10 December, 2009

Threaded Headset Basics


We get a lot of questions about threaded headsets, so I thought I'd post a little basic information about them.

Threaded Headset Sizes

There are five fairly common threaded headset sizes: ISO, Italian, French,  JIS, and BMX.

ISO is by far the most common size and is used on virtually every modern bike with a 1" steerer. The steerer inside diameter (ID) is 22.2mm. The pressed race ID is 30.2mm (that's the inside of the head tube). The crown race (on the fork) measures 26.4mm and the threading is 24tpi. Velo Orange stocks three ISO headsets, the Grand Cru sealed bearing headset, the VO loose ball headset, the Tange Levin NJS loose ball headset.

It's worth noting here that ISO, and most other, headsets use a keyed lock washer. A groove or keyway is machined into the steerer and the key in the washer fits into it. This is intended to prevent the top nut from loosening. But many custom bike builders don't machine a keyway. In this case simply throw away the washers and use a drop of Locktite on the top nut,

Italian headsets are virtually the same as ISO. The crown race ID is 26.5mm rather than 26.4mm and the threads are a tiny bit different, but ISO headsets are so close that they work absolutely perfectly on Italian frames.

French sized frames use a 25.0mm steerer with a 22.0mm ID. The crown race is 26.5mm and the pressed race is 30.2 mm.  Thread pitch is 1mm, or 25.4tpi. The final difference is that the steerer has a flat machined onto the back rather than a keyway, so a different washer is used. French headsets are getting very hard to find, but Velo Orange will soon be making one. It will arrive early next year.

JIS headsets are used mostly on older Japanese frames and on Keirin racing frames. They differ from ISO headsets in having a 27.0mm crown race and 30.0mm pressed race. VO makes a JIS headset.

BMX-sized headsets were used on some older lower quality American and Japanese frames and on BMX bikes. The steerer ID is 21.15mm, the crown race is 26.4mm, and the pressed race is 32.6mm. This size is still made, but VO does not stock them.

There are also a few odd headset sizes including French tandem, Austrian, Raleigh, and 1/1-4" tandem. I don't have any experience with these and don't know of a source for replacements other than E-bay.

Stack Height

Stack height is the total height, or thickness, of the headset, not including the parts that fit into the head tube. In other words, it's the vertical distance required to fit the headset. Stack height is important because if it's greater than the available space on the fork the headset will not fit. This is rarely an issue on modern frames, but older frames often had their steerer tube lengths sized for a low-stack-height steel headset, so taller modern headsets might not fit. It pays to measure first. On a fork that has extra length, spacers are added to take up the excess.

If you're fitting a headset but find you lack just a millimeter or two of room, simply remove the lock washer and use a drop of Locktite on the top nut instead.

Loose Ball or Sealed Bearing

I am completely sold on sealed cartridge bearing headsets and they are the only type I will now install on my own bikes. The advantages of sealed bearings is that they last much longer, are smoother, are sealed against moisture, and require no maintenance. With the Grand Cru headset, which I use, the crown race is split so no tools are required to install or remove it. And if the bearings do someday wear out you simply lift out the two bearing cartridges and drop in new ones. (Note that some sealed bearing headsets have pressed in bearings and traditional crown races.)

This is not to say that loose ball headsets are bad. Cyclists have been using them for over a hundred years. If you ride mostly in nice weather and don't mind a bit of maintenance, they are a good way to save some money.

Roller bearing headsets also had a strong following, particularly the now discontinued Stronglight A9 headset. But with modern sealed bearing headsets available for the same price, I can see no reason to use a roller bearing headset. Some claim that roller bearing headsets reduce shimmy, but so do sealed bearing headsets.

Installing and Maintaining Headsets

Installing headsets is not difficult, but it does require some costly tools. So my recommendation is to pay the local bike mechanic to do it for you. It's only 10 or 15 minutes of work so it shouldn't cost much. For those of you who really want to do it yourselves, I'll simply point you to the Park Tools' excellent instructions.

That Park Tools article also explains how to disassemble the headset to grease or replace bearings, something that should be done a couple of times a year with loose ball headsets. It's an easy at-home job requiring only a headset wrench and some grease.

Are threaded headsets better than threadless?

Most bike manufacturers now make frames that use threadless forks and 1-1/8" threadless headsets, a size that was originally developed for mountain bikes. It is true that 1-1/8" threadless headsets are stronger than 1" threaded, but road bikes don't need the extra strength. It is massive overkill. The big disadvantage of threadless headsets is that they don't use quill stems, which allow easy up and down adjustment. With the threadless system you cut the fork steerer to length and then adjust the height by using a different stem or by shuffling spacers. If you cut and set up your fork correctly it's fine, but if you need to later adjust handlebar height upward it gets expensive or even impossible.

So why are threadless systems popular? They are promoted by big bike manufacturers to lower production cost. Only one size fork need be made for each frame and it does not need the additional steps of cutting a keyway and threading. Then the fork steerer is cut to size by the customer or bike shop. This results in a huge cost saving for a big bike manufacturer.

With threaded forks, like those used by Velo Orange, forks are made for each frame size. Beyond the adjustability of a quill stem, an additional benefit of making a specific forks for each frame size is that it allows us to make slight rake adjustments for smaller frame sizes. This results in optimal handling for those small frames.

Hope this answers some questions. Some of my other informational articles can be found on the VO Tech Info section.

43 comments:

Anonymous said...

When I install a headset, I just grease up the cups and gently hammer them into the head tube with a plastic mallet (originally for tent stakes). I don't need no stinking headset press!

Anonymous said...

I use a rock!

Og

philcycles said...

May I comment on HS adjustment?
Rather than tightening the lock nut into the screwed race I do the reverse: I tighten the screwed race into the lock nut. This requires several tries-usually-to get the proper adjustment but once done is absolutely rock solid. My HS never loosen and never require readjustment.
BTW, I'm a frame builder and I usually file a flat on the steerer for the keyed washer if I'm installing it but if I'm not I just leave it off.
And I ALWAYS use a head set press.
Phil Brown

scott said...

Hi Chris,

Thanks for taking the time to post useful information about threaded headsets.

Regarding production threaded forks ... any word on a revised production V/O rando fork?
Scott

Chris Kulczycki said...

Scott, we don't plan to sell forks separately, but are still working on a new fork with a traditional bend for our production frames. We were not happy with the first tooling and are trying again. I was at the factory and thought the bend was close, but not perfect.

Anonymous said...

One footnote: French headset bikes do have a flattened section on the fork as you describe rather than a keyway, but just because a fork has this rather than a proper keyway don't assume it's French. A lot of cheap older bikes of various origins and headset dimensions have this design as well since it's easier to machine. The washer often spins around when you tighten the headset and mangles some threads on the fork.

Larry Leveen said...

Before anyone jumps down your throat about it, I'll (hopefully) politely point out that there are a couple other threaded sizes you didn't mention in your post: 1 1/8" & 1 1/4", which, of course, have their own individual crown race and pressed cup dimensions. I know VO is largely a 1"-oriented outfit. Just sayin' is all....

I too am a fan of sealed bearing headsets for the same reason as you -- folks never seem to take care of that bearing (or any other, for that matter). Bearing durability is partially dependent on maintaining a thin film of lubricant between bearings (ball or roller) and the surfaces on which they roll. Contaminate or perforate the film, and you get direct metal-to-metal contact, resulting in rapid pitting/damage (from what I have been told, the physics involved are amazing). Pedal, hub and crank bearings spin "round and round" and this motion helps replenish the lubricant film. Headset bearings, however, do not normally move like that; their arcing motion is thought by some to facilitate lube film failure and resultant bearing damage. Therefore, why not be able to pop out a couple cartridges and have the system work like new?

Several years ago I was pleasantly surprised to find out that Shimano made ISO crown races and pressed cups for their _cartridge bearing_ headsets (!), though I am not sure if they still do as they seem to be phasing out threaded headsets altogether. I still have a set each of 1" JIS/30.0 cups in stock (it's easy to mill down a fork from 27.0 to 26.4), and it's nice to be able to offer that to customers with ISO framesets.

Chris, is the VO headset compatible with Shimano's cartridges? I'd assume so, but please verify. If so, it means that VO headsets are more easily serviced anywhere in the developed world.

Leighton said...

"[The lockwasher] is intended to prevent the top nut from loosening."

True. It also stops the bottom nut from rotating while you're tightening the top nut. Without a lock washer, two wrenches are required; with one, you can theoretically get away with one wrench.

superfreak said...

now that vello orange sells french headsets and french bbs when are you going to start selling a french threaded frameset. french threads make a huge improvement in the ride, much bigger effect than low trial or 650b wheels. thx superfreak

Pierre said...

Chris,

I sometimes post anonymously on here about things that I don't really agree with, like 650B for example. But thank you for taking the time to post this headset piece. Very informative for a cyclist like me who rides but is not really into the more complicated mechanical stuff.

I'm glad to see someone else with some level of authority posting about threaded vs threadless headsets. I've heard all the arguments about advantages and disadvantages, and I've taken the beatings on usenet and bike forums about it for more than a decade now, but I still want nothing to do with threadless headsets.

I'm no racer or pro of any kind, but I like my stem easily and readily adjustable for height. I actually do vary that height over the course of a season, and I've been riding road bikes for more decades than I care to say. I'll take my traditional threaded system over my daughter's new bike with the ugly, threadless, glorified pipe-clamp stem which can only be adjusted in wide increments by frigging around with spacers, and which side of the stem is up with which side of a special washer... and then worrying about getting the preload on the bearing just right. No thanks. I mean, talk about kludgy!

I've been bold enough to openly disagree with many supposed "experts" on this, even the great engineer of wheelbuilding fame. People like me who prefer threaded are always dismissed as hopeless curmudgeons and dinosaurs.

Roy said...

Can the cartridge bearings in the Grand Cru be serviced? Do you sell replacement cartridges? Do you know if the cartridge is the same as catridge in the old (mid 90's ?) shimano 600 and 105 headsets? It does look very similar but I was too lazy to disassemble my other headset to check.

Thanks!

Jan said...

I am a huge fan of the threaded headset. My favorite? That would be the one on my "oldie", a 1964 Moulton Continental. It has a steel headset (naturally) and must have about 20 balls in the lower race, an absolutely amazing piece of kit. That headset will be spinning smoothly long after I am dead and gone.

John B. said...

Chris, Thanks for putting together this primer on threaded headsets. Very informative. Here's one thing I've always wondered. Given that threadless headsets came about as a cost-saving device (which I believe), why is it that cheap bicycles such as WalMart bikes and low end cruisers all use threaded headsets? Doesn't make sense to me that the least costly bikes to buy would use a more costly manufacturing process. I think most serious cyclists' aversion to threaded headsets in the US is at least partially driven by their association with cheap bicycles.

Anonymous said...

Great writeup! VO is not only a source for parts but also for reliable information. Keep up the good work!

johnson said...

john b.-

one of the reasons could be that most walmart bikes & cruisers only come in one size, so the company would only need to cut and thread to one length. is is also possible that the cheapest OEM parts spec is still cheapo quill stems and steel threaded headsets. or a combo.

Chris Kulczycki said...

I don't know if the bearing cartridges we use are the same as those used in old Shimano headsets, probably not.

We have a few replacement bearing cartridges. But since they typically last for many years there is no demand for them yet and probably won't be for quite some time. The bearings are serviced by simply lifting out the cartridge and dropping in a new one. The only tool required is a headset wrench.

Anonymous said...

Will the French headset be usable with the short stack height? I have a 1980 PX10, and it has, at the most, 37mm of stack height. If I can use it, I am a potential customer.

Anonymous said...

Someone should invent a threadless that allows for an adjustable quill.

Tom said...

The threadless headset design was 'invented' by Dia Compe (although that's arguable, with prior art by Pino Moroni, Hi-E, and some French constructors). That invention is protected by worldwide patents. Every manufacturer has to pay a licensing fee to produce a threadless headset, and this additional fee makes it much more expensive than an cheapo steel threaded version. When you counting costs to the Taiwan dollar (NT) or Chinese Yuan, a $3 per headset licensing fee (or whatever it is- it's not exactly cheap)pushes threadless headsets out of the commodity WalMart Opening Price Point market.

The Dia Compe patent is going to expire relatively soon. There are a lot of rumours on the supply side as to how this will affect threadless headsets and the bikes they will be speced on. It will definitely go down market.

Tom said...

anon 12/11/09 11:29 AM:

Rocket power parts did just that in the mid-90's: an adjustable height threadless stem. Kinda clunky, and headset spacers pretty much did the same thing, as long as the steerer was cut with that in mind.

Adjustable angle stems are common on hybrids. Ugly as sin, but very common.

lee.watkins said...

With the Raleigh, it's usually the bottom races that wear out or get
"brinnelled," and those parts are interchangeable with those from an ISO headset. You can mix and match parts between B.S.C./ISO and Raleigh headsets, since all of the other mounting dimensions are the same except the threading. If your Raleigh headset cups are worn out or rusted on the load-bearing bottom section, which is almost always the only issue with them, you can replace just the bottom with any standard ISO 1" headset parts, and re-use the Raleigh upper assembly... provided the "stack" of original and replacement parts is close enough.

Headset stack height problems can be solved (within a small window of
opportunity) by using a different thickness spacer between the topmost (threaded-on) race and its locknut. A lot of headsets come with one that's on the order of 5 mm thick, and you can get them down to 2 or 1.5 even. Of course, if your previous stack height was too large -- generally not the problem -- then you can use a thicker/additional spacer. Or, if you're fearless enough, you can lop a few mm off the top of the steerer tube.

Ideally, a "brinelled" headset part should be replaced, but you can often cure the problem by replacing the retainer with loose balls. You use the same size balls, but can usually fit more of them into the races if you leave the retainer out. As a result, the greater number of balls, closer together, no longer all line up with the dimples in the races.


American-style bike frames use the same headset threading and diameter as ISO standard (British) headsets, also the same 26.4 mm fork crown race size, but the frames have larger diameter head tubes. I thought that standard was closer to 32.7mm ? Usually American size uses 24 threads per inch, but some bikes, particularly older Schwinn and Mongoose models can use 28 threads per inch parts.

Early mountain bikes used American "cruiser" frames with these standards. While the imported European bikes, and later Asian bikes were undeniably lighter and faster (partially due to higher tariffs on heavier models in those days), the American bikes were made with a greater emphasis on durability and ruggedness. BMX and children's department store bikes are subject to rough usage, and they are also the only type of crankset that can be serviced with ordinary household tools, hence they have held out longer on one-piece steel cranks and other American dimensional tolerances. People began to associate the American dimensions with these low-end bikes, and to forget that many high-quality machines had been made to these standards... as a result American dimensional tolerances went into retreat, and were increasingly relegated to department store bicycles, such as Huffy and Murray, which was self-perpetuating.

Anonymous said...

My own PERSONAL opinion is that stem adjustability, as in being able to adjust on the road, is less of a deal than many make it out to be. I love to play around with different bars and stuff on project bikes, but I also like to fool around with cranks and derailleurs--I suppose someone could put together an adjustable crank arm (or derailleur cage with multiple jockey wheel positions) that some would find themselves fiddling with; but most riders are content to find a stem height and stick with it.
Everyone is different, but I pretty much stick with saddle height, but I once read that the great Eddy Merckx carried not only an allen wrench to adjust his saddle height several times in a ride, but he also carried an extra binder bolt because he was worried his frequent adjustments would fatigue the bolt and it would break mid-ride.
Again, this is my opinion, but both standards are fine, and it you are doing something wrong if you find yourself thinking enough about stem height while you are riding that you need to change it.
M Burdge

Anonymous said...

I made a headset press for maybe $5out of a long bolt, nut, and washers from the hardware store. It's lasted 20 years so far.

Mark G
Longmont CO

philcycles said...

Everyone is different, but I pretty much stick with saddle height, but I once read that the great Eddy Merckx carried not only an allen wrench to adjust his saddle height several times in a ride, but he also carried an extra binder bolt because he was worried his frequent adjustments would fatigue the bolt and it would break mid-ride.

Eddy had a horrible crash on the track in 1969(I believe) and after that fiddled with his position endlessly. I don't think he was ever comfortable on the bike after the crash.
Phil Brown
Phil Brown

Pierre said...

Threadless on a road bike pretty much guarantees you are getting a generic fork with a rake that is not customized for the frame size. A win for the big bike megafactories in China, a loss for the average bike rider. Really useful though, if you ever have to put a mountain bike suspension fork on your road bike, or if you weigh 300 lbs.

Like almost everything else in the bicycle world, threadless has been done before. Maybe it will eventually go away again this time. Aesthetically-speaking, a threadless headset and stem only look marginally acceptable only if the handlebars are well-below saddle height and few spacers are used... hardly appropriate for a French fit style of road bike.

benny said...

lee.watkins: I have a 1972 Schwinn Sports Tourer that I suspect has a larger "American" head tube. Any idea where I can find a replacement headset?

Anonymous said...

'Eddy had a horrible crash on the track in 1969(I believe) and after that fiddled with his position endlessly. I don't think he was ever comfortable on the bike after the crash.'
I don't think you are trying to generate an argument--neither am I--but the fact that Merckx's need for constant adjustment was not a normative thing, but the result of a chronic injury only lends weight to the point that stem adjustment may be less of a deal for people without damaged backs or necks. It was only after he got hurt that he needed to adjust constantly.
I want to keep good natured about this; especially since we are talking about little metal bits that hold other metal bits up in the air on what amount to non-essential items for most of us. And one of the things I love about cycling is the variety with which individual persons set up their machines.
And all I want to say is that we have all seen lovely bikes with threadless stems. Heck, many of us have piloted bikes with them, and enjoyed the scenery and conversations with fellow riders and the exercise just as much as with someone using a Technomic.
M Burdge

philcycles said...

Not trying to generate argument at all. I think that Eddy's fiddling was also in part trying to gain a bit of a performance increase. Let's face it, 1% is a tremendous increase and if position fiddling would get it Eddy was enough of a perfectionist to go for it.
Myself, I've been riding with the same position for about 15 years or so through several injuries and the like. I'm comfortable.
Phil Brown

fridaycyclotouriste said...

...another potential french headset customer here (i assume that's what i'll be needing for a vintage peugeot mixte restoration project).

Nathan

Roy said...

I realize this thread has wound down, but I installed my second Grand Cru headset last night. It's wonderfully buttery. However, I did notice that the my first Grand Cru had a split ring crown race while the second has an ordinary ring. Is there any reason for the change? The split ring seemed convenient.

Troy DuFrene said...

What terrific news about the roll out of the new French thread headset. I'm in the middle of rebuilding a early 70s Motobecane Grand Jubilee, and I was really grumpy about having to live with the eroded chrome on the original. Can you be any more specific than "early next year" about the ETA? Not like I have a choice but to wait...

Chris Kulczycki said...

Roy, Thanks for pointing that out. It seems the factory shipped the last order with non-split crown races. They should be back on the next production run.

Chris Kulczycki said...

The French threaded headsets have a stack height of 41mm, or about 39mm without the washer. They will be loose ball with an alloy body.

We don't yet have a firm ETA from the factory.

Anonymous said...

threaded systems are much more aesthetic than threadless systems!

OlyBikes said...

Usually a curmudgeon and retro-grouch, I actually like threadless headsets. They:

- Allow adjustment of steering bearings without expensive/bulky tools -- "power to the people!"

- Do not rely on the health of fork threads which can be damaged/rendered useless (rare, but I've seen it and it's a bummer). You can drive out a bunged-up starnut and sink a new one in and viola -- new threads! Sort of like cartridge bearings in headsets that way.

- They ARE now height adjustable, if you get an NVO-type stem . Granted, you do need to keep your steerer long. "Beauty in the eye" and all, but I find these industrial black stems butt-ugly (Chris, how about an similar stem from VO that's cold-forged silver alloy? If you do it, _please_ consider a two or four bolt "endcap design" for faster stem/bar swaps.)).

- They are more universally available, and with Cane Creek's patent about to expire, I'd expect prices to plummet.

- They come in various forms for all of the stupid pseudo-innovations in head tube shaping/machining that the industry spews out..... :-/

... Strike that last one...

I like threaded ones too, though. My main ride has an Ultegra cartridge unit on it. Love it.

OlyBikes said...

I am not anti-DIY, but want to offer a few words of caution on DIY headset presses and crown race installers:

Cartridge bearing systems rely on a different portion of the cups/crown race than loose-ball systems.

Professional install tools are specifically designed to avoid damaging those respective areas of the headset.

VO (and any other headset maker, regardless of design)should not be held accountable for damage during installs without proper tools.

Kazuo said...

I'd like to ask a question here. I have an old Derosa and a Colnago. Both frames are equipped with a Campagnolo Nuovo Record headset. Back in the NR days, Campagnolo was manufacturing French, Italian and British standard headsets, and I believe my frames use the Italian. Now, when you look at the 2010 Campagnolo catalog, they sell only British standard headsets. Is it totally OK to use this on my bikes? If they are compatible, how come Campagnolo was selling both British and Italian headsets separately in the NR era?

seablister said...

Is it possible to convert a threadless steerer tube to a threaded one for use with a conventional (old school) threaded headset?

Kazuo said...

I have seen a Derosa Neo Primato, of which fork was converted from an original thread-less to a threaded. The guy said he had it threaded by a frame builder, so technically speaking, it is not impossible.

garagepunkfan said...

Chris, any plans for a nice vintage-look forged alloy quill for 1" threaded steerers anytime soon? i have a nice, vintage looking but somewhat nondescript Compe 60mm forged alloy quill on my project bike but what something more distinctive. I've been looking for an "English" stem (of which i've never seen a forged alloy version) or a 60mm SR JUN "chest-buster" for a while because the Kalloys simply do not have the "look" and are a little too '80's.

Anonymous said...

It's hard to come across this information online. Most people talk garbage to make themselves look high and mighty, thanks for posting

Anonymous said...

Just installed one today after battling with the rattling rusting of a cheaper headset that has just been binned after one winter.

Very very pleased with the VO so far. No play and smooth.

I used a mallet as well.

(headset press? Pfftt)

Anonymous said...

French forks tend to have 27mm crown race not 26.5