Question about threads: Vintage Super Record Headset
Will a 1'x24Tpi-BSC Headset work on my 1983 Bianchi Specialissima?
I Know BSC stands for British Standard Cycle, so will I mess up my threads trying to install this unit?
Do I need an Italian Specific Headset, or will this work? What about the whole thing about Italian threads being cut at 55 degrees?
Italian and "English" threaded headsets and forks aren't an exact match but will work with each other so you should have no problems. The difference is in the thread form angle (55° for Italian and 60° for English/ISO) but they have the same diameter and pitch.
The headset should fit, but it WILL mess up the threads a bit. If this is a one-time-only instalation, you should be OK. Just don't try to re-install the headset back to a BSC fork/frame. The threads will start to rip out and bind tightly. Been there, done that (on a 1980 Bianchi, no less) Good Luck w/that. Dr. D. p.s. For a better result, find an Italian threaded headset on........eBay!!!
My Sutherland's Handbook for Bicycle Mechanics, 3rd edition - 1980 describes the fit between british and italian headset threads as a "class B" fit, which is defined as:
"Will fit and be serviceable but slight damage to the parts may result."
I would make sure that the steering tube is italian threaded before you actually buy one. While it would seem to be, some manufacturers used british threading for bikes imported to the US. I have no idea if Bianchi did this at any time in the past, but some manufacturers did. Your local hardware store or bike shop should have a thread pitch gauge, just take the locknut in.
I would try other sources before ebay, even though I do buy on ebay, you should be able to find an italian headset from "regular" source. Just my opinion.
The thread pitch (and diameter) will match as I said above, It's the "form" of the threads that differs with the root and top angles being slightly different. A pitch gauge will tell you they are identical.
Originally Posted by ridesoldtrek