Bikepacking - a viable alternative to racks & panniers

What material do people use to stiffen up bags (thinking particularly of a bag base) and give them some structure and where's best to order a hobbyist quantity from?

HDPE sheet, 1mm thickness. Used in lots of bikebags, for example the Wizard Works Shazam and Revelate Mag-Tank.

You can get it here for reasonable prices, shit website though.

https://www.directplastics.co.uk/

Thanks, have bought this: https://www.lomo.co.uk/acatalog/30L-dry-bag-holdall-top-opening.html

and am hoping to use it as a rack bag.

will post up here when I get it done

Should be perfect. In my experience the sheets are easily cut with a scissor, so I wouldn't bother with their cutting service.

Around here coroplast is widely used in commercial and election signs. Since most of them are illegally posted on boulevards I just pick one up when required.

More locally coroplast or fluted board is used for Estate Agent signs. Lots of that about.

did consider coroplast but i never see any about and isn't it only strong in the one direction? in the other direction it will fold, right?. Not necessarily the biggest problem but I dunno, seems best not to have that.

You need 5 mm spong foamex but it isnt waterproof.

I usually cut it to fit the entire inner circumference with the 'grain' running along the length of the bag, fold to suit and sometimes anchor it, sometimes not.
I've used it in multiple Carradice bags, never been a problem.

I am tooling up for a summer of cycling...

Does anyone lug an iPad around with them? If so, where are you placing it on the bike/in what type of bag? It’s a 12.9” so not exactly small...

Any views on using a bag stabiliser for a saddle pack? Do they really help hold the bag in place?

what, like a rack. yes they do!

A big fragile rectangle is an ideal job for a ... [looks around, whispers] pannier.

My 11" MacBook Air does fit it my saddle pack but it pretty much becomes a structural member, so I've never tried riding with it (except in a you-know-what).

A friend of mine is using the Wizard Works Shazam rip-off I made him to commute with a 15" laptop.

I have the alpkit one, works well.

same, although I use a carradice. Not ideal, but don't want to shell out for panniers just yet.

Yeah, I need bigger bag(s).

Currently have 9L handlebar pack and 9L rear seat pack. Both quite nice so I’m reluctant to replace them despite the small capacity. I did spend 5 years of my life learning to pattern cut and sew, so could always get off my arse and make something.

For those using full frame bags... How much of a pain is not having a bottle in the usual place/where do you put it instead?

I use one go those stem bags for my water bottle. Actually prefer it as I remember to drink more.
The 5 quid one from decathlon works well enough

Another option is to put a bladder in the frame bag. Laner's stem bag method is good for keeping bottles up out of the range of most trail crud.

+1 for the decathlon bottle bag

buy 5 decathlon bottle bags. You won't regret it.

Are there any handlebar bags designed specifically to hang off TT bars apart from the Apidura Racing bag?

Get something custom made.

StraightCut for example. Better than shoehorning a square into a circle.

Restrap have designed/prototyped/tested, should be available in March.

I’ve seen an early version, dis gon b gud.

What's the forum recommendation for stem bags?