The tracking characteristics of your motorbike have deteriorated. What might be the cause of this?

You are correct in choosing that uneven adjustment of the chain tensioner and worn bearings of the swingarm can cause deteriorated tracking characteristics of a motorbike.

In German traffic rules and vehicle regulations, proper maintenance of the motorcycle's suspension and drivetrain components is essential for safe handling. If the chain tensioner is unevenly adjusted, it affects the rear wheel alignment and can cause instability while riding. Similarly, worn swingarm bearings lead to excessive play in the rear suspension, making the bike track poorly and reducing control.

On the other hand, the engine idling speed being too high does not affect the tracking or handling directly; it relates more to engine performance rather than vehicle stability. Therefore, only the first two options are correct as they directly impact the bike’s tracking characteristics.