Mixing old and new, old TA / Stronglight compact with modern

Wish I could fit more in the subject line...

To be clearer, I'm wondering about mixing modernish 10spd 105 (5700) with an older style compact on a square taper compact with say a 28/ 46 for instance. Something like the French manufacturers used to make or (but this is out of my price range) René Herse/ Compass do make?

I currently have a full 105 groupset, but feel limited by it for the riding I want to do, which includes less than perfect lanes, rough stuff and future light touring and audax. I've got a lot fitter since March, but sometimes the current set up, 50 / 34 crankset with a 14- 30 block isn't quite enough. Basically I would like to be able to run lower gears without losing Brifters, chain, mechs and cassette.

Frame is a late 90s Roberts Clubman.

What chainrings would be compatible, would I need to get something 10 spd specific? Would it be possible to adjust the front mech to work with this combination?

I can see myself eventually losing Brifters completely and going to bar end (possibly downtube) shifters and possibly getting a triple. The eventual aim is to replace the Roberts with 650b frame, but that's a long way off right now.

Happy to be told what will/ won't work, just intrested on how I can adapt what I have to fit closer to what I want?

I thought about the same thing, using a Stronglight 49D or 100 with an 86mm pcd setup.
There are likely to be two problems:
1 Chainring thickness - 10 speed chain is narrower inside
2 The risk of a dead-zone between rings which the super-narrow 10s chain can drop into, or at the very least ride with the chain sides sitting on the inner teeth.

Velo Orange do some 'reissue' lookalike cranks that are (IIRC) 10s compatible. Holdsworth (PlanetX) also do some, althoguh being PlanetX they may only occasionally be available.
On my son's CX bike we run a 10 speed 105 setup with a Middleburn MTB chainset as a 32/46 double. It works fine with stock 105 front mech. Other cheaper chainsets would work just as well, simply remove the inner ring, and ideally fit a shorter bottom bracket to neaten up the chainline. I hate pedalling like a duck with wide-spaced cranks.

Tadah!

Ernie Clements with 10spd indexed and old-er Stronglight

And those were the stock Stronglight rings? Good to know it works.

I'm currently using dura ace 7800 10 speed kit with chainrings from the 80s - 36/48 biopace which came off a deore chainset. No problems at all. Prior to this I was using it with ultegra 6700 kit (I swapped to the 7800 cos 6700 looks black and modern)

So it's definitely possible then!

LeGrandFromage and Pigman, what are you running at the back?

Mine is - 9 speed shimano cassette, 10 speed campag ergo levers, 7800 dura ace gears, the Deore biopace chainrings and 10 speed kmc chain

Sram 10spd cassette, Mt60 Deore mechs, dura Ace 10spd shifters, KMC chain

LGF, what's the Q-factor like with those Stronglight cranks? I hate the 'walking like a duck' feel with wide cranks.

Not a clue! Cranks were bendy, frame was small, sold it