stumpypete

I hope this isn’t a stupid question, but I’m looking for some help concerning chain rings:

I currently have an 8 speed Trek 9800 that needs to have some drive train components replaced. I'm pretty mechanically inclined and plan on doing the work myself. I understand that a 9 speed chain is thinner and that the cassette spacing is thinner compared to 8 speed. Are there specific 8 vs. 9 speed chain rings (not including 4 bolt vs. 5 bolt and bolt diameter)?

Thanks

HillRider

9-speed (and 10-speed) chainrings are slightly closer together to keep the narrower chains from dropping between the rings if shifted under a large load. Shimano says you can use an 8-speed crank with 9-speed chains if you shift "sitting down", i.e. under light load.

You can also convert an 8-speed crank to 9-speed by replacing just the inner (or middle on a triple) chainring with a 9-speed ring which is offset slightly closer to the large ring.

stumpypete

Here's my problem: How do you tell if your buying an 8 or 9 speed chainring? I at least need to replace my center chainring, sticking with 8 speed, I'm not looking to convert to 9 speed. I've not seen any web dealer idenifying whether your buying an 8 or 9 speed chainring, cassettes yes, but not chainrings.

One other thing I forgot, this is for a mtb with LX components.

HillRider

I'm not sure about MTB rings but the 9-speed Ultega 42T and 39T middle/inner road chainrings I have are stamped "9S" on the inner face near one of the bolt holes. The 8-speed and earlier rings i have don't have any "speed" indicator markings.

I expect MTB rings are similarly stamped if they are 9-speed.