Hi Dan, thank you for the reply. Herewith more history regarding why I have changed from 172.5mm to 165mm to maybe give some insight into my problem. Sorry for the long explanation. I live in a rural area so physical bike fitting is not really an option here. I had a TURP procedure late last year to correct an enlarged prostate, I was using the 172.5mm cranks but had a very upright position on the bike as to relieve pressure and pain from my prostate, (I have also changed my saddle to the SQ Lab Active for pressure relieve). After the operation I still had issues with pressure from my prostate so I decided to change the crank length to see if the forward hip rotation would assist with reducing the pressure. The new position on the bike feels much better with the shorter cranks but now the knee issue is troubling me. Now to get back to my issue and to answer your questions above: - The knee pain start immediately when cycling but increases as soon as the effort increases as well i.e. hill climbing, acceleration in lower gear with lower cadence. With higher cadence with higher gear it's less obvious. - I want to get back to normal training as before the operation so yes my intensity on the bike as well on the trainer has increased. I would like to know from people that maybe changed to shorter cranks if they had the same or similar experience by changing them? Maybe I must just give it some time to get used to the new position and action of the shorter pedals? I will post some images to show my position on the bike to assist with a diagnosis. Once again sorry for the long explanation.. Any assistance will be greatly appreciated. Regards, Marius

@Simon Jackson Hi Simon, thank you for the input. I will move the saddle back a bit and do some longer rides at a lower intensity to get used to the new position. Regards Marius.