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XT front deraileur capacity(9 posts)

XT front deraileur capacityAndante
Feb 11, 2002 8:01 AM
I have a XT front Deraileur on my cyclocross/touring bike (Ritchey triple cranks). Currently I have a 46 large chainring, but often I spin this out. I would like to put a 52 or 53 on, but I am unsure what the tooth capacity on the deraileur is. Anyone know?
re: XT front deraileur capacity_Marty_
Feb 11, 2002 8:29 AM
it is a mtb front der.. but im guessing you could rig something up if your granny is big enough.. the total range would be the same.. just higher up... give it a shot.. if you cant go to a lerger small ring.. a 48 i think is the biggest you can go on the ring..
re: XT front deraileur capacityAndante
Feb 11, 2002 9:20 AM
They certainly sell chainrings in 50, 52, and 54 in the correct bolt pattern. I figured it would have more to do with the total tooth range capacity, which is what I am trying to find out. Yes, it is a MTB component, but also quite common on touring bike set-ups.
why not just go to shimano.com and see for yourselfstr8dum1
Feb 11, 2002 9:30 AM
it took more time to post and read than would be just to tyoe shimanos URL

copied without answers directely from shimano.com

Top Swing Action yes
Differential Plate Mechanisim yes
Rear Compatibility 9-Speed
Total Top-low Max. Capacity
Top-middle Min. Capacity
Top Gear Teeth
Cable Routing System top & bottom routes available
Chain Stay Angle degrees
re: XT front deraileur capacityChen2
Feb 11, 2002 11:08 AM
Something else to consider is the curvature of the derailleur rails. If you go to a 52 or larger I wonder if the road derailleur would be better.
-Al
re: XT front deraileur capacityRusty Coggs
Feb 11, 2002 11:46 AM
QBP catalogue says the xt is for 42 and 44 rings, and the xtr is for 46 and 48 tooth. They are usually good for a few more than spec.Max capacity for both is 22 teeth.A road type may shift better due to the cage length and curvature.Shimano use to say not to mix sti shifters and mtb front derailers, and mtb shifters and road derailers. No problem with dountube or barends.
re: XT front deraileur capacityChen2
Feb 11, 2002 1:47 PM
If you're looking for a way to run bigger rings you might consider what we've done to my wife's Trek 5220. We replaced the crank set and bottom bracket with the Campy Racing T triple with 50-40-30 rings, leaving the rest of the drive train and shifters Ultegra triple. It shifts just as well as when it was all Ultegra and the gear ratios fit her needs better. It still has the Ultegra front and rear deraillers. I'm calling it the "Shimangolo" drive train.
I suspect you will have better results if your crank set and front derailleur are all of the same type, all road or all mtn. I don't think it will shift well if you try to mix chain ring types.
-Al
re: XT front deraileur capacitySteve Bailey
Feb 11, 2002 3:55 PM
Among the many things you need to check would be can you raise the derailer up on the seat post a 1/2 inch or so. Sometimes the water bottle cage mounting bolts get in the way. That would be the 1st big question and would need to happen with bigger rings.

Beyond that, many questions:

1) What shifters ?. If using STI, you would want to stay with rings that are ramped and pinned as STI gets pissy without them.

2) What's the current crank BCD ?. If 110/74 ?. If so, bigger rings are available, but watch for that ramp/pinned thing....

3) If your current crank is 110/74, chances are you have an older XT derailer designed for standard mt. drive, not the current compact drive. Older Shimano front derailers had a range of 24 teeth and could be pushed to 26 or 28. Newer F. derailers are rated to 22 and can be pushed to 24. Going to a 52 puts your small ring at 28 or so.

Another option would be a 105/Ultegra F. triple which can handle a 53, also with a 22 tooth range, mated to a different rear cassette to get the desired range.

SB
How does your front derailleur work?Spoke Wrench
Feb 11, 2002 4:42 PM
As a general rule, to go from a 46t big ring to a 52t big ring is going to require a different front derailleur. The issue is the arc of the cage. A cage that is shaped to work with a 46t big ring is going to have to be mounted way high to clear the 52. It isn't going to work as well and its going to look goofy.

One solution is to install a road front derailleur, but that might not be as simple as it sounds. All of the road front derailleurs in the QBP catalogue are bottom pull. Lots of cyclecross bikes use top pull front derailleurs.
If you don't have a cable stop on your down tube, you might be out of luck.