City Bike Chain Line

I was building a city bike I could transport and I ran into a problem.  The original frame was from an Ibis Trials bike that I bought in Ohio after it sat in a garage with a leaky roof.  It was so oxidized that I couldn't get the seatpost or stem out of it for the longest time.  Anyway, I got it together and used the stem extension and seatpost from Xootr - they sell their parts pretty cheap.

I assembled it as a single speed for simplicity and took it for a couple of test rides.  The gear was pretty low because of the tiny wheels but I couldn't go any bigger with the chainring since it would strike the chainstay.  Plus the chain was already rumbling since the 42 tooth chainring had to be splayed so wide that the ring and the freewheel were out of alignment.

A smaller freewheel wouldn't solve the problem and I figured I needed at least 50 teeth up front with the 16 tooth rear so I finally decided to change the shape of the right chainstay.

I tried hammering it but that was just plain stupid.  Seriously dumb.  But I knew it was steel and I could always cut out the damaged part and put in something else.  Then I remembered my collection of frames and parts in the basement.  I searched a bit and found the perfect curve from another BMX I had already cut up for another project.

They were symmetrical chainstays for a tiny chainring.

 The rear dropouts were braced with two axles.

The plastic bag houses the chain.

 Some careful cutting and grinding and fitting

Sometimes I don't take the five minutes required to remove things like the chain and the bottom braket.  It's silly.  I don't know why I think it's easier to leave them on.  Maybe the tools are more than three steps away.

 Finished braze joints

Plenty of room for a huge chainring

I installed a 50 tooth chainring and rode it.  I think I could even run a 52 but there's room for about a 60.  It doesn't look it like it but there's plenty of clearance for the tire as long as I don't use anything larger than that Primo Comet.

I could easily buy something like the Xootr Swift but I love going cheap and solving problems like this.  It takes a really long time and I get nothing important done, but I learn so much.

And, I don't know why, but it makes me feel accomplished and relaxed.  Men need their toys.