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-   -   8-speed/9-speed question... (https://www.bikeforums.net/bicycle-mechanics/113917-8-speed-9-speed-question.html)

Brad01 06-14-05 09:25 AM
8-speed/9-speed question...
 
Is it possible to run a 9 speed chain/drivetrain with a crank designed for an 8-speed on temporary basis without mucking something up??

sydney 06-14-05 09:34 AM
Originally Posted by Brad01
Is it possible to run a 9 speed chain/drivetrain with a crank designed for an 8-speed on temporary basis without mucking something up??
You can even do it long term.

Brad01 06-14-05 09:41 AM
Alright! Thanks a lot sydney!

Sheldon Brown 06-14-05 09:45 AM
Originally Posted by Brad01
Is it possible to run a 9 speed chain/drivetrain with a crank designed for an 8-speed on temporary basis without mucking something up??
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 [i]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.

Sheldon "Don't Believe The Marketeers" Brown
Code:
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|    Always store beer in a dark place        |
|                    --Robert A. Heinlein      |
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capwater 06-14-05 09:56 AM
On my beater, I replaced a 9 speed Tiagra triple crank with an older 8 speed 105 double, no problem many, many miles later.

Aw crap, forgive me Sheldon for answering the question after your expertise has already blessed his configuration. :D

sydney 06-14-05 09:57 AM
Originally Posted by Sheldon Brown
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 [i]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.

Sheldon "Don't Believe The Marketeers" Brown
Code:
+----------------------------------------------+
|    Always store beer in a dark place        |
|                    --Robert A. Heinlein      |
+----------------------------------------------+
In actual long term use, I had a '8 speed' shimano 600 crankset matched up with campy 10 speed with no issues at all. Several other 8/9/10 mismatches in cranksets have also resulted in no issues. As stated, Shimano plays the marketing game,and CYA. Campy does alot of the same.If you do it their way, you won't go wrong,but you will spend more money.

Brad01 06-14-05 10:05 AM
Wow, Thanks guys.
I'll still need to replace my crank eventually, the chainrings are not bolted, just rivited (Yuk) and it's flexy and sorta bent too...
Thanks again for your help.


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