The bowstring (tsuru) is the cheapest thing on a kyudo bow and the one with a defined service life. The important point is not that strings break — it is that a string should be replaced before it breaks, for a reason that has nothing to do with safety.
Replace at 600–700 shots, not at failure
For synthetic strings the general guideline is about 600 to 700 shots. The reason given is not wear or fraying:
The elasticity is lost, making it difficult to propel the arrow properly.
So a string that looks perfectly intact can already be doing its job badly. If your groupings have quietly drifted and nothing else has changed, the string’s age is worth checking before your form is.
Count shots, not months. Two archers can reach 600 shots months apart. A calendar reminder measures the wrong thing.
Synthetic and hemp are matched to the bow
| Synthetic (合成弦) | Hemp (麻弦) | |
|---|---|---|
| Material | High-strength synthetic fibres such as Technora or Zylon | Natural fibre |
| Character | High strength, high elasticity, heat resistance | Low elongation, clean string sound |
| Used with | Widely used | Typically bamboo bows only |
The compatibility warning that matters: if you want to use a synthetic string on a bamboo bow, the bow itself must be built for synthetic strings. This is not a preference — it is a construction requirement, and getting it wrong puts the load somewhere the bow was not designed to take it.
This connects directly to the material decision for the bow itself — see Bamboo or Synthetic Yumi.
Why this matters more from overseas
- Strings are the cheapest thing to stock and the most disruptive to lack. A broken string with no spare ends practice until a parcel arrives from Japan.
- Buy several with the bow. They are light, small, and have no fitting problem — unlike almost everything else in the kit.
- Confirm compatibility at the time of the bow order, while you are still talking to the shop, rather than discovering the constraint later.
For the rest of the kit and the order to acquire it, see The Equipment You Need to Start Kyudo. For arrows, the other true consumable, see Kyudo Arrow Length.
Sources. The 600–700 shot replacement guideline and the loss-of-elasticity reason, the synthetic fibre types (Technora, Zylon), the characteristics of hemp strings, and the requirement that a bamboo bow be built for synthetic strings: Suizan Miyabi (kyudo equipment retailer). Checked 2026-08-18. We do not stock equipment, but we can order it from Japan for you (see Ordering from overseas) — confirm string choice and compatibility with your instructor and the bow’s maker.