Friday, December 7, 2012

Headset Index Steering

Headset index steering is a very common phenomena that presents itself as a notched movement of the handlebar in the headset; it's as if there are index detents controlling the the steering with a preferred home position. If one looks inside the headset, usually at the lower cone, you will be equally spaced dents in the race. While this has been blamed on too loose a preload, the real cause is false brinneling; picture from
The most common cause of headset indexing is fretting or "false brinneling". This is a well documented phenomenon. Unlike all the other bearings on your bike, the headset is basically a stationary bearing. You spend 99% of the time riding straight ahead or moving the headset only a few degrees in either direction. The constant road vibration works all the lubricant out from under the balls and there's not enough movement to bring fresh lube to the point of contact.The "dry" contact allows an etching sort of wear, eventually forming pockets, which cause the indexing. FBinNY

I have a Nuovo Record headset that is indexing and tried a number of fixes that might be helpful to others with the same problem. First, this is on a 30 year old Italian bike that had the headset when I bought it a couple of years ago. Also, if you don't know, part of riding vintage bicycle is to keep the vintage components working as long as possible. I noticed the indexing about 6 months ago and overhauled the headset which seemed to make it better, but it returned a short time later. The indexing isn't dangerous and is unnoticeable while riding so it is an OCD matter if anything; so of course I must fix it!

The two fixes (after an overhaul) normally mentioned are to remove the ball bearing retainer and install loose bearings or to remove the crown race and turn it 90 deg (to change the position of the divots with bearings in the retainer. I first turned the crown race, but all that seemed to accomplish was to move the location where the headset indexed. This may work depending how badly the race is fretted and when I took the time to inspect better inspect the crown race I saw the fretting covered almost the entire race. I then removed the ball bearing retainer and installed what turned out to be 22 3/16" loose ball bearings (2 more than what was used with the retainer). But this really didn't work either. The fretting made it difficult to properly preset the bearings and while the bearings didn't index , they still felt rough none the same.


The last thing I tried was using the crown race off of a Tange NJS Levin, which is advertised as a Nuovo Record copy. However it turned out it wasn't a good fit; as you can see above, the Levin is more of a Nuovo Gran Sport copy (with the addition of the banded engraving of a Nuovo Record). The Levin uses 5/32 balls (the same as a Nuovo Gran Sport) and the Record uses 3/16". The result is the crown race is smaller in diameter, leaving a larger gap between the lip of the crown race and lower cup, which will allow more crud to get into the bearings. If I had to go this way I would probably use the lower cup of the Levin as well.

My fix finally came from Boulder Bicycle/ Rene Herse who was selling the crown race for what is most likely a Vicotry/Triomphe headset. The Triomphe and Victory headset parts are pretty much imterchangeable with Nuovo Record including 3/16' bearings and the crown race; Victory and Triomphe headsets also share the same crown race . A little history here; Triomphe and Victory were designed not only as a mid-level component but also as a legacy design to those that preferred the old Nuovo Record (Triomphe) and Super Record (Victory) over the new C-Record. In the the case of headsets Campagnolo chose not to make an alloy like the Super Record, so the Victory was made to resembled a Nuovo Record instead. To differentiate the Triomphe headset it was made without the banded engraving similar to a Nuovo Gran Sport; the Triomphe headset used the same locknut and upper cone, all other parts differed in model number. The Victory is such a close copy of the Nuovo Record that the only obvious way to tell them apart is the tool flats on the threaded top cap; Nuovo Record has 6 flats, Victory and Triomphe has 2 flats.

Installed the s the Victory /Triomphe crown race but after a few rides it was obvious that the problem had not gone away. The problem was there was also fretting in the lower cup. Fortunately the NR lower cups are still available on ebay. After it arrived I installed it with the new crown race and the indexing was finally gone.

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