Post P2A Bottom Bracket/Crank spindle woes

This question is for the bike mechanics in the club.

In case anyone thought I was exaggerating about the horrible noises my bike was making at the end of the race here are some photos of my bottom bracket and spindle:

The non drive side of BB was totally destroyed–the bearing housing was fused to and came out with the crank spindle. The spindle is deeply scored. I probably should have stopped riding when the noise got bad but I guess I’m too stubborn! Not only the noise but think of all those lost watts–I could’ve been a contender :wink:

I had the BB replaced after the original failed after the P2A last year. Now I bought a bearing press to replace it myself as it seems to be a recurring issue.

My question is why do you think this keeps happening? It seems out of the ordinary that a BB fails so spectacularly even in the mud bath of the P2A. Has anyone had similar issues? I generally keep my bike clean and well maintained so I don’t think its from neglect.

I have installed a new BB and it looks like I need a new crankset as well–this years P2A is continues to get more expensive!

I am by no means a mechanic and am someone who can be talked into more expensive parts. Last year I had to replace my BB also. This year, I did an upgrade on my bike and was talked into a ceramic bearing BB. When I called to laugh at the quote and ask why I should spend an extra $300 or so on this “fancy” BB I was told that it would have to be replaced a lot less often especially when riding in wet/dirty conditions.
Not sure if that is actually true, but I can say that post P2A this year, my crank is spinning like a dream and completely quiet.
My headset bearings on the other hand are toast.

Thanks Amy–I thought the same thing so I bought a Kogel Ceramic bearing BB I found on for half price hoping it will last longer. Time will tell! Sorry about your headset bearings–that race sure is hard on bikes!

1 Like

I just replaced a BB on one of our P2A bikes last evening. My sons both have identical Canyon CX bikes and they raced the same distance at the same time. On one of them the BB was completely fine. On the other one it was toast and missing half of the bearings. :man_shrugging:
I think it mostly depends on how well the seal is able to keep the dirt out. If sand gets into the bearings they are not going to last.

Thankfully all of our CX and road bikes use the same Shimano BB. I just order a bunch of Shimano Ultegra bottom brackets from Merlin Cycles for ~$25 each and replace them myself whenever they aren’t spinning smoothly. Actually I just made a mental note to put in another order. doh.

To keep them running longer my tip is to cover everything with marine grease in an attempt to keep the water out. It doesn’t solve the problem but I think it helps.


Some bikes are just worse whether it be frame design or manufacturing tolerances. I had an old CX bike 15,000km and the bearings still felt like new of pretty much exclusively riding it in dirt and and the winter. I have others where it seems to be an annual repair with low km.

I think I’d rather go cheapish and replace often if needed. On that topic a member recently wrote their frame off from seized bearings spinning and wearing the BB shell on a pressfit frame.

1 Like

The other tip that I would add is that if you can clean out the bearings after the mud race they can sometimes be salvaged without having to remove from the frame. Just don’t ride on them very long when there is sand in the bearings. That can work IF there is a way to remove the seals from the bearings with damaging any plastic caps.

The approach that has worked for me is basically

  • remove the crank (pretty easy but might require a few specialized tools like the plastic Shimano Hollowtech crank removal tool
  • with a tiny screwdriver carefully remove the bearing seal
  • place some paper towel in the BB past the bearing to prevent any gunk from getting to the other side
  • use a spray bottle filled with rubbing alcohol to fill the bearing. Let it sit for a minute or two and spin the bearing the help wash it out
  • use a compressor with a small nozzle to spray out all of the grease, rubbing alcohol, and grease
  • repeat a few times and then blast air at the bearing to dry out the rubbing alcohol
  • regrease and insert the bearing seal
  • cover everything with marine grease and reassemble

I have also removed the bearing to clean in a sonic bath with degreaser, but after spending the effort to remove the bearing and/or BB it probably makes more sense to just replace. Removing the bearing or the BB does really require specific tools.

If anyone has a better approach though I’d love to hear it :slightly_smiling_face:

Thanks for the tips! @bike_daniells I was worried about it being the bike as I’ve watched videos from that strange guy on YouTube (Hambini) saying that poor tolerances can cause early failure of bottom brackets.

@KevinGoertz I will try your tips on cleaning the bearings even though I don’t like removing the cranks that much as it’s often difficulty to do!