Last week I was called in to the bike shop for a project the apprentice mechanic couldn't handle. Understandable as the bike is older than he is.
It's an early 90's Klein Pinnacle that belongs to my family doctor. With all due respect...he's a bit frugal and has often come in asking for used 6-speed freewheels, etc. Well, he brought it in this time for bottom bracket bearings and for those unfamiliar with Kleins...it's a proprietary press-in design. Sure, many modern bikes now have press-in bearings, but the new two piece crankarms have an advantage: They don't have to accommodate the movement inherent with a square taper crank interface. Two piece cranks simply require the bearings be pressed in place (sometimes even by hand), the crank slides through and fastens with two pinch bolts (or similar). Easy-peasy. No, this old Klein actually requires a special removal and installation tool. Problem: The shop doesn't have one. Worse problem: You can't even buy one any more.
My mechanic's integrity requires me to do my homework before causing any damage to a customer's bike. I read instructions, follow them and use the correct tools. Since obviously I couldn't do that now that Klein is defunct, I got online and found out what I could. I was able to find out the correct bearing replacement size and even that Phil Wood makes a specific compatible complete bottom bracket assembly. The Phil would've been my choice as it would most likely last the rest of the bike's lifetime, but I gave all the options to my manager to discuss with the doc. Sure enough, he chose the cheapest option, replacing just the bearings.
This week the bearings came in and I was called to perform the swap. This is when problem #2
cropped up: The non-drive crank extractor threads were completely stripped. Yikes. A specialty company called J.A. Stein makes tooling for fixing this issue, but no, we don't have it. No, the manager didn't want to spend that kind of money for what may be a one time occurrence. OK, time to get provisional. The owner had removed the drive crank but couldn't get the bottom bracket to budge. Lacking the extraction tool, I got medieval and drove it out with a brass hammer. Being a carpenter as well as a bicycle mechanic does have an advantage: I'm very accurate with a hammer and caused no damage. The spindle did eventually come out, but with the non-drive bearing and crankarm still attached. The drive side bearing was still stuck inside the bottom bracket shell. I tried using a pickle fork to pull the crank off the spindle, but all it did was push the bearing further inboard. This got me to thinking I may have to enlist some help. I left the project for the day and went home to get a heatgun and to use my lifeline to call a friend.
I've never met my friend other than knowing him from a forum. He lives in the bay area though and has seen far more bikes than I ever have, being a professional mechanic and nothing else for his adult life. He's also very much into early vintage mountain bikes and I knew he'd know how to handle it. When I contacted him through Facebook, he hooked me up with links to forum threads showing how to use the tool (that I don't have and can't get, but still useful to see how it works) as well as a Klein spec sheet that details the spindle offset for a specific crank to maintain the correct driveline spacing. If I'm going above your head with all this tech talk, I do apologize. Talking with him was a very refreshing experience akin to finding someone that speaks your language in a foreign land. He was encouraging and helpful and gave me the info I needed which I saved to my tablet.
The next day I brought everything I thought I needed to get aggro with the crankarm. Since we found the exact replacement crankarm in our used bin (minus the stripped threads) I went to put the arm in the vise to heat and punch the spindle out of it...that is until I saw only half a vise there. My apprentice had actually broken the vise. Without even clocking in I left, figuring I would work on it on my own time with the vise in my shop. After getting home, cooking dinner and doing chores...I was too beat to do anything about it. The shop owner had said we'd get a new vise the next day.
The next day...no vise. OK, let's get primitive. My buddy had mentioned that the last crankarm like this he'd dealt with had to be cut off. With no luck heating and punching the spindle out while clamping it into the bike stand, I busted out the Dremel cutoff wheel and made some noise...for a long time. I cut carefully to meet the corners of the square spindle opening, and with a punch and a big hammer finally got it to split and release the spindle.
After that, driving the bearing off the spindle was cake using half the vise as a shelf. I called it a day.
Today with visions of what it might take and the approximate dimensions in my head plus a crankarm bolt, I went to the hardware store to build an installation tool. I was amazingly able to find a M8X1.0 thread pitch bolt that matched the crank bolt. After an additional trip into paint for emery and steel wool and a detour to plumbing I came up with all this:
The smaller pipe adapters didn't fit over the spindle, but the larger did. Now reading the instructions from the tablet, I did the math to calculate the non-drive spindle offset (125mm spindle length for the XT M730 crank minus driveside offset of 26mm minus 76mm bottom bracket shell width = 23mm) and realized I didn't have the correct thread locking compound required. After a trip to the auto parts store I cleaned the spindle and bearing and pressed it carefully on. This would be much easier with the correct tool, but I just went in small increments until it gauged out correctly.
Now, leaving the assembly on that side to hold it at the correct offset, I cleaned the bottom bracket shell, the drive bearing and spindle and applied the threadlock compound to all the mating surfaces. The instructions for that said I had an hour of working time before it sets. The spacers wouldn't work for the drive side. I started going through all the drawers for appropriate spacers, fumbling with all the pieces until I got the bolt threads started, then started pressing, having to turn in so far, adding spacers to keep it pressing until the drive side bearing seated flush as it should be. Thing is, that was the friction of only one bearing and the shell. When the non-drive bearing started, I was forcing it onto the spindle too. I was having a hard time applying enough pressure with the wrench while simultaneously holding the opposing wrench and the bike steady. That's when the bolt stripped. My manager could see I was visibly frustrated and offered to go get another bolt. While she was gone I did manage to rig up different spacers and a bolt, but I was applying so much pressure I feared snapping the bolt and perhaps even hurting myself. I knew I should chase the spindle threads with a tap, but no such M8X1.0 tap was to be found. When she got back with the new bolts, I took off to find a tap. Two auto parts stores and a Sears later...no dice. I couldn't even find a kit with the right pitch.
With time running very short on the threadlock working time, I got barbaric and again with the brass hammer drove the non-drive bearing in with the apparatus. This drove the drive side bearing out, but fortunately I was able to keep my cool and using the coupler and the big washer, drove it in too. It came out perfectly spaced and no visible signs of the trouble I went through.
I wonder what they'll charge and whether I'll get a tip.