How far back can one safely go with Campagnolo track ends?
 

My Mercian was ordered with clearance for 28 mm tires and mudguards. The mudguards attach with through-bolts that run up into a boss on the underside of the fork crown and a hole drilled into the underside of the rear brake bridge. This has worked beautifully for many years, but now I think I would prefer to run 32 mm tires. This is not a problem up front - there is sufficient clearance there. The rear is the problem, specifically if I want to run fixed on one side and a Dos Eno 17/19T freewheel on the other.

If I leave the chain length as it has been, the axle sits a bit to the rear of midpoint on the track end. With 28 mm tires I can run 42x16, 42x17 and 42x19 with no issues.

If I leave the chain length as it has been, and the axle in the same place, with 32 mm tires I can run 42x16, 42x17 is very close to the end rear fender bolt, and 42x19 is a no-go.

If I add ONE link of chain, I can get all three gears to work with 32 mm tires - BUT for the 42x16, the axle is at the end of the rear-opening Campagnolo track ends, such that while the axle itself is entirely surrounded by the track ends, the skewer nut and clamp extend back past the end of the clamp surfaces. There's still 3/4 of the clamping action happening, but it's back there over an unsupported end of the track ends, not triangulated by the stays.

Is this a problem? Would this create stresses that could damage the frame or the Campagnolo ends?

I have a plan B that I think would work - when I replace my mudguards I could simply mount them with the supplied hardware and get some of Sheldon Brown's Fender Nuts and dispense with the through-bolts.

Thoughts?

I think you are in uncharted territory on this one. Maybe someone has done similar but with all of the variables it is difficult to imagine that this EXACT situation has been tested. So in that case, I have to fall back to plain old common sense and say that it probably isn't a good idea. I think that halfway or perhaps a bit over halfway in the track end would be as far as I'd want to go.

It could be that there is no issue, but being wrong could be fatal for the frame if not for yourself.

i may not be a math scientist but when entering 3 minus 2 in my mind calculator it doesn't equal 0, which means one of these cogs is not on the wheel. if you are going through the trouble of removing cogs why not just throw a master link on the chain when using the 19t and take it off when using the 16 and 17.

2 chainz

The nut overhanging the end of the track end isn't going to do anything to the track end except perhaps chip a little paint. Maybe scratch it a hair. If the nut has any issues at all, it will be that it sits slightly below the back of the track end, ensuring it cannot slide forward. You are never going to be pulling the hub back, the chain only pulls so that is only good. I suppose if the nut sits cock-eyed enough, you could bend the axle but a quick eye check will tell you that things aren't right.

You do know about half links, don't you? 1/2" links that are male to female instead male-male or female-female. They allow you to shorten teh chain 1/2" instead of a pair of link = 1'.

Does your mudguard fit just behind the tube/brace between the chainstays then hit or come close to the seat tube? I have done two things that help here. I run the fender in front of the tube/brace (this might require a creative metal strap, rather than the one provided - a drill press and pop-rivets are your friend). And on fenders that hit the seat tube, I've cut a long, narrow ellipse out of the front of the fender so the fender can now sit forward a little more. Now the limiting factor for the tire is the same seat tube you had to deal with before you put the fender on.

Edit: I just saw you are using a quick release. Don't. Yes, you can but it is living life the hard way. Proper chain slack is very important for fix gear/single speed operation, especially fix gear. With a QR, every time you insert the wheel, you have to try to get chain slack and wheel alignment between the chainstays simultaneously. If you are having a bad day (you just fixed a flat after dark, it's raining and you are cold and tired), this could be a long struggle or you simple limp home with a too tight chain doing harm to BB and hub bearings as well as itself or too slack and risk throwing it off on the next downhill. With good track nuts, you do your first guess for chain slack and when that is good, you adjust the tire side-to-side with the left nut, barely changing the chain slack. And if you are having the ultimate bad day, you can just "walk" the wheel back, one nut at a time until you get it dialed in - no brains required what-so-ever. That track nut is going to take far more kindly to the insult of overhanging the track end also. (Keep a spare in your tool bag. They eventually break and this might speed that up. It will be when you are using tools, not riding, so no worries there.

Ben

Don't do it! Or use the half link. I recently had the same issue on a bike and the thought of the axle bolted all the way the end of the track end made me so nervous I couldn't enjoy riding it. Is being short a gear combo worth potential damage to the frame?

Call Mercian and ask if they think it's okay. I'm tempted to think that track ends extending past the seat stay triangulation are expected to take the load, otherwise they would not be made that way. :)

After looking at it some more, reading your answers, etc., I have decided I will explore plan B, which is to leave the chain at its original length, dispense with the through-bolts and mount the fenders using Sheldon's Fender Nuts and the stock fender mounts. That way the axle will remain in portions of the dropout that are supported more by the seat and chain stays, rather than cantilevered out.

The issue isn't one of trouble where the seat tube and chain stays come together, but rather where the head of the bolt meant to run through the fender into the underside of the brake bridge protrudes too far down. The bolt heads are just too bulky. Since the stock hardware mounts from above, this way I'll only have the thickness of the mudguard itself to worry about, and that should clear well enough - and if not, I can notch the fender itself and raise it so that the brake bridge actually protrudes down into the fender well. We'll see.

@REDMASTA, it's not about removing cogs; it's about having the option of flipping my wheel 'round from the 16T fixed cog to either the 17T or 19T cogs on the Dos Eno 2-speed freewheel, which would allow me to run either 67-in or 60-in coastie gears as bail-outs. Or, for that matter, if I get really crazy and decide to load the Mercian up for a S24O, to have a low enough gear to cope with lugging light camping equipment without breaking down and running a derailleur, which would not be the same experience. It's still a work in progress. If I start riding dirt roads again a lot, the Dos Eno will come back off and the 18T EAI fixed cog will go back on, or maybe I'll just compromise with a conventional 18T SS freewheel.

@79mooney, I do understand your concern re: running a QR rather than track nuts, and your method of dialing in rear wheel position with the option of walking the wheel back in place certainly works effectively - but I have used this setup for nearly a dozen years now on this bike, and I have used QRs on fixed-gears since 1998 or so without mishap. On this Mercian, I found it reduced the time I needed to flip the wheel 'round when I wanted to transition from my 70-in pavement gear to my 63-in dirt and fire road gear for the long hauls through the back o' beyond, South Carolina. When I once again have fenders/mudguards on this bike, it will actually speed the process, especially as I know the crank/chainring orientation that facilitates ideal chain tension. I gently squeeze the wheel backward with one hand around the back of the fender, fingers pulling the rim rearwards and visually align things before squeezing the QR lever into place. A quick double check of chain tension - always! - and voila, good to go.