Derailleur advice please

[Fric]

Just had my sons MTB returned after a theft, the rear derailleur was missing, I am going to purchase another but not sure which one, bike is 7 speed and the original was shimano acera , there are quite a few to choose from so not sure. Would any shimano 7 speed do, ( the crank has 52 teeth, not sure if that makes a difference)

Appreciate any help/advice

thanks Fric

 

[Ajax Bay]

Chainring tooth number makes no difference. Yes - any 7 speed MTB (as opposed to road) type will do, and a fair few others - the cable pull is the same.

 

[Fric]

Thanx Ajax, appreciate your prompt reply.

 

[Cycleops]

The rear freewheel is the one you need to count, the biggest one for number of teeth, this needs to be within the range of the derailleur which should be stated on the sales site.
I assume there is a lug on the dropout that it screws into, it's called a hanger that slots into the frame and if the thieves took it as well you'll need on of those too.

 

[Fric]

Thanks
the hangar is still there, I will count teeth as you suggest

cheers

 

[Ajax Bay]

Unless the OP has a silly large large sprocket (and I suspect "my son's MTB" will have a 'normal' range cassette or freewheel block one eg 12-34), all 'normal' MTB RDs will handle it. The Shimano Acera RD did.

 

[Fric]

Thanks

 

[Sharky]

How did they manage to remove the derailleur?
Did they split the chain and do you still have it? Have you lost any links?
Not wishing to worry you, but if needing a new chain, you might need a new cassette as well, plus the tools needed. But one step at a time and replace the derailleur first.

Good luck

 

[Fric]

Thanks for tip. As I have never or had the inclination to steal any parts off a bike I have no idea how they took it , seems silly to me considering the low value of the item. I had to collect bike from police station and the chain was broke the split link is missing but I will get new chain anyway.
As you say, see how it goes with just new derailleur and chain.

cheers fric