Derailleur and Chain
Front Derailleur
No choice here, the Shimano XT derailleur is compatible with the compact drive crankset whereas the XTR derailleur isn't.
Rear Derailleur
According to mtbr.com, the Shimano XTR seems to be the favorite.
The concept of "CAPACITY" Posted by Eeny Bear
There are at least two "capacity" references at play in the drive-train. Min/Max capacity is a front derailleur characteristic and Total Capacity is a rear derailleur characteristic. I'll define both with a bit of detail.
Why do you care? If you are building a drive-train you should know the impact of the choices you make on the whole system. In order, here are the decisions at hand:
- pick your rings
- pick your front derailleur that works best (min/max capacity)
- pick your cassette
- pick the rear derailleur that can accommodate your prior choices. (tot. capacity)
If you go to extremes you may get stumped on #4 because of a little thing called "total capacity". Let me tell you about min/max capacity first and then I'll follow-up with total capacity.
Min/Max CAPACITY
There are three numbers associated with a front derailleur that define its capabilities:
- Top gear teeth (min/max tooth count)
- Top/middle minimum capacity
- Top low max. capacity
Let's use the 1999 XTR FD-M952 as an example:
- Top gear teeth (min/max tooth count) = 46/48T
- Top/middle minimum capacity = 12T
- Top low max.
capacity = 22T
This tells you that this derailleur will work best when the big ring is at least 46 and no more than 48 teeth. If you choose 46 teeth then the middle ring can be no more than 34 teeth and the granny can be no less than 24 teeth. It's no coincidence that this is the common XTR chainring group 24-34-46. If you choose 48 teeth then the middle ring can be no more than 36 teeth and the granny can be no less than 26 teeth. You can see that a 48-34-26 would meet the test but a 48-34-24 would fail on the granny spec.
TOTAL CAPACITY
Total capacity is a reference to the rear derailleur and defines the capability of the derailleur to take up the slack chain for given extremes in gearing on the bike (i.e. small/small). A longer cage will be more capable of taking up the slack and thereby accommodating more gear combinations.
To know what the total capacity number value is:
1. subtract the small chainring from the large chainring
2. subtract the small rear cog from the large rear cog
3. add the difference from the two equations
this sum will give you your total chain wrap capacity.
Example: 24/34/46 chain-rings and a 11-30 cassette (46-24= 22) + (30-11=19) = 41T total capacity
The 1999 XTR SGS has at least a 42Tcapacity (43 in the non-rapid-rise) so it will work fine.
Here's an example where derailleur wouldn't work well in the extreme gears.
e.g. there wouldn't be enough chain to shift into big/big and things might break.
Another example: 24/34/46 chain-rings and a 11-34 cassette (46-24= 22) + (34-11=23) = 45T total capacity
The 1999 XTR SGS has at least a 42Tcapacity (43 in the non-rapid-rise) so it will NOT work fine. However, you could fix this by reducing your large ring to 44 teeth, for example
Derailleur cable housing
Since I have disk brakes, there is no need to purchase a cable set (derailleur & brake cable/housing). In addition, the shifters come with derailleur cables, so only derailleur cable housing is necessary. Even though they look identical, cable housing is constructed differently for brakes and derailleurs. Brake and derailleur housing are NOT interchangeable.
Cable housing come in 5 ft lengths and need to be cut to fit with a special cable cutter which cuts without crushing the cable.. Reviews on mtbr recommended purchasing the Shimano cable cutter.
Ferrules are end caps for cable housing, grubs are end caps for the derailleur cable purchase a bunch of these to prevent fraying of the ends.
Chain
A 9 speed bike needs a 9 speed specific chain. The Sachs chain with the powerlink seems to be the winner. I picked the cheapie PC 59 Sachs 9 speed chain because chains are supposed to be replaced often. Wrap chain around largest chainring and largest cog without going through the derailleurs. Note where link where chain overlaps, chain should be joined at next FULL link (ie 1").
Powerlink removal posted by Mike T ...
Powerlink info from SACH's tech rep Edmund Nasjleti -
"To take it apart: Get the chain off the chainrings to remove derailer tension. Make a loop of chain, about 7 or 8 links long, with the Power Link in the middle. Hold on to it with your fist.
Your other hand is free. Using just your index finger and your thumb, lightly touch the flat side plates of the Power Link. The two plates should move in a small amount, almost imperceptable. Now gently push the two riveted points (where the pin is riveted into the plate end) towards each other.
The pins should slide towards each other, and allow you to release the pins through the larger holes in the side plates. This is so easy, you won't believe it's the way to release the Power Link."
Cassette
The XT cassette is both inexpensive and strong. The mtbr.com favorite. I purchased the 11-32 cassette. Use a wheel skewer to hold the lockring tool in place. Wrap the chain whip around the middle cog. Torque to 40 Nm.
Tip: Wear work gloves to prevent injury in case of wrench slippage.
Distance, in inches, travelled in one pedal stroke
Teeth on 11-32 XT cassette 44 chainring 32 chainring 22 chainring 32 not usable 82 57 28 129 94 63 24 151 110 75 21 170 126 85 18 201 145 101 16 226 163 113 14 258 189 129 12 298 217 151 11 327 239 not usable
It seems to me that its a little silly to have the exact same gear ratios for multiple chainring/cassette cog combinations. Sort of defeats the purpose of 9 speed. Maybe 11-34 would have been a better choice for a rear cassette.