One of the hex bolts attaching my rear Tubus pannier rack to my Nomad's seat stays seized... about 5 years ago. It happened when I was travelling in asia and with my limited tool set I managed to do little more than round out the hex socket in my attempts to undo it. Ever since then replacing the bolt has been one of those projects that I'll get to 'soon'. In the meantime if I had to remove the rack for air transport I simply undid the affected horizontal rail that connected the rack to the seat stay at the rack end and would tape the rail to the seat stay during transport.
With a new tour coming up I decided now was the time to finally solve the problem. I mean how much more seized could a bolt become in 5 years?
First I tried lying the bike on it's side, bolt head down, and filling the opposite side of the braze-on hole with WD-40 and leaving it to 'penetrate' for a day. I didn't hold out much hope as after 24 hours the WD-40 was still pooled in the braze-on, not much sign of any penetration happening. Then I used a hacksaw to cut a screwdriver style slot across the head. No dice. Not enough leverage from a screwdriver and a number of bent and damaged knife blades and steel rules from attempting to use them as 'superwide mega-leverage' screwdriver blades.
Next I filed two parallel flat sides onto the bolt head and repeated the soaking trick, this time with "PB Blaster", another penetrating oil.
Again, no dice, my shifting spanners couldn't budge the damn thing.
At this point I had spent quite a few hours on this fruitless quest and was thinking I'd have to get a local engineer to drill the thing out. But in one last desperate measure, I googled 'seized bolt' and the internet answered - "use a 50/50 mix of acetone and Automatic Transmission Fluid". Great! The only hardware store in 75km sells them both, in two litre and five litre bottles respectively. I need about two drops of each.
Lucky for me the local chemist had a small bottle of pure acetone nail polish remover. For the oil I thought laterally - Rohloff oil!? Well I have some and I vaguely recall a link from this forum to an engineers description of disassembling a Rohloff hub. He said something about short chain polymers in Rohloff oil or something like that and some expert anti-seize guy on youtube prattled on and on about short chain polymers or somesuch in Automatic Transmission Fluid. So I decided to combine all of my half remembered and probably misheard and misunderstood knowledge about oils and use Rohloff thinning oil for the oil component. For a lazy person like myself this is much easier than trying to confirm the facts.
Fifteen minutes of soaking this time... and.... IT WORKED!