# New Chain now grinding feel



## shjbrown (Nov 16, 2010)

Hi,

IGH newbie here.

I just installed a new chain (NX-10) on my Giant CRX City Pro. Once installed, the drivetrain felt terible, with a grinding feel. At first I thought the chain was too tight, but now have loosened it signifigantly (with the eccentric BB) and it feels even worse. Any torque and it feels like it is grinding. I can feel it through the pedals and hear a noise. Almost just like when the chain is much too tight, but it is so loose it will almost de-rail.

I checked the length before install and removed links on the new chain to match. The new chain was about 1/2" shorter due to stretch of the old one, as expected. 

I am at a loss of what I could have done wrong.

Thanks for any help.


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## shjbrown (Nov 16, 2010)

Should have mentioned it runs an Alfine 8-speed and has about 5000km on it.


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## shjbrown (Nov 16, 2010)

Ah ha! Turned out it was the rear sprocket was worn. Loosening the chain made the links line up even worse and therefore made it sound worse.

Lesson learned to check the rear sprocket when replacing the chain, even on a single speed drive train...


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## bikeisbetter (Aug 15, 2009)

To be honest, it doesn't make sense to replace the chain leaving the old rear sprocket/cassette in place at all. 

The old sprocket is worn, the new chain is tight. Instead of spreading the load on every link of the chain being in contact with the sprocket teeth when in use, you concentrate the load on a single link/teeth pair at a given time.

This is probably the best method for shortening bicycle chain service life known to the mankind, also one of the most decent examples of what false economy is.


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