Defeated by a GXP bottom bracket- Resolved

[Kontact]

Originally Posted by kppolich

stock crank on stock BB spun just fine, it was 24mm and not gxp. Stock shell is 68, but with the Eccentric BB its wider with the cups, say 73mm. With no spacers installed there is considerable drag, most likely needing a widde spindle

So it sounds like you are trying to install a crank designed for a 68mm BB shell in a 73mm BB shell. You're going to need a different crank.

[bikinchris]

Originally Posted by Kontact

So it sounds like you are trying to install a crank designed for a 68mm BB shell in a 73mm BB shell. You're going to need a different crank.

^^^This^^^ is your answer.

[kppolich]

Hold the phone with some late day magic. Had a pink chris king BB with GXP kit on my other bike. Swapped the bb's and its good to go. Can anyone explain this? The king bottom bracket is a bit narrower, but the big thing is the bearings and how that load is handled. No spacers and it's good.

Shell is 68 but the outside of the EBB was 73, pink looks better anyway

Pics cuz....pics!

[Kontact]

Originally Posted by kppolich

Hold the phone with some late day magic. Had a pink chris king BB with GXP kit on my other bike. Swapped the bb's and its good to go. Can anyone explain this? The king bottom bracket is a bit narrower, but the big thing is the bearings and how that load is handled. No spacers and it's good.

It is just that it was narrow enough to work. The load isn't being 'handled' differently.

[cmbicycles]

Not sure about king/sram, but with shimano external BB the mountain bearings are not as wide as the road bearings. If you have a narrower mountain BB that may be why it seems to work. I don't know that I would rely on that "maybe it will work" without getting an OK from either king or sram as you still have a 73mm shell and a 68mm crankset so not an ideal match up in my eye. It could end up damaging the crank spindle and if that should fail, possibly yourself. Ymmv of course.

[yinzerniner]

Originally Posted by Kontact

It is just that it was narrow enough to work. The load isn't being 'handled' differently.

Not quite what is happening here.

The Chris King bottom bracket is not gxp specific, but rather is a threadfit style with conversion kits for different standards. The kit includes the necessary spacers to make up for different widths.

The OP's frame has a 68mm wide PF30 bottom bracket shell, and it looks like a 73mm wide sleeve was installed, thus the extra room on both sides sticking out. While regular gxp bb cups can be installed in either sleeve width it expects the spindle length to change. On the Chris King the cups are a bit narrower than a gxp or shimano hollowtech so the extra play is taken up by the conversion kit spacers.

Only problem with the current setup the OP has is that there might still need to be some spacers or shields for any installation of the Chris King bottom bracket, so while it works ok now over time there could be some extra play or detritus infiltration. If the OP is certain that they'll use the SRAM gxp crank then they should remove the current 73mm wide sleeve and replace it with a 68mm wide one so either a regular gxp or the threadfit Chris King will be installed correctly.

[Kontact]

Originally Posted by yinzerniner

Not quite what is happening here.

The Chris King bottom bracket is not gxp specific, but rather is a threadfit style with conversion kits for different standards. The kit includes the necessary spacers to make up for different widths.

The OP's frame has a 68mm wide PF30 bottom bracket shell, and it looks like a 73mm wide sleeve was installed, thus the extra room on both sides sticking out. While regular gxp bb cups can be installed in either sleeve width it expects the spindle length to change. On the Chris King the cups are a bit narrower than a gxp or shimano hollowtech so the extra play is taken up by the conversion kit spacers.

Only problem with the current setup the OP has is that there might still need to be some spacers or shields for any installation of the Chris King bottom bracket, so while it works ok now over time there could be some extra play or detritus infiltration. If the OP is certain that they'll use the SRAM gxp crank then they should remove the current 73mm wide sleeve and replace it with a 68mm wide one so either a regular gxp or the threadfit Chris King will be installed correctly.

What leads you to believe the OP didn't install the bearing shields?

[yinzerniner]

Originally Posted by Kontact

What leads you to believe the OP didn't install the bearing shields?

Didn't state that the bearing shields weren't installed, just that there's no pictorial or written evidence that there were installed. Also noting from the OP states that other shields, spacers or shims were installed, which isn't in compliance with the CK installation instructions.

Given that the OP couldn't figure out that the spindle lengths were different between the old and new cranksets and thus the bottom bracket installation would need more than simple plug and play replacement gives me pause on presuming errors were minimized.

[kppolich]

King bearing shields are installed, but not the drive side one that came with the GXP kit. It was too wide, so i swapped it out for the stock king BB drive side bearing shield that had less of a lip.

No wavy washers other spacers installed.

I agree that a proper EBB that is 68mm wide is in my future, but not now.

[kppolich]

new EBB here from Bushnell, very nice and easy to install

[kppolich]

Bumping this up again with an update. The binding of the BB was just too much with the Road 68mm GXP Crankset. I moved to a SRAM S952 wide axle and it is much better now, smooth as butter.