Framebuilders - Frame Alignment Question

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View Full Version : Frame Alignment Question


w98seeng
06-10-08, 01:44 PM
I have an 80's Bianchi frame and I am in the middle of rebuilding it. I have checked the rear triangle alignment with the string method. I tied a string from one rear dropout up and around the head tube, down around to the other rear dropout.

I then measure the distance from the seat tube to the string. I measured 32mm on the left side and 36mm on the right.
http://i23.photobucket.com/albums/b390/w98seeng/Picture010.jpg

I know I can adjust the frame as found here, should I? Is 4mm enough to cause a problem riding the bike? Is the amount it is out necessitate spreading the rear triangle?
http://www.sheldonbrown.com/frame-spacing.html

Also, the bend in the rear dropouts, how do I tell if the angle is correct? I presume the dropout has to be parallel to the centerline of the bike. I do not have any tools to measure this and I really can't afford to buy any. Are there methods to check alignment at home using string, a building square, a tape measure, etc?
http://i23.photobucket.com/albums/b390/w98seeng/Picture007.jpg
http://i23.photobucket.com/albums/b390/w98seeng/Picture005-1.jpg

Thanks for the help.


sstorkel
06-10-08, 07:17 PM
Also, the bend in the rear dropouts, how do I tell if the angle is correct? I presume the dropout has to be parallel to the centerline of the bike. I do not have any tools to measure this and I really can't afford to buy any. Are there methods to check alignment at home using string, a building square, a tape measure, etc?

Here's what I do in situations like these: pull enough components out of the junk box to build the bike, throw some wheels on it, then ride it down the street. If it tracks relatively straight and feels fine, then it's good to go! Given that you don't have any money to spend on tools, or a professional alignment, what else can you do?

Nessism
06-10-08, 09:51 PM
I'd fix it. Sheldon Brown's site details how. Pretty easy fix.