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frame alignment - acceptable error?(3 posts)

frame alignment - acceptable error?DaveG
Jan 20, 2002 6:59 PM
I started reading the new Zinn repair book I got for Christmas and in the frame section was reading about checking frame alignment with a string tied at each dropout and looped around the head tube. I decided do a check of my bikes. I was surpised to find one of my frames was 1.3mm off center (difference in distance from seat tube to string on each side). Zinn indicates you're golden if you are within 1mm. What is an acceptable range of error? When can this impact handling and ride? What does the industry consider acceptable error? Thoughts?
re: frame alignment - acceptable error?Nessism
Jan 22, 2002 7:51 PM
My understanding is that out of plane errors less than 2mm are considered acceptable within the industry. I do know that allowable tubing bow is 1mm so it's easy to imagine this much misalignment being built in.

As far as how much misalignment before you notice, I think it depends on where the misalignment is occuring. If the head tube is twisted for example, the front wheel will be tilted relative to the rear wheel.

Another thought relates to dynamnic loading when riding. Frames are springs and move around under the rider depending on conditions. I should think that the movement while riding will be far more than the 2mm industry standard for alignment.

Regarding your particular frame, I would just leave it alone. 1.3mm is not bad at all. Have fun.
re: frame alignment - acceptable error?DaveG
Jan 23, 2002 10:23 AM
Thanks for the response. I'll stop worrying. The thing that surprised me here was that the frame in question is from a small company that touts its attention to craftmanship and quality. Whereas, my inexpensive Taiwanese-built touring bike frame was near dead-on in alignment.