48t crankset on mtb

[cateye333]

I remembered shimano XT used to have 48t on the crankset for mtb, why did they stop making them? And i do find comfort or trekking mtb with 48t (which, in theory, are faster than an XTR )

i was thinking of switching the 44t crankset with a 48t to speed things up since i always find that there is no resistance left on a 44t-11t when i am cycling on the road/downhill. Any real advantage in speed or complications? Shd i or shdnt i? Any other options to speed up my mtb??

I dont usually do dirtjumps or stunts, just cross-country and occassional trails/bushes for fun. I do find 44t-32t pretty useful when going up almost any hill while xc; so if i change to a 48t i gonna lose that gear ratio...


Another matter, how do i know if i fit a 170,172 or 175mm on the crankset?


cheers

 

[Scotty_Dog]

For the same cadence, your speed should increase by 9.1% (48/44=1.091).

As far as complications, you might need a new front derailleur (or a grinding wheel if you're savvy).

Also check out this thread from forum member gclark8:
http://www.cyclingforums.com/showthread.php?t=363004

 

[gclark8]

It would help to know what brand and model the bike is, and what crankset is currently fitted. Shimano make many Triple cranksets with 48t big ring for MTB, I will try to find one that will fit your existing Bottom Bracket.

As for crank arm length how tall are you? However, not many to choose from with 48t, mainly 170mm and a few 175mm, again depending on BB type.

 

[cateye333]

It would help to know what brand and model the bike is, and what crankset is currently fitted. Shimano make many Triple cranksets with 48t big ring for MTB, I will try to find one that will fit your existing Bottom Bracket.

As for crank arm length how tall are you? However, not many to choose from with 48t, mainly 170mm and a few 175mm, again depending on BB type.

I've got a GT Zaskar Pro 2003 in Medium, and it has a XT hollow II in it ( i think its a 44,32,22). And i am 178cm; but my legs are kinda long...


Is 48t the largest for mtb? And i thought i coulkd just re-adjust the front derailleur slightly higher to accommodate the larger teeth

 

[gclark8]

For Deore XT Hollowtech II, 26/36/48 tooth a 170mm, 175mm or 180mm crankset is available. Ask for part number FC-M761 # the length of your choice.

See how you go with adjusting the height of the FD, however, if you have trouble getting up to the 48t smoothly, the angle between the chain stay and seat tube will need to be checked before ordering a new Front Derailleur:
for 63-66 degree use FD-M761-3
for 66-69 degree use FD-M761-6
(from the pix, it looks like 69 deg)

(See Page 178 of the 2005 Shimano Manual)

Print this out and take to your LBS.