Repair the bike or buy a new bike?

[LemonJuice]

I have bought a new cassette and chain.

I can’t seem to find Shimano RD 2300 or 2400 to buy. I have only see ‘out of stock’.

What rear derailleur should I buy?

https://www.wiggle.co.uk/shimano-acera-m360-rear-mech-78-speed/

Is that derailleur compatible since it is a Shimano and for an 8-speed?

 

[LemonJuice]

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/

I think I’m overthinking the rear derailleur compatibility aspect when it comes to buying a new rear derailleur.

https://www.wiggle.co.uk/shimano-acera-m360-rear-mech-78-speed/

Am I right in thinking that the rear derailleur I linked to will be compatible since it’s a Shimano and reigned for an 8-speed?

Am I right in thinking that the numbers 2300, 2400, etc, just refer to the models of the rear derailleur and don’t change the compatibility as long as the rear derailleur is the same make and designed for the same speed?

 

[C R]

I think I’m overthinking the rear derailleur compatibility aspect when it comes to buying a new rear derailleur.

https://www.wiggle.co.uk/shimano-acera-m360-rear-mech-78-speed/

Am I right in thinking that the rear derailleur I linked to will be compatible since it’s a Shimano and reigned for an 8-speed?

Am I right in thinking that the numbers 2300, 2400, etc, just refer to the models of the rear derailleur and don’t change the compatibility as long as the rear derailleur is the same make and designed for the same speed?

Yes, that will be compatible, but you've been told several times, do you know that you need it?

 

[LemonJuice]

Yes, that will be compatible, but you've been told several times, do you know that you need it?

Sorry, I just want to make sure that I’m understanding the compatibility derailleurs.

http://www.jtekengineering.com/shiftmate/shiftmate-compatibility-charts-choices/

So, am I right in thinking that Shimano 9-speed shifters are compatible are compatible with any Shimano 8-speed rear derailleur?

Or, does it have to be part of the Claris groupset?

I thought road bikes used short cage rear derailleurs, the rear derailleur I linked to is a long cage.

I’ve found a derailleur I like.

https://bike.shimano.com/en-EU/product/component/claris-r2000/RD-R2000-SS.html

Would that be compatible? I think so, I just want to double check.

 

[C R]

Sorry, I just want to make sure that I’m understanding the compatibility derailleurs.

http://www.jtekengineering.com/shiftmate/shiftmate-compatibility-charts-choices/

So, am I right in thinking that Shimano 9-speed shifters are compatible are compatible with any Shimano 8-speed rear derailleur?

Or, does it have to be part of the Claris groupset?

I thought road bikes used short cage rear derailleurs, the rear derailleur I linked to is a long cage.

I’ve found a derailleur I like.

https://bike.shimano.com/en-EU/product/component/claris-r2000/RD-R2000-SS.html

Would that be compatible? I think so, I just want to double check.

Short and long cage is related to the size of largest sprocket, in general, if you want a large sprocket at the back, say above 30T you will need a longer cage to take the slack of the extra length of chain needed.

Re eight and nine speed, I don't think you can mix, but other people with more experience will be able to comment.

 

[jay clock]

I think I’m overthinking

couldn't resist it. Sorry

 

[LemonJuice]

Yes, that will be compatible, but you've been told several times, do you know that you need it?

Short and long cage is related to the size of largest sprocket, in general, if you want a large sprocket at the back, say above 30T you will need a longer cage to take the slack of the extra length of chain needed.

Re eight and nine speed, I don't think you can mix, but other people with more experience will be able to comment.

I’ve ordered an 8-speed casette and chain.

https://winstanleysbikes.co.uk/shimano-claris-rd-r2000-8-speed-rear-derailleur

Is that rear derailleur fine?

 

[C R]

I’ve ordered an 8-speed casette and chain.

https://winstanleysbikes.co.uk/shimano-claris-rd-r2000-8-speed-rear-derailleur

Is that rear derailleur fine?

It depends on the cassette.

 

[LemonJuice]

It depends on the cassette.

https://winstanleysbikes.co.uk/components/drivetrain/cassettes/sram-pg850-8-speed-cassette

I bought the 12-26T, the same as the original.

 

[C R]

https://winstanleysbikes.co.uk/components/drivetrain/cassettes/sram-pg850-8-speed-cassette

I bought the 12-26T, the same as the original.

Short cage will be fine with that cassette, but again, do you really need a new derailleur?

 

[LemonJuice]

Short cage will be fine with that cassette, but again, do you really need a new derailleur?

I don’t think so. But, I’m a perfectionist and I think a brand new cassette and a brand new chain with a used rear derailleur will look odd so I’m going to get a new one.

 

[C R]

I don’t think so. But, I’m a perfectionist and I think a brand new cassette and a brand new chain with a used rear derailleur will look odd so I’m going to get a new one.

Cassettes and chains are consumables, derailleurs are not.

 

[Ajax Bay]

I’m a perfectionist and I think a brand new cassette and a brand new chain with a used rear derailleur will look odd so I’m going to get a new one.

This is complete b****ks - you're confusing perfection with perception. You don't need a new RD. The "brand new cassette and a brand new chain" with be 'used' and dirty after your first ride and noone will be able to tell or gaf.
Bicycle-rear-hub-compatibility
Think on these matters:
1) Have you got a chain the right length?
2) Is its colour going to suit the frame?
3) Is your hanger straight (make sure the bike shop commits to check this)?
4) Have you got a second bottle cage? (of a colour which matches the red frame)?

 

[DSK]

This thread takes some keeping up with...
LJ what are you buying from ebay now?
I'm just going to wait and see the update once the bike is collected from the LBS.

 

[Ajax Bay]

He's bought an 8sp chain and an 8sp cassettee (12-26; I'd have gone for a Shimano HG50, 8 speed, 11-28t (11-13-15-17-19-21- 24-28) personally but OP didn't seek advice on that ) and looking to buy a RD-2000 (Claris) from Winstanley Bikes. This RD is a step down from the perfectly functional RD his brother's Boardman has fitted at present (and which he's cleaned). LBS appointment is on 27th. If I was the LBS I would include corkage in my bill. Don't hold your breath @DSK.