K2 / Proflex Riders Group
General => Tech Forum => Topic started by: Colin on September 17, 2007, 05:22:48 am
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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.
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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.
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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