The LBS is blowing out XTR 8 speed cogsets. The low price, combined with the wrench there wistfully recalling the days of 8 speed cogsets and how smooth the shifting was on them makes me interested in purchasing one for my mtb. I also read about an mtb pro running an 8 speed cogset, primarily for chainline reasons.
Would my 9 speed chain work?
What would i have to do, tuning wise, to make my 9 speed shifters work on 8 cogs?
Thoughts?!
Funny, you have to do nothing and the shifting is awesome. I use 8 speed cassettes exclusively on my HED-3 with 9 speed shifters, mainly cause I have a whole whack of 8 speed cassettes and things work fine, often better than 9 speed…and my chains are 9 speed.
Dev
Is there anything that has be done to the derailleur? Ie - my 9 speed has 9 ‘clicks’ to it, would i end up throwing the chain off at all?
bump, cause i’m really interested.
The derailleur isn’t responsible for indexing - the shifter is. You may need to adjust the limit screws on the derailleur to keep from throwing your chain into your spokes, but that’s it as far as the derailleur is concerned. I’m very surprised that Paul is able to run an 8 speed cassette with 9 speed shifters, but he’s also talking about a road setup which doesn’t necessarily mean that you’ll have the same results on your MTB.
Nipsy,
I’ve been doing this for quite some time. As someone else pointed out - the key is to set the limit screws on your rear derailleur.
You can’t control the fact that the shifter has 9 clicks - so what you end up with if you actually shift the ninth time is a slightly slack cable. Because you’ve set the limit screws - the cable will move but the derailleur will not.
Would my 9 speed chain work?
What would i have to do, tuning wise, to make my 9 speed shifters work on 8 cogs?
Thoughts?!
Yes
You have two choices. Use an old Dura-ace rear derailer (pre 9-speed), or use an alternate cable attachment method. See the “Any 9-speed shifter” and “8-speed cassette” entry in this table http://www.sheldonbrown.com/dura-ace.html#indexing
More questions - so, even though my 9 speed shifter is indexed for a 9 speed cog, the amount of cable pull will still provide decent shifting? The cogs on an 8 speed cog are spaced the same as on a 9 speed cog?
whew!
No, the spacing between the two different cogs are different. The 8 speed has 4.8mm between the center to center of each cog while the 9 speed has 4.32mm c-t-c.
The sheldon brown reference says to attach the cable differently to the rear derailleur, which will change the amount of distance the derailleur moves the chain per shift.
Think of the shifting thing as a equal sided teetter-totter for a moment…If the end of the left side goes up and down 4 feet, then the end of the right side goes up and down 4 feet. But, if you chop the right side in half lengthwise, moving the left side up and down 4 feet now creates only 2 feet of travel on the shortened right side.
If I didn’t lose you there, that it how clamping the cable differently fixes the cog spacing issues.
ps. Good call on finding that Sheldon Brown link.
The LBS is blowing out XTR 8 speed cogsets. The low price, combined with the wrench there wistfully recalling the days of 8 speed cogsets and how smooth the shifting was on them makes me interested in purchasing one for my mtb. I also read about an mtb pro running an 8 speed cogset, primarily for chainline reasons.
Would my 9 speed chain work?
What would i have to do, tuning wise, to make my 9 speed shifters work on 8 cogs?
Nipsy - you are asking about MTB’s right? Some of the posts here seem to be referring to road bikes. Sorry my friend, it won’t work. 1. No - a 9 speed MTB chain is narrower than the cogs. The cogs on an 8 speed derailleir are thicker than those found on a 9, and the chains are built accordingly. It will be rougher shifting. Get an 8 speed chain - they’re cheap, and more durable. 2. Sorry again…the detents on 9 speed shifters are different than on 8sp. Think of it this way - both the 8 and the 9 cassette are the same width, but the shifter has to make one move 9 times in that given distance, and the other makes it move 8 times. You will always have some gears where the indent places the derailleur in the middle of a sprocket. Better example…Picture a 10 meter driveway. Now get two people with wet paint on their feet to walk this 10 meters, one guy in 9 evenly spaced steps and the other guys in 8 even steps. Will their ‘wet paint’ footsteps match up? No. Each step is a cog, so there you have your answer. The derailleur though, is fine. A derailleur is a derailleur. The wrench is right. 8 speeds shift WAY better than 9 speeds - everything has to be so finely tuned on a 9sp MTB that the moment you get a bit of cable stretch or dirt, the shifting is off. One more thing…stick with XT or LX cassettes…the cogs are stronger. XTR is lighter, but more prone to bending.
You came REALLY close to losing me there, but if clamping the cable differently helps, then i’ll try that. However, i notice that article refers repeatedly to dura ace, so it may not be an issue.
I don’t think the chains are any different for road or mtb. When you buy the 7700 chain, it is the chain for both the Dura Ace/XTR. As for the individual cassette cog widths and spacing, I have not come across any documentation stating that the road and mtn are any different. The IG cassettes are a bit different, but almost everything now is the HG (hyperglide).
I personally have used mountain cassettes on my road bike and road bike cassettes on my mountain bike without any change in shifting performace. Granted, I have never tried the mixing of 8 spd with 9spd shifting, but the Sheldon Brown article makes sense, and I would be interested in seeing if it does work. I would not necessarily dicount trying to see if your XTR thing wont work until you try.
You right about the chains…no difference in width between road and MTB. I didn’t mean to imply that there was. A 9 speed road cassette is compatible with a 9 speed MTB chain, and vice versa.
The problesm(s) is that
an 8 sp cassette is not compatable with a 9 speed chain. The actual cogs are too wide to fit into the narrower 9 speed chain.
a 9sp shifter is not compatable with an 8 speed cassette. Spacing of the indents is off, and this can’t be changed (it’s the actual indent wheel inside the shifter that determines the cable throw).
Sorry - won’t work. We used to fix this stuff all the time in the shop when Shimano 9 came out for MTB’s. Guys would buy their own parts, not knowing that they had bought 9sp for their 8sd rigs.
It’s a Shimano thing, and they’re purposefully built not to work together. That way, you need to buy the entire setup and they keep selling product.
BUT…pick up a set of 8sp shifters and a chain on ebay, and you’ll have a MTB that shifts better than most fo the race bikes out there.
Cool - thanks for that. Guess i’ll head back to the store
Nipsy
Looked up the cog widths for 8 and 9 speed. 8spd cogs are 1.8mm thick and 9spd cogs are 1.76mm thick. Not sure if that .04 millimeters is inside the tolerance range for the 9spd chain. The only thing I do know, is that the chain is .8mm narrower on the outside to outside measurement and that if you are using an 8spd crank with 8spd rings, the chain is most likely to fall inbetween the front chainrings when shifting in the front. Since you mentioned that you originally had a 9spd system, I am assuming you have a 9spd crank, and that will not be a problem.