Monday, October 21, 2013

Roller "Needle" Bearing Headsets

Every now and then, I like to highlight some great components that are either getting scarce or gone. Today, I want to take a look at roller or "needle" bearing headsets ("roller" bearing is generally the preferred term, so I'll use it from here on). They aren't gone, but they aren't very common -- actually, they never really were that common to begin with. Nowadays, with so many threadless headsets out there, and excellent sealed units available, they are pretty much forgotten. They aren't the perfect headset in any way, but they are serviceable, last a long, long time and I like them.

The thing about ball bearings as they are used in headsets is that they are excellent at reducing the friction of the fork rotating in the frame, but not as great at handling loads. The fork of a bike (as I've described in an earlier post) is like a "front line of assault." Every bump, large or small, travels directly up the fork, transmitting shock through the headset. Ball bearings have very little contact area with their races (which is why they are so good at reducing friction), but that small contact area also means those forces are concentrated on a much smaller surface area. Over time, the bearing races can become dimpled or pitted, which leads to "notchy" steering. 

Stronglight A9, set out so all the internal parts can be seen:
(From top left) Lock nut; top adjustable cup; steel bearing
race; roller bearings/retainer; steel bearing race; upper
pressed in race; lower pressed in cup; steel bearing race;
roller bearings; steel bearing race; fork crown race.
Roller bearings have a larger contact area, which makes them better at handling loads. On the other hand, critics of roller bearing headsets will point out that they have more friction (I'll explain why later in the post. Read on.) -- they don't allow the fork to turn quite as freely as ball bearings. Then again, in actual riding, forks don't really move that much -- bikes turn or change direction more from leaning than by "steering." In the small amount that forks actually rotate in the frame, roller bearings work fine. 

Another benefit of roller bearing headsets is they are believed to add a bit of stability to some bikes. Occasionally, some bicycles will experience something referred to as "shimmy." There are different explanations (and some disagreements) about exactly what causes shimmy, but it is essentially a rhythmic, almost resonant shaking of a bicycle that one can feel through the steering. It seems to come from a combination of the gyroscopic action of the wheels and perhaps an oscillation or twisting in the frame. The steering action twists the frame one direction, then that energy is momentarily stored then released, twisting the frame back the other direction, then back again. In some cases, it can also be exacerbated by loading a bike with luggage/bags. Some bikes that feel fine with hands on the bars can shimmy badly when riding no-hands. I should point out that if a bike that never had a shimmy problem suddenly develops one, it could be a sign that something is actually wrong -- loose spokes, loose headset, cracked frame or fork -- so if it happens, definitely investigate, but be aware that sometimes it just happens. (read more about shimmy HERE)

In any case, sometimes a frame with a mild shimmy can be mitigated by a roller bearing headset because of that bit of extra friction. Rivendell's Grant Petersen describes it like this:
A roller bearing headset "increases rotating resistance. The thing is, headsets can be too smooth. A little smooth-stiffness, a little gumminess in the bearings, seems to eliminate the tendency of a bike to shimmy. . . Sometimes, fact of life, a bike will shimmy. It's almost always when you're doing something stupid, like riding no hands at 19 mph with a loaded bike. . . And in that case, a gummier rotation helps." (http://www.rivbike.com/product-p/hsrd.htm)

Stronglight A9. 
Over the years, there have been different roller bearing headsets introduced, though most were pretty similar to one another in design. Stronglight of France was one of the main manufacturers of them, having made several versions. Tange of Japan has made, discontinued, then re-introduced them at various times. Velo-Orange briefly offered their own version, but they don't seem to be currently available. Here are a few examples that were pretty common or notable:

Stronglight A9: This is probably the best-known, most common roller bearing headset one is likely to find. These were available throughout the 70s and 80s. French racing legend Bernard Hinault must have used them, because they had a "Bernard Hinault" edition of the A9 -- though other than having his name on it, I don't think it was any different from the basic version. Mostly aluminum in construction, with floating steel bearing races. The roller bearings were held in nylon retainers. It was lightweight, had a relatively low stack height, and was just a good all-around headset. Most roller bearing headsets use essentially the same basic design as this one, so I suppose one could say it set the standard. They weren't terribly expensive when new, and one can occasionally find NOS (new old stock) ones on eBay for a lot less than some of the deluxe sealed-bearing headsets of today.

Stronglight Delta -- with a lot of extra spacers and
a cable stop for cantilever brakes.
Stronglight Delta: The Delta was essentially a more deluxe version of the A9. It had a slightly taller stack height and included some extra seals that were supposed to help keep out water and dirt. I don't think those seals made any difference compared to the regular non-sealed A9, however. Apart from the outward appearance and the additional seals, the two headsets were pretty similar mechanically. I'm pretty certain that the bearings and races are exactly interchangeable between the two versions.

I have one of the Delta headsets installed on my Rivendell Long-Low. Twelve years and I don't even know how many miles, and it still works like new.

Saavedra (Argentina): This one is kind of an oddball and not well known. Saavedra was an Argentinian component maker that was probably best known for rims -- but "best known" is relative -- they weren't really well known for anything in the USA. The headset has the basic shape of the Stronglight Delta but without the seals, as well as internal parts that appear to be identical to the Stronglights. The design of the wrench flats is a little different from the Stronglight, though, perhaps a bit more reminiscent of the Campagnolo C-Record headset.  Like the A9, it is a very light component. Occasionally these will come up for sale, NOS, on eBay -- usually pretty inexpensive. When you can find them, these are a good bargain for a well-made, nice-looking headset.
Saavedra, from Argentina.

Tange/IRD RollerDrive: This is kind of a roller/ball bearing hybrid design, with roller bearings on the lower part and ball bearings on the upper part. The idea is that the lower race, which takes the most pounding from the road, uses roller bearings to better handle that load, while the upper part (which is much less prone to load damage) uses ball bearings for slightly less friction -- essentially delivering the best of both worlds. Made by Tange in Japan for Interloc Racing Design. Available from Rivendell.

I mentioned above that roller bearing headsets don't move quite as freely as ball bearing designs. This has to do with the fact that roller bearings are like tiny cylinders. When they roll, they want to roll in a straight line. That makes them work really well in bottom brackets and pedals or other places where they can follow a straight-line path around a more or less straight or cylindrical axle (yet as ideal as they are for those applications, their use is still fairly uncommon except in more expensive examples). But when put into use in a headset, they have to follow a curved path.
Tange/IRD RollerDrive: Long life
and low friction.
One way to help that is by setting the bearings up at an angle. The bearing races and the bearing retainer are set up in almost a conical arrangement around the bicycle's head-tube and fork steerer. That helps, but the bearings still have to travel in a bit of a curved line, and they have a certain amount of resistance to it. Given that a headset doesn't rotate very much in actual use, as I pointed out already, it isn't really that bad of a trade-off: Slightly more friction (in a component that isn't hurt so much by a bit of friction), in exchange for really long bearing life. One thing that would probably make them work even better would be to make the roller bearings tapered -- thicker at one end than the other -- but making precision tapered roller bearings is pretty expensive, so the added cost would be hard to justify for the tiny decrease in friction.

Roller bearing headsets aren't perfect or revolutionary in any way. If they did completely disappear, I'm sure we'd all survive. Many riders would never even notice. But I'll still hang on to the ones I have, and keep some spare parts handy in the unlikely event that one of them ever needs to be rebuilt. Who knows, that 12-year-old Stronglight Delta I have might need a rebuild some 15 years from now. I want to be ready.

3 comments:

  1. Brilliant article, RG!! I already own 2 relatively modern carbon bikes - an '04 LOOK KG486 Team Edition & an '11 LOOK 566 Origin - but I recently purchased & began building up my 3 all-time dream "vintage" frames, in honour of my all-time cycling hero, Monsieur Lemond - a LOOK KG76 Kevlar Hinault (ooh, the irony of its name!!), a Team ADR TVT/Bottecchia & a Lemond Team Z (the Bilato Bros model, hand-built with Columbus EL-OS tubing & painted in the pink/yellow/blue fade paint scheme)…anyway, the KG76 came with a nice, traditional "vintage" Stronglight headset with caged bearings but the friend I bought it from in Holland (I'm an Aussie, btw) didn't completely trust the ability of that headset to tighten sufficiently, so he also threw in a new-in-box Stronglight B-10 Bernard Hinault headset (by the way, as well as having the "Badger's" name upon the lock nut, the headset cups/races are made from black plastic, rather than aluminium - it only weighs a total of 68 grams!!) & the thing is AWESOME!! I'd never encountered any headset like these before but I'm very, very impressed by it & your very interesting article has me even more "sold" on needle bearing headsets now. I'm now on the hunt for a couple more sets, for future use, perhaps even to fit upon the TVT/Bottecchia?! Once again, a French bonded carbon frame with a French brand of headset - they blend well in my opinion!! Anyway mate, love your articles & your attitude…hope you had a great Xmas & that 2014 begins well for you in a few days time…cheers & best wishes from 'Down Under', RG.

    ReplyDelete
    Replies
    1. Thanks for the comments! I've never seen one of the Bernard Hinault editions up close -- I've seen them pictured, and I thought it was just black-anodized aluminum, so it's good to know. Thanks.

      Delete
    2. My pleasure, Brooks/RG…& my apologies for being so verbose - but now that I've introduced myself & my background, at least I don't have to run over that info' again! Yeah, I would also have assumed that it was merely black-painted aluminium but it's not & I'm rapt about that, because not only is it incredibly light but it'll be a breeze to fit to/remove from the head tube with my bare hands, unlike metal cups/races. And I also have a leather & a suede (both NOS & black) Selle Italia Turbo Bernard Hinault limited edition saddle for the KG76 Hinault frame, which I really do find quite amusing, when all 3 of the frames are supposed to be a testament to Monsieur Lemond & not "The Badger"!! If you ever want any photos of anything that I've mentioned sent to you at anytime, just let me know. And keep the great articles coming, you're much appreciated & respected upon this hemisphere of the planet as well…cheers & best wishes for 2014 once again from "Down Under", mate…Matt.

      Delete