In general, you have a statutory warranty of 2 years.

This is to ensure that the goods are free of defects of quality and free of defects of title at the time of delivery.

Should there be a defect within the first 2 years you can demand rectification:

• Repair
  
• Replacement
  
• Refund.

Is the rectification you demand associated with disproportionately high costs bike-discount.de can reject it and choose one of the other two options of rectification.

Within the first 12 months after delivery of the goods it is assumed that a defect is a concealed defect. 

Excluded from this are damages caused by external influences or normal abrasion. After these 12 months, the so-called reversal of the burden of proof takes place.
After the first 12 months you have to proof, that the item had a concealed defect already with the delivery when the defect has occurred afterwards.

Please note:
The statutory warranty is no durability guarantee. In particular the warranty does not cover damage caused by external influences (e.g. crashes) or normal abrasion (e.g. tires, brake pads etc.).