I use a triple with a 50t outer, by having the chainring teeth ,
close to the outside diameter of the chainguard,
The Front derailleur adjustment is as close to best , as if the chainguard was Not there..

To up shift well, the outside plate of the FD has to clear the outside of the chain guard.

the compromise is an unknown shifting performance degradation, ... from this end.

I have used only friction shifting, for many years.. so how STI works with this kit change.. IDK


42t chainguards are common in cyclocross racing single ring setups, so nice ones are made.