Are there any clothing brands that just make plain and simple bike clothing? Flat colours minimal logos etc?
They also have to make sizes for Wookie sized people, not just Hobbits.
How much d'wanna spend, and what kind of style are you looking for? Tight jerseys,and Lycra shorts or baggies and T-shirt sort of thing
For summer tops, I just use stuff from the likes of Mountain Warehouse. Plain, lightweight and dirt cheap.
I like Salomon tops, Northwave shorts. Have logos, but not loud and enormo ones. As said, depends what yer after.
TK Maxx sports section. It's full of generic sporty t-shirts, shorts, leggings etc. from all the usual brands plus some you've never heard of.
I've got a bunch of plain, stretchy t-shirts in muted colours that were maximum 15 quid each. None of it looks like mtb style racing pyjamas.
Luckily for you it's usually only the wookie and ewok sizes left on the rack. Normals like me have to get there on delivery day.
Baggies and Ts in big sizes for long bodies are what I'm after, most companies XXL don't go around my shoulders or are super wide but only come down to my second rib.
It depends on what you’re looking for.
It’s easy enough to pick up plain black, grey or blue baggy cycling shorts and pair it with an equally plain technical t-shirt from basically any sports shop you care to find. Look in the Hiking or running section if you can’t find what you want in the cycling section.
If you want Lycra, again, the bottom half is easy to sort, top half look at Galibier, Torn or even Rapha. In fact, I can’t think of to many brands that don’t make plain ish kit.
POC, but it’s not the cheapest
Some Madison stuff is good, IMO.
I like Club Ride kit. It's not low cost though, but built for BIG Americans, so XXL really is XXL, not normal cycling XXL which normally means chest sizes of 44" chests.
Go have a poke about in your nearest Decathlon, their cheapest lines of cycling kit tends to be quite plain, and come in lots of sizes.
Also worth looking at their other non-cycling ranges too for Airtex type tops (you can cycle in comfortably), Ski winter base layers (can also work on a bike in winter) and baggy shorts that can still be work as "Baggies" for MTBing if that's what you want....
Patagonia - not cheap but ethically made, lots of recycled materials and plain colours available.
I spent a fair bit of time looking for the same thing and with a focus on Jerseys in particular, found that some had the traditional road jersey pockets, some with just a zip pocket and others that were basically just a t-shirt with a longer back better suited to a cycling position.
In no particular order...
Jerseys - Endura, Madison, Gonso, Craft, Decathlon, Chapeau, Torm, Morvelo (currently moving), LaPassione, Velocio, PH Apparel, Isadore, Etxeondo, Cafe Du Cycliste, Pedaled, Q36.5, Cycology, Ashmei, Loffler.
T-Shirts - Castelli, 100percent, Leatt, Vaude, Loffler.
Hope that helps a little and that you find something suitable.
Decathlon walking, hiking gear. Decent vented stuff but doesn’t look like a clown would choose it.
My shorts look alit like h&m shorts...
In the perfect workd i would like normal shorts ie no commando pockets. In a slightly technical fabric with a crotch gusset thing.
Overlander seems to get the closest but... Pricing.
I wear general outdoor brands and running brands. Better quality than much MTB stuff, better cut and no LOGOS over everything.
Running tops are often good.
Shorts are the only MTB specific clothing I wear, everything else is either running or hill stuff. Most outdoor clothing is fairly plain, so you have loads of choice, really.
I agree with wearing cycle specific shorts - but again I have plain black for two of my pairs. I just bought a rather nice pair of plain Northwave ones:

A second vote for Patagonia. They make some excellent technical t shirts which can usually be had in a sale somewhere and definitely come in cheaper than boutique bike brands. Their sizing is also American so XXL probably is a genuine big!
I haven't bought an MTB jersey in twenty yesrs, t shirts in the summer and same t shirts with windproof in winter.
Their sizing is also American so XXL probably is a genuine big!
Aye was going to say something similar, head to American/Canadian sites, their kits comes in a much wider size selection .
I'm OK for shorts, I like the POC ones, it was tops I'm after really.
I have HH winter tops which are good, and I wear mostly T Shirts for the summer. I just wanted to get a wicking Tfor longer rides.
I have ordered a couple of Under Armour T in long/tall sizes from Amazon.com
I'll also take a look at Patagucci but seam to remember their stuff still comes up small.
Big fan of the Scott stuff when it's on offer.
Can often pick up jerseys for sub £20 and usually decent colours, a single S logo and well fitting.
Edit: Start fitness seem to have quite a bit in at the moment.