A friend of mine needs a new shock for her bike – it’s 184×44 – a kind of unusual size so not lots of options about. She plans to get a new bike in the next year or so.
I’ve a 200×57 sitting in a box – would it mess up the geometry too much to fit this if it even does fit in the frame? Seems like a daft question even to ask this….
<ducks and takes cover>

You’re right… It is a daft question to ask.

Best thing to do is speak to a tuning company and see if the shock can be resized down to the required size.

What frame is it?
Will the shock actually fit in the space required?
If you do fit it.. Make sure there’s no air in the shock and then compress the bike and check for any parts that would contact each other.
If it does fit then you’ll need a longer fork as you’ll be increasing the rear travel and raising the bb height a fair bit… Without a longer fork the bike could end up higher at the rear than front

Thanks @transporter13 just wanted to check that I wasn’t missing anything.
Back to the drawing board – it’s not worth resizing it.

Few cheap options here

http://www.rczbikeshop.com/en_ue/mtb1/suspensions/rear-shocks.html

Crc have something cheap if it helps?
https://www.chainreactioncycles.com/mobile/fox-suspension-float-performance-rear-shock-2016/rp-prod161493?gs=1&sku=sku653766&pgrid=60711843258&ptaid=pla-430662535861&utm_source=google&utm_term=&utm_campaign=PLA+All+Products&utm_medium=base&utm_content=mkwid|sd3TBFdQB_dm|pcrid|309840119912|pkw||pmt||prd|653766UK&gclid=CjwKCAjw36DpBRAYEiwAmVVDMJdNB31W-G0lX4bRvaSdx1aqwush2Fs3x1cmgzff7E1bwamPJQRYABoCOxwQAvD_BwE