So we all know about the new 10-42 11 speed cassette. I love the idea of having a 42t rear cog to go on my 1x8 setup.

I had some time tonight, so I made it a happen.

Heres how I did it:

My idea was to make a 34t cog that you can bolt a chainring too.

Here you can see the difference between the 34 and a 42. Pretty big jump, but not too crazy.



I went to my hardware store and got some steel washers that are the same thickness as a cog and have the right size hole for a chainring bolt:



The hardest part was trimming the cog to flush fit the washers. The steel is HARD. Here is the cog trimmed sitting on top of the chainring:



Next I bolted everything to an old ring and tack welded them in place:



Once it was tacked and secure, I welded the washers soled from both sides and ground the welds smooth.



I found these nylon spacers at the hardware store for cheap. They may not last, but I though I would give them a try. They are the perfect thickness for an 8 speed cassette:



I bolted the rings together and this is what I ended up with: