Kuroko’s bottom bracket has been making noise over the past two months, and I needed to get it sorted out before the Tour de Tohoku next weekend. In fact the deadline is Tuesday, because that’s when the delivery company will pick up Kuroko and take her up to Ishinomaki.
I’d tried removing the crankset more than a month ago, thinking I could retighten the bearings and that might help. I had no trouble removing the right crank (including the chainrings), but then I discovered the left crank and spindle were stuck in the bearings. I hammered on the end of the spindle quite a bit, but it didn’t budge.
At that point I decided not to attempt any further repairs until I had a replacement bearing set. I ordered that and crossed my fingers: it was coming from Italy and there was no guarantee of a delivery date.
Meanwhile, I’d been on a couple of more rides. It was very clear on the last one, a mostly flat ride to Yokohama, that the bearings would have to be replaced. They were making more noise than before — almost like a coffee grinder. I’d also done some research on stuck BB spindles, and everyone was pretty much in agreement: use a bigger hammer.
They said it couldn’t be done
The replacement bearing set finally arrived, but I held off for a few days. With so much at stake (including the possibility of ruining Kuroko’s frame if I forced things too much), I was a bit shy of taking the next step. Instead, I took Kuroko and the shop where I’d bought Ol’ Paint, near my office. I knew from experience the mechanic there was very good, and that he was willing to take on bikes he hadn’t sold. When I explained the problem to him and showed him I had the replacement bearings, he was willing enough to take on the job. He even quoted me his standard labor rate for it, not jacking it up because it wasn’t his bike or his replacement part.
After a few hours, though, he called to say that the left crank was stuck and he couldn’t finish the job. I don’t blame him for not pursuing it. The risk to him was high and reward rather low. When I picked up the bike he was apologetic and wouldn’t charge me anything. As I said, he’s a good mechanic, and it was helpful for me to have him confirm what I’d found. It showed I was on the right track.
And so I was back where I started, with even less time to make the fix. I gathered up all the needed tools and parts, and today I finally made the do-or-die effort.
The first step was to remove everything that would come off easily: the bags and lights, the wheels, the pedals. (Note to self: It’s easier to take off the pedals when the wheels are still on and the bike is on the ground.) Then I removed the right crank. (Note to self: ditto.) In the process I discovered the mechanic had tightened it quite a bit more than expected when he’d put it back on. But I was able to get it off without too much fuss.
With the preliminaries out of the way, it was time to lay the frame on its side. I propped it up with some pieces of lumber. I sprayed some apple cider vinegar (good for aluminum-to-steel corrosion) around the spindle where it contacted the bearings. And then I broke out the special sauce.
I’d read a post from a few years ago on a bike forum that spraying an entire can of compressed air into the spindle would cool it down, causing it to contract and helping to free it from the bearings. I knew from experience at the office that a compressed air can will quickly get cold when the air is released. But I was feeling sceptical as I emptied the can into Kuroko’s guts. The spindle was cooling down, but not as much as I’d hoped. I didn’t know if it was going to be enough to help.
I set down the icy spray can and reached for the mallet. After just a couple of sharp raps, the crank popped right out! I’d used far less force than I had done on the previous occasion, when I couldn’t get it to budge. So I can confirm: between the vinegar and the compressed air, the job got done.
The spindle was covered with a surprising amount of rust. Most came off immediately with just a touch of degreaser.
The rust that remained was right in the trouble spot — where the spindle rides in the bearings. This was probably a job for Scotch-Brite, but I didn’t have any on hand. Instead I spent a good 10 minutes going over it with steel wool, and that mostly did the trick.
It’s hammer time!
The next problem was getting the old bearings out. The bottom bracket extraction tool was too narrow to be of help. It’s made for the original Shimano crankset that came with the bike, while these bearings have a much larger internal diameter. In the end I just stuck a screwdriver against the inside of each bearing and hammered, working my way around the bearing so it wouldn’t go cockeyed in the bottom bracket shell. It took a good bit of hammering, but in the end all the old bits came out.
With the bearings out, I could see quite a bit of rust in the bottom bracket shell. Most of it was in the center part, not where the bearings contact the shell on both ends. I spent a couple of minutes cleaning up as much as I could with the degreaser.
With the bearings out and everything cleaned up, I put Kuroko back in the work stand and measured the bottom bracket shell. I wanted to compare two measurements at right angles on each side. Working with a vernier for this is not perfect, but I don’t have a laser alignment rig on my balcony. As near as I could make it, all measurements were within 0.1mm — reassuring me that the shell hasn’t been distorted.
Satisfied of a good fit, I greased up the new bearing assembly and inserted it into the bottom bracket shell. Then I used the bearing press to make it all snug.
I read the instructions several times through and confirmed that the bearings just need to be flush with the edges of the shell. I don’t need to torque them down.
I made sure to put plenty of grease on the spindle before inserting it. The instructions call for grease just on the contact areas, and I’d read advice that it’s best not to put too much grease on, but I want to avoid a rerun of this situation in another six months. Even after 10 minutes with steel wool, there were some pitted spots on the spindle. So in this case I think some extra grease is warranted.
The spindle went back in with just a couple of whacks of the persuasion tool. But then I realized I’d left out the washer! Believe it or not, after all the research and effort I’d put into this, it took me two tries to remember the washers — a wave washer on the left and a regular washer on the right.
At last, I got the right washers in the right places (and the left one in the left place) and torqued the crankset back to the correct spec. I put the chain back on the chainring and gave it a spin — perfect! Or at least, no grinding or unevenness that I could detect.
It took me a few minutes to clean everything up and put the tools back where they belong, then wash my hands. I got my helmet and shades and a pair of minimalist shoes, and then carried Kuroko through the flat to the elevator.
The shake-down ride was very brief — just once around the block (about 2.5km). Not a hint of bearing trouble. Just smooth spinning. I ran through all the gears, front and back, and it’s all good. There are a couple of little things to take care of: the rear brake needs to be adjusted and the headset is a little bit loose. I can easily do both tomorrow in less than five minutes.
What am I to think about the BB going bad in just half a year (albeit with some strenuous conditions), and the spindle freezing to the bearings? Is this something I’m going to have to put up with every six months? In other words — as a friend asked — have I built myself a Jaguar here? Something that requires repairs all week so I can enjoy it on the weekend? Or did I just do a bad job the first time around — which was my first time doing anything like this with a bike? (I did a lot of research and watched a lot of videos, but there was no sempai to guide me through my baby steps.)
The answers to these questions will only come with time. Most comments I’ve found on the web seems to suggest the bearings should be good for 10,000-50,000km. Meanwhile, since I installed this crankset, Shimano has introduced a similar model with 46T-30T capability. (They didn’t offer this when I made the replacement). It’s a lot cheaper. On the other hand, it’s not carbon fiber. Regardless, if I find myself replacing this BB after another six months, I’m going to switch to the Shimano crankset or a Sugino one with the same tooth count.