Please note the spindle/axle length is fairly important, because we believe Shimano made this model bottom bracket in two spindle lengths and this is the longer of the two lengths. From what we can tell, Shimano intended this longer spindle to be used when a chain line of 50.0 mm was desired (measured from the center of the seat tube to the middle chainring on a triple crankset). We believe this chain line was usually desired when the front derailleur was mounted on an oversized seat tube...pushing the front derailleur further to the right.

We also want to emphasize this bottom bracket incorporates Shimano's advanced Octalink technology, which resulted in a complete re-design of the bottom bracket to include a hollow (and larger) 22 mm pipe billet spindle/axle with an 8-spline interface to the crank arm...for greater strength and reduced weight. Additionally, it is important to note that Shimano designed two different Octalink spindle ends...a V1 design with each spline measuring 5 mm long x 2.2 mm wide (intended primarily for it's XTR, Dura-Ace, Ultegra and 105 Octalink compatible cranksets)...and a V2 design with each spline measuring 9 mm long x 2.8 mm wide (intended primairly for it's various Deore series, Tiagra and Sora Octalink compatible cranksets).

Our research further indicates this model/size was intended for selected Shimano mountain bike cranksets from the first half of this decade. More specifically, it's compatible with Deore XT triple cranksets (Models FC-M751 and FC-M752)...among others...so very close to Shimano's top-of-the-line in a bottom bracket offering at the time. Also (and as noted above), the V2 Octalink spindle ends are compatible with other Shimano cranksets, but please check your crankset's spindle/axle length requirements before attempting to use this offering with another Shimano crankset...and we can try to help in this regard should you have questions). We empasize this last point, because chainline has a direct impact on shifting performance, so even though selected Shimano crank arms may have the same V2 Octalink interface, if their spindle/axle length requirements are different from this offering, then there is a strong possibility that shifting performance will suffer...so please pay particular attention to spindle lengths when it comes to purchasing any bottom bracket.