Stronglight toothed headset 'washer/spacer' grind-down...
 

OK, besides the sacrilegious aspect to this idea......
I'd like to use a V-O decaleur (because it's what I have, it's simple, etc etc), but there isn't quite enough threading on the steerer tube to add it to the stack. The toothed spacer is quite thick and I'm wondering about grinding a mm or two off the top to give me room in the stack for the decaleur. Other than the aesthetic horror of permanently altering a (not so rare) vintage component, are there reasons I shouldn't do this?

Rather than ruin the toothed one, I'd ask a mechanic at my local bike shop for a flat headset washer. Chances are that, at worst, you'd have to pay a few bucks for a complete used headset.

I found those steerer-mounted decaleurs to be really problematic. No amount of tightening would prevent them from moving around, particularly if I had any kind of weight in my front bag. V-O also made a stem-bolt mounted version, which works much better or up your game and ask @gugie to make you one of his custom models.

Ah, yeah, I wondered about whether it might move..... and thus loosen the locknut, too. OK, no sacrilegiousness then.

Wow, Gugie's are nice looking. One of them may be in my future......

My Gugificazione custom incorporates the housing stop (no room on the steerer threads) and inverted the tubes for my tall frame, stem and big Waxwing bag. He also inverted the clamp bolt direction at my behest which improves the bag lid elastic loop retention.

https://photos.smugmug.com/photos/i-...-RwwK7DH-L.jpg

I have done this very thing with a toothy washer for the same reason (to make the headset fit just right) and have ridden it out in public with no stern rebukes whatsoever. If it steel it might discolor from the heat. If aluminum, no problem.

@Dfrost, can't have too many publicists, eh?

:rolleyes:

Try to do the thinning precisely (maybe obvious?), keeping the top and bottom faces parallel, or else you could risk having the headset screwed race kicked out of square. There's always some slop in the threads, which can allow the race to be out of parallel with the cone that's pressed into the top of the head tube. This out of parallel situation can cause weird symptoms like a headset that's both loose and tight at different points in the rotation of the steerer. Also possibly accelerated wear.

Honestly though the effects will probably be minuscule unless your headset threads are extra sloppy. Parallelism is much more important for the lower race, which carries more of the load from your weight and dynamic loads from road irregularities. You can usually get away with some imprecision in the upper race. Just something to be aware of.

When I need some more steerer length, I'm more inclined to mill down the head tube. There's almost always some extra room to shorten the amount of headtube above the toptube joint. I mill the top of the HT preferentially (as opposed to the bottom of the tube) since that doesn't change the frame geo, but I'll mill the bottom too if needed, since frame geo is not very sensitive to small changes in the length of the HT.

But then that's easy for me since I have the HT milling/facing cutter. Most people have to bring the frame to a specialist to have that done, and lots of people don't even live near anyone equipped to do it. (If any Seattle folks need that done, you can PM me.) Oh and some "specialists" have the tool but don't know how to use it, and consequently they can ruin the frame. So make sure your guy knows his potatoes. Milling the frame with a Campy cutter might make your existing headset no longer fit, if your headset expects a smaller inside diameter on the HT. I suspect Campy settled on a larger diameter there expressly to prevent people from putting any other brand of headset on a frame that had been reamed for Campy. Ac ompetitive advantage that only lasted until so many other headset makers adopted the larger Campy size. There are still lot of headsets out there that need a smaller headtube ID though, so beware, and measure twice before cutting.

If I had to thin a headset washer I would do it on a belt sander (aka belt grinder) with a flat platen. As opposed to a bench grinder, that likes to make curved shapes matching the grinding wheel, the platen on the sander likes to make flat shapes, or keep flat things flat. You just need to take off the same amount all the way around.

Use a fresh belt since that requires the least force, and cuts without putting as much heat into the part. I would hold the part against the belt by hand (no gloves), which guarantees you won't get the part too hot — you'll need to dunk it in water quite frequently to keep from burning your fingers. Maybe that's dangerous though? I've been doing it so long I forget what it's like to be a beginner. Maybe most people should push that part against the belt with a pusher stick, wood or what-have-you. Less sensitive, but no doubt safer.

I know ehcoplex has moved on from the washer-thinning idea, but being moot never stopped me from flapping my gums...

gugie's decaleurs are a thing of beaty, and practical to boot, but another interesting one to check out is Tom Matchak's "Dock-it". Super clever. With the B2B (barrel-to-bike) kit, you can make a custom decaleur to fit most any size of bag to most any size bike (with certain limits of course). No brazing rquired. Bag detaches with a slight roation of a knurled ring, but it's held securely while riding. OK, maybe it's not very "C&V looking". He did sorta throw tradition out the window with this design.

Mark B