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Old 05-12-10, 12:58 AM   #1
meb
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Alternative BB cable guide mounting techniques vs. the traditional screw/rivet

I was wanting to replace a destroyed bottom bracket with an internal gear bottom bracket in my Bridgestone MB-4 mountain bike. The internal gear bottom bracket takes up the entire diameter of the shell so the screw mounting the cable runs protrudes into the shell blocking insertion. As this was an early mountain bike, it has a bottom pull FD and the canti brakes are on the chainstays. So if I make a less than secure attachment of the cable runs we may have a braking safety issue.

Any alternatives on how to mount the chainstays on this frame?
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Old 05-12-10, 07:56 AM   #2
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I was wanting to replace a destroyed bottom bracket with an internal gear bottom bracket in my Bridgestone MB-4 mountain bike. The internal gear bottom bracket takes up the entire diameter of the shell so the screw mounting the cable runs protrudes into the shell blocking insertion. As this was an early mountain bike, it has a bottom pull FD and the canti brakes are on the chainstays. So if I make a less than secure attachment of the cable runs we may have a braking safety issue.

Any alternatives on how to mount the chainstays on this frame?
Any part of the screw that extends into the shell is superfluous anyway. Dremmel it down flush with the surface. I've done it with no ill effects.
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Old 05-12-10, 08:18 AM   #3
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Any part of the screw that extends into the shell is superfluous anyway. Dremmel it down flush with the surface. I've done it with no ill effects.
+1. Trim the screw and/or superglue.
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Old 05-12-10, 08:24 AM   #4
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Yep, shorter screw or use a small washer or two under the head of the screw so it doesn't protrude into the shell.
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Old 05-12-10, 08:25 AM   #5
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BTW, which internal gear bb. Schlumpf, FSA, Hammerschmidt?
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Old 05-12-10, 08:52 AM   #6
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You are getting rid of the FD right? For the rear brake, you could replace with V brakes and no more need for a cable stop (though that means new lever too)

But are you going toward full internal gearing? Then you can get a rear hub with integrated drum brake :-)
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Old 05-12-10, 09:10 AM   #7
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Or you could use a clamp-on cable guide (the 2nd & 3rd pictures are from (http://www.phred.org/~alex/bikes/trekroad.html).





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Old 05-13-10, 01:42 AM   #8
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BTW, which internal gear bb. Schlumpf, FSA, Hammerschmidt?
SuperGear-they are now out of business.
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Old 05-13-10, 01:54 AM   #9
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You are getting rid of the FD right? For the rear brake, you could replace with V brakes and no more need for a cable stop (though that means new lever too)

But are you going toward full internal gearing? Then you can get a rear hub with integrated drum brake :-)
It's a triple ring 2 speed internal gear BB. Was planning on keeping the triple FDer unitl I discovered these things will accept a ringed crank outboard the triple (just put a single or double crank on its square taper bottom bracket) so if I find a FDer with enough throw I can turn this into a quadruple or quintuple crank plus 2 speed internal gear on the 3 smallest rings and become king of overkill and would substitute the FDer accordingly. The low gear is only 20% lower than direct drive so still prefer a triple, particularly since this bike has a Turner AWD system on it.
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Old 05-13-10, 01:56 AM   #10
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That might be doable. My cables go underneath the shell but I think one could reroute cables with a little effort and get that to work.
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Old 05-13-10, 09:51 AM   #11
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Glue.
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Old 05-13-10, 10:17 AM   #12
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How small is the clearance inside the shell? Could you use a machine screw with the head on the inside of the shell and secure with a nut on the outside?
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Old 05-13-10, 09:09 PM   #13
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I agree. Today's special adhesives are strong enough, I believe. The cable guide shouldn't move or shift off position with the (I think) minor friction of a moving cable.
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Old 05-14-10, 12:22 AM   #14
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Yep, shorter screw or use a small washer or two under the head of the screw so it doesn't protrude into the shell.
If the washer approach is employed, would lock washers work better than flat washers? Any idea what the i.d. of the washer should be to go around those screw?
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Old 05-14-10, 10:31 AM   #15
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Be careful as these screws tend to be tapered sheet-metal screws. If you back them out with washers, they won't grip as tightly and may wiggle loose. I would go with grinding down the tip so that you'd have the fat base of the screw in the BB-shell rather than the tip.

If however, your BB is actually tapped for machine-screw threads, then the bolt most likely would be 5x0.8mm or 6x1mm. In which case, washers would work. Measure the bolt with calipers to determine which it is.
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Old 05-14-10, 11:26 AM   #16
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If the washer approach is employed, would lock washers work better than flat washers? Any idea what the i.d. of the washer should be to go around those screw?
You're just taking up space with the washers, it shouldn't matter.
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