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#1
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HELP: XTR/XT Hollowtech construction
Can anyone shed any light on exactly how the M960/760 cranks are
attached to the BB axle? Any way of getting them apart in order to fiddle with the axle length for purposes of reducing the Q factor? |
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#2
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HELP: XTR/XT Hollowtech construction
On 14 Jan 2006 11:42:23 -0800, "montyzuma"
wrote: Can anyone shed any light on exactly how the M960/760 cranks are attached to the BB axle? Any way of getting them apart in order to fiddle with the axle length for purposes of reducing the Q factor? It's Octalink. With an XTR, if it's a V1 Octalink double, you might be able to swap to the longer (triple) Octalink BB, or with either V1 or V2 you might get away with shimming the BB out from the BB shell a bit on the right if the left crank has enough chainstay clearance. There's nothing that you can do to change the position of the crank on the BB shaft without reducing the amount of spline engagement, and there's not enough of that to begin with. Octalink BB units are not supplied in a variety of lengths like tapered square, so you don't have much to work with if you want to fine-tune something. (In theory, this is a Feature; the cranks made for use with an Octalink BB are all supposed to be set up for the same BB shaft length, eliminating the need to have multiple BB versions. In practice, things are not always this simple.) -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#3
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HELP: XTR/XT Hollowtech construction
Werehatrack wrote:
On 14 Jan 2006 11:42:23 -0800, "montyzuma" wrote: Can anyone shed any light on exactly how the M960/760 cranks are attached to the BB axle? Any way of getting them apart in order to fiddle with the axle length for purposes of reducing the Q factor? It's Octalink. With an XTR, if it's a V1 Octalink double, you might be able to swap to the longer (triple) Octalink BB, or with either V1 or V2 you might get away with shimming the BB out from the BB shell a bit on the right if the left crank has enough chainstay clearance. There's nothing that you can do to change the position of the crank on the BB shaft without reducing the amount of spline engagement, and there's not enough of that to begin with. Octalink BB units are not supplied in a variety of lengths like tapered square, so you don't have much to work with if you want to fine-tune something. (In theory, this is a Feature; the cranks made for use with an Octalink BB are all supposed to be set up for the same BB shaft length, eliminating the need to have multiple BB versions. In practice, things are not always this simple.) Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's absolutely nothing OP can do to change to effect chainline or Q-factor. Robin Hubert |
#4
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HELP: XTR/XT Hollowtech construction
On Sat, 14 Jan 2006 23:22:09 GMT, Robin Hubert
wrote: Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's absolutely nothing OP can do to change to effect chainline or Q-factor. Oh, bloody. So the Shimano-or-nothing movement (which has only one willing participant IMO) has expanded downward into the XT as well? Not good news. Octalink was bad enough. This thing's not enough better than the stuff that's open-standard to justify getting slaved to a single source (at least, not for a lot of people), and I'm betting that before the patents run out, Shimano will have dumped it in favor of their *next* "Ultimate New Thing", ensuring that the existing installed base will not be interesting to the aftermarket replacement parts suppliers. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#5
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HELP: XTR/XT Hollowtech construction
montyzuma wrote: Can anyone shed any light on exactly how the M960/760 cranks are attached to the BB axle? Any way of getting them apart in order to fiddle with the axle length for purposes of reducing the Q factor? Cannot take them apart...you are pretty much SOL. The distance between the crank arm pedal holes IS larger in spite of shimano propaganda. There are plenty of really good MTB cranks on the market that use the old fashioed square taper BB..like first gen XTR or XT-ebay or google search. |
#6
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HELP: XTR/XT Hollowtech construction
Werehatrack wrote in
: On Sat, 14 Jan 2006 23:22:09 GMT, Robin Hubert wrote: Wrong, Kimosabe. It's a Hollowtech II with integrated spindle. There's absolutely nothing OP can do to change to effect chainline or Q-factor. Oh, bloody. So the Shimano-or-nothing movement (which has only one willing participant IMO) has expanded downward into the XT as well? Not good news. Not Just XT, but LX (and 105 for 2006) as well. You could filldle with chainline by shuffling the bearing spacers, since a 68mm BB shell uses 2 spacers on the right if you have a clamp-on FD. Take away 1 each for E-type FD and 73mm shell to reduce the chainline, or add the one from the left to increase it. But, yeah, nothing to do for q-factor. |
#7
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HELP: XTR/XT Hollowtech construction
I saw an article recently in one of the magazines - you know, the
"Inside the pro's bike" profile thing, where the pro in question had the axle specially modifies to reduce Q factor. I suppose Shimano did it for him, but since they're unlikely to do it for me I've had a look at the problem with a couple of light engineering shops. Cutting the splines on the left side 7.5mm futher in, shortening the axle & cutting the threads inside deeper is easy enough, but not with the right arm still attached. Hence attempts to figure out how to remove the spider/arm. It looks like its pressed then swaged? Anyone know anyone at Shimano who could add light? For interests sake, these are my meaurements of the Q distances of the cranks: Dura Ace 7700 (9speed) 145 mm DA triple 7700 154 XTR M960 167 XT M760 178 |
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