Trying to keep up 220 miles a day over Christmas really hammered my bike too. New brake pads every 4 days and a new chain every 2 days. Tandems are renowned for eating transmission components and brake pads. I'm going to switch from V brakes to BB7 disk brakes during the year. I thought brake pads on Vs would last a bit longer than they do and it's not as if I was doing especially hilly rides!
The roads weren't gritted, it was just very wet with lots of flooded roads. I also trashed a cassette by using one chain for 3 days instead of 2. I wasn't using cheap chains, I was using KMC.
I also had 2 punctures a day (about one very hundred miles) with my Vredsteins but none with Marathon Plusses, though riding with Marathon Plusses meant less sleep time because they were notably slower.
My chainrings are getting ropey now too. Plus my gear and brake cables get very sticky after 1-200km of wet miles, so I've just invested in some Gore Tex gear cables at about £35 a set. The gear cables got very sticky on some rides and I needed several fingers to change gear.
Winter also hammers anything electrical like GPS and lights, but srprisingly, I've had no isses with electrical stuff this winter, which I think is a first. I bodged my GPS with inslation tape after my 3 wet summer 1000k rides removed the rubber around it's buttons and water got inside and messed it up.
It still cuts out now and then, but I just need to clean the contacts with the batteries.
Front lights tend to expire before rear light, probably because handlebars get much more vibration and take the brunt of rain where rear lights get protected from rain by the rider and mudguards. The vibration isn't so bad on the rear either. My cheapo Chineese T6 Cree lights seem to have fared better than my Exposure!
Wet weather also destroys bearings, which is why I invested in Hope hubs and BB bearings, which are fantastic and last a very long time.
Shimano pedals are holding up very well indeed and at £5 or so a go, that's very good.
