Installing fenders on a road bike not designed for them

Most bikes are designed with provisions for installation of  “extras”, such as racks, fenders, and bottle cages.  This usually means small threaded bosses brazed onto the frame at carefully chosen locations.  Touring bikes, which are designed to be ridden long distances loaded up with everything the rider needs to be self-sustaining for days, weeks, even months, usually contain braze-ons for just about everything:  racks front and rear to hold camping gear, fenders to keep the rider and bike clean in wet weather, frame pump, multiple bottle cages, etc.  However, not all bikes are designed to accommodate all types of accessories.  For example, a city bike may not have threaded bosses for bottle cages or braze-ons for a frame pump.  Conversely, a racing bike will have provisions for at least two bottle cages, and most likely a frame pump.  But since racing bikes are designed to be as light and fast as possible and not carry luggage, they usually lack provisions for racks and fenders.  I have such a road bike, a 1988 Trek 560:

But I’m also a firm believer that all bikes should have fenders, and I was determined to get this bike appropriately clad. When I started researching my fender options, I found that some companies like Planet Bike and SKS sell ready-made solutions for bikes not designed for fenders, including “clip-on” fenders.  However, all of these designs leave something to be desired. Either the mounting schemes seem weak or crude, or the fenders lack “full coverage”, i.e., they don’t span the full arc length of a standard fender and only provide limited protection from water spray. I wasn’t pleased with any of these options.  So, I decided to “force” fit a conventional set of full-coverage fenders onto my bike.

After measuring the clearances at critical locations on my bike, I decided that the bike actually could fit standard road-sized fenders, i.e., 35mm wide fenders designed for road bikes with tires up to 28mm wide.  The tires on my Trek are 25mm wide, and there is enough clearance under the brake calipers for the fenders to fit.  What the bike lacks is threaded eyelets on the dropouts, and a chainstay bridge. Examples of these are shown below:

Double threaded eyelets on the rear dropout of this touring bike provide for installation of a fender and a rack.

 Chainstay bridge on this bike supports the bottom end of the rear fender.

 No chainstay bridge on the Trek…

…nor threaded eyelets!

The chainstay bridge is necessary to support the front, or bottom, end of the rear fender, and usually contains either a threaded boss or a hole drilled through it to accommodate a bolt with which to anchor the fender.  So, I was going to have to fabricate solutions to these two deficiencies. I’ll return to this later.  For now, my next step was to choose a set of fenders.  I wanted a set that would provide full coverage but also have a look befitting the bike. The Trek 560 has a nice lugged steel frame of classic proportions, but is not quite vintage.  I felt that fender offerings from my two favorite brands, Honjo and Velo Orange, were a little too classic for this bike.  I wanted to find a set of fenders that had a clean yet modern look that would complement the Trek’s contemporary black anodized rims.  Planet Bike has a nice line of fenders called Cascadia, which are available in a nice satin aluminum “chromoplastic” finish.  SKS has a similar chromoplastic line of fenders.  After reading reviews of both and finding a fantastic deal on the SKS fenders, I opted for the SKS. As a side note, the screaming deal I got was from an online seller in the UK (due to the weakening pound).  The SKS fenders sold there are actually nicer than the ones sold in the US– they include a really large front mudflap! So I got the nicer UK version for less than the US version.

So, back to solving the problem of not having threaded eyelets or a chainstay bridge.  Of these two obstacles, the eyelets are the easier to overcome:  P-clamps are a widely used and proven substitute for eyelets.  They are inexpensive, and stocked by most bike shops.  They wrap around the fork and seatstays, and the fender stays bolt to them.  You can buy them with a rubber coating so they won’t mar your bike’s paint.  After measuring my fork blades and seatstays, I determined I needed 9/16″ clamps for the front, and 3/8″ clamps for the rear.

The lack of a chainstay bridge proved more challenging. At first I thought I could use two P-clamps, one around each chainstay, with a hollow tubular aluminum spacer spanned between them.  In effect, this would create a bridge.  But this seemed awkward and cumbersome.  Next, I thought I might be able to use just one P-clamp around one of the chainstays (probably on the driveside chainstay, which would be less noticeable, hidden by the chainring).  Then I could make a small metal “L” bracket to connect to the P-clamp on one end and to the fender on the other.  But then, I imagined it would look hacked and crude at best.  Then I thought about how LED headlamps and taillamps are mounted, and I realized that it’s often a variation of the P-clamp method.  The difference being, that attached to the clamp is another plastic piece that attaches to the light and pivots to allow it to be properly aimed.  Hmm… could a headlamp mount be the perfect “adapter” piece to secure the rear fender via the chainstay?  It seemed like it could look very clean if done right.  As it happens, I had amassed a stockpile of surplus mounting hardware from all the LED lights I’ve had over the years.  Time to raid my parts boxes!  I found a seatpost mount from a Planet Bike blinky, and discovered that it fits almost perfectly around the chainstay (it was a little big, so I cut a piece of an old inner tube to use as a shim).  I trimmed the piece that attaches to the light, and this is what I ended up with.

I lined the front of the fender up with the trimmed piece that normally attaches to the light, drilled a hole and screwed it onto the fender.  Then I screwed the other end into the circular seatpost clamp.  Here it is in place:
You can see from the pictures that the pivoting part came in handy, since the fender is not at a right angle with the chainstay (the top photo shows this the best).  The mounting system allows one to “dial in” a perfect alignment with the fender.
With that obstacle overcome, all that remained was to attach the supplied fender stays according to the instructions, except that instead of attaching them to eyelets, they were attached to the P-clamps:
Here’s the finished installation, as well as some purely gratuitous shots of the bike:

15 Responses to “Installing fenders on a road bike not designed for them”

  1. mtalinm says:

    thank you!! I’ve been wondering how to do the same to my road bike

  2. CYCLER says:

    A nice solution!

  3. David says:

    Thanks for this. I’ve been hearing about the many ways people add fenders to roadies, but this is the first really comprehensive look at the bits and bobs involved. Thanks again.

  4. Ron says:

    Thanks for this write-up and description.

    I’m trying to do the same (mount these on a bike without eyelets) and I’m about to lose my mind. Had trouble finding p-clamps, then the right size, and now having all sorts of installation problems.

    1) Hard to tell in the photos – did you use the “mount clip” on the rear fender? This is a little piece that goes over the fender and holds it up. I’m trying to get mine in front of the rear brake caliper, but behind the brake bride. It seems like my caliper is not going to be happy trying to close with it there. Not sure if I can/should just mount the clip in front of the BB.

    2) Also can’t see from the photos. I too have a recessed front brake nut. How did you mount the front tab/clip? In front of the fork and behind the brake caliper?

    I feel as if I might lose my mind soon. I’ve been monkeying with these fenders for four days now, and when I had them installed in the past I could never get all the rattles and noise to stop, so the finished project isn’t even something to look forward to. Ugh.

    Any help is appreciated.

  5. Alex says:

    Thank you so much! I have been looking EVERYWHERE! You have inspired me to do the same thing. Thank you!!!!

  6. mc312 says:

    Amazing! Ok I know it’s the internet and virtually everything has been done already, but I have exactly this same problem with an old Bottechia frame and ordered silver sks’s arriving from Germany next week. The dimensions look very similar, so as long as I can squeeze the fenders under the campy brakes I am home free!

    Will keep you posted.

  7. Roman says:

    Hi

    Great solution, I’ve a Cinelli 1981 bicycle and wanted to add fenders to it. I was only wondering if sometimes dirt, and/or mud does not get in between the fender and the tires causing some friction, because of the close clearance? on the other hand I like to ride “clean” and appreciate the fenders and mudguards I’ve on my other, the mountain/commuter bicycle.

    Thanks for posting it!!!

  8. Alex says:

    Thanks for sharing and taking your time with this post.

  9. Ron says:

    I have those two parts from Planet Bike and I don’t have a chain stay bridge.

    Could you please tell me how you “trimmed” the part that connects to the light so that it would sit flush against the fender? The plastic is kind of hard, not sure how to get rid of those two edges/lips.

    Thanks!

    Slick bike, great write-up!

  10. Philippe says:

    Great post. I’ve got the solution to my bridgeless chainstay now. Thanks a bunch! Great writeup and pictures. You made my day :-)

  11. You are a *#$&! genius. As it happens, I’m also building up a Trek 560, although I’m going with the VO fenders (so we’ll actually get to see if it looks *too* classic when I’m done :^) ). I thought through the p-clamp part, but not the no-chainstay bridge part. Glad there is a (hopefully) easy solution.

  12. Richard Hart says:

    Thank you for a great solution and posting it. I installed fenders on bike but the front of the rear fender wasn’t completely secure because my bike lacks a chainstay bridge. I decided to check the Internet for a solution and found your site. Thanks again.

  13. booger says:

    they look pretty nice on the bike, although very snug fitting.. your wheels must be very true ,no? do you think the p-clamps would hold a rear rack?

  14. booger says:

    Is it just trial and error to find the max tire size with fenders? I can’t seem to find a max tire size on my frame.