Yeah I had the same issue when I upgraded to the light Cannondale road fork, had to use 30mm for that (I believe Cannondale use a 27mm)
Oh, although my fork dates from around the mid 80's, I think it was simply that I was trying to use a rear brake which has a shorter thread, than due to the width of the fork crown, as it seems very similar to the size of some of my other road forks, unlike the much wider designs manufactured today.
Oh, although my fork dates from around the mid 80's, I think it was simply that I was trying to use a rear brake which has a shorter thread, than due to the width of the fork crown, as it seems very similar to the size of some of my other road forks, unlike the much wider designs manufactured today.