8-speed vs. 9-speed chainrings

drewski said:

Are 8-speed and 9-speed chainrings that different? Wider teeth? Will
they end up with bigger gaps between the rings when installed?

OK, here's some background so you know where I'm coming from . . . my
trusty 8-speed Deore XT rear deraileur has bit the dust so I'm thinking
of changing over to 9-speed for my MTB. Do I really need to change my
chainrings to '9-speed' versions too? Or can I just change cassette,
chain, shifter, deraileur?

You need only 3 things:

1. Shifters

B. Cassette

III. Chain

Your present derailers ought to work fine if they're otherwise in good
shape.

As to the chainrings, this is a Frequently Aske Question to which I have
a canned boilerplate response, viz.:

There is a lot of confusion about the compatibility of narrow 9-speed
chains with older cranksets. Shimano says you should replace the inner
chainring(s) with specially designated 9-speed ones, but then they're
all too eager to sell you stuff, whether you need it or not.

Shimano is also concerned about clueless users. The worst-case scenario
is that you will be riding along with the bike in its highest gear
(large front, small rear) and then for some bizarre reason shift down in
front before downshifting in the back. (There is no shift pattern in
which it is reasonable to shift in this sequence.) If you _do_ shift
this way, there's a small chance that the chain might "skate" over the
edges of the teeth for maybe half a turn.

In practice this "problem" almost never materializes. Many, many
cyclists are using 9-speed chains with older cranksets and having no
problems whatever.

My advice is to go ahead and upgrade your drivetrain, but leave the
crankset alone until you've tried it out with the new chain. Most
likely, you don't need to do anything to it.

All the best,

Sheldon

Sheldon "Insert Nickname Here" Brown
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quote='Sheldon Brown'drewski said:

Are 8-speed and 9-speed chainrings that different? Wider teeth? Will
they end up with bigger gaps between the rings when installed?

OK, here's some background so you know where I'm coming from . . . my
trusty 8-speed Deore XT rear deraileur has bit the dust so I'm thinking
of changing over to 9-speed for my MTB. Do I really need to change my
chainrings to '9-speed' versions too? Or can I just change cassette,
chain, shifter, deraileur?

You need only 3 things:

1. Shifters

B. Cassette

III. Chain

Your present derailers ought to work fine if they're otherwise in good
shape.

As to the chainrings, this is a Frequently Aske Question to which I have
a canned boilerplate response, viz.:

There is a lot of confusion about the compatibility of narrow 9-speed
chains with older cranksets. Shimano says you should replace the inner
chainring(s) with specially designated 9-speed ones, but then they're
all too eager to sell you stuff, whether you need it or not.

Shimano is also concerned about clueless users. The worst-case scenario
is that you will be riding along with the bike in its highest gear
(large front, small rear) and then for some bizarre reason shift down in
front before downshifting in the back. (There is no shift pattern in
which it is reasonable to shift in this sequence.) If you _do_ shift
this way, there's a small chance that the chain might "skate" over the
edges of the teeth for maybe half a turn.

In practice this "problem" almost never materializes. Many, many
cyclists are using 9-speed chains with older cranksets and having no
problems whatever.

My advice is to go ahead and upgrade your drivetrain, but leave the
crankset alone until you've tried it out with the new chain. Most
likely, you don't need to do anything to it.

All the best,

Sheldon

Sheldon "Insert Nickname Here" Brown
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Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com[/QUOTE]
Sheldon's answer is right (of course), but he missed a small element.

The original poster said that his rear derailleur (XT) has bitten dust.

Well, you can keep your 8-speed drivetrain if you want to. All Shimano derailleurs (except the first crop of DuraAce) are 7- 8- and 9-speed compatible. It means that your old derailleur was already 9-speed compatible... and that the new XT (or LX or...) derailleur is compatible with your existing 8-speed set-up, and will be compatible to 9-speed if/when you decide to switch.

Adding relevant personal experience to Sheldon's answer:

Drewski, I am riding with a Turbine LP crankset with stock 8 speed
rings, with all SRAM 9 speed gear and it works beautifully. I am
certain 9S Shimano will behave exactly the same. I heard a lot of
warnings from "experts" about how I would jam the chain between rings
but it proved to be a lot of nonsense. I have been riding this set up
for over four years, with exactly zero jams.

Good Luck,

Terry

Sheldon Brown said:

drewski said:

Are 8-speed and 9-speed chainrings that different? Wider teeth? Will
they end up with bigger gaps between the rings when installed?

OK, here's some background so you know where I'm coming from . . . my
trusty 8-speed Deore XT rear deraileur has bit the dust so I'm thinking
of changing over to 9-speed for my MTB. Do I really need to change my
chainrings to '9-speed' versions too? Or can I just change cassette,
chain, shifter, deraileur?

You need only 3 things:

1. Shifters

B. Cassette

III. Chain

Your present derailers ought to work fine if they're otherwise in good
shape.

As to the chainrings, this is a Frequently Aske Question to which I have
a canned boilerplate response, viz.:

There is a lot of confusion about the compatibility of narrow 9-speed
chains with older cranksets. Shimano says you should replace the inner
chainring(s) with specially designated 9-speed ones, but then they're
all too eager to sell you stuff, whether you need it or not.

Shimano is also concerned about clueless users. The worst-case scenario
is that you will be riding along with the bike in its highest gear
(large front, small rear) and then for some bizarre reason shift down in
front before downshifting in the back. (There is no shift pattern in
which it is reasonable to shift in this sequence.) If you _do_ shift
this way, there's a small chance that the chain might "skate" over the
edges of the teeth for maybe half a turn.

In practice this "problem" almost never materializes. Many, many
cyclists are using 9-speed chains with older cranksets and having no
problems whatever.

My advice is to go ahead and upgrade your drivetrain, but leave the
crankset alone until you've tried it out with the new chain. Most
likely, you don't need to do anything to it.

All the best,

Sheldon

Sheldon "Insert Nickname Here" Brown
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| This message has been sent to you using recycled electrons |
| exclusively. Please do not discard them after use, |
| send them along and help conserve these irreplaceable |
| sub-atomic resources for future generations. |
+-----------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

mgagnonlv said:

Sheldon's answer is right (of course), but he missed a small element.

The original poster said that his rear derailleur (XT) has bitten dust.

Well, you can keep your 8-speed drivetrain if you want to. All Shimano derailleurs (except the first crop of DuraAce) are 7- 8- and 9-speed compatible. It means that your old derailleur was already 9-speed compatible... and that the new XT (or LX or...) derailleur is compatible with your existing 8-speed set-up, and will be compatible to 9-speed if/when you decide to switch.

thanks for the responses. if the skating is the only issue i don't feel as nervous. i was wondering about chain jamming between rings and me getting ejected onto rocky terrain!!

so if i read this thread right, this means, if i can find any well functioning Shimano MTB deraileur, i can use that, but i still need to get 9-speed shifters so that it will be compatible with a 9-speed cassette spacing?

so what, then, is the advantage of the current XT vs. what i had? more durable? lighter? asthetics? other highly debatable shimano marketing schpiel? maybe too philosophical a question . . . at least it's not planned obselesence, right?

Quoted message said:

thanks for the responses. if the skating is the only issue i don't feel
as nervous. i was wondering about chain jamming between rings and me
getting ejected onto rocky terrain!!

so if i read this thread right, this means, if i can find any well
functioning Shimano MTB deraileur, i can use that, but i still need to
get 9-speed shifters so that it will be compatible with a 9-speed
cassette spacing?

so what, then, is the advantage of the current XT vs. what i had? more
durable? lighter? asthetics? other highly debatable shimano marketing
schpiel? maybe too philosophical a question . . . at least it's not
planned obselesence, right?

I am using an 8 speed XTR crank/rings (1st generation 5 blot) with 9
speed chain/cassette/shifters. The crank has seperate spacers (not
part of the crank arms) for the small ring. I had to swap out the
spacers for thinner ones when I went to 9speed. The chain could jam
between the small ring and the arms, and it did not shift well. I do
not belive this is an issue with your cranks. Otherwise, the mid and
outer 8 speed rings work fine.

If you like your current 8 speed setup and it works fine for you, I
would get a 9 speed rear deraileur and save a bunch of cash. It will
work just as well as your old 8 speed, maybe better. There is no
advantage to going 9 speed except if you need t use the 12x34 cassete
that has a lot of well spaced low grears. This is the reason I went 9
speed from my 7 speed (I skipped 8 speed).

The downside to 9 is: A lot of $$$, and the narrow 9 speed chain may
not be as strong as the old 8 speed (so far, so good). The new 9 speed
does not feel as solid as my old 7 speed. I never used 8, so I can
not compare it to the 9.

drewski said:

thanks for the responses. if the skating is the only issue i don't feel
as nervous. i was wondering about chain jamming between rings and me
getting ejected onto rocky terrain!!

I am currently using a Sram PC-59 9-speed chain with a 1971 vintage
Campy crank with no problems whatsoever. There is no reason to change
chainrings - provided they aren't worn out ;(

Quoted message said:

so if i read this thread right, this means, if i can find any well
functioning Shimano MTB deraileur, i can use that, but i still need to
get 9-speed shifters so that it will be compatible with a 9-speed
cassette spacing?

Yes - to convert from 8 to 9 speeds, you need a new cassette, rear
shifter, and chain.

Jack Fortune