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I'm trying to disassemble the crankset on my 2006 Trek Pilot 2.1; the bike has all OEM parts.

The crank is a Bontrager race crankset, which I'm to understand is a a rebranded Truvativ crank.

For a bottom bracket, it uses an SRAM Giga X Pipe (GXP).

The crank is a two-piece press-fit: it's a hollow tube press fit into the drive side, with ISIS splines on the non-drive side.

I'm trying to disassemble the crank and bottom bracket, so that I can clean the crank and crank spindle, and replace the bottom bracket.

I've unscrewed the GXP bearing cups and removed the crank from the frame, but there's this one last little component on the crank spindle that's keeping me from removing the rest of the GXP bottom bracket. I want to know how I should remove it so that I don't damage the spindle. I'm not sure what the part is, or if I'll need it for installing the new GXP bottom bracket.

Here's a shot showing the crank, spindle, and GXP bottom bracket as it is right now:

Crank side view.

And here's a close-up of the spine, showing the collet I can't get off:

Spline close-up

Yeah, I know it's a mess; that's why I'm trying to disassemble and clean everything and replace the GXP bottom bracket. That grease isn't grease anymore, it's more like metallic paste. Yuck.

I've already tried some light tap-work to try to get it off; it didn't budge, but I didn't go hard because I don't know if I'll damage it. Also, interestingly, it spins very freely in place.

In summary:

  • I'm replacing the GXP bottom bracket in whole, so I don't care about destroying it or old pieces that came out of it.
  • Do I need to preserve this collet? Did it come from the old GXP bottom bracket?
  • If I do need to preserve it, how do I get it off?

If I don't need it, I plan on trying to tap it off with screwdriver and a hammer; if that doesn't work, then cut it in half and split it open.


Also, since a few other people I had asked had been confused about this - the drive side of the spindle is permanently press-fit into the drive side bracket / crank arm assembly, since it's all one piece. Here's a picture:

Drive-side showing press-fit spindle.

  • I've missed something here -- A GXP VV installs into the frame with one threaded part on the drive side and another threaded part on the non-drive side. You push the drive side crankarm into the bottom bracket and attach the non-drive arm to the drive arm's tube with a bolt. To remove it, you undo the bolt, remove the non-drive arm and then push the drive arm out (possibly with a few taps from a mallet). Then, if you want to remove the bb, you remove the non drive side bb then the drive side. – Batman Jun 27 '16 at 21:53
  • It looks like you removed the non-drive arm, then the non-drive side of the BB, then removed the drive side of the BB which still had the drive side crank arm in it? – Batman Jun 27 '16 at 21:53
  • That "metallic paste" is likely ant-seize paste. It's designed to keep metal parts from bonding|corroding to one another (like your bottom bracket cups from corroding|bonding to your frame). The fact that it is there at all (and in such good condition!) means at some point someone who knew what they were doing assembled your bottom bracket and crankset. – Deleted User Jun 27 '16 at 22:42
  • @Batman - Your hypothesis is correct; I removed the non-drive arm, then the non-drive cup, then unscrewed the drive cup, then removed the whole assembly. I tried removing it the right way (remove the non-drive arm and tap out the whole spindle), but it wouldn't budge. With only the non-drive arm and cup removed and everything else still assembled, I tried tapping out the spindle, but that collet would push past the middle plastic portion of the GXP. So I pulled the whole thing out, and here we are. – antiduh Jun 27 '16 at 22:43
  • @SuspendedUser - the metallic paste wasn't on the crank when this started; it was on the inside of the GXP, but my man-handling got it everywhere before I decided to stop and ask. The bearings are chunky, and I don't think this bike has ever been serviced, so I'm inclined to believe it's grease plus the Spirit of Bearings Past. – antiduh Jun 27 '16 at 22:45
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I would try reinstalling the drive side and non drive side cups to the frame (to keep the spindle centered). Then I would recommend a game of whack-a-mole on the spindle with a rubber mallet. I have often had to remove a crankset this way. A rubber mallet should be in pretty much any home mechanics tool kit. The rubber mallet has almost no chance of damaging the spindle. Provided you don't smash/dent your frame with it, it should be fine.

With the cups on tightly and nondrive side crank off, you may also try rocking the drive side crank arm back and forth some as you rubber mallet the spindle.

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I was able to get the collet off with some gentle tapping from a screwdriver and a hammer. The collet is a soft metal, my screwdriver definitely made a mess of the metal. If someone in the future has the same problem, use some sort of hard plastic to buffer the hits.

I did try to bash it out by reassembling everything and applying wood + hammer to the spindle end. This cracked the GXP plastic middle sleeve, so I do not recommend this method to anybody else in the future. It doesn't matter to me because I'm replacing the GXP BB wholesale.

The collet was part of the inner race of the bearing - its purpose is to push against the GXP inner plastic sleeve.

Here's a picture showing the dry-fit assembled crank: Dry-fit assembled crank.

You can see the gap between the non-drive arm and the textured metal where that collet used to be, which is where the bearing supports the spindle.

Here's a close-up of the splines, you can tell by the wear marks where the collet sat and where the arm meshes: Spindle closeup

Here's a close-up of the collet (with plenty of gouge marks from my screwdriver): Collet close-up

The bearings didn't fall apart with this removed because it's just there to push on the GXP middle plastic sleeve:

enter image description here

You can see the same collet on the new bearing, though it's much thicker, and appears to be more integrated into the bearing; I'd bet the bearing would fall apart if the new bearing had this piece removed:

enter image description here

enter image description here

Big thanks to everybody for the ideas on what this piece was and how to take it apart. Thanks guys!

  • You can accept your answer so that it doesn't come up on the front page repeatedly later. – Batman Jun 28 '16 at 16:18
  • @Batman - I know (I've got 6k on stackoverflow), but stackexchange requires you to wait a day before marking your own response as the answer. – antiduh Jun 28 '16 at 16:45
  • I'm giving you a +1 simply for the nice quality photos! Looks like DSLR + Macro lens instead of a camera phone. – FreeMan Jun 28 '16 at 17:08
  • @FreeMan - That's amazing then, because it's from my Droid Turbo :) A clean lens, decent lighting, and careful control of focus goes a long way. – antiduh Jun 28 '16 at 18:27
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From what can tell from the photos it looks like the inner race is seized to the crank axle. When you removed the non drive side bearing did the ball bearings fall out? You can try to carefully cut the race off with a Dremel with a cut off wheel. You must be very careful not to go too deep and hit the crank axle. I would cut 9/10th of the way through. Then hit the slot with a chisel and see if it will split the race. If you aren't really comfortable doing this ask your LBS to do it for you. A mistake will be costly.

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