How hard is it to install a new cog? I want to change out my track cog on an IRO hub. It was just put on about 3 weeks ago but the gearing is too low. I'd like to try and do it myself, obviously it'll be more expensive because I have to purchaser a chain whip and lockring spanner but it's the principal damn it. I wondered though if it was hard to do without stripping the threads etc? Also any recs on best place to order new cog/tools from?