Meet Kal
Kaloyan Kostadinov, Kal to everyone, is a tennis coach and a qualified racket stringer. He runs Racket Stringing Hub from his own workshop in Doncaster, stringing for club, junior and competitive players across Doncaster and, by post, the whole UK.
Why players come to Kal
Kal coaches tennis, so he knows what a racket should feel like on court. Every racket is strung on a professional machine, to the tension you ask for, and most are ready within 24 hours.
He strings tennis, badminton, squash and racketball rackets, fits grips and grommets, and matches rackets so a spare plays exactly like your favourite.
Qualifications
- ERSA Master Professional Stringer, tennis. A current member of the European Racquet Stringers Association.
- UK Racket Stringers Association. Trained as a professional stringer, with a two-day course in racket servicing, and certified for tennis, badminton and squash stringing.
- Racket customisation. ERSA International's racket customisation workshop, July 2026.
The workshop
Built for stringing
A dedicated room with a professional stringing machine, a HEAD racket diagnostic machine for matching, and strings from Solinco, Luxilon, Yonex, Tecnifibre, Head, Wilson and more on the wall.
Drop your racket off at 48 Lake View, Doncaster DN4 5NQ, any day from 7am to 10pm.
Off court, on court
When he is not at the machine, Kal is coaching. Follow his stringing on Instagram and Facebook, and his coaching at @tennis_coach_kal.