Remembering it has to carry the weight of the bike when folded and wheeled around, of course!...so maybe a rack not as heavily built would be o.k. The Brompton rack is an expensive beast but I've found them super useful and worth it.
If you haven't ridden a Brompton with a rack, have a careful think about what you want to carry. I don't find mine (a Brompton rack, bought with the bike) to be of much use at all because I get heel-strike if I put anything of any size on there. It's only good for a little bag with a waterproof and a sandwich. And then I find it gets in the way as I can't flip the rear wheel underneath.
So if I need to carry stuff on the Brompton, I take a rucksack. (Edit, or the front bag. I don't know why I forgot to say that. Also note that I have bigger than average feet, so I'm more prone to heel-strike).
Remembering it has to carry the weight of the bike when folded and wheeled around, of course!
I find it useful in winter... start off wearing a thick coat but then have to put it somewhere when you've warmed up. I also have a rear B bag whch works well for the occasional fully-loaded journey, but a bit of a pain for regular use as you have to remove it before folding.
Thanks Dogtrousers, guess I could forgo one in truth, as most of my trips will be day only. Heel strike is not something I thought about either, thanks good point.
If you don't have a front bag, then consider getting one of those first. IMO that's the best way to carry stuff on a Brompton. THe Brompton ones are a bit pricey though. I don't know if there are others available.
Regarding luggage my strategy is, depending from the needed storage amount, in that order:
1. front bag (15-32l)
2. front bag (15-32l) + saddle bag (10-25l) -> up to 57l
3. front bag (15-32l) + (huge) rucksack on the carrier (30-70l) -> up to 100l
4. front bag (15-32l) + trailer (~120l) -> up to 150l
5. front bag (15-32l) + saddle bag (10-25l) + trailer (~120l) -> up to 170l
6. front bag (15-32l) + huge rucksack on the carrier (30-70l) + trailer (~120l) -> up to 220l
In most cases option 1 or 2 is fully sufficient, option 6 is barely ever needed.
Still, this does not in any way help with the thread or the question that @rhb123 has as he wants to know if an unknown but cheap 3rd party rear carrier is as good as the original from Brompton but did neither line out what carrier he is talking about nor what problem he wants so solve at all (apart from saving money).
If you haven't ridden a Brompton with a rack, have a careful think about what you want to carry. I don't find mine (a Brompton rack, bought with the bike) to be of much use at all because I get heel-strike if I put anything of any size on there. It's only good for a little bag with a waterproof and a sandwich. And then I find it gets in the way as I can't flip the rear wheel underneath.
So if I need to carry stuff on the Brompton, I take a rucksack. (Edit, or the front bag. I don't know why I forgot to say that. Also note that I have bigger than average feet, so I'm more prone to heel-strike).
Really? In my experience it is the other way round, at least for my taste. As the Brompton is back loaded from factory a mildy loaded front-bag evens this out. Plus if you carry a Brompton with weight on the rear carrier it is a bet wether the locking mechanism for the rear frame will give up or not while carrying.Rear rack is first to be filled here, with various rack loading options, mostly ~20l rack bag. One reason is that a rear loaded Bromton is easy to lift and carry without removing the rear load. A front loaded Brompton is a dog as far as the lifting is concerned.