Stronglight bottom bracket sanity check
 

Hello All,

I am reinstalling a Stronglight 118 BB in it’s original home (70s Lejeune Pro) to spin the original Stronglight 93 crankset. I cleaned it up and replaced the bearings with fresh 1/4” from Wheels mfg. When I put everything back together, I have two indications of an improper install.
1: NDS spindle does not clear the shell enough to install crank arm when bearings are properly set. NDS crank arm bottoms out on BB.
2: When I set proper bearing clearance (no play in spindle, and spindle spins freely) I can hear the bearings rolling.

I’ve tried 10 and 11 ball bearings and neither fixed the issue. It doesn’t matter which direction the asymmetric spindle is set up; same issue.

The spindle races and cups all look good.

What am I doing wrong?

Thanks for for your help.

https://cimg8.ibsrv.net/gimg/bikefor...ed704ee39.jpeg
I did not ride the bike prior to disassembly, but the crank arms spun freely.

It needed an over haul, as I had no maintenance history. Theoretically, the issue could have been present and the NDS crank arm was not properly seated on the taper.

Picture taken prior to disassembly attached.

Stronglights should take 11 1/4" balls. You could remove the spindle and check how the balls are tracking, basically the ball track should be centred in the middle of the arc of the bearing surface. If not, someone may have used the wrong bearings in previous life. New BB may be in order.

In all the years I tinkered with this stuff, I never really wound up working with a Stronglight BB (but quite a few TAs) - but if there's anything that jumps out at me immediately, the NDS cup seems to be sitting outboard of the lockring about an extra mm than it should.

Have you also checked to make sure the cranks aren't near bottoming out on the taper?

Have you also taken it apart and checked the grease for witness marks of where the bearings are riding?

-Kurt

Thanks for confirming the bearing count, Clubman.

If the bearing surfaces were shot, could that explain the spindle length issue? I’ve pulled this thing apart about a dozen times, and it doesn’t make sense to me.

I would take it all apart and start over, Make sure your ball bearings are the right size. Loose bearings are better than caged bearings. Make sure the drive side cup is fully seated all the way down into the bottom bracket shell. Tighten the adjustable side cup all the way down until the axle has significant resistance to turning before tightening the lock ring. I always assemble my loose cone bottom brackets way tighter than common sense would consider necessary. It's been my experience that if I don't overtighten this assembly at first, I'll have to come back and tighten it up later. Crankshaft forces are strong. Things can loosen up down there.

Best course of action - if you intend to rely on the forum for assistance - is to take it apart again and get some really good photos of all the bits spread out on a table. Get some closeups. Someone is bound to spot a clue.

-Kurt

Will do! I’ll get back to y’all tomorrow. Thanks for the input.

Is it possible you have a MTB spindle. The bearings sit differently(don't ask me how so) on the spindle race compared hto a road bike spindle. I had the exact same problem. Previously the bearing cups may have been done up loosely so the cranks would spin without binding. Fine as long as you don't try and ride it.

If the NDS arm is contacting the cup then the taper must also be nearly bottoming out to the bolt head.

This sounds like the arm may have been installed using grease where none should be used (on the tapers). I clearly recall that Stronglight's dealers such as Wheelsmith warned customers against using grease on these lightweight crank's tapers back in the day.

At what bolt torque level does the arm begin to rub on the cup?

If it begins rubbing on the cup before much torque has been applied, the taper must really be shot.
But if the bolt can be torqued somewhat well before the arm contacts the cup, then some metal can be shaved off of the arm to gain needed clearance at the cup. Some metal could also be shaved off of the face of the cup using a belt sander (the chrome will ruin a file).
If the torque level is still needing to be on the low side, then the bolt should be installed using blue LocTite on the threads.
Remember that the arm will move inward slightly during the first ride after tightening the bolt.
If the bolt bottoms on the end of the spindle after the arm has been relieved then at least the bolt can be fully torqued, and the spindle end can also be ground a bit shorter.


One last check would be to confirm that the ball bearings are exactly 1/4" in diameter.

amillhench-

Do you have an actual Stronglight axle?

https://cimg4.ibsrv.net/gimg/bikefor...69521d108.jpeg
https://cimg3.ibsrv.net/gimg/bikefor...3500974ee.jpeg
https://cimg5.ibsrv.net/gimg/bikefor...7740fd470.jpeg
https://cimg8.ibsrv.net/gimg/bikefor...679d8eec2.jpeg
Pictures as promised. Looks like the cups are more worn out that I originally thought. My eyes say the spindle still looks good.

I measured both the original and new ball bearings and they are spot on 1/4”.

I am not suspecting bearing wear as the culprit since wear would only make the spindle stand further out from the face of the adjustable cup.

And with the cup not looking sunken-in at the lockring, that leaves the inside taper of the NDS arm as the only real problem area.

Did you perhaps grease the taper at all? And what level of torque did you apply to the bolt?

It now comes down to either replacing the left arm (harder to find than a right arm from what I have seen) or removing metal from the faces of the arm and/or cup.

Don't grease the tapers at all, and use LocTite on the bolt threads in lieu of torqueing fully to the vicinity of 30 ft-lbs.

https://cimg4.ibsrv.net/gimg/bikefor...f0f87c1dc.jpeg
4d,

I did not grease the tapers, but I’ll admit I rarely if ever use a torque wrench on crank arms. I’ve never had a problem (until this one!)

an interesting observation: the tapers are differing lengths on this spindle. The drive side taper is 20mm and the NDS taper is 16mm. Both crank arms seat similarly onto the spindles, but obviously the 16mm taper runs out of taper sooner. I’ve attached the Stronglight catalog showing the spindle lengths and while they are asymmetric, I can’t tell if the asymmetry comes from the taper or the spindle area between the race and taper.

Regardless, I guess I’ll be ordering a Velo Orange BB to use a modern Stronglight Impact I have waiting in a box.

Interesting, the tapers on my Stronglight are also asymmetrical. Must match their crankarms specifically.
I'm not sure your spindle is in great condition, it looks like there's ball indentations in the one shot.

Note that both ends of the spindle have exactly the same taper thickness and taper angle, so any difference in the lengths of the actual taper would have to be from a different machining endpoint at the inward end of the tapers (where the taper curves up toward the OD of the round section of the spindle.
This won't affect the positioning of the arm on the taper at all (unless and until the arm collides with the end of the taper, at which point the bolt would most likely also be bottoming on the end of the spindle).

It would be interesting to see if either crankarm's bore is longer than the other to match the longer taper on the same end of the spindle.

Note that the right arm has a lot more metal surrounding the hole, preventing the bore from ever getting stretched larger over time. So perhaps the shorter taper on the left end of the spindle is designed to prevent the less-reinforced left arm's taper bore from moving too far up the spindle and creating the problem that you have described. But if so, why has this ceased to be effective in your bike's case?

Another possibility (since I don't know for sure which end of your spindle was given the longer taper), is that the shorter taper is designed to preserve a narrower range of chainline, much like Shimano's use of a pressed-on, hardened-steel bottoming ring on the drive-side some of their cartridge bottom bracket's spindles.

Spindle orientation
 

Have you tried reversing the spindle?

Yes, he did.

-Kurt

This is starting to get really interesting, since all of the 118mm Stronglight spindles I've handled were significantly longer on the drive side from the bearing race to the end of the spindle.

So if reversing the spindle didn't at least remove the problem from one crankarm and transfer it to the other, then there is something quite strange about this particular 118mm Stronglight spindle.

Could the OP perhaps measure the distance on each end from the spindle end to the same-side bearing track?
Is the drive side end not at least 2mm longer than the non-driveside end of the spindle?
And wouldn't reversing the spindle then surely give ample clearance between the adjustable cup and the non-driveside arm?

Unless, perhaps, the cup is significantly thicker on one side? Just throwing that out there.

-Kurt

Interesting. Reversing the spindle should have made a drastic difference. I'm wondering if the BB shell has been aggressively faced. Did you measure it? There should not really be any threads showing on the adjustable cup if it is set up normally. The cranks even when set up properly do end up very close to the BB on the NDS.

Stronglight cranks have rather soft alloy, and do tend to creep up on the spindle over time. This is made worse if they are overly loved and regularly maintained. Plus side is they are not prone to cracking. If the cranks have not completely bottomed out, what I suggest is to simply use a modern JIS BB. Should be just very slightly fatter than original spindle, and will work perfectly with the 93 cranks.

BTW, in the olde days, all BB spindles were asymmetric.

If you flipped the spindle and it made no difference, chances are the crank arms are wallowed out.

Worn cup test
 

Put bearing in one side and tighten up. Put on crank and get required clearence. Do other side and you get rubbing.?Reverse the sequence and does the rubbing change sides? If cups are worn out the first side is pulling the axle too far one way and 2nd side bearing has too far to travel and the crank hits the frame instead.
Solution - keep cranks, axle, ball bearing and change cups.

It's a forty year old crank, and if the previous owners took good care of it, they may have overhauled the BB forty times or so if rhey did an annual overhaul. Forty tightenings might have bottomed out the crank. I wonder how much longer my 49D will be usable.

Another possibility is the odd Stronglight crank extractor diameter meant the bearings were changed way too late too often. Guess how I know about that problem and its consequences? :innocent: