What can I do to improve an old Stumpy?

Anglesets?

Maybe look for a new frame to swap everything across to.

You could try an angleset but that is only going to shave 1 or 2 degrees off the head angle.

Set the suspension up properly. Dropper post (and learn how to use it).

Big, lightweight, large volume tyres.

(70 deg HA... you sure?)

Yup. Amgleset.
My son's new bike is a size tiny Giant from around 2009. It's great, and the suspension works for him, but he said it feels a bit twitchy. 69HA. It's getting an angleset!

Angleset will def help make the thing less twitchy, but so will wider bars and longer stems which might be easier to fit and less costly.

I would look for a set of Revelation or Pike U-Turn forks so you can raise the front for descents and drop it for climbs. U-Turn Revs are adjustable from 100 mm to 130 mm. That will slacken it by about 2 degrees for descents. Fit the longest dropper post you can and slide the saddle as far forward as possible. Fit wider bars and a shorter stem. It still won't descent like a modern enduro bike, but it will be much less sketchy than stock.

Short stem and wider bars should help. Dropper if you have the budget, or back to a good old fashioned QR and try some seat down descending.

I think you're probably on a losing streak trying to make it handle like a current geometry bike.

I still ride my 2009 Stumpjumper, alongside a 2023 one, the way you ride them is just different. Takes me a while to get used to switching.

sell it and buy a more moden bike. your wasting money

sell it and buy a more moden bike. your wasting money

I have  to say, these were my thoughts too.

Sounds like the bike is too small for your wife (as they all were back then), no amount of turd polishing will fix that.

That's a bike that predates the great geometry shift. Anything you try to do to make it closer to today's geometry will make it worse somewhere else.

Make sure the sag is correct, the suspension is serviced and works properly and apart from that probably just suck it up and change it for something more modern.

Get rid and get something that fits, there is plenty of choice now.

Does it actually have a tapered headtube? Not sure you can use an angleset without one, and if so it might be very limited in what you can achieve.

Offset shock bushings are worth investigating - Bounce make really good, durable ones at a fair price.

And I'd consider bumping the fork travel up 20mm, even if that means getting a different fork.

Are you sure it has the correct fork on? I thought the 2008 Stumpy was 120mm - my mate had the silver & blue one.

Also - perhaps a flatter, wider bar to put more weight forwards - that's what we were all doing at the time (copying Sam Hill IIRC)

It's a hardtail, straight steerer tube with external cups, fork is actually 90mm and have set preload/sag/rebound.

Stem is 70mm, I think any shorter and it'd be chronically too small, even with a wider bar, same goes for shifting the saddle forward.

I think selling it to someone with a kid that'll fit it, and scooping up a cycling industry crisis bargain is the best best too!

Angleset will def help make the thing less twitchy, but so will wider bars and longer stems

A longer stem and wider bars will not improve handling one bit, especially on a short reach 2008 frame

Convert it for gravel

will not improve handling one bit

depends of your definition of "improve handling". Bike handling is mostly fashion - people aren't significantly faster on modern bikes than they are on older ones. A longer stem puts more weight on the front which makes it less wayward on climbs, combined with a short reach can make getting over the back of the bike easier than you think, meaning descending is fine too.

I've got a short stem on a long frame, but it isn't "better" than my 1999 xc bike with a short top tube and long stem, its just got different compromises.

Get rid - honestly not worth throwing money at - especially if it has a straight steerer so anglesets aren’t possible.

So many bargains at the moment - if thenVitus Nucleus women’s bike is still on at £250 I’d snap one of those straight up. Air fork, sensible modernnish geometry, ok tyres, ok brakes, 1x drivetrain etc

Bike handling is mostly fashion

Get rid – honestly not worth throwing money at

I was going to say the same. There are so many absolute bargains out there at the moment. Not just the new stuff like the Vitus. Facebook buy and sell groups are awash with really nice, hardly-used second hand bikes that are going for silly money now the arse appears to have dropped out of the market

Or just look locally on Facebook marketplace. All the bikes that people bought during lockdown, rode them twice around the local park and have been sat gathering dust in the garage ever since are now up for sale

I've just had a quick look and one of the first things that came up was this

https://www.facebook.com/marketplace/item/3874768992751061?ref=marketplace_profile&referral_code=undefined

Brand new with a nice spec for less than 600 quid. Thats going to feel a whole world better than a 15 year old Stumy

‘Get rid’

are my thoughts too tbh.

fwiw, I’ve been riding mtbs since 1986, and bikes that felt bloody great back then just don’t nowadays, and it’s mostly geometry that makes em feel (relatively) awful. <br />there have been incremental improvements in every area over the decades, tyres, gears, brakes, droppers, suspension etc, but it’s geometry that makes modern bikes feel so confidence inspiring. 

people aren’t significantly faster on modern bikes than they are on older ones.

I'm not looking for an argument here but personally I'm a lot faster up and down (and 15yrs older) on my Hightower than I was on the Cannondale Prophet I had around 2008. As for op's original question I'd have to say

Get rid – honestly not worth throwing money at

Or

Convert it for gravel

I spent a while on a similar era bike. Did quite a few tweaks to make it work, adjustable travel forks, wider bars, fatter tyres. All helped but replaced it with a cheap hardtail with more modern geometry and it was miles better in every way.

You could get a cheap frame and swap the bits over, probably for less than the cost of an angleset that won't fit a straight steerer anyway. Maybe find a 27.5" frame. The 26" stuff will work and you can upgrade some parts over time.

An angleset isn't going to stop the bike looping out on climbs. Everything you do to fix one issue will make another issue worse. If you try and polish that turd, all you will end up with is a big poo smear all over the floor.....

I really don't think bikes if that era were that bad. They just need a different style of riding.

But yeah, I don't think you can make them handle like a current bike just by switching components around.

I had one from a couple years later than that, but of the same 'era' if you like, and it was probably suited most to long days in the saddle over flattish terrain. The last of the old school cross country geometry.

Reviews from the time even suggest it was a very short bike and discuss potentially sizing up.

people aren’t significantly faster on modern bikes than they are on older ones

True I have a KOM down through Manners Wood to Rowsley (that hasn't got any harder - in fact some of it's been sanitised) that stands from 2014 ridden on a 2009 Spesh Enduro

I really don’t think bikes if that era were that bad. They just need a different style of riding.

Yep, you adapted to what you had at the time, as bikes evolved - the Spesh at the time felt like it would ride anything - fast. And was significantly better than anything I'd had before.

If I got on it now, it would feel horrific, I'd be slow AF and probably fall off a few times

I went from a ~2009 Scott Genius to a 2017 Yt Jeffsy so similar travel trail bikes. It was night and day how much better the Yt was than the Scott.

I think my Ragley Marley is as big a step forward again. My Stumpjumper Evo is insanely competent in comparison.

Modern geometry is awesome.

I went from a ~2009 Scott Genius to a 2017 Yt Jeffsy so similar travel trail bikes. It was night and day how much better the Yt was than the Scott.

Likewise - 2009 Spesh Enduro to 2016 YT Capra, so much better in every way

Ebike inbetween, but now Ragley Big Al and it feels so competent

If I got on it now, it would feel horrific, I’d be slow AF and probably fall off a few times

For me, the thing is that it's easy to go from 2009->2023. Newer one is really planted and stable. Going back the other way feels weird, and it takes a ride or two to recalibrate. It doesn't feel *bad*, though.

imo, newer is faster downhill, and better at being winched uphill, but at the expense of everything else. Harder through fast singletrack (too wide, and too slow steering), slower climbing, and out of the saddle climbing just doesn't work.

It's just a different compromise, I don't think either is "better", and it's nice to have options.

Does your OH really want to ride bikes?

If so then no matter how good the condition, some ~20YO bike with steep angles is not going to instil the same confidence for MTBing that a newer, slacker one with big wheels and wide bars will.

Get something newer that fits well.