I don’t know if an Ultegra 34t small ring will work with a 52t big ring - but I would not do this
Ultegra 34t small ring is prob best used with a 46 or 50t big ring
be aware - Shimano rings are expensive ... big ring alone can retail for $100 and over ... QBP currently has the 6800 46t ring ‘discounted’ to around $80 - and that is dealer cost ... small ring is much less expensive though
not sure which model Ultegra components you have - I believe 6800 RD (GS / long cage) is designed for 32t max rear cog - later R8000 series GS RD’s are designed for 34t max rear cog
Last edited by t2p; 06-02-23 at 07:53 AM.