Hi there never having had a half decent bike before no idea so….I ride 16 odd mile a day on the road in winter and track in summer what sort of time do components last like

chain (KMC X9SL)9 speed
Cassette (Shimano HG50 9-speed, 11-34 T)
Shimano Deore Mountain Bike MTB Chainset / Crankset M590
Shimano RD-M772 XT (long)

etc etc would you buy spare parts if you come across them new but cheap ????

Depends how often you oil and clean, and the geology of where you live, some places seem to eat components more than others. It’s a bit like how long does a brake pad last?

well only used in the dry and use GT85 for lube keep immaculate clean

GT85 is crap lube

Should get a couple of years at least. Would look to a more chain biased lubricant, the GT85 is fine for cables and mech pivots, but it’s not really a chain lubricant.

GT85 will be OK as he only uses the bike in the dry .

Ok so that answers the but spare parts if some come up then BUY THEM so what parts wear the fastest ????

I wouldn’t bother buying spare parts for that kit. I have roughly the same setup part for part on my full sus (I have a slightly different KMC chain) and have done for the past two years.

The Deore HG50 cassette still looks like new despite being ridden through two very wet winters. I read a post on another forum from some buy who had that cassette on his touring bike and clocked up over 4000 miles before replacing.

It wouldn’t hurt to pick up a spare cassette and chain if you plan on running that setup for a long time as the 9 speed stuff is being rapidly phased out and they’re going for dirt cheap now (9 speed HG50 cassettes are only around a tenner online) but in all fairness I think you’ll probably want to upgrade the bike and / or whole drivetrain long before the kit starts failing.

Most of my bikes are specced with the cheapest to buy steel Shimano HG50 9 spd cassettes, and Truvativ steel chain rings, a 3×9 set of these will cost under £30. Add a decent nickle Sram PC991 for £16 from CRC and your under £50 (tank full of petrol for a small car)
Your cassette/ chainrings will last easily 2 years or to 3 of these nickle coated chains if you use a dry lube – Squirt lube is what i use as it collects no crap and your nickle chain will not rust after washing. You often get sent some extra Squirt Lube if you order a few bottles.

GT85 will indeed also work fine with this set up and smells nice too 🙂

Ok well just brought a chain so far for £12 so not to bad Seen the cassette for £14 and the main crank and cogs set up for £63

If you shop around you will get spares for years yet (at deore/Tiagra level) no point stockpiling. Just clean and lube chain regularly, and replace cassette and chain every 2500-3000 miles IME