cs1

To all the experts out there, I've just about finished up a build. I would like to put fenders on. Here is my problem. How big can you fit without trying them on? Right now I can fit 37C tires. The chainstays are the limiting factor. My calipers measure just slightly wider than 38mm. I'm sure having a set is the ideal solution but if the do not fit I am out of luck. Any advice?

oddjob2

Buy them from a place that accepts returns.

Lascauxcaveman 

Some fender kits have hardware that lets you mount the bottom end of the fender just above the chainstays, making their width irrelevant. A dremel tool (or maybe even tin snips) will allow you to customize the bottom end of a fender if you must have it bolted down between the chainstays, making their width irrelevant. Or, if they are metal fenders, you could bend the ends in a bit, making the chainstay width irrelevant.

Seems the wrong detail to be focusing on. Do you have clearance between tires and the brake bridge, fork crown, etc? If yes, it's pretty easy to make everything else work.

Take a couple pics of your clearances in those areas and post them here, and people will have lots of suggestions as to what may be the best fit.

icepick_trotsky 

If you're nuying aluminum fenders, you can squeeze them a bit narrower at that spot, too.

cs1

Best advice ever. I just haven't that place yet. It's like a unicorn. I know they exist. The trouble is finding it.

rhm

You can't always know whether a fender will fit. It is often obvious that it will or it won't, but in between the two, not so much.

Best thing you can do, if you're patient, is look at photos of the fenders you're considering, look at how they attach, what kind of adjustment the hardware allows, and so on. Once you've settled on a given model, ask for photos of that model, installed on forum members' bikes. Other than that, just go for it and hope for the best.

Velognome 

Too much thought going on here Buy the fender you like, try it, if it doesn't work, put them in the parts stash for the next bike and buy another set.

A general rule, the fender should be 8-10mm wider than the tire you intend to use and the tire a bit narrower than what you can run without a fender

The the stays at 38mm, you could, just maybe, run a 38mm fender with a 28 tire or more likely, a safer bet, would be a 35 fender with a 25 tire.

Stay clearance is one issue, Crown and brake bridges are the other.

Chrome Molly

Aluminum fenders will be easier to re-shape to work around the stays (using a dowel to work shapely "dents" into them). If you get them and they clearly won't work on the chainstay, then you can try mounting them to end just above the stay (as was mentioned). All kinds of hardware exists if you look around. I usually expect fender mounting to be about a two week job (with all the shaping, small parts orders, frustration, and final alignment), any less and I'm doing really well.

oddjob2

Nashbar, Amazon, REI are fairly liberal.

clubman 

Sometimes you have to trim the profile of the mudguards around the chainstay to make it work. Of course there's no returns after that.

SJX426 

The one bike in the stable with fenders was an exercise in improvisation. Everything was a squeeze on top of not having enough features, both holes and length.
[IMG]P1000033 on Flickr[/IMG]
[IMG]P1000035 on Flickr[/IMG]

The end result was good enough:
[IMG]P1000030 on Flickr[/IMG]

JohnDThompson 

What I've done for situations like this is drill a small hole in the underside of the bridge and use a sheet metal screw through the fender to hold it in place. The result is very clean looking; no visible hardware at all.

SJX426 

@JohnDThompson - Good approach!. I have this think about modifying frames. Since this picture, I added a Topeak rack and simplified the hanging configuration. Part of the problem is that the fender and cross cable/noodle/bracket like to rub on the fender. I have thought of cutting a relief for them but it works and I really don't mind the scratches on the fender. Functional Patina! Cutting a relief slot would allow the water to get over everything in that location as well, sooo.......

My other option would be to creat a typical brake bridge hole which would look "normal" too.

The front fender was a surprise fitment as the mounting tang was too short to reach the hole. I was thinking of mounting the fend above the brake cable but then cleaning would be a mess and removal of the tire challenging. Adjusting the fender stays (bending the stay mounts in or out) was an exercise of trial and error to get the fender from not rubbing on the excessively large tire. In the end it works well and makes nearly no noise. When I remove one hand from the handlebars, there is enough deflection in the system to get some touch-rubbing over bumps! They work really well in the rain and on wet pavement.

cs1

That's the sad part. I am really looking at either Hammered Honjo or Portland Design Works full metal fenders. Because of the cost I really cannot afford any screw ups.

SJX426 

@cs1 - measure twice, cut once! When I was young, I sometimes cut twice and found it was still too short. Guess I wasn't listening....characteristic of youth.

cs1

Great advice @SJX426 I really like the looks of metal fenders on a steel bike. The SKS work great. The just aren't as nice looking.

due ruote 

https://www.bikeforums.net/classic-vi...se-things.html

That thread has all kinds of good mounting tips.

In my experience, it's almost never 100% straightforward. There is usually some trimming, bending, fabricating brackets, etc. that has to take place. With plastic fenders, you can (carefully) warm them with a heat gun and form them slightly to fit tight forks.

I wouldn't fret it; just assume you will have to make mods, then as said above, take careful measurements. When cutting metal fenders I like to leave enough material to bend over to match the factory edge.

JohnDThompson 

The Andrew Hague brake bridges we used on some Trek models came with a pre-drilled fender mount underneath, which I thought was a nice touch:



But then you have that ugly bracket, which can create its own clearance problems...

SJX426 

Now that is cool! Were these used on the touring models?

Which ugly bracket are you referring too? Is it named Specialized?

JohnDThompson 

720s had them, and a lot of the other high-end models, even "racing" models without dropout eyelets.

Gyrine

The take your bike into the shop. Wheel it to where the fenders are and start trying them on. Make sure your bike has the projected attachment points for the fenders and that everything lines up. If not, pass.

I did did this for my daughters bike and the floor salesman even helped me.