Lightweight budget riding jackets

No experience of the two you've mentioned, but another option (slightly over your budget) might be the Nukeproof Blackline that CRC on sale for £85 instead of 150ish. Not crazy heavy and seems to get OK reviews.

I had a Madison Roam, it was quite a bulky jacket. The Altura range (Esker) was on a recent PSA https://www.cyclestore.co.uk/altura_esker_packable_waterproof_jacket_mustard-ID_88567?opt=198183&gad_source=1&gclid=CjwKCAiAnL-sBhBnEiwAJRGigjxNZ6LCt6G2g437fwe2jeWvE-KEf_trAtN_GAwV0jR2v0kgXQDSdBoCUT8QAvD_BwE

.
£70 Decathlon waterproof jacket might be worth trying on
.
decently waterproof and fits in a 10 litre raptor backpack fine
.
Only jacket I have found with a mighty hood that fits over the peak of helmet visors

Couple of options on sportspursuit (great website, a bit like the online version of tk maxx for outdoors kit):

https://www.sportpursuit.com/clothing/jackets-tops-jerseys?sp_nav=ct-4.bp-clothing.pc-jackets.pt-waterproof_jackets.&clothing_features=Waterproof&upper_body_type=Jackets&gender=Male&sport=Mountain_Biking%2CRoad_Cycling&order=special_price&dir=asc

The decathlon jacket is only £60 in store! I picked one up today!

I bought an altura typhoon from cyclestore for 39 quid, massively impressed.  I have a night vision so wanted similar and at 39 quid, a steal.

I quite liked my endura singletrack jacket. The right sleeve has suffered following my unplanned rapid deceleration event but I plan to tape the rips internally and patch the outers. Seems a shame to chuck out an otherwise good jacket for one damaged sleeve

I've got a Singletrack 2 jacket - seems to be very good at keeping the weather out. I don't think it'll be very packable though...

That Decathlon jacket is a good option as more of a leave-it-on-all-ride jacket, as long as your arms fit in the rather slender sleeves!

I picked up the Decathlon Jacket yesterday for 50 quid. It's end of line. You do have to size up though.

I've bought one of the altura jackets above.

No idea how good it is, there are some mixed reviews.

I bought an Esker for £40 from Cyclesstore, I've yet to test it out but it feels and looks good and has vents in the back which should help with the overheating.

I bought the wife this one, which is even nicer and despite the description as Navy, its a nice dark, slate blue/grey. So if you can fit in a size 14 might be worth a go.

https://www.cyclestore.co.uk/productDetails.asp?productID=82910

I'd always recommend looking at  Galibier any time you want decent gear at very reasonable prices... they have a selection of jackets, starting at the VentUltra which is extremely pocket-packable and going up from there - but obviously as you increase waterproofness and warmth, you increase bulk - or price!!

Came to say Galibier as well.

I've got a Nukeproof Blackline that is my light weight packable jacket. Very light, goes in a hip pack, pretty waterproof, decent breathable but not too durable.

I've also got the Singletrack. It's considerably heavier, a lot warmer and feels more robust. It would go in a large backpack but I'd say it's the heavier end of mid weight if that makes sense.

I wore mine for 4 hours of ming yesterday, pit flaps open and managed temperature with the front zip and my effort. It breathed ok.

The only odd bit is the front seems kind of baggy when on the bike, despite a fairly snug fit when stood up. Decent length arms though.

I bought an Ion Shelter 3L jacket from SportPursuit after a recomendation from here.

It arrived the other day - the material is soft and pliable and light so packs down small. I was expecting something stiffer as it is described as 3 layer.

It has a large helmet sized hood as well.

https://www.sportpursuit.com/catalog/product/view/id/2656116

£73.99

Ive a Humvee, which ticks 90% of my boxes, packable enough, warm enough, but i dont rave about its waterproofness (unlike the Fohn Supercell 3L Waterproof, which i bought in the summer, which tbf i dont think i would ride in.. but if i did, i would stay dry)

+1 Galibier

This is my go-to packable jacket when I don't need a hood.

https://www.galibier.cc/product/tempest-pro/

Not sure how you'd get hold of one, but I got some ETC arid stasher jackets from the moore large auction sell off, and I'm so far so good for the kind of usage you're looking at

I have the Singletrack 1 and really like it. I find I wear it a lot more than I expected as the pit zips are ace. It can get a bit hot with a back pack though and you'll need a back pack to stash it.

I wanted something a bit thinner to save that for proper wet days and bought the Fox Ranger wind jacket which is just a boil in the bag jobby.

Currently looking at the Madison Roam myself as it could be the sweet spot for me. It looks that bit thinner and easier to stash but with all the good bits like pit zips.

Can anyone with the Madison Roam give me a clue on sizing? True to size? Am a large in Endura jackets but look to be in between on Madison size chart..  thanks

Pearson?

Haven't worn mine yet in anger but very nice lightweight material with nice finishing touches. I bought mine for £10 more than current price 🙄

https://www.pearson1860.com/products/bryter-layter-waterproof-jacket-navy

Thanks for all the suggestions. Look like there a lot more options than I first thought. Seem to be quite a lot without a hood but I think I'd like the option just for the extra crappy weather.

What are people's thoughts on non-bike specific jackets? I can't imagine there's masses of differences, but it feels like an extended back would be good to keep spray off your ass as much as possible. Reason I ask is because I was looking at the fohn packable jacket https://www.wiggle.com/p/fohn-mens-packable-2-5l-hooded-jacket?color=umber&sizeStandard=M++&utm_source=google&utm_term=&utm_campaign=&utm_medium=base&gad_source=1&gclid=CjwKCAiAqNSsBhAvEiwAn_tmxV6X7MHTVujVQjPp4pKyBN1Gh0mzY-KWLfgx8Ul2gk_qnWMGo_hnwhoCuhUQAvD_BwE&gclsrc=aw.ds not come across them before but it seems it's the general non-bike specific equivalent to the nukeproof kit. Seems to have good waterproofing and breathability ratings compared to a lot of similarly priced options. Not sure how small it packs down though either

I bought an altura Esker jacket.

I won't recommend it after two rides.

The arms are very short- I am 6"4, but L and XL in most things fit my arms. This is two or three inches short.

It's got an odd cut. When in riding an MTB pose it pulls tight across the chest.

The fabric feels nice and it beads well.

I would recommend the ion shelter hybrid jacket. 5 rides in and I'm loving it

What are people’s thoughts on non-bike specific jackets?

My most-worn jacket on the bike is a 10-year-old Patagonia softshell that I think was for trail running. It's awesome.

But for a waterproof it's nice to have a dropped tail to cover your arse a bit.

Cheaper walking waterproof jackets may be less breathable, but then cheap bike waterproofs may not be great either.

Decathlon if you don't want to worry about crashing.

They've a few jackets aimed at either radius, mtb or gravel. All much of a muchness and keep the rain off.

What are people’s thoughts on non-bike specific jackets?

Can be OK, but be careful, as the may not have (in no particular order) not enough across the shoulders, arm length, and rear length (bum coverage) and too much material on the front (flappage). Cycling - even upright on a MTB, can make you an odd shape, and your new jacket could be an uncomfy mistake. 

I picked up a Montane Minimus jacket off eBay for £55, think it's sold for running. Pertex Shield fabric, 20000/20000 waterproof/breathability, very light and packs down small.
I run very hot and the above works well for me, much more breathable than my Endura Singletrack jacket and much more packable.

I looked at the Decathlon jacket last time I was in a store, it felt heavy and bulky to me, would probably fit in a Camelbak but no way would it pack into a bum bag or rear pocket.

Have a look at Vinted. My Goretex Gore bike wear jacket is lovely, second hand, and £20 on Vinted. Cuts down on landfill, cheap, really good quality.

What are people’s thoughts on non-bike specific jackets?

It varies massively depending on the jacket. Some lightweight, waterproof running jackets work quite well - Montane's stuff is as good anything out there - but more all-round outdoor jackets tend to be cut looser and also festooned with pockets which add complexity and weight, and, depending on construction can mean you have a double or even triple layer of fabric in some areas, which compromises breathability. They also have a tendency - as above - to sit oddly when you're in a riding position. Sometimes outdoor brands make a cracking cycling shell by mistake, but it's a random thing ime. 

Berghaus did some mega-light waterproofs, which are great as an emergency shell,  but a little fragile for regular use in the saddle. Also people's concept of 'lightweight' is quite variable. The Berghaus Hyper whatever it's called is genuinely under 100g and very breathable with it and packs tiny, but costs/used to cost £250 odd. 

Got blue one of https://www.merlincycles.com/funkier-dryride-pro-showerproof-cycling-jacket-193438.html for ~£24 last year, passable off the bike, decent windproof and showerproof (not been out in it in proper rain so far).

I picked up an ion 3 layer coat from sportspursuit - it’s lighter than I expected tbh. My other cost is a Royal Racing Matrix jacket which is definitely bulkier.

Haven’t tried it on the bike yet as I don’t want to get it dirty lol

I'd been looking at those the other day. Seems like a good option other than potentially being a bit bulky. How small does it pack down?

I picked up an ion 3 layer coat from sportspursuit

I bought one the Ion Shelter 3L jacket from SportPursuit, then bought another in Tidal Hreen from BikeInn as they had it on a further reduction from their sale price, so £58.49