The chain mobility in crystals of a homopolymer of poly(ethylene oxide) (PEO) with 22 monomer units (PEO22) is compared with that of a PEO having the identical number of monomer units but additionally a 1,4-disubstituted 1,2,3-triazole (TR) point defect in the middle of the chain (PEO11-TR-PEO11). In crystals of PEO22, the characteristic αc-relaxation (helix jumps) is detected and the activation energy of this process is calculated from the pure crystalline 1H FIDs to 67 kJ/mol. PEO11-TR-PEO11 exhibits a more complex behavior, i.e. a transition into the high temperature phase HTPh is noticed during heating in the temperature range between -5 and 10 °C which is attributed to the incorporation of the TR ring into the crystalline lamellae. The crystal mobility of the low temperature phase LTPh of PEO11-TR-PEO11 is in good agreement with PEO22 since helical jump motions could also be detected by analysis of the 1H FIDs and the corresponding values of their second moments M2. In contrast, the high temperature phase of PEO11-TR-PEO11 shows a completely different behavior of the crystal mobility. The crystalline PEO chains are rigid in this HTPh on the time scale of both, the 1H time-domain technique and in 13C MAS CODEX NMR spectroscopy, i.e. the αc-mobility of PEO in the HTPh of PEO11-TR-PEO11 is completely suppressed and the PEO11 chains are converted into a crystal-fixed polymer due to the incorporation of the TR rings into the crystal structure. However, the TR defect of PEO11-TR-PEO11 shows in the HTPh characteristic π-flip motions with an Arrhenius type activation energy of 223 kJ/mol measured by dielectric relaxation spectroscopy. This motion cannot be observed by corresponding 13C MAS CODEX NMR measurements due to an interfering spin-dynamic effect.