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Checking frame alignment?

JohnpsandersonJohnpsanderson Posts: 380
edited July 2012 in Workshop
In an attempt to breathe new life into an old frame I finally got round to stripping my Trek 1000 (c. 2003!) which has been in the loft for ages.

The cranks were seized onto the tapered BB so, after trying and failing with a crank extractor, I ended up giving the crank arms a serious beating with a hammer to try and get them off. It didn't work, and now I'm wondering whether I will have twisted the frame - after all - that force has to go somewhere, doesn't it...

Any tips/guidance on how to check if a frame is still straight or not - short of building a jig to offer it up against...
Put me back on my bike...

t' blog: http://meandthemountain.wordpress.com/

Posts

  • dennisndennisn Posts: 10,561
    Here's a concept. Hope I can explain it well enough. Take any STRAIGHT yardstick or a 3 foot metal ruler.
    Place one end on its edge against the headtube and the other end against the outside of the rear dropout(on the same side of course). Now measure from the edge of the ruler to the outside of the seatpost. Note this dimension.
    Now switch sides of the frame and repeat in "hopefully" pretty much the same position on the frame. If both dimensions are the same, well, at least then you know that the headtube and dropouts are still in the proper positions.
  • nicklousenicklouse Posts: 81,520 Lives Here
    As above but with a tool and pics. My help with idea.

    http://www.parktool.com/blog/repair-hel ... -alignment
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Thanks chaps - not sure why I didn't think of that myself - I was considering marking a centre line on a plank of wood - offering up the drop outs and front fork with the line bang in the middle and using a plumb line to take incremental measurements either side of the frame to see if they were equal distance from the centre - but your way is much simpler!
    Put me back on my bike...

    t' blog: http://meandthemountain.wordpress.com/
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