ThermionicScott 

Yep, that's from the blackbirdsf site! I'm usually better about attributing these things.

It's interesting, comparing the Rene Herse and Alex Singer designs. From the ones I've seen, RH put the pivot where the lever joins the FD, so that the FD cage moves in the same direction as the lever. Singer put the pivot above the FD, which allows the end of the lever to be much higher and easier to reach, but then the FD cage moves in the opposite direction of the lever. Hmm...

P.S. I wouldn't turn down a prototype for beta-testing.

scarlson 

OK so I owe it to you lever front derailleur nerds, particularly @ThermionicScott to bring this one back up to date. I haven't done much, and it's been out of embarrassment, mostly. Here is why.
I was building this René Herse style front derailleur having never seen one. Now, I have a real one.
And René Herse's work puts mine to shame. You see, I'm too American about this, in the most stereotypical way possible: I made it too big.



The actual Herse thing is there for comparison. Not only is it much more delicate, but it also has a hollow push-rod. What did I think I was building? A locomotive? Geez. Anyway now the question is whether to push on or to re-do it. I am thinking I'll bore down the center of my push-rod to add lightness, at the very least, and probably keep my work the way it is on this bike.

For reference, mine is a 3/8" OD square bar going through a 1/2" OD square tube. René Herse's is a 7mm OD square tube going through a 9 or 10mm OD square tube. The walls of these tubes are really only about 1mm thick. In comparison, mine are much thicker.

The nice thing about having an actual Herse front derailleur, made to shift a 28-48, is that I can now just copy his cage to shift my 28-48.

Trying hard to look on the bright side here. This thing looks like a boat anchor in comparison to what René Herse built, but I don't think square tubing is available to make something like what René Herse made. I think I can get 10mm OD/1mm thick wall square tubing from China, which might be an appropriate way forward in the future.

Insidious C. 

So it's big-boned? I vote push on. You can change it up next time around. Pretty impressive work IMO.

scarlson 

With a blessing like that from the frame's original owner, I think I no longer have a choice. Big-boned, I like that.

ThermionicScott 

Hey, you don't know what you don't know.

scarlson 

OK, I've been making some progress on the front derailleur, but now waiting on sheet metal in 12 or 13ga to use for the front derailleur cage. Herse himself used 2mm metal, so I'm making mine a little beefier since mine's a bit farther away from the chainrings.

But I have also been working on fenders. Specifically, old Lefol fenders. I'm slowly wrangling them into place and thinking about rinko options, to truly drink koolaid with this bike. And I have a question for everyone.

You know the "rinko nuts" that the shop formerly known as Compass sells for some outrageous sum? Why not just use a rivnut in the fender? Is there some reason I'm not thinking of? Searching turns up nothing on the subject. Generally, I'm a "just say no to rivnuts" type person, but for this purpose they almost seem ideal. I'd have easy access to both sides of the rivnut to grip it for alignment and to provide reaction torque as I crank down the bolt to "set" it. It doesn't even seem like an M5 rivnut would protrude any farther into the fender than the "rinko nut" with its bulky jam-nut. If it did, I could just grind it down a bit. Rivnuts come in stainless, which is a plus. And of course using rivnuts allows me a bit more freedom to put plates and things inside the fenders to lessen the stress-risers. Also, I can buy about a hundred rivnuts for the price of one "rinko nut".

Any thoughts?

scarlson 

A little more frame repair. Someone messed up the seat lug ears a little bit, turning the keyed side of a binder bolt. I turned a nice thing on the lathe and brazed it in place.

eeuuugh

I wouldn't put a steel rivnut in aluminum, especially in a fender where it's exposed to grime and water, sounds like a recipe for bad corrosion. A brass or aluminum rivnut would probably be fine though!

gugie 

Yeah, just copy what Mssr. Weigle does. Slot the splice piece, bolt it all together like so:





Gugie's Grander Sportier

scarlson 

I do like that. Nothing gets completely unscrewed so there's less chance of dropping hardware. Just so I understand this, how does the head of the bolt keep from turning when you tighten that acorn nut?

The Weigle approach would be the approach I'd take, but I'm not planning on splitting the fender. I have designed it so that you just remove it in one piece, since it's going next to the rear wheel anyway. The bolts that hold it to the seat stay- and chain stay bridges will be held captive in the seat stay and chain stay bridge holes on my setup by tight-fitting leather or rubber washers (or snap-rings if those don't work well enough). I think this should work, and I think it's worth trying as an alternative to the canonical setup.

scarlson 

Stainless steel rivnuts are available. The stainless steel hardware in my other fenders seems to be doing OK, so I think this should be a fine option.

And I think the Compass rinko nut is ordinary steel

Seriously what is up with those? René Herse himself often used brass nuts on the inside of fenders, in my experience (n=1 actual Herse bike). It was easier to take apart than my Taylor, which used all mild steel or CrMo hardware, that's for sure. Torch was used as often as wrench! Sometimes I had to use the grinder.

gugie 

Allen wrench, part of the tool kit you’re probably carrying.

scarlson 

I think I mentioned, this summer, on French Ebay, I bought a pair of old Lefol fenders for the Trek. Old Lefol fenders almost invariably come with tons of holes drilled in them, and generally the more holes there are, the cheaper they come. I think this pair was 25 EUR including shipping to my friend in Germany. I counted at least 10 superfluous holes drilled in them. Seems about right.

gugie has put bumper stickers over them. This is a good idea. Quick and affordable. But I really wanted to know if I could weld them. It was a burning question for me. I finally got the chance to use a really nice TIG welder that can do AC with high-frequency arc stabilization. This allowed me to answer my burning question.

So I tried it out. I prepped the fenders using a stainless wire brush and clamped some copper sheet to the back of the fender to cover the hole. I used 70% "cleaning" (electrode positive) bias. 60A max on the foot pedal. I used 1/32" 4043 filler rod. Pretty standard procedure, I thought. I messed up a lot and contaminated a lot of tungsten (the arc changes color and you get black schmutz everywhere when you do this) and finally developed/aped the technique in which I rested the ceramic cup of the tig torch on the fender and made a steady arc, which I pulsed using the foot pedal to alternately get more filler rod melted in (low amps) and get penetration on the hole's edges (high amps). By "walking the cup" (moving the tig torch's ceramic cup by degrees) around the hole, I could get to all sides.

There were 9 holes to fill in this rear fender. It took me about 2 hours to do it all. The welds are a little bit more brittle than the rest of the fender, but they could be cold-worked, by peening or crimping, to a certain degree. Here are the results. Six holes in the bottom photo and three and a half in the top photo.




There were two holes in the front that I did not want. I did these last, so they are the best of all.


You can see I was even able to preserve the hammered pattern a little. I am proud of this!

Was it worth it? Probably not if all I got was a pair of beat-up-looking fenders. Should just cough up the money to buy new Honjos, and save myself the time and effort. I'll still have to buy some Berthoud mounting stays for these, after all! But I learned a lot of difficult welding technique, and that makes it worth it.

scarlson 

I did the thing I said I would, and reinvented the wheel. Or, rather, the fender. Close enough to the wheel, both literally and figuratively. Jokes aside, I think using rivnuts and removing the whole fender is a viable system. Here’s what I did.

First, I brazed a nice flat plate under the seatstay bridge of the frame This has holes fore and aft of the bridge.

Then I put two stainless M5 rivnuts in the fender. You can see I’ve got a nice stainless reinforcement plate on the inside, peened to match the curve of the fender. The rivnuts were actually pretty hard to “set”, probably because they are stainless. I couldn’t do it with a bolt and a nut, even a good quality, well-lubricated bolt and nut. I rounded off the nut and bent the bolt trying. I ended up setting the rivnuts on the arbor press, but it would be possible to do in the jaws of a vise as well.




Second, I put a rivnut in the bottom-front of the fender, along with an aluminum reinforcement plate.





The bike looks like this with fenders. The fenderlines are perfect as it stands, and the rear wheel is all the way forward in the dropouts. It has room to slide farther forward and come out with the tire fully inflated and the fender installed!



And like this rinko’d.



I also TIG welded a reinforcement plate to the rivnut flanges on the top of the fender. While it looks pretty, I do not recommend doing this. I cracked one of the rivnuts in the process and had to re-weld part of it, and I wonder how long it will last.


My observations about installing the rivnuts are mainly that the hole in the fender must be exactly the right size, or else the rivnut will get set asymmetrically and screw things up, and that setting the stainless rivnuts requires great force. Also, you must pay attention to the maximum allowed thickness for the rivnut. If you try to put a rivnut through too many layers, it will just end up a big mess. Other than that, they are straightforward, and this is feasible for the home shop user.

The bolts have leather washers on them, so they are (lightly) retained when the fender is removed. The lower one uses some home-made thick washers that are significantly better at retaining the bolt, so maybe I will home-make some more for the upper bolts. I also think I need to make the front hole in the upper mounting plate a little slotted so the bolt can slide backward a little as it is undone. This will make rinko a little easier.

Chr0m0ly 

I’m loving this thread thank you for photographing all the steps!

bwilli88 

if the aluminum welds in the fender are a bit brittle, heat them with a torch to just at red hot and then let them cool, they will anneal the weld and be soft.

Kuromori

Annealing may very well harm the fatigue strength though, which is the primary mode of failure for metal fenders.

thumpism 

Looks like some of your science junk is 80/20 stock, the T-slot material. Very popular for van interior build-outs these days.

scarlson 

Yeah, that's right. Everybody here uses it for all manner of experimental rigs, from neurobiology to atomic physics and everything in between. It's expensive but it's easy to build nice things quickly. I have access to boxes of off-cut sections in shorter lengths. They don't get thrown away, but they're kinda like "take-a-scrap, leave-a-scrap."

gugie 

Rather than rivnuts, why not just rivets?

Really liking your fenderlines! I don't think most people appreciate the planning it takes to get them even all the way around and matching front to back without spacers. Also getting the chainstay bridge placement just right with horizontal dropouts so you can just get the tire out fully inflated takes some forethought and planning.

scarlson 

Rivets to hold the fender to the frame? Like hollow ones and then have nuts under the fender? Or rivets to hold the reinforcements on? I really don't like using pop rivets, but I'd like to get into flush riveting as was done on the old CAR-MAXI hub flanges and also some aircraft.

Well, I am cheating a little with the thicker leather washers on the chainstay bridge and the thinner ones up top. But I will say that my Taylor has between three and zero of those homemade thick leather washers depending on what bridge the fender's attached to, so I've definitely got him beat!

The Herse is, of course, perfect...

I have to give credit to the Trek design team for that. People said this bike was ideal for a 650b conversion, and so far it has not disappointed me. I was really a little shocked that things worked out so well.

A framebuilder I will not name replaced the chainstays and bridge on my Ron Cooper and he definitely screwed that up. You have to deflate the tire for sure. I'm still miffed with him, six years later. I may redo it now that I have practice.

OldsCOOL

OP, could you move in next door so I can watch you work in your shop? We think alike in more ways for us not to be related.

gugie 

Epoxy + rivets

scarlson 

Gotcha. Picture worth a thousand words! That seems like something I'll do when/if I revamp the Cooper. Not a bad plan, and I could TIG instead of braze since that's stainless and super easy to weld right angle joints of non-mystery metal.

Also, the tab makes it a little easier to unmount the fender since it has to move back as it comes down. I guess I had eschewed tabs because I didn't like the VO fender clamp thing on my commuting bike. Silly me, as that is one of the few things on that bike that *hasn't* broken.

scarlson 

Ha, maybe when I finish grad school and am no longer indentured here. For now, come on over any time.