Seat tube to down tube angle
For my last two frames, I changed the way I braze the BB (lugged).
I used to braze the seat and down tubes in at the same time.
Now, I braze the seat tube in first, clean it up, then braze the down tube.
I use a piece of square aluminum bolted onto a BB face to place the tube parallel to the BB face.
Then, I pin the joint with 4 pins.
Then, I take off the aluminum and braze free standing.
The seat to down tube angle ends up being a little more acute (just a bit smaller) than I had when I pinned the joint before brazing.
So, frame drop was a bit more than I originally planned. (The ride is great, but I do strike a pedal now and then.)
So, is this common?
Do you set the joint up a bit wider to compensate for this?
Thanks for any advice.
Mark Walberg
Building bike frames for fun since 1973.
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