I got the inevitable coffee grinder noise from my bike a week or two ago announcing the imminent demise of the bottom bracket.
I’ve had 5 years out of the bike though, so other than the fact that everything on it has now been replaced, I can’t complain…
It appeared from searching the internet that I had a rare and difficult bracket, a Truvative GXP, so I first thought that I’d probably err on the side of safety and get a LBS to fit it. Then I thought, since I’ve had such poor luck with that, I may as well have a go myself, especially as it turns out that the LBS I was going to try has problems with getting that part as well.
I’m also hoping that this will be the bike’s last year of being my only bike, so if I shorten the lifespan a little, it’s not the end of the world.
I managed to find a contradictory post on almost every aspect of this when I started researching it, from ‘don’t do this yourself ever’ to ‘it’s a doodle’ and most points in between.
I also decided against buying a torque wrench specifically for this. I’ve managed without one so far, and I’m not going near carbon fibre, and I found enough places using descriptive measurements that I thought I’d be OK for now.
It did make me think that we need a new SI measurements system for torque for cyclist though. I might write one up later.
So, in case this ever shows up on a search for some other soul wrestling with a similar problem, here are the steps I took.
(If I never post again due to a horrible crank related incident, feel free to disregard the rest of this post).
The Truvative Elite cranks are held on by a 10mm outer and an 8mm inner nut which unscrew in the normal anticlockwise direction (hey, with bikes you never know).
If you leave the 10mm on, it works as an extraction tool and pulls the crank arm off, but I had to remove it first, then jump on the 8mm allan key to free it with my wife putting her foot on the pedal to counteract it, then put the 10mm back on tight. I think in our real world torque measurement, this is “Angry Heavy Man Kick” force.
Once the arm was off, you can take the chain off the crankset and leave it on the frame bracket, then gently knock the spindle through using something wooden or rubber (or your hand) to remove the drive side.
I then used a Park Tools Hollowtech II BB And Crank Arm Tool, though I didn’t need the Crank Arm Part for the Tuvative arms.
At this point, you can go back and forward between You Tube and the bike triple checking the direction of the threads (like I might have done), or just look at the arrow on the existing cups which shows the direction of tightening, and to do the opposite.
The power required to unstick the cups was me holding the top of the frame with two hands and pushing down on the BB tool with my foot. So, 1 point less force than the crank arm bolt I think.
Once free, I could finger loosen it. I then did the other side (noting it’s reversed thread from the previous side) and removed the bottom bracket.
A clean and grease of the housing next, and I put the new BB back using the other steps in reverse. You have to watch the non drive BB cover, as it needs a bit of a wiggle to get it working and it wants to pop the BB cap off.
The amount of torque used so far for the BB was “as much strength as I could manage just by using my arms” and it was pretty much the same for the 8mm bolt at the end.
I considered “a good push with my foot” for both of them, but I was trying t find a compromise between the various things other people seem to have done.
So, fingers crossed that all works. We have 60mph winds this weekend, so I won’t be trying out the repairs until later in the week.
Other things to note: I didn’t need the spacers, the new part was silver not black (but I’ll live) and apart from the ridiculous force needed to unscrew everything, it’s much easier putting it all back than taking it apart.
I’m not sure I’d call this “easy” exactly, but the hard part was the sheer force required, which I suspect is also a lot to do with it being a 5 year old bracket.