What is causing strange resistance when pedalling forward? I noticed today a strange resistance when cycling home.
I've done some investigating and by removing the chain have isolated the issue to the bottom bracket area.
When I move the pedals forward there is some resistance which lessons the faster I spin. If I spin slowly the resistance will come then go then come then go and so on. I would liken it to the brakes being applied then released then applied (but obviously this is not the cause as I have removed the chain)
When I reverse the direction (as if pedalling backwards) there is no resistance.
Any ideas on what is wrong? Is this something I should try and fix myself or take to be repaired?
Sounds like your bottom bracket is having issues.  Specifically, since it's having issues in one direction that it isn't having in the other, it's probably a lack of grease or the bearing retainers crumbling.  Remove and inspect/regrease or replace your bottom bracket, depending on type and what condition it's in when you get it apart.