Rear mech advice

[DRHysted]

Following my examination of the tarmac last week, my rear mech is touching the spokes on the inner two gears (sort term bodge was to lock out the inner three gears using the adjuster screws).
The groupset is Shimano 2300 (8 speed rear, triple front), so I was intending to upgrade at a latter date to 105.
If I was to get a 10 speed 105 rear mech would it work with my current 8 speed 2300 shifter and chain?
Given I run a triple, would I need long cage, or would a medium cage cope?
I'm not used to modifying bikes so is this a possibility?

 

[MrJamie]

Im not sure if you're implying you're upgrading because of it being broken, but its probably just the hanger which is bent and needs replacing anyway.

No idea about the upgrade though, other than the cage size depends on the range between largest and smallest at both front and back

 

[Psycolist]

I'm forever messin about with different mech setups and gearing options. In my experience, long. medium or short cage rear mechs are all going to work, so long as you are prepared to fiddle and fettle long enough, but what wont work is 7-8 speed chain running on a set of derailleur jockies &/or chain rings intended for 9-10 speed chains and visa-versa. And before any 'experts' chip in, this is my experience, not out of a text book.

 

[HovR]

If I was to get a 10 speed 105 rear mech would it work with my current 8 speed 2300 shifter and chain?
?

No, unfortunately that won't work. You'll need a new 10 speed Shimano compatible shifter and chain. By the sounds of it you'll also need a new derailleur hanger (which will be specific to your model of bike) as well, as the current one is bent.

 

[DRHysted]

Thanks folks.
I did look at the hanger, but it appeared undamaged. I'll take it off tomorrow and pop to the shop for a replacement.

I do intend upgrading the groupset at a latter date, as the 2300 is fickle in it's settings, and I find the sweep for gear changes just a bit too far.

Thanks for the advice, stopped me wasting money (for now).

 

[Drago]

It WILL work. My Pinnacle Dolomite is running a 2012 105 rear mech on a 2012 2300 8 speed cassette and it works perfectly.

The jockey wheels on the 105 are plain and work with normal Shinano chain of 8, 9 and 10 speed varieties. It's the latest 10 speed 105 upwards cassette that works best with the new unidirectional 105 groupsets chain, not the mech.

 

[HovR]

Sorry, I assumed that the OP was also changing the derailleur and cassette to 10 speed, as he made no mention of keeping the cassette whereas he did mention keeping the shifter and chain.

Drago is right in that if you stay with the 8 speed cassette then your 8 speed shifter and 105 rear mech will work, however if you upgrade both the rear mech and cassette to 10 speed then you will need to also upgrade your shifter and chain.

The rear mech is just a 'slave unit', and will do whatever the shifter tells it to do - So it's important you have the right shifter!

My mistake, didn't read the original post properly.

 

[Graham]

Why is your cage touching the spokes? I ask because when I came off a few weeks ago I snapped the hanger and bent the cage. I bought a new hanger and then used an adjustable mole wrench to straighten out the cage. It's not perfect, but it's good enough so that I don't have to shell out for a new mech.

(also, I read somewhere that the 'top end' stuff (105 and above) is more fragile that the lower end stuff (what I've got!) to save weight)

 

[DRHysted]

Well the new mech hanger did the job, even holding the new and old against each other I couldn't see anything wrong. But on the bike job done.

Now I just need the shoulder to stop aching and I'll start riding again.

 

[Psycolist]

Excellent news, glad y'sorted