Hi I have a chance to get a few new nanospeed 9900 and I was wondering what is the best string to use and at what tension
Only you can tell which string and tension suits you best. There is no such thing as "the perfect string and tension for racket XYZ", sorry.
To guide you in a starting direction (aka check out this string and that tension), try to answer the following question to give us some hints: 1. What age are you (roughly) ? 2. How many years experience do you have in badminton ? 3. Are you a club player or league player, low league or higher league ? 4. Are you playing with plastic or feather ? 5. How often are you willing to restring you racket (once in half a year, every week ) ? 6. Do you prefer a control or attacking style ?
Honestly if you don’t know just get BG 80. It’s the most widely available, bang for buck, great for beginners and good enough to be the most popular string in the pro circuit type of string. Durability is pretty good too, feel is top tier, repulsion is great, power is great, everything is either good or great start at around 25lbs + 2lbs
I have several players in my club 5-10 years older than you, 30-40 years of experience, diffenent leagues, even a current WC in his age bracket, and all do not really care about their strings and tension. They pick bg 65 and are still able to do a full court backhand clear with it. Tension wise they tend to pick lower tension (10kg) and less stiff rackets. With your experience I guess, that you have a good hitting point but lack the overall speed and power of a 20yo. So many strings at lower tension (10kg) will last longer. Keeping that in mind, you could try to go for a control string or a string with a nice hitting sound if you like it, or just a durable string if you don't really care about sound or that extra bit of control. I.e. a 20yo in my club, playing at 14kg (areobite?), will need to restring atleast every second week. I (49yo, 11.5kg, areobite) need to restring in 4-6 weeks. Check out this video for an overview of yonex strings:
I'm jealous... I've been hunting for this racket, the 2u version in Malaysia but it's all gone. Nanogy 98 at 28lbs would be lovely with this.