thiocyclist

I have a Salsa Vaya with VO hammered fenders on it and stock tires, and there is a little bit of rub on the rear tire all the time the tire spins. Even my bike shop's service tech didn't quite fix it, though he helped. I don't want to keep playing that game.

Thus, I will probably tackle this myself. Is there a systematic way to approach this, rather than just making hopeful adjustments? Since fenders tend to move all over when you pull on one part, I know it can be dangerous to tinker.

I know this could seem like a stupid question to some, but I'm ready to take the abuse and hopefully some helpful advice... Thanks!

aggiegrads

The one piece of advice I can give is to "pre-bend" the stays. When all of the pieces of the system are in tension, it is much more difficult to balance all of the forces.

What are your tire sizes, and what width fenders do you have?

Andrew R Stewart 

You look at the fender and the tire, as the wheel is spinning, and see if you can hear/see the point(s) of rubbing. Gently pressing on various points along the fender can help find the rubs by causing tem to either increase or decrease. Once you find the contact points then you have to figure out how to reposition the fender to better clear the tire. Sometimes this is a simple brace pushing to one side, sometimes lengthening them and sometimes it's rotating the bridge mounting points.

But fenders also have a tire width preference, much less then a few MMs of clearance and expect rub as bumps and door way incidents happen. Also some fender braces and frame eyelet locations don't like each other. (I've made short strips of 1/2"x1/8" AL with a couple of holes to use and fender strut extenders). The there's fenders and racks playing nice, but that's another thread.

I have to admit that the current cool fenders (metal with 1 pair of braces and poor bridge mounting options) are among the worst for being minimally adjustable, time consuming to mount without rattles, lacking a second strut pair they tend to wobble and rub over bumps and they don't like following a different curvature then what they were originally made with. Andy.

thiocyclist

42 mm tires and 52 mm VO fenders.

Andrew R Stewart 

So on paper you have 5mm of clearance between the fender and tire, on paper. Fenders are almost never completely centered over the tires for the full length. Add in the frequent compression of the fender at the bridges as well as the thickness of the actual fender edge and real life is more likely less. Along comes wheel wobble and tires with less then best seating and those few MMs get lost quickly. Andy.

rm -rf

VO says their 52mm fenders will fit 42mm tires.


A repair stand helps a lot. Clamping the bike by the seatpost off the floor lets you turn the wheel and see where it's rubbing. And it's way easier to work on the fender if you have to remove the wheel to do some of the fitting. I suppose this would work with the bike upside down on the floor.

With a different fender and bike, I had to make some custom fittings at the brakes and the chainstay bridge.

The connection at the brakes on the rear fender was too short, so I got a 1/8 inch by 1/2 inch strip of aluminum, and some stainless M5 bolts, washers and nuts with the nylon inserts at the hardware store. I drilled two holes and cut a piece about 1 inch long to extend the brake fender fitting.

Once those two points are approximately correct, you can get the stays fairly close to correct, bolt everything together, and see where the fender is rubbing. Then loosen the stays and see how far to move them. It took a few tries for me.

The fender didn't quite reach the chain stay bridge, so I got a longer M5 stainless bolt and a nylon spacer tube at the hardware store.

~~~~~~~~~~~~~~~~~~
From the Andrew R Stewart post:
I have the (pricey) Portland Design Works fenders now. They were kind of a pain to set up, but they work very well, with no problems after the initial setups.

I had to do the custom brake bridge extension (1/2 inch by 1/8 inch thick aluminum) on the back wheel for these. Quite tedious to get just right. I made a test one first,then a final one.

The single fender stays had to be hacksawed a little shorter to be the right length into the hub fittings. But that was easy.

Now they are stable, never rub, and are quiet after I put a drop of oil on each stay's fitting. And they do a great job of keeping water off me.

CafeVelo

+1000

AnkleWork

Why not just remove the wheel and look for rub marks on the underside of the fender? What am I missing?

Andrew R Stewart 

What you're missing is that some people are missing the ability to follow the logic flow of how things work mechanically. I didn't want to go here and I don't place any blame or negativeness on the OP for his question and need to learn. I see customers every day how can't figure out this stuff and I understand that some have the ability to think one way and others another way. (Don't ask me to spell or sing). Andy.

corrado33

The fender shouldn't be in tension when it's properly set up. You should carefully bend the fender so that it's not in tension after you have everything held down (velo oranges instructions.) Having a fender in tension is a good way to end up with a cracked fender.

My velo orange hammered fenders are sublime. I used all three mounting points for the rear (both bridges and the braces in the back) and they're rock solid. No rattles, and I can lift the bike by the fender without affect the position. I'm not sure how much more adjustment you could have since they have you drill the seatstay bridge mount hole yourself. I DID have to stick a spacer or two between the fender and the chainstay bridge to make the fender hug the tire more closely. Again though, I bent the fenders to match my bike and wheels. They're not in tension.

As for the OP... I'd vote looking for rub marks. Barring that a bit of force and you should be able to make them fit no problem. The tech that worked on your bike probably didn't do a great job because it takes a good bit of time to fit fenders correctly. And time is something a bike mechanic is always short on.

AnkleWork

Of course I only addressed finding the rubs, but you think that it is easier for those same people to find the rubs by "Gently pressing on various points along the fender"? OK, I'll take your word.

fietsbob

Remove the wheel and you should see marks where the tire contacted the mudguard underside..


I dont try for such a low mudguard clearance over the tires in the 1st place.

but the low clearance with those aluminum ones is fashionable..

Tim_Iowa

The VO hammered fenders look nice, and have good coverage.

But, they bolt the fender struts through the fender itself, so those bolts protrude into the usable space.

So, you have to run the fender stays a little longer to ensure the bolts completely clear the tire. This is especially evident if your tire is slightly out of round (could be a casing irregularity or a tire that isn't fully seated in the bead) and rubs only once a revolution.

The design of the SKS fenders puts the stay attachment bolts on the side of the fender, where they don't intrude on fender space.


If the fender is rubbing against the tire in one spot, you can spread the fender open with pliers/wrenches.

NYMXer

I read the OP's question differently and think that even after basic tweaking of the fenders, during a ride they wiggle around, not holding any preride adjustments and rub. Is it minor rubbing that is more annoying than hurting performance?

Maybe in an effort to save weight (cyclists and their weight concerns), the fender manufacturer used fender stays that are a little undersized. Look to over bend a little or reinforce the weak points or if it doesn't hurt performance, ignore it. Worst case scenario, replace the offending fenders with better ones

aggiegrads

Corrado33 stated this more eloquently than I did. When the fenders are set up, no part of the fender should be under stress. This often means bending parts to relieve stress before you mount them. The tricky part is knowing where to bend and how much to bend. I have accidentally creased really expensive Honjos, but because they are not stressed, they have not cracked in several years and many thousands of miles.

pdlamb

You have to find the rub before you can fix it. Most of the problems I've had ended up being tire or wheel problems. There can be one bit of tire that isn't seated right or has a slight bulge in it (replace the tire or seat it right). Or the wheel's a bit out of true, so the tire rubs when that part of the wheel comes around (re-true the wheel).

Only blame the fender if the rubbing doesn't occur once per wheel revolution.

Marcus_Ti

Each design has its pros and cons.

-The VO design is great because there's a single round surface for the fender and the water will always ride along inside the fender, from front all the way to the back to be dumped. Catch being, that bolt for the stay needs careful setup as you note.

vs

-The SKS design avoids the bolt problem above....but places a metal bracket across the inside of the fender in doing so. Which means water from the front of the fender will meet it like a wall in its path....and water/gunk will spit out the sides at those brace points. And gunk will accumulate at those points.


-The SKS uses clothes-hanger wire for stays which is light and malleable, and makes centering adjustments easy....but is very whippy, which when combined with plastic not-stiff fenders, even with two fender braces each will move around a great deal on bumpy roads.

vs

-The VO that uses 5mm (IIRC) metal rods that are much stiffer, but heavier...and a bit of a pain to metal work if you need to, but you really shouldn't need to do any other than cut to length....as the fender itself uses the brace just for bracing an already stiff metal fender.

rmfnla

Now I understand why I don't see you on the Road Cycling sub-forum...

Tim_Iowa

Completely correct, @Marcus_Ti.

My bike in question has limited clearance, so that aspect of the VO design bothered me. However, I was able to get the VO fenders to provide adequate tire clearance with enough fiddling. I do appreciate that the VO aluminum fenders are stiffer than SKS chromoplastics, so they tend to stay fixed once you fix them, where the SKS fenders are easier to bump or bend out of alignment.

I also dislike that the VO fenders include NO quick-release tabs, where SKS fenders include one pair for the front and spares for the rear are available. I ordered two pair of the PDW FMF safety tabs and used those on front and rear. The VO and PDW FMF fenders use the same 5 mm diameter stays.

I had SKS P45 fenders on my bike previously, and I wrecked the rear when I managed to pick up a thumb-sized stick in the spokes. Now, I put safety quick-release tabs on all fender mounts, front and rear.

The VO fenders are undoubtedly more handsome than any SKS fender (even the cream ones that matched my Riv's head tube and decals almost perfectly).
I picked up a clearance pair of Honjos to replace the VOs when they finally fail on me. I'm in no rush to switch them out; Honjos are notorious for difficult installs.