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 alpha(c)-relaxation (helix jumps) is detected and the activation energy of this process is calculated from the pure crystalline H-1 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 degrees 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 H-1 FIDs and the corresponding values of their second moments A. In contrast, the high temperature phase of PEO11 TR-PEO, 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 H-1 time-domain technique and in C-13 MAS CODEX NMR spectroscopy, i.e. the alpha(c)-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 pi-flip motions with an Arrhenius type activation energy of 223 kJ/mol measured by dielectric relaxation spectroscopy. This motion cannot be observed by corresponding C-13 MAS CODEX NMR measurements due to an interfering spin-dynamic effect.