Repair the bike or buy a new bike?

[Ajax Bay]

The RD you linked to will screw onto the hanger currently fitted with the perfectly good RD. And it has an 'oversized' tension pulley - other riders will notice this.
Rather than a new cassette, you could go for replacing the RH (and maybe LH too) shifter with a used 9 speed one (ST-3400 or ST4400 say). Would cost about the same as a new 8sp cassette and chain. Then you'd have a 9sp drivetrain - a step up. And the design of the 9 speed shifters is the same as the 10 and 11 speed shifters, whereas the 8 speed ones you have on can be recognised as entry-level by other riders - if that matters to you.
Either the current or a new RD would work with this shifter.
Several people have said that they find the Tektro brakes really weak so why not consider replacing the brake calipers?
This thread discusses that: https://www.cyclechat.net/threads/new-brakes-2017-boardman-team-carbon-c7.260881/
At least get some better brake pads than those fitted.
Has it still got the Vitoria Zaffiro tyres fitted. Upgrading those would be an excellent (probably the best vfm of all).
https://www.cyclechat.net/threads/tyre-advice-please.261561/

 

[LemonJuice]

Maybe because the original one broke? The derailleur being different doesn't mean it will need changing. I know I repeat myself, but just let the mechanic do their job.

I’m not disputing what you have posted, but I thought that only a specific derailleur fitted a specific bike.

 

[Ajax Bay]

Nearly all RDs screw on to nearly all bikes. Same thread - thank goodness for some things being standard. RDs are one of the most flexible items, but some have different cable pull ratios (this does not affect your choices for the Boardman - which is why you could swap the RH STI (shifter) for a 9sp and the RD would work fine (with the current 9sp cassette)).

 

[C R]

I’m not disputing what you have posted, but I thought that only specific derailleur fitted specific bikes.

The derailleur, the shifter and the cassette/freewheel must be compatible for things to work, other than that, the only thing to consider with the frame is if you have a hanger for direct mount, your case, or you need a claw mount.

 

[LemonJuice]

So, what is the difference between a Shimano rear derailleur 2300 and a Shimano rear derailleur 2400?

 

[vickster]

Granted.

But, how come a different derailleur is on the bike?

Ask your brother hasn’t he had it from new?

 

[Ajax Bay]

Different to what? For others' entertainment, there is a 'spot the difference' game at the bottom.
The RD-2300 is part of the Shimano Claris groupset introduced a few years ago. The RD-2400 (pictured below) is a new 'release' of the Claris RD. No difference in performance or compatibility.
"Number-wise – all Shimano groupsets have to have a number – this is 2400, so it's replacing the 2300 groupset which was called, erm, 2300. "As the market continues to grow and the entry level becomes more important, we thought it was important that the groupset had a name for next year," Shimano's Mark Greshon told us."
I offer you this March 20-20 link to read about Shimano groupsets. Please do me a favour and read it.
https://road.cc/content/buyers-guide/206768-your-complete-guide-shimano-road-bike-groupsets
Don't really understand what you're mithering on about. If you look at the 'back' of your rear mech it will say 'RD-2300 Singapore VIA'.
PS You don't need a new RD.
RD-2400 (OP please note, for the avoidance of doubt) that the RD is 'normally at a different angle to the vertical when screwed to a hanger/dropout.)

RD-2300

 

[vickster]

A new 8 speed chain and cassette (same ratios as stock) will be under £30. Don’t think he’ll get undamaged Sora brifters for that (remember he’s a perfectionist) 👍

 

[BigMeatball]

So, what is the difference between a Shimano rear derailleur 2300 and a Shimano rear derailleur 2400?

Great question. A mechanic will have a great answer for you.

 

[Ajax Bay]

A mechanic will have a great answer for you.

Yes. OP: please take careful note of the mechanic's great answer and let us know, provided his answer is polite.

 

[C R]

Yes. Op: please take careful note of the mechanic's great answer and let us know, provided his answer is polite.

SFA comes to mind ...

 

[Black Sheep]

I’m not disputing what you have posted, but I thought that only specific derailleur fitted specific bikes.

Nah, my road bike is running a Deore (mountain bike) rear derailleur simply because it's what I had spare at the time, never got round to replacing it, this is on a 5 speed set up.

Haven't a clue what is on the wife's bike without looking, but the shifters don't match it and everything is fine.

The reason for this is, the derailleur reacts to how much the shifter moves the cable, I changed the shifters on the wife's bike when I changed it from roadracer bars to flat bars, fitted new cables and adjusted everything and it all works happily.

If you stick to one manufacturer then you should be fine, so if the shifters are Shimano then the derailleur should be also.

I think the best thing you can do at present is let a bike shop look at it, discuss your options with them for parts, don't be shy of politely asking if there's a less expensive option on parts (you might be told yes, but you'll simply wear them out quicker or that there is a cheaper option, but not recommended)

You say you want to get this fixed, ride it for a bit then buy a nicer bike and use this one for work - buy decent kit but not expensive, it's going to be out in all weathers and locked up somewhere, save the flash expensive stuff for the nice bike.

 

[LemonJuice]

Nah, my road bike is running a Deore (mountain bike) rear derailleur simply because it's what I had spare at the time, never got round to replacing it, this is on a 5 speed set up.

Haven't a clue what is on the wife's bike without looking, but the shifters don't match it and everything is fine.

The reason for this is, the derailleur reacts to how much the shifter moves the cable, I changed the shifters on the wife's bike when I changed it from roadracer bars to flat bars, fitted new cables and adjusted everything and it all works happily.

If you stick to one manufacturer then you should be fine, so if the shifters are Shimano then the derailleur should be also.

I think the best thing you can do at present is let a bike shop look at it, discuss your options with them for parts, don't be shy of politely asking if there's a less expensive option on parts (you might be told yes, but you'll simply wear them out quicker or that there is a cheaper option, but not recommended)

You say you want to get this fixed, ride it for a bit then buy a nicer bike and use this one for work - buy decent kit but not expensive, it's going to be out in all weathers and locked up somewhere, save the flash expensive stuff for the nice bike.

Thanks for your advice.

 

[LemonJuice]

Has anyone ever used LightInTheBox? I’ve seen road shoes, cleats and clipless pedals for under £100.

 

[vickster]

Has anyone ever used LightInTheBox? I’ve seen road shoes, cleats and clipless pedals for under £100.

I posted a link to them for something the other day and the response was that they have shocking reviews.

Buy genuine articles from a bonafide UK seller.
You should be able to get Shimano shoes and pedals for £125 or so and they'll not be fakes and you'll get them in the next week or so

eg
https://www.sigmasports.com/item/Shimano/RP3-SPD-SL-Road-Cycling-Shoes/JYLY
https://www.sigmasports.com/item/Shimano/RS500-SPD-SL-Road-Cycling-Pedals/OI41