Swapped over tyres and re-fitted rear rack to cross bike for commuter duties (Damn me moving to a more hilly area!). Once wheel re-fitted there was a bit of noise and and some odd resistance when turning the pedals. A bit of investigation revealed the cassette lockring was loose, so presumed that was the issue, tightened up again, and re-fitted wheel. Still the issue is there, curious... Take out wheel again, and all seems fine. Decide to take apart and re-assemble cassette in case is that is the issue somehow. Once all done, re-fit wheel to bike again to find noise/resistance still there. Only then do I realise the bolt I used to mount the rack is a bit too long and coming out the back and rubbing against the cassette lockring