Another Crank swap question FC-M391 > FC-M590
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Another Crank swap question FC-M391 > FC-M590
My Trek 7.4fx has a 68mm BB shell. It's stock crankset is a Shimano model FC-M391 with a 48-36-26 tooth configuration. I would like to know if a Shimano FC-M590 Deore Hollowtech II would be a compatible swap? I understand I would have to remove the current BB and install the outboard bearings along with any other related derailleur positioning etc.
Thanks in advance,
TMT
Thanks in advance,
TMT
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The specs say 68 or 73 BB shell but I had problems using this exact model on an older trek-850 (with 68 shell and 130 rear drops). There were not enough spacers to get it installed with the correct and balanced extensions on both sides. I set it aside and ordered a road crank (tiagra I think) because I wanted the best Q. I have since installed it into a 73 BB shell and it fit perfectly.
#3
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The specs say 68 or 73 BB shell but I had problems using this exact model on an older trek-850 (with 68 shell and 130 rear drops). There were not enough spacers to get it installed with the correct and balanced extensions on both sides. I set it aside and ordered a road crank (tiagra I think) because I wanted the best Q. I have since installed it into a 73 BB shell and it fit perfectly.
To the OP, the Deore crank should swap in just fine. You might not even need to adjust your front derailler if you get lucky enough. Read the instructions and install the appropriate spacers to ensure proper preloading of the bearings and chainline. A 68mm shell gets one 2.5mm spacer on the non-drive side and two of the same spacer on the drive side.
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To the OP, the Deore crank should swap in just fine. You might not even need to adjust your front derailler if you get lucky enough. Read the instructions and install the appropriate spacers to ensure proper preloading of the bearings and chainline. A 68mm shell gets one 2.5mm spacer on the non-drive side and two of the same spacer on the drive side.
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How many spacers did you try to use for the 68mm shell? The crankset/BB should have included three 2.5mm spacers for use with a 68mm shell and a standard (non-E-type) front derailler. How many spacers did you use for the 73mm shell? There should be only one on the drive side.
Good luck. Post success story --so I can second guess myself forevermore.
[edit: am anticipating someone suggesting I was confusing DS and nonDS. I'm not going back to disassemble two bikes to check, but I can't help thinking that myself --in retrospect]
Last edited by dbg; 09-13-13 at 02:29 PM.
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