Some cheap silicon has water content, more expensive has acetone, I have used silicon on my B40 primary chain case for many years, and cant say I have noticed oxidization in the that area.
Thought it was at Christmas ?
Remember at the time being surprised they let us ride in there, I think the steps you remember were in the burn below the ruin of the old house, there were also sections going in and out of the burn, the banks were near vertical and 2or3 feet high.
Ross
Didnt watch, but did he mention checking if there was enough clearance between the caliper & rim ?
eg (my)406 Peugeot had so little clearance that you could not use stick on wheel balance weights,
