Sunday, October 21, 2007

The NJS Bike Part 2 and Headsets

Well pretty much every part but the frame has been purchased. I'm still waiting on who is 3 weeks late with the Dura Ace chainring, cog and NJS chain. I was a bit concerned as they have a track record of losing orders from time to time and they recently have had practically no NJS parts left on their site. But, they immediately returned my email and said the parts will be re-shipped; I think that means, "Oops we didn't ship your order", but the price is good so I have hope.

Under the heading of new parts on an old bike, I have mounted some of the NJS parts on my the old green machine. So you don't have to look back it looks like this;

I call it my sanity bike and sent this photo to; they have yet to post it but it's only been a couple of weeks. With the new parts I call it, what else? My insanity bike (the Green machines evil twin).

As you can see the brakes and the lights are gone. I also added a beautiful Chris King headset; in green of course.

The old headset was a Stronglight A9 that worked great, and would have probably outlived the frame. But because it is made of fairly soft aluminum and had come loose several times, it had become pretty nicked up. It also had this strange habit of not wanting to tighen up. I would have to over-tighten the adjusting ring, tighten the lockring and then loosen the adjusting ring into the lockring. After about 3 years of this, I finally figured out the lockring was galling against the aluminum washer between the two rings. Once I coated the washer with grease the problem went away. Unfortunately some damage had been done to the lower race (with a Stronglight the steel races are separate from the cups and come as two discs that sandwich around the roller bearings). The damage was minor and similar to the notchiness I've seen with cage ball bearing, but I did not feel any of the associated "indexing". Due to the fact that I have the same headset on my Peugeot, I bought two bearing sets in case I ever needed them. This is something I always do and generally find I end up replacing the part before or at the time I would need to re-build it. Anyway I sold the rebuilding kits on ebay a few days before I pulled off the headset; I actually made money on them too! The previous headset was a chromed Campagnolo that was started to suffer from what I previously called indexing and is also called "notchiness", this is why I went to the Stronglight.

From Wikipedia;

On bicycles ridden only in dry conditions and/or with fenders, the normal failure mode is a progressive notchiness in the steering, caused by pitting of the races. This is normally called "brinelling", although this stems from a misunderstanding of the cause; true brinelling is caused merely by pressing the ball axially into the race, and it is almost impossible to replicate this damage even by striking the fork crown repeatedly with a hammer. The pits are by far deepest at the front and back of the head tube, and are actually caused by flexing of the fork blades, which is transmitted to the steerer tube. This misaligns the bearings and causes "fretting", a small amplitude, large stress movement which tears metal from the races at the points where the balls rest.
The solution is to have a 45 degree interface in the headset where this flexing movement can be accommodated, preserving the relative alignment of the races and allowing the ball bearings to take pure axial and rotational loads. Shimano cartridge bearing headsets do this by allowing the cartridges to move relative to the pressed-in cups, while Stronglight roller bearing headsets, and most threadless headsets, now have loose upper and lower races which can move relative to the cups. Modern headsets, therefore, rarely suffer from "brinelling".

And from Sheldon Brown:

Roller Bearing
A bearing that uses cylindrical or conical rollers instead of balls. The major bicycle application of roller bearings is in some headsets. Roller bearing headsets are very long lasting, due to the greater contact surface area as opposed to ball bearings. Current units, however do not turn as freely as ball bearing headsets. This is due to the use of cylindrical rollers, rather than conical rollers. Cylindrical rollers do not naturally roll in a circle, but in a straight line.

For those of you that don't know about the Chris King Headset, they are way overbuilt and will probably outlast several frames. While there may be more innovative headsets, Chris King has certainly set the standard. From NYC Bike Snob;

Another financial investment. Regardless of whether they're worth the price, nothing inside our outside of cycling holds its value like these things. This is not an endorsement, it's just a fact. You can’t even get a used one cheap on eBay. I’ve tracked the retail price of these things over the years against the price of gold and the indices of all the world's stock markets and believe me when I say they offer a better return than any of them. As long as Mr. King successfully continues his anti-integrated headset scare tactics I’m putting all my money in his headsets.

Previously Ritchey made a their threaded WCS headset with needle bearings. This head set is no longer in production, but I believe it is the Ritchey WCS headset still sold by Rivendell. The only other headset I know of is the Woodman Saturn. The headset has a upper cartridge bearing on the top and a roller bearing on the bottom. I know nothing about this headset and it's only available as a threadless headset, but it looks interesting.