https://inception.davepedu.com/

Checked out the right one too today. Taper is fine although the mechanic says it has about 2 pressings left..

Best response video ever. +500

Your mechanic is bull****ting you.

Actually, just send the crankset to me and buy another one. Seems like that's what you want to do anyway.

+1.

What the hell???

I realize this question is going to make me sound like an idiot, but I'm gonna go ahead and jump in anyway. I was actually unaware that there were different sizes (shapes?) of square-taper BB spindles. Can you tell me what dimensions I need to measure and look for to match a spindle to crankset?

JIS spindles are most common. What crankset do you have?

Spindle width is most important.

Campy and a couple of other cranks have different taper which will make the crank sit out a few mm and wreck your chainline if on an JIS BB spindle (by far the least common).

*** Ooops, typo caught by Scrod in proceeding post now fixed.

You're saying ISO is most common?

Here you go.

https://sheldonbrown.com/bbtaper.html

https://velo-orange.blogspot.com/2009/10/bb-basics.html

Thanks for the info. I will take measurements when I get home.

I'm pretty sure my crankset is un-branded, and I got it 2nd hand, so I couldn't say for sure what it is. Super low-end. Regardless, I'm going to need a new crankset because the holes have been worn totally round and the arms are really wobbly on the spindle. It's probably because of a mismatch between the crankset and the BB.

Probabaly not. It's most likely due to riding with improperly torqued crank arm bolts.

Too tight or not tight enough, would you say? Tightening the bolts minimizes the wobble, but only temporarily - it seems like the crankarms work the bolts loose again.

He says there's a limit to how many times you can take a crankset on and off?

If so, you wasted one checking the interface.

According to that Sheldon Brown article quoted above, removing and reinstalling the cranks causes the holes in the cranks to get gradually bigger. So there may be some truth in what the LBS mechanic says.

Over tightening enlarges holes more than properly torquing. Extreme cases will crack crank around hole and repeated mounting/unmounting will result in crank bottoming out on BB, this can happen faster if overtorquing.

Undertightening then riding 'em loose causes hole to be not-quite-square. This renders them Un-tightenable. They might seem tight for a couple miles but will eventually creak and get loose and hole will become even more un-square.

That could definitely be it. I should also probably mention that the bike with this problem is not my regular bike, it's a tall-bike. The top frame isn't lined up well with the bottom frame, so the chainline is pretty radically imperfect, which could maybe be compounding the issue. Regardless, I'm going to get a new crankset, make sure it's the right size, fiddle with which sprocket the chain sits on the cassette, and not tighten the crank bolts down too hard. Thanks!

Perhaps, but I really doubt he can tell how many more installs they have left by looking at them.

Yep. They have a finite uninstall/reinstall count. Dude can't tell how many are left unless he's got electron scanning microscope, maybe some other analysis tools, though.

Total ballpark, dude you need new crank comment.

Everything has a finite uninstall/reinstall count.

I use a JIS square taper BB with my Sugino 75 cranks, and it works fine. I have uninstalled and reinstalled the cranks a handful of times or so, and the chainline is still straight (the cranks are still sitting at the same place on the spindle). I don't use a torque wrench to install, but I just try not to overtighten them.

If you find yourself flexing very hard and a vein is popping out of your arm when youre torquing your bolts back on, then youre probably over-tightening...

I think I might have messed up my Campy Athena (1997) square taper bottom crank (left crankarm) by riding on it while loose. I'd didn't ride the bike much and didn't have the 8mm allen wrench with me to test the tightness, so I just rode without checking. Lesson learned. I know have the 8mm hex wrench and the left crankarm will tighten down and not seem to move, but after maybe 30 miles of riding needs to be tightened some more. Hmm.. So, the crankarm is probably damaged, but I'm not sure if the bottom bracket taper has also been damaged. From what I've read on here, it seems like people are saying that it's not likely because it is steel and the crankarm is aluminum. We'll see. I ordered a new (used) crankarm and will see how that works. And whether or not it stays tight.