Hi guys,
I'm pretty sure there are many experts of Octalink system here that could give me a hint regarding my issue.
I've been using Dura-Ace BB-7710 with my SRM Track for over a year now. After about 1000km I started to hear occasional creaking under my legs during accelerations (AFAIR standing and seated) with high power (1000W+). Occasional means it was about 5 creaks in total maybe (I'm endurance, not sprinting that much) for 2 training sessions or so. I verified it my hand and while pushing crank arms by hands (obviously by using a lot of body weight) I could hear the creak, so I decided to tighten the crank arm (I'm referring here to the 8mm allen wrench) as I haven't done it since I built the bike 1000km ago. It turned out I needed about a full turn to get torque of 40Nm (SRM specs says 40-50Nm). After that I rode another 500km including few races and some massive acceleration workouts on 58x12 - no problem at all.
Well, few days ago I was doing a standing acceleration (1200W) on a low gear (52x16) and again, I heard the creak! Rechecked with a torque wrench, I could turn maybe about 1/4 on one arm and 1/3 on another to receive desired torque values this time - basically not much, but still.
I am not a mechanic and I am not really into this kind of engineering, so I did a research on the Internet and I read that Octalink basically should never loosen by itself, once it was mounted correctly. Also, most of the problems with creaking crankarms mounted on octalinks turned out to be an actual problem with the octalink bottom bracket itself and it should be remounted (with cleaning and regreasing). As the SRM is pretty expensive and I don't really want to break it, I went to my LBS that actually assembled the bike and components and I asked for a help.
The LBS claimed this cannot be a bottom bracket issue and they refused to remounted it or even retighten. They claimed this as a normal situation, especially on track as track riders generate more power and there is more forces on velodrome than any other place and there is a chance a crankarm can be loosen from time to time. They unscrewed the crank bolt self extract (I believe this is a correct English name - I am referring to this parts:
https://www.bicyclehero.com/us/p-s-p...f-extract.html), put a blue loctite on the threads and tighten the bolts again.
Is it possible that the crankarms on octalink can loosen from time to time? After 500km? That would mean some elite riders would need to recheck the bolt every single session I guess as I am a small guy compared to the big guys. This is not a square taper and it does not make sense to me what they were saying. I cannot remember even one loosen on my other track bike with Sugino 75 (square taper!) that I was riding for years (also on street). In fact, I am scared if the crankarm arm interface is not smashed now or something. I know this can happen on square taper crankset. Shall I remount/tighten the bottom bracket? Or maybe this time the creak could come from a pedal this time? Unfortunately I haven't verified by hand this time but I had my pedals demounted after flying from a competition, so there is a chance I didn't tighten pedals enough (which actually never happened before!).
There is also another thing. I'm attaching a picture of my right crankarm. As you can see the self extract bolt does not fit nice into the crankarm. It looks weird but threads are fine for sure and basically it looks like the hole was made not super precisely but threads are fine. I was told this is not an issue as this bolt doesn't matter much and I shouldn't even send it to SRM under warranty as this is cosmetic. Is it? The last creak I would say was from the right side (this is actually why I also thought about pedals as I definitely felt it more under my right foot).
What do you think about it? I am a bit worried that something is really wrong and it's going to cost money, I'm not sure who is responsible for it ;/
