Sweet success

Bicycle frame laying on newspaper with screwdrivers and destroyed bottom bracket sleeve

In the two and a half weeks since my last ride, I’ve been trying to swap out the crankset on bottom bracket on Kuroko. The FSA that I’d installed in preparation for my Lejog attempt had chewed through another set of bearings — in a scant three months this time — and I knew that it had to go. Fortunately, in the time since returning from England last July, I’d located a replacement candidate from Sugino which offered me the same small chainrings but with a standard 24mm spindle. This allows me to use the bottom bracket bearings that Kuroko is designed for, rather than the undersized and troublesome bearings needed to fit the FSA’s 30mm spindle.

Sugino crankset after chainring replacement
Sugino crankset after chainring replacement

Sadly, the bbinfinite BB I’d just installed in January had other ideas: It was locked in solid. I used a number of press tools in an attempt to remove it, and even ended up fabricating my own accessories from pieces of PVC pipe. Nothing worked, and I finally realized I was going to have to employ drastic measures.

Hacksaw inserted in bicycle bottom bracket
Drastic measures

Screwdriver prying a cut sleeve out of a bicycle bottom bracket
A chink in the armor

Bike mechanics regularly use hacksaws when setting up new bikes, but certainly not in this fashion! (They use them to cut the steerer tube to the correct length.) I knew I could saw through the bbinfinite sleeve, but I was terrified I would damage Kuroko’s BB shell. And that would be GAME OVER.

Working as slowly and methodically as possible, I cut a groove through the bbinfinite sleeve and only made a very shallow scratch in the BB shell. From that start I was able to get a screwdriver blade under the sleeve and start hammering and prying the sleeve away from the shell.

It took more than a bit of hammering even so. I managed to split the sleeve along the cut I’d made for about 80% of the total length, and from there hammered and pried using several screwdrivers and a liberal application of WD-40.

Screwdriver prying a cut sleeve out of a bicycle bottom bracket
Making progress

Finally some dirty WD-40 poured out on the newspaper under the bike, and I knew I’d broken through the full length. From there it was a few more hammer whacks and then the whole miserable, smashed, rusty thing dropped out of the frame. Sweet success!

Bicycle frame laying on newspaper with screwdrivers and destroyed bottom bracket sleeve
Free at last

Now for the installation

I spent a few minutes cleaning up the inside of the BB shell with degreaser and inspecting it for damage. It just had some surface scratching from the sawing and prying. I used a micrometer to make sure I hadn’t bent the shell, and it measured out round.

I took a moment in the middle of all this to weigh the various pieces. I knew the aluminum Sugino would be heavier than the carbon fibre FSA, but as I’ve said before: It’s not saving weight if it doesn’t work. Including the BB, the Sugino came it at 96g heavier, and I’m happy with that.

Bicycle cranksets on scales
Weighing the difference

Sugino’s recommended tool for BB installation happens to be the Shimano that I already had on hand (from when I first installed the FSA crankset), so I happily greased up the bearing cups and pressed them into Kuroko’s newly empty BB shell. There was absolutely no problem with the installation.

Photos showing a bottom bracket being pressed into a bicycle frame
New BB goes in smoothly

The crankset spindle was already greased, and it slid into the bearings with hardly any force. (I’d gotten used to smacking the FSA into place with the flat of my hand or with the mallet.) I had the recommended tool on hand for the adjusting screw and so the crank was on in a matter of moments. Finally, I tightened the crank bolts to the recommended torque.

Adjusting a bicycle crank and tightening with a torque wrench
Adjusting and tightening

I gave the new crank a few spins, and it happily turned round and round for me.

Finishing up

With the new crankset in place I had to adjust the front derailleur. I’ve gone from a 46-tooth outer ring to 44, so the derailleur had to come down a bit. When the adjusting was finished I ran through all the gears. On the bike stand at least, it’s shifting smoothly and quietly.

Bicycle on balcony overlooking city
I’m happy with that!

I’ve been joking for the past month that I’m “working” from home. With Kuroko back in action and the weather behaving, I may soon be “working” from “home.” I’m looking forward now to the first ride with the new gear.

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