The problem – Carla’s granny ring is shot. It’s already been rotated 90 degress for more life, so that’s not an option. What’s more is that the Specialized Four Arm chainset takes a non standard granny ring, and only TA Spécialités make them. We have one on order, but it won’t arrive in time for Sundays VTT Rando at Bessines. Some lateral thinking is required.
The thinking – I thinking about eliptical chainrings, and how it wouldn’t matter too much if the granny ring wasn’t exactly centered as the rear mech could cope (certainly for a couple of hours). Maybe it would be possible to mount a standard Shimano granny ring just using one bolt to anchor it, and some of the others to hold it. I decided to try it.
A stroke of luck – After removing the old granny ring, I was offering up, checking, measuring, when I noticed that the outer edge of the bolt holes lined up nicely with the inner edge of the granny ring. So thinking about which way the pedaling force operates I bodged the chain ring on as per the picture. It worked perfectly!!!
Carla rode the Rando, which was excellent by the way. The bodge worked perfectly!