https://www.spacycles.co.uk/m8b0s109p2188/STRONGLIGHT-ST55-Single-Chainset
(...) This might be the answer.
Does anyone think this replacement would be a good/perfect match or indeed have reservations?
I'd say totally valid. You should be aware that the current Stronglight 55S seems to be designed for a JIS bottom bracket rather than for an ISO bottom bracket like you have now. It will however still work (with a slightly changed chainline) but personally I'd change the bottom bracket along the line as this is neither a difficult nor an expensive exercise. In fact there are many many 3rd party cranks that you could use.
I think
@u_i has a point rearding the chainguard - always possible to add one aftermarket, but typically needs tinkering and adds to the cost. So in the end you may overall end up not that much cheaper than the original actual Brompton crankset with the disadvantage of still having a fixed chainwheel and the advantage of the 55S looking relatively similar to the original. One advantage of the original Brompton cranks since 2008 is that the non-drive-side crank has a little nob on the inside which successfully hinders the folding pedal from rubbing agains the frame. Older cranks as well as 3rd party cranks lack that feature and furthermore often enough the non-drive-side crank has to be treated with an angle grinder at the outer edge to make the folding pedal do what it is supposed to.
Going Stronglight you could i.e. also consider i.e. the
"Mygal S" or one of the
Impact ones, depending on the price. All three do offer various sizes of the chainwheel and the ability to change it, the Mygal is a 130 one which means typically for chainwheels 39t and bigger whereas the Impact ones are 110 ones which means getting chainwheels with more than like 46t is possible but those are hard to find and typically expensive. For small chainwheels no issues (and easier to find than 130 ones).
You could even go for a double crank set like i.e. the
Impact Compact or
Impact E Compact and, with a combination of i.e. 50/34t, 50/36 or 46/34 gain a granny gear that will take you up most hills, referencing to your original problem. Downshift goes with a heelstrike, upshifting is manual - no need for a derailler on the front and easier than it sounds. You could even simply add a i.e. 39t or 34t to your
existing chainwheel, massively saving on cost, and achieving the same effect. Has been relatively common with Bromptons for a while as the old crankset offers the possibility (though not officially) through the holes in the chainwheel.
You may check the effects here:
http://xldev.co.uk/bgc.html
So many options...
