage solution for mountain bikes.
28 backers pledged $3,001 to help bring this project to life.
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About

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$3,001

28

What is a prototype?

A prototype is a preliminary model of something. Projects that offer physical products need to show backers documentation of a working prototype. This gallery features photos, videos, and other visual documentation that will give backers a sense of what’s been accomplished so far and what’s left to do. Though the development process can vary for each project, these are the stages we typically see:

Proof of Concept

Explorations that test ideas and functionality.

Functional Prototype

Demonstrates the functionality of the final product, but looks different.

Appearance Prototype

Looks like the final product, but is not functional.

Design Prototype

Appearance and function match the final product, but is made with different manufacturing methods.

Production Prototype

Appearance, function, and manufacturing methods match the final product.

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Prototype Gallery

These photos and videos provide a detailed look at this project’s development.

The FenderBag was designed to help get everything off of your back while cycling. It provides easy to access storage in an out of the way location and includes fender protection too. Getting as much of your riding gear off of your back is more comfortable, allows your perspiration to dry and can improve your riding agility without your bike backpack bouncing on your back, or stuff flying out of your pockets. 

Our first model of FenderBag is for full suspension mountain bikes. However, this design does fit almost all hardtail bikes too. Attaching onto the back of your seat post/seat tube it comes in two sizes depending on how much you want to carry and how much space you have on your bike between your saddle and the travel of your rear wheel. Designed for a 72 degree seat tube angle and around the arc of a 29 inch tire the FenderBag will work on the majority of full suspension bikes on the market today.

The benefits of the bicycle FenderBag include: 

  • Provides easy access storage. 
  •  Is simple to install. 
  •  Has a modest carrying capacity. 
  •  Works well with dropper style seat posts.
  •  Includes a fender. 
  •  Provides a sleek look in a well placed out of the way location.
  • Compares favorably to the seat bag with its more convenient access, larger carrying capacity and lower center of gravity.

Putting your tools, tubes and other equipment on your bike and getting everything off of your back allows you to:

  • Stay cooler by avoiding "swamp back" where perspiration is trapped between you and your gear. 
  • Ride more dynamically without your gear hitting you in the back of the head or flying out of your pockets. 
  • Put less weight on your lower back. 
  • Keep everything on your bike so you don't forget to bring it.

To help you get everything off of your back, and for those of you without a full suspension mountain bike we are also offering a branded hook and loop strap to help you strap your gear on to your frame. It has silicone grip material on one side to help keep it in place and a 2 inch (5cm) width to hold your stuff securely.

Design Features

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Our first model of FenderBags is for full suspension mountain bikes and it fits onto the seat tube/post on the rear of your bike. Its low mounting position means that it can work with dropper style seat posts. 

The FenderBag has an interior stretch pocket next to the seat tube, it's a great place to put your tools and a patch kit. 

 The fender on our initial models are built around the arc of a twenty-nine inch wheel and will easily accommodate a smaller wheel size. The bag is designed for a 72 degree seat tube angle and may not fit bikes with extremely laid back seat tube angles. 

The silicone grip material that comes with your FenderBag should be wrapped around the frame at the points where you want to attach it. This will help keep the FenderBag from slipping down and from "flagging" from side to side. This stuff is very sticky but it is not very strong, if you want to straighten the FenderBag loosen the attachments first or you may tear the silicone grip material. It can be washed with soap and water and then dried to restore its stickiness.

FenderBag on full suspension bike
FenderBag on full suspension bike

The small sized bag takes up 9 inches/23 cm of the seat tube and seat post on the back of your bike and has about 70 cubic inches/1.1 liters of storage capacity. The large FenderBag takes up 11 inches/28 cm on the back of your bike and has about 140 cubic inches/2.2 liters of storage capacity. You will need to make sure there is enough room on the back of your bike between the travel of your rear wheel and your saddle to accommodate the FenderBag you want.

The fender does more than you would think. While it is not going to keep your backside dry in a rainstorm it is in a great position to keep suspension parts from gathering trail dirt and to keep the back of your legs from getting splashed in a creek crossing.

When setup correctly the FenderBag can provide protection from your rear wheel when you are in the off the back of the saddle position. If you position the FenderBag just above the limit of you rear wheel travel and then put your backside on the FenderBag you will know that the rear wheel won't be able to come up and make sudden and violent contact with your backside, an experience that leaves a lasting impression.

Small FenderBag
Small FenderBag

Both FenderBags have suggested weight limit of 3 pounds/1.3 kilograms. While this is only a suggested weight limit you can put more into your FenderBag depending on how you load it. Any heavier items should be placed up next to the seat tube/seat post to help prevent what we call "wagging". There will be some wagg with your FenderBag anyway. The lightweight nature of the design where the bag supports the fender means the fender has some give to it which will keep you from snapping it off if you should fall on it. This also means that the FenderBag will have some wag to it under normal riding conditions. This is not something that you will notice once you are on your bike and riding.

Large FenderBag
Large FenderBag

The small sized FenderBag weighs 5.9 ounces/168 grams and the large FenderBag weighs 6.7 ounces/190 grams. Both models come in a black bag and fender combination only for our first production models. We reserve the option to make further changes to our design based on our ongoing rider review program, production difficulties and general improvements, all of our backer will be notified of any changes before we ship their rewards.

Specifications

Small FenderBag

  • Weight: 5.9 oz./168 g 
  • Volume: 70 cubic inches/1.1 liters
  • Fender Length: 15 inches/41 cm 
  • Mounting space: 9 inches/32 cm

Large FenderBag

  • Weight: 6.7 oz./190 g 
  • Volume: 140 cubic inches/2.3 liters 
  • Fender Length: 18.5 inches/47 cm 
  • Mounting space: 11 inches/28 cm

Mounting Instructions

VIDEO

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To mount the FenderBag on your bike start by estimating where you want to put it. Then wrap the stick silicone material provided with your bag around the frame/seatpost at the points where you want to attach the FenderBag. The sticky material is to prevent the FenderBag from slipping down and from "flagging" from side to side. It is very sticky, but it is not very strong, you don't need to stretch it to make it adhere to your frame. It can be washed with soap and water to restore its stickiness after it gets dirty. If you need to straighten your FenderBag once it is already on the bike loosen the straps first or you may tear the silicone material.

Check to make sure your rear wheel doesn't hit the FenderBag when your rear wheel bottoms out. You can try pushing down hard on the back of your bike. If you have an air shock try letting some air out of it and pushing down or you can just go and ride off of something and land on your rear wheel to see if your rear wheel hits the fender when you land. If it hits move the FenderBag up higher and try again.

Medium/Small FenderBag with Dropper Post
Medium/Small FenderBag with Dropper Post

 History

Doug Demusz built the first FenderBag prototype in 2011 as a personal solution to the problem of carrying enough warm clothes and rain gear to survive an icy cold Colorado rain storm while out on an epic ride. Not one to let the weather determine what kind of day he's going to have and not interested in carrying a full on backpack on an all day ride he looked at his full suspension mountain bike and saw some unused space right behind the seat tube and just above the rear wheel. Taking all of the air out of the rear shock and pushing the wheel into the frame he traced out that pocket of unused space on a piece of paper and the shape of the first FenderBag was born. As someone who had been designing and making all of his own outdoor gear since 2003 this was just another addition to his personal collection of tents, backpacks, clothing, frame bags and other innovative solutions to his outdoor lifestyle until a local bike shop owner stopped him on the street and asked, "What is that?" and with a knowing nod and sparkle in his eye that said more than his words he said, "That is a great idea." and the journey to bring the FenderBag to the masses had begun.

The Large FenderBag with Dropper post
The Large FenderBag with Dropper post

Prototypes

The first FenderBag was a primitive affair. Before realizing that the bag itself could be used to support the fender, the fender was supported by an aluminum strut hand bent to fit around the bottom of the seat post. A bag with a waterproof liner was sewn to fit around the strut and then the strut was riveted to the fender. It used a piece of nylon webbing to hold everything inside instead of a zipper since it was only meant to hold rain gear. The next prototypes had a zipper on the top, interior pockets on the sides to hold tools and eliminated the aluminum strut using the fabric of the bag itself to support the fender. The bag was glued to the fender which created some durability issues once you stuffed the bag full but Kathleen has been using this prototype for three seasons now with only a few repairs.  

The Second FenderBag
The Second FenderBag

The design has evolved with stretch pockets for tools placed up against the seat tube and a sticky silicone material to stabilize the FenderBag where it attaches to the frame. 

 The orange bags featured in the introduction video were built to be super light. They have a thin sheet of ABS plastic as a fender and the bag is a lightweight stretch fabric sewn directly to the fender. Our newest prototypes have a stiffer thermoformed fender and a tough nylon bag. The fender is now riveted to the bag for extra durability and only the top of the bag is made from stretch material to avoid blowing out the zipper if it is overloaded. 

Most recent design modifications include making the lower mounting position narrower to fit between the linkage and seat stays, a small flare on the end of the fender in so that it won't catch on the tire if it is positioned too low and a stiffer backplate that won't flex as much when the straps are pulled tight. We expect there will be more improvements made to our current prototypes before we go into production and we will keep our backers informed about any changes before we ship out their rewards.

Extralight Orange Prototype
Extralight Orange Prototype

Patent Pending 

The current status of The bicycle FenderBag is patent pending. This unique design is not just a unique way to carry stuff on your bike, but also represents a new way to mount a rear fender onto a bicycle. By using the bag itself to attach and support the fender we feel we have created a innovative solution that deserves patent protection. We have also applied for patents incorporating new ways of attaching the bag to the bicycle beyond the simple hook and loop straps that we are offering on our initial FenderBag model.

Timeline 

2011: The first FenderBag 

2012-2015: Just riding along 

2016: Patent applied for 

2017: Prototyping and business plan development 

2018 March: Launch rider review program 

2018 April: Industry preview at OuterBike and final design modifications. 

2018 May: Kickstarter launch 

2018 June: Procuring Bags, Fenders and Straps. Assembly

 2018 July/August: Shipping

Out On The Trail
Out On The Trail

Risks and challenges

Producing a product that has never been manufactured before carries extra risk. Utilizing multiple suppliers to produce the FenderBag exposes us to the possibility of supply chain delays that are out of our control. Assembling FenderBags in mass quantities is not a proven process yet and may be subject to further bottlenecks and unexpected difficulties. We reserve the right to make further design modifications to the existing prototypes in order to improve the finial product. Our backers will be updated to any changes or modifications before we ship their rewards.
We have tried to estimate our shipping of rewards with these unknown variables. However, our goal is to develop a supply chain that will deliver a quality product to our backers first. Our goal is for you have a FenderBag for this summer's riding season.

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Support

  1. Select this reward

    Pledge $10 or more About $10

    FenderBag Frame Strap

    Support our project and receive a logo embellished strap. A handy hook and loop strap to attach items to your bike and get them off your back.

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    3 backers
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  2. Select this reward

    Pledge $55 or more About $55

    Early Bird - A Small FenderBag

    -Small size FenderBag
    -70 cubic inches/1.1 liters of storage
    -2 silicone adhesive strips

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    Ships to Anywhere in the world
    Limited 5 backers
    $

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  3. Select this reward

    Pledge $55 or more About $55

    Early Bird - A Large FenderBag

    -Large size FenderBag
    -140 cubic inches/2.2 liters of storage
    -2 silicone adhesive strips

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    Estimated delivery
    Ships to Anywhere in the world
    Limited 8 backers
    $

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  4. Select this reward

    Pledge $70 or more About $70

    A Large FenderBag

    - Large size FenderBag
    - 140 cubic inches/2.2 liters of storage
    - Includes a FenderBag Frame Strap
    - 2 silicone adhesive strips

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    Estimated delivery
    Ships to Anywhere in the world
    1 backer
    $

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  5. Select this reward

    Pledge $70 or more About $70

    A Small FenderBag

    - Small size FenderBag
    - 70 cubic inches/1.1 liters of storage
    - Includes a FenderBag Frame Strap
    - 2 silicone adhesive strips

    Less
    Estimated delivery
    Ships to Anywhere in the world
    0 backers
    $

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    It's a way to bring creative projects to life.

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  6. Select this reward

    Pledge $120 or more About $120

    A Large and Small FenderBag

    - One of each, large & small FenderBag
    - Includes 1 FenderBag Frame Straps
    - 4 silicone adhesive strips

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    Estimated delivery
    Ships to Anywhere in the world
    5 backers
    $

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Funding period

- (30 days)

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