On a motorised Moulton with overnight stuff in a light load.
The worst of the worn brick cobbly steep and narrow industrial revolution canal infrastructure is the section of the Birmingham & Fazeley between where it joins the Birmingham Canal Main Line, through the Jewellery Quarter, through to about where it turns into the Digbeth Branch Canal, although there are a few bridges after that that can be a challenge and the Ashted Tunnel under Jennens Road is narrow (not much space with two panniers on an upright). There's a gate contraption between the railway lines from Snow Hill Station and Loveday Street which, if it's locked, will need you to walk your bike through on its back wheel, but sometimes it's left open. Generally I think what I'm saying is to make sure everything's securely attached - I've had water bottles bounce out on the bricks a few times!
Second all this. Having ridden it on varying degrees of Mildly Inappropriate Bike, I consider that entire section to be Type 2 Fun and best avoided if you've got Serious Luggage or tyres that are disinclined to grip on wet brick, which is a shame because it's a lovely perspective on Birmingham in you're not in a rush to get anywhere. On a summer evening it can get quite busy with pedestrians, probably more so in these covid times.
Broken glass, recreational pharmacists and the Aston ASBO Geese are seasonal hazards throughout the urban part of the Birmingham & Fazeley, though it's the frequent wharf bridges that really wear you down.
On the other hand, central Birmingham is basically impenetrable to cyclists by road. And there are some fairly horrid roads.
