Monday, June 22, 2020


Over the winter of 2019-2020, the red fixed gear tandem got just a little creaky.  To the point that it became obvious it was time to take it all apart, clean it, grease it, and put it back together.  And, there were a couple of specific issues that needed attention.

First, the front bottom bracket.  The shell is so thin that each set screw only has a few threads available to engage. 

A friend-with-a-welder beefed up this area by welding a pair of M6-threaded nuts over the existing holes

I can torque these bolts without worrying about damaging the threads.

Second, after I took the bike apart, I realized the two sync chain wheels weren't in a good chainline.  Also, the stoker crankset wasn't setup for the best chainline, either.  So, I spent some time mathing out a solution:  123mm bottom brackets front and rear, with the drive chainring mounted to the inside of the crank spider.

Last, I wanted to replace the drive chainring because it wasn't "round";  the mounting holes were not concentric, which means there was a high spot and a low spot in the chain tension as the cranks are rotated. Which is all the time.

Here we go:

This new frame color is Antique Bronze.  It's metallic, so it really lights up in the sun.