How is a Barebow string different from an Olympic Recurve string? They are both a single string used on a bow with recurve limbs. And the exact same riser and limbs could be used to shoot either Barebow or Olympic Recurve. So what's the difference??? There are a couple:
Center serving material
For those shooters who use string walking as an aiming method, it's more important that they be able to hold a crawl once set. For that reason a grippier center serving material (such as BCY Powergrip) will work better for such a shooter. Olympic recurve shooters tend to prefer a slicker material for a smoother release as they have no concerns about holding a crawl since they hook the string above and below the nock every time.
Center serving length & position
For Barebow shooters who participate in any events governed by World Archery, there is a rule that the upper end of the center serving cannot be in their field of vision at full draw. The intent is that the transition from center serving to string material not be used as an aiming reference.
World Archery Rules, Book 3, Chapter 11 (Athletes Equipment - Barebow Division):
This can be addressed by changing the length and/or position of the center serving. Some archers aim to keep upper end of the serving below their eye while most extend it further up the string so the top end is always above their eye at all crawl positions.
The best way to determine where yours should be is by taking a photo of yourself at anchor at both your highest and lowest crawl positions. Using an existing string as a reference you can then figure out where you would like that serving to end. Typically that measurement is specified by the number of inches above and below the center point of the string but some archers indicate this as the center serving starting point from the tip of the top loop.
Here's an example:
For Matthew Seidemann (pictured - with his enthusiastic permission) we increased the length of his center serving resulting in 7" above the center of the string. In the before pictures above it was 4" above the center point.
Hint: As long as the center serving is above the archer's vision while the crawl is directly against the nock, it will be fine as you crawl down the string and the top of the serving moves higher for longer crawls.
Please keep this in mind the next time you are ordering a string or preparing for a tournament. You don't want to be caught at a competition being forced to panic-serve™ extra length above your center serving, blacking out your string material with a sharpie, or even worse ... disqualified.