Rear Mech replacement options?

[Colin]

I’ve managed to smash the rear derailleur off of my  PRO~FLEX 4000se.
My question is what is the best matching current rear mech model to replace it with? (Shimano or SRAM)

It’s a Shimano Deore XT RD-M750 with an 86mm long cage (Jockey wheels centre to centre)
I’ve got an 8 speed 11 to 34 teeth rear cassette (Megarange) and 22-32-42 front Chainrings
And a KMC 8 speed chain.

Will a 9 speed mech work with this set up or is the cage and jockey wheels too narrow for an 8 speed chain? Or can I just change to a 9 speed chain? (I’ve just replaced the chain as chain failure was the cause of the mech jamming and smashing)

I've also asked Chain Reaction for their advice.

Just had a smashing week in the west coast of Scotland, took the bikes with us and did a few of their excellently marked out forest trails. Managed to just about destroy the drivetrain on the 4000 though! Replaced the bottom bracket as it was making a grinding noise, then the chain broke and jammed the rear mech and tore it off! replaced the chain and put a cheap mech on and then the front derraileur cable sleeve burst so no front gear changing!  And now the freewheel sounds a bit noisy and has some play in it and I think the teeth have worn out so the chain isn't sitting perfectly tight!
I think this will prove to be expensive!

Col.

[Colin]

A bit more research and I’ve realised that the M750 is a 9 speed mech so it's obviously not the original part, also it’s a SGS long cage model I’ve got.

http://www.orangebikes.co.uk/technical/SHIMANO/GEARS/RD_M750.PDF

So I guess the 9 speed question is irrelevent?

Still interested in what's the best replacement.

Col.

[mizunole]

I have had XT, LX, XTR and am running  9,8 and 7 speeds on my current rides.  The only difference in the megarange ders. is setting the range screw ( I currently have an LX megarange on a 21 speed bike) so definately go with the 9 speed to futureproof it if needed.  Other than weight and bling I do not notice a considerable difference between LX and XTR.  My XTR 960 was bought used, my LX came new so there may or may not be a difference in spring tension, but I can't feel the difference.  The sealed pullys on the XTR may make a difference, but it is certainly relative to price.

Keep in mind people are realllllllllly finicky about Rapid rise Shimano.  I personally like it, some hate it, some do not care.

Remember the accuracy of the shift comes from the shifter not the der.

Hope this helps