Chainring compatability

[call_me_bruce]

Hi All,

I needed a new middle chainring for my 8 speed alivio crankset (I know, living the dream!) and the shop sent me a 9 speed one because they ran out of 8 speed ones (without checking with me first). Are they compatible?

I understand that the 8 & 9 speed chainrings are the same width as the inner dimension of 8 & 9 speed chains is the same, but will the shifting ramps etc on the 9 speed chainring work with the 8 speed chain working with an 8 speed chainring either side?

I found this:

http://www.rotorburn.com/forums/showthread.php?269783

Which indicates that it will work, but that was talking about was chaining all the chainrings as a set. I also found a forum on the net that said the gears won't change properly (I know shifting isn't as good anyway with cheap stuff, but I don't want to make it worse). I can send it back for a refund, but am happy to fit it if it will work so I can get back out there and ride.

Thanks very much for your help!

 

[pharmaboy]

They might be or not be compatible but not because of 8 sp versus 9 speed, there was a change from shimano in the tab depth, maybe 5 or 6 years ago, so the distance the ring mounted was different which if course stuffs up the ability to shift. So, age difference is a bigger problem than chain width (8 v9)

 

[call_me_bruce]

The equipment is all new (less than 1 year old) but I have no idea how old the design for the parts is.

 

[pharmaboy]

You are all good to go then.

 

[steve job's pancreas]

All I can offer is make sure you put on the right way round and you won't need to get out the dremel to grind things off it to make it fit and spend forever trying to get the chain to shift efficiently.

The joy of pre-owned bikes :loco::loco::loco:

 

[The Duckmeister]

Chainrings are the least fussy part of 8/9/10-sp. mashing, so it's unlikely you'll have any real issues. Sometimes the locating step on the spider arms can be a bit different between models, even though the BCD is the same, so you may need to do a little bit of filing on the inner edge of the ring's mounts if it doesn't quite sit on.

 

[moorey]

^
people won't tell you 8 and 10 are compatible.... Buuut,8/9 are compatible, and 9/10 are compatible, sooooo

As duck says, a little filing on some rings on some cranks is occasionally required, otherwise, go nuts.

 

[richie_gt]

I've just had a 9 speed chainring put on an 8 speed setup and it works fine!

 

[call_me_bruce]

Thanks to all for your advice. I tried it out and it's fine. Everything is running like a swiss...bike? No excuse for going easy on the climbs now!

Cheers again. Nice to have a think tank to tap into.