----- Original Message ----- From: "Eric Elman" <tr4play@cox.net>
> On ebay there is one (see link below), for a "1" Threaded 27.0 Crown
Race."
>
> With the exception of the crown race, any reason I can't use this on a
> 1970's road bike with English threaded steerer tube?
>
> http://ebay.com/
>
First, I'd confirm with the seller whether this is a complete JIS headset, or a BSC with a substituted 27.0mm crown race. The auction doesn't specify.
Either way, the JIS stuff can be used on BSC frames, but it's a bit of a fudge job. The cups are too small (30.0mm) and the crown race too big. You can install both cups and crown race with Loctite retaining compound and it will be completely functionally reliable. Personally, I wouldn't do this for a top-end restoration, show bike, etc. It just comes off as jakey. But for a user, even a nice one, it's acceptable. I'm sure opinions vary as to where that line falls.
Just use the retaining compound at both the cup and crown race interfaces (it shouldn't take much) and install as normal. Unless the frame prep is out of spec the parts should not require any press-fit at all. Be sure to finish the headset installation and adjustment immediately. This will force the loose fitting parts to self-center on their seats. Then leave things to allow the Loctite to set overnight. It will last the life of the frame, but still be removable just like a proper fitting one.
Jon Schaer
Columbus, OH