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Shimano BB(4 posts)

Shimano BB4bykn
Apr 20, 2002 5:23 AM
I posted this a few days back in another discussion, but it got quickly bumped off the first page, so I'll try again.

I have a splined Ultegra BB on my bike, and I've read that it is possible (even easy) to mis-assemble. To avoid this wouldnt an easy solution be to take a permanent marker and put a small line on the axle showing how it was assembled? I realize that this works only on previously assembled BB's, not for new never assembled units. My understanding is that all the splines save one are the same size, with one off-sized for alignment purposes, but only by a small amount, making it possible to force the BB together incorrectly, ruining the axle. Sounds like a bad design to me, and I'm a "Shimano guy".
Additionally, is grease used on the splines for assembly, unlike the "old" square-tapers?
re: Shimano BBdavet
Apr 20, 2002 7:24 AM
I am sitting here staring at my Shimano Ultegra BB trying to find an "off" sized spline. I cannot find one, nor can I find any reference to one in the directions that came with the bottom bracket. I think what is referred to as 'misalignment' is when you are installing the crank arm and don't get the spline recesses on the cranks lined up with the splines on the BB before tightening down the crank. This is easy to do if you leave the self-extracting bolt in the crank arm. If you remove the bolt, you can peer into the hole and visibly see that the splines are lined up correctly. Then, on the left crank, all you have to do is set it 180* from the right and tighten away. It makes NO difference where the cranks are installed on the BB, just that the splines and their mating surfaces are aligned. Shimano recommends a small amount of grease on the splines.
re: Shimano BB4bykn
Apr 20, 2002 8:09 AM
I see, that makes more sense now, thanks

Bike in Peace.....Mike
Davet has the answer!Kerry
Apr 20, 2002 12:41 PM
I just put one of these together for a friend, and remembered the comments I'd seen about not aligning the splines. I started to tighten the crank bolt, and realized I had no idea whether the splines were aligned. Then it hit me: remove the self-extractor and slide things together with a visual check. Piece of cake.