Rather than measuring your shoulders, I just take a broom stick and hold it to see what feels the most comfortable and then measure. Width is a bit of a trade off between having a more open chest for breathing while riding, comfort and aero profile. I went with 42 which I thought was a good balance of comfort and aero since I have not found that my breathing is better with wider bars.
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The problem with the gene pool is that there is no lifeguard and the shallow end is much too large
2013 Noah RS