Agree on all counts. I changed my road bars from 41 (stock) to 44 and really was more comfortable. My mtn bars seem to be shorter than average while my shoulders are probably slightly larger than average, and the fact that I'm naturally always creeping to the ends is what made me wonder about this. Regardless of bar ends, I think I'm going to try wider mtn bars.
Originally Posted by
rat fink
If that's case, enjoy your bar ends.
To answer the original question, I don't know my shoulder size, but it's probably about the same as my road bar width, which is 42cm. I use a 71cm bar and am a firm believer that road ≠ mtn when it comes to setup needs. You'd be better off erring on the long side than the short side of bar length, and you may need a shorter stem as well. BUT, it really depends on the kind of riding you want to do.
Some rules of thumb I found while Googling,
Rule of thumb for mountain bike handlebar width: Position the grips so the inside edge of each hand (where the index finger and thumb encircle the grip) lines up just outside the crease of the armpits. While holding the grips in a position where you can comfortably work both the shifters and the brakes, with shoulders and upper arms relaxed, the forearms should aim straight forward.
another rule of thumb from BikeRadar,
The general consensus is that the most efficient compromise between comfort, control, leverage and confidence is 4-6in (10-15cm) wider than your shoulders. Some riders might prefer more width for more leverage, some might prefer less because their wrists or shoulders hurt on wider bars. Try a few and pick your favourite.