Modify old bike or buy another?

[Jameshow]

Unlike @Jameshow pretty much every bike I have runs a 52/36 double and an 11/28 rear cassette. It's OK on almost every gradient. Mine are medium sized as well.

Hard man!

 

[Ajax Bay]

West Yorkshire . . . scenic . . . not spending much time on the middle front ring; . . . , I was thinking that a 2 speed front with 10, 11 or 12 speed rear would make more sense.
like the idea of a 50/34T front and 11-36T rear; though in reality a 48/32T front would be more appropriate
replaced the chain and rear cassette about 5 years ago. . . .

A compact (50-34t) would be fine and your current LH shifter and FD would shift between rings perfectly.
As said, you could move from 8sp to 10sp on this bike (new 10sp shifters, 10sp cassette (and chain to go with it) as well as a compact chainset (though you could go to 10sp with the triple, but why?). For 48-32t you need to look for 'sub-compact', and with an 11t smallest sprocket, you won't spin out till at 25mph+ ie a decent downhill.
Choosing a dinner plate large sprocket (eg 36t) brings challenges with capacity of the RD to cope: a reduced small ring is a better technical solution to the Riding's/rider's need for a low 'crawler' gear (length).
But you have this range already 52-42-30 and 11-30 (which is exactly what I have on my triple btw).
11sp will require new wheelset - which means N+1 is the way ahead. Your bike cannot be equipped with 12sp (the groupset and wheels will likely cost about 5 times the current bike's value).

The gear cables and outers are the originals (though I keep them well oiled).
the bike struggles between the middle and smallest front chain ring, and frequently seems to end up between two chain rings (thinking about it now: maybe that's a "sticky" gear cable?)
As for the wheelset; I do recall when I bought the bike one criticism in reviews was the Alex DA1 rims. What specifically would be improved by getting better wheels (e.g. the Vision 30, as mentioned by Chislenko)?
I understand that over the years the Shimano ranges have generally improved (such that a 2024 Tiagra should be better than my 2006 Tiagra)? Part of the reason I wanted to upgrade was that I've never been able to shift under power on this bike. I have an older mountain bike that was twice the price 5 years earlier (so a higher level groupset). That's never had any problems shifting under load, and has always been much smoother. But I don't have any experience with modern (or better) road bike groupsets.

Be kind and replace the gear cables and outers. You may not have ridden this bike much, but the cables and outers are 17 years old! The sticky FD downshift symptom is exactly the result of cable friction. See above the immediate 3in1 oil dribble (or @wafter's waxing - but that requires the cable end to be trimmed and pulled out so bang another one in).
As for wheelset, disregarding the reviews, what's deficient about your wheels? Given you haven't replaced the chain for 5 years, I infer you have cycled less than 1000 miles a year (average <20 a week). The Vision30 wheels are £220. And they go round. They have rather few spokes (not good).
If keeping bike, consider replacing tyres with decent ones (see other threads for interminable discussion on choices) and brake pads: I prefer Koolstop Dura2 Salmon, ?£10 a pair, particularly on the front.
The current Tiagra groupset is 10sp (in 2006 it was Sora 8sp, Tiagra 9sp and 105 10sp). Ignoring your chainset, you have Sora (8sp) and current (modern) Sora 9sp really only differs in the '+1' and the Campagnolo style downshift thumb lever on the STIs (as mentioned upthread).
No road bike likes trying to shift spockets under load nor to shift down to a smaller chain ring. Anticipation is key.
And that has not changed with "modern (or better) groupsets". You can get away with it in the smaller sprockets because it's a climb of only one tooth (so a 10 or 11sp helps there) but in the larger sprockets, which is where you'll be when, on a hill, you might wish to keep the power on and shift up (lower gear), the gaps will always be 2 or 3t (or even more with some 11sp outsized cassette (£50+) eg 11-36t).

So, noting the thread title, modify nothing, change the cables (that's all), and look out for a new and affordable (to you) bike with a sub-compact chainset, 11sp, probably hydraulic disc braked. There's a lot of 2020 and 2021 impulse bought bikes out there so you might find a bargain.

 

[Jameshow]

Re the wheels, in Yorkshire a lighter pair of wheels would make a difference. Going up Norwood edge for example 500gms off the wheels feels like a load of weight.

 

[biggs682]

@sploo do both gets my vote

 

[Kingfisher101]

There's a barely used Allez on Marketplace for £300. Size 54. This is with a trainer and a new looking pair of shoes. You could easily sell them on if they were not for you.
What I would do is see what's available second-hand and also cost up exactly how much it would be to refurbish your bike, then decide what you want to do?

 

[Chislenko]

Just as a point of interest why are people saying 11 to 8 wheels don't work?

I bought the Vision 35 designed for 11 speed and they work perfectly well on my 8 speed triple with the appropriate spacer. No fitment or changing issues at all.

Or are people saying the OP's original wheels won't take an 11?

 

[Jameshow]

Look at Yorkshire cycle sales on Facebook.

 

[Ajax Bay]

Yes, @Chislenko : the OP's freehub will be 8-9-10sp and not take an 11sp road cassette (but could take an 'MTB' 11sp cassette). 11sp freehubs (such as on your Vision35s) can take any cassette (with spacers).

 

[wafter]

Yes; can confirm freehub dims are different. I recall my Boardman (Tiagra 4700) would need a new hub to go to 11. 11sp hubs are backward compatable with cassettes of fewer speeds with the appropriate spacer, but it doesn't work the other way around unless the hub is machined... at which point it might as well be replaced with an 11sp item.

 

[Chislenko]

Thanks both for clarifying.

 

[simongt]

If you like the bike and it fits well I'd personally refresh the drive train, brake pads, bar tape, cables as needed. For £250 you could make it as good as new.

Agree. As long as the frame is still good, everything else can be replaced / upgraded.

 

[fossyant]

Hard man!

Try 39x26 on two bikes. That's part of the reason I got the CX bike. Got 34 front and 34 on the road wheels, 32 on the CX wheels.

 

[Jameshow]

Try 39x26 on two bikes. That's part of the reason I got the CX bike. Got 34 front and 34 on the road wheels, 32 on the CX wheels.

Thats nothing I use 42x21 and I get up Norwood edge easy..... !🦵🤣

 

[fossyant]

Thats nothing I use 42x21 and I get up Norwood edge easy..... !🦵🤣

I remember those days...

 

[All uphill]

Thats nothing I use 42x21 and I get up Norwood edge easy..... !🦵🤣

21 at the front and 42 at the back sounds about right to me.