String Types and Tension:
Zipstrips provide additional elastic response to the strings of the string-bed, particularly the cross strings. This quality is factored into BOLT string tension recommendations and should be taken into account in string type and tension choices for players.
BOLT recommends generally an increase of 1 - 3 lbs above a conventional racquet string tension in order to achieve equivalent rebound characteristics. Variations are according to string type. With natural gut for example, a very elastic string, an increase in tension of 2 - 3 lbs may be appropriate.
BOLT recommends a tension differential between the cross strings and the main strings in order to achieve tensile equilibrium across the entire string-bed. For example, in a synthetic gut stringing, we string the crosses +.5 to 1 lb over the mains. This takes into account the fact that the cross strings are supported by Zipstrips on both sides of the head frame and the main strings are supported by Zipstrips on one side.
Of course the tension differential will vary according to string type and will likely be in a range of .5 - 2.5 lbs. This is particularly important in a hybrid stringing in which the strings likely have significantly different performance properties.
Recommended String Tension Range:
100s and 98s v2 (Quick Flex X-30 Zipstrips): 52 - 62 lbs.
100s and 98s (Soft Flex X-30 Zipstrips):
52 - 60 lbs.
100s and 98s (Firm Flex X-30 Zipstrips):
52 - 62 lbs.
The stiffness of polyester string is a good fit for BOLT racquets. Zipstrips make even the stiffest strings comfortable and relatively lively. Generally the tension of polyester doesn't need to be low in a BOLT in order to achieve a comfortable elastic response. A tension increase in a range of 1 - 3 lbs generally is recommended for a 100% polyester set up in order to achieve equivalent conventional rebound characteristics.
Synthetic Gut and Multifilament
Due to the relative softness of these strings an increase generally of 1.5 - 3 lbs above a conventional racquet tension is recommended in order to achieve equivalent conventional racquet tension rebound characteristics.
Hybrid - Polyester and SG or Multifilament
As with a conventional racquet, careful consideration should be given to the relative different mechanical properties of the string types in a hybrid set up. Though this applies less to a BOLT, it's important to "equalize" the relative tension of the two different string types in order to achieve a consistent response across the entire string-bed.
Generally best play-testing results in a BOLT have been achieved for example with a polyester main tension of .5 to 1.5 lbs less than a softer cross string. In the case of a polyester cross string and soft main string, the Zipstrip arrangement tends to equalize the string response such that the tension of the mains and crosses tend more toward equal.
As with a conventional racquet, the launch angle of the string-bed can be significantly modified by changing the tension differential between the cross strings and the mains. This will vary greatly by string type and applies particularly to hybrid stringing set ups.