Challenge Holborn 20 inch Wheel Size Unisex Folding Bike £146 using collection @ Argos

I would not recommend it I dislike it as the mechanism is very difficult and it does not stay closed but the main problem is the handlebars do not fold down (edited)

Update now that I’ve had this bike for over a year, replaced the saddle as the supplied one is not really a saddle but apart from that, it has cost me nothing, works well, as it did when it was new, useful simple bike, unbelievable value.

My advice is go to Sports Direct or wherever & lift up a 15kg dumbbell. With 2 hands if you want.

Cheap steel-framed bikes are rarely a good idea. Likewise cheap folding bikes. A cheap steel-framed folding bike for less than the cost of a budget bike is too good to be true.
I know it's tiresome on bike deals being told that this pricepoint won't get you something worth riding so you need to look secondhand or spend a bit more, but it's tiresome because retailers like Argos and SportsDirect insist on marketing steel-framed BSOs that really aren't fit for purpose.

Have a look at the Halford Carrera range of folders (ignore the cheaper, steel-framed Apollos) which start at about £350. Or go to Decathlon and check our their B'Twin folders - their cheapest is a single speed for a mere £199. Single speed would make it only suitable for occasional use but that might be all you need. I've only ridden it around the shop but it was an absolute hoot to ride! £80 more gets you some basic gears to cope with hills and keep up with traffic.

I have Decalthon's £700 folding ebike as a spare bike. It's pretty basic but does a great job for the money. Like all folders with 20" wheels it doesn't fold as small as a Brompton (they start at about £900 though and an electric Brompton is a LOT more) and is too heavy to carry any distance folded. However, it's decent to ride and folds into the boot of a car. Unfolded it's light enough to carry up or down a flight of steps by the frame. In an emergency I can fold it into a bag (Halfords do a nice one, thought the shoulder strap is a bit fragile) and pretend I don't have a bike- just a very cumbersome bag - to get it onto a train or into a hotel room.

I really wish these folding bikes were not quite so heavy. near 15kg which you will have to man handle up stairs and onto trains. That'll get old very quickly. I remember the old bromptons, after a month of lugging that chunky monkey around you look like spitting image of Arnold Schwarzenegger

@timmy_w There were deals posted in the past for the same product here on HUKD, you can search and read what other people said on those posts about this product. Hope that helps!

Please don't buy this bike. I bought it as my first bike, really hard to use. Had rust near joints within a month and some bits broke.
This bike will put you off from cycling.

Update: I ended up buying a 2nd hand Dahon Vitesse D8 at £90. It weighs 11.2kg, which is 3.3kg lighter than this Holborn bike, and I still found it a bit too heavy to be taken upstairs. The lower cost and weight do not come with no price. The chainring guard has minor crack, which will cost me about £10-20 for the part and tools, and the time to replace it when it is completely cracked.

Therefore, if you do not have the time to fix the problems of a 2nd hand bike, and you only transport it in a car or bus, I think this Holborn bike is not a bad choice. If you plan to take it in rail and tube, you may find something lighter in the 2nd hand market instead, and do some research on maintenance before buying one.

Can you fit a child seat on a foldable bike?

Not sure if trains would accept as a folder or not as wheel size is 20. So would have to be booked on and then put into the bike area. If you don't use trains then not an issue.

I had a Brompton so can carry on to any carriage, as wheels are 16".