After first comments I realised that I should get a knowledge base about what we are talking about to not to mess up with your valuable informations. So, here I am back
First of all, I presented 2 issues separately in my original post (the creaking crankset, the extract bolt not sitting properly). So, some comments were regarding one thing, some regarding another. I understand that there can be many independent circumstances, however after some research, I've been coming to think this both issues might be connected.
I highly doubt that manufacturer could crooked threads. I also doubt that a mechanic could tighten bolt while installing in a wrong manner and didn't say a single word. I believe I would notice it immediately and ask questions. I also need to add that once the issue was discovered it wasn't that super easy to unscrew the extractor bolt compared to the left arm. The bolt was slightly roasted. This gives me thinking that some unexpected forces were in the game.
So, what about this 2 articles I found as references in some Octalink issue related questions?
https://www.sheldonbrown.com/brandt/...ng-cranks.html
https://www.sheldonbrown.com/brandt/...ng-cranks.html
This crank attachment was apparently designed assuming that all riders lead with the left foot when standing on both pedals, typically over rough terrain. Properly tightened retaining bolts can loosen only with weight on both pedals, right foot forward, because this is the only condition under which the crank spindle torque reverses.
The left crank transmits driving torque through the spindle to the right crank and chainwheel while the right crank drives the chainwheel directly. Besides that, the right crank transmits torque to the spindle only when standing on both pedals. Doing this with the right foot forward (goofy footed) is the only time the spindle transmits reverse torque.
And more in these 2 articles. I must admit that I remember creaking from the right side (under right foot) and only while starting a massive sprint. This could mean I start the sprints in similar conditions to "standing start with right foot forward". And yes, I am goofy footed. So what about if this makes the crank spindle torque reverses and as the crank bolt unscrews with massive reverse torque it loosens (this makes creaks later) and hits the extractor bolt. As the crank arm threads are softer than extractor bolt this finishes with crooked threads in the crank arm and extractor bolt not sited perpendicular to the bottom bracket. Does it make any sense? Or I'm overthinking?
I only inspected threads on the extractor bolt (they were OK), haven't verified threads on the crank arm that could be crooked.
So, this is what I think should be done now:
- Unscrew the extractor bolt, verify threads both on the bolt and in the crank arm. I could try to tighten another bolt to see how it sits, or use a calliper. Basically, I need to find a source of not properly sited extractor bolt.
- Put the extractor bolt back into position, and try to take the crank arms off. This can be tricky as it may damage the extractor threads that @
CliffordK referred to.
- Verify connector condition for roundness and strips.
- Check if spindle has no loosen in any directions. If so, remount bottom bracket.
- Remove seals from bearings to spin more smoothly
- Regrease spindle and rotate it to not match the same connectors from the crank arm (just in case some are rounded or so)
- Replace the alu crank bolt for steel crank bolt
- Tight more than alu crank bolt. Alu crank bolt torque is 40-50Nm recommended, so I guess 60Nm would be fine for steel bolt.
- How to fix the probably crooked threads for the extractor bolt?
And maybe replace alu one with a steel version if anywhere available?
What do you think guys? Does it make sense? I am not experienced with engineering, so maybe there are better options? Who is responsible for eventual damage?
I also verified some videos of 1 kilo starts of elite riders and definitely I wouldn't say nobody starts from the right foot. 50/50 which makes sense as some are regular, some goofy..
Originally Posted by Dalai
I have had the crank arms loosen a couple of times over the years. I just regreased the bolts and retightened to the correct torque. No issues with the interface.
Have you experienced creaks when arms were loosen? BTW. I never felt like crank arm was loosen or wanted to fall off, just creaks mainly.
Originally Posted by brawlo
I came across a snippet from someone that said that newer bolts were ever so slightly different in dimension to older ones. So I still had the old cranks and bolts so I re-used the old bolts and never had a problem since. Until going to Vision cranks in November I was still using those original bolts and zero issues. Now I don't know just how correct that info I found was, but when I went back to the older bolts and zero issues it was enough for me to say there's definitely something there.
As @
Dalai already answered this are SRM bolts, not DA. However, as long as I can imagine that your newer bolts came slightly different (like a bit shorter thread) I don't think this could be a rule of thumb. There could be some individual cases but nothing that could be in production line for years. I am pretty sure Shimano would noticed an issue with wrong bolts shorter or later. However, my optimism could be too high :-)