I commute on a 24 sp rigid mtb and am very happy with it EXCEPT when we get sticky wet snow. By the time I get to work only my biggest cog is of any use because the rest are all packed with snow and the chain skips.

I'm thinking if I replaced two cogs from the cassette with some type of spacer (leaving cogs 1, 2, 3, 5, 7, 8) that I could ride normally in gears 1, 2, and 3 and if the snow built up I could move the chain onto cog 5 by hand to finish my ride. Hopefully the extra space on either side of the cog would help shed the snow.

Do you guys see any problem with this? Any other suggestions (keep in mind that I like my gears and swap between two wheelsets depending on road conditions).