More Tech - Truing Head Tube Alignment

[dougfisk]

In the past, I have just discarded frames with the head tube out of alignment. But recently I decided to try and save this frame. If you read the fancy shmancy service manuals, this is not supposed to be possible.... Nevertheless, here is my high tech head tube alignment fixture.

To operate - you press on the top region of the seat tube with your foot to apply a twisting force to the front triangle.

Another view ...Maybe I should be embarassed to admit - I went back and forth from side to side 4 or 5 times until I got it exactly right! :o

After getting the head tube in alignment, I aligned the rear triangle as I have illustrated previously.

More to come.

 

[OldRider]

Doug, I don't believe I have such high tech tools in my arsenal! Good job on saving that frame

 

[SirMike1983]

The steel on these is pretty basic, heavy steel. The pipes are usually thick-walled, part of why the frames are so heavy. It should be perfectly possible to bend a frame to spec so long as the adjustment is relatively small and the shape/tube walls are intact. I had an Elgin last year that same with a crushed chainstay. I managed to straighten the rear triangle, but the damage to the tube wall was such that it seemed to yield and want to kink right around the crush. I parted the bike and trashed the frame. If your frame tubes are intact structurually, these lever-bending methods actually are among the best way a person can do this stuff at home.

I'm a big fan of the string triangle method of measuring as shown below:

http://sheldonbrown.com/frame-spacing.html