I’ve been thinking about this recently. I’ve got an old straight top tube five and would like ot try and slacken it off a bit. Been looking at the on one slackset, or works components, but would it be better to get off set bushings as well or one or the other? And what would it actually do to the bike?
I did this with a 2006 frame. I used a 1 degree works components headset (the biggest change you can get with that old 1 1/8 headtube)and a set of burgtec bushings.
The headset decreases the head angle by 1 degree and increases the seat angle by 1 degree
The bushings also reduce the head angle by 1 degree, but also reduce the seat angle by 1 degree.
So, using them both together knocks 2 degrees off the head angle while keeping the seat angle the same.
Both reduce BB height though, so I combined this with a 150mm fork (20mm longer than the 130mm fork that was originally specc’ed on the bike), which also knocks a degree off the head and set angles, but raises the bottom bracket. Overall I thought it worked pretty well, but not well enough to cover up for the fact that the frame was too small for me.