Rear Derailleur mech and chain broke....

[ray316]

l have been having problems with my specialised racer the last couple of days, when l put pressure on the pedal or going up hill the chain was coming off.
Anyway today l went out on the bike and the chain came off twice before a third time when the bike locked up with the chain coming off and the derailleur mech swung up .
I was going slow lucky enough so clipped out the pedal quickly.
On close inspection the wheel was out the bracket so it could of been worse.
Anyway the derailleur hanger was bent so l had to snap it off and so l could wheel it home.
So now l need a derailleur mech , new cable as l cut that at the derailleur mech and a new chain.

Can someone tell me can l use any derailleur mech, the one l have at the moment is shimano 105.
Anyone have links to the cheapest one l could use.
Can l buy any gear cable for the derailleur.
One last question , how hard is it to fit a derailleur mech , cable and set it up.
Oh also need to get a new chain.
Help , advice and information appreciated....

 

[tommaguzzi]

Reading your post makes me think you should take it to your local bike shop and let them do the repair.

 

[Ajax Bay]

take it to your local bike shop

You probably did this damage by trying to cycle (ie put 'power' through the drive train) with the wheel axle not secure in the drop outs. That's why the chain kept coming off.
Go to your LBS. You'll need a new hanger - and your LBS is the best place to get one of those (there are hundreds of different designs and are rather unlikely to have in stock but can make sure you get the correct one: take the broken bits in). They can also show you how to work the Quick Release lever so the axle of the wheel is fixed securely in the drop outs. Why do you think the derailleur is unservicable? How is it broken? Was the chain actually damaged? How can you tell? Your LBS will also sell you a gear cable (road bike) and a new chain, if you need one (need to know number of sprockets in the cassette on the rear hub or the serial number of the right hand shifter (under the rubber hood eg ST-5700)). Edit: I see from last week's 'I need a new chain' thread that your bike is 9 speed so ST-5500, say.
To replace the cable, release the tension in the shifter (STI) (as if you're dropping to the top gear (smallest sprocket)) before trying to remove the cable from the STI. Note how it comes out and insert the new one accordingly. To index the gears, google index rear gears and take your pick.The Bike Guy ones are generally easy to understand.

 

[ray316]

Well not sure if derailleur is unusable but the hanger definitely wants replacing as does the cable.
The chain like l did mention in a earlier post wanted replacing and l took it off when l got home and started taken links out thinking l could use the bike as a fixed gear for now but the chain seems to slack so now l don't know what length l need to line a new chain to the old chain... is there a way to set up a new bike chain without knowing the original chain length.

I have seen some derailleur on line , medium 28-32T and short 23-28T , can someone tell me what this means and which was would l need for my 9 speed .

 

[Lozz360]

I have seen some derailleur on line , medium 28-32T and short 23-28T , can someone tell me what this means and which was would l need for my 9 speed .

It's referring to the number of teeth on the biggest cog of your cassette. More teeth = bigger diameter cog. So if your biggest cog has 25 teeth then a short derailleur would work but a 32 toothed cog would require the medium.

 

[Ajax Bay]

Do not concern yourself with your rear derailleur (RD) at this stage.The three items you surely need are the correct hanger, a gear cable for a road bike and, sounds like, a 9sp chain. Google "Sheldon chain length" to discover how to determine how long the chain needs to be. I truly recommend your LBS is your first port of call (@tommaguzzi - you were spot on) and they will also be able to judge whether the RD is fecked, and may be prepared to cut a chain you buy from them to the correct length. You can't use your bike as a fixed, at least not with the level of mechanical expertise that is evidenced so far. @derrick - I hope this meets your 'helpful' threshold.

 

[ray316]

Thanks for the replys and advice on taking it to my LBS, but l believe with the right information and advice l can repair it myself (at least have a go) as l'm quite mechanically minded on cars just not worked on bikes but if pointed in the right direction so l'm following the right instructions it will give me good experience for future problems..
Worth a try ..

 

[ray316]

I have took note of the advice given and will get a hanger, chain and cable.. Thanks

 

[Ajax Bay]

Best of luck, especially getting the correct hanger. I am not suggesting your get the LBS to do the work, btw, but I think they will help with the parts you need and "point you in the right direction". Do let us know how you get on.
Hanger maybe £20; chain £13; cable £3. 20, 20 and 5 in LBS, but will come with priceless advice.

 

[S-Express]

Sprocket - not 'cog'

 

[Lozz360]

Sprocket - not 'cog'

You're right. I now know the difference. Won't confuse the two again.