I think I posted this elsewhere on the forum, but for this discussion, I'll do it again. Haibike Full FatSix with the 2 front FSA chainring set up, 44 teeth big chain ring. Although I was very thorough in keeping my chain clean and lubed all the time, I was not thorough in changing that chain out every few thousand miles.
End result? Starting out from 0 mph and the chain came right off the front chain ring. Multiple times.
I think it was poster
@Nova Haibike here who in one of his posts, linked the FSA chain OEM chain ring, right from FSA. I believe I paid 57 dollars for that in summer, 2020. Important Note: I DID NOT order the chain ring bolts and nuts, thinking I'll reuse the old ones. Being the nut is aluminum, this is not a good idea.
You also need that special spanner that holds the nut while you unscrew the chain ring bolt. I thought I could get by with needle nose plier (and did, but not without mangling the soft aluminum nut sert). And I also found that needle nose pliers will not catch the nutsert with the chain ring attached to the motor. So the crank arm, and the spider with chain rings attached have to come off. Note what poster
@Brooks said about that nut; it's a 36mm socket and it is left hand thread.
I replaced the big chain ring, the chain (Shimano 10 speed HG replacement......this is what came with the bike originally. I believe it's not a good idea to go with a 9 speed or 12 speed chain....stick with the 10 as it's properly spaced for the cassette.) Along with the big chain ring, chain, I also replaced the rear cassette with the same Shimano cassette. And for good measure, I replaced the rear derailleur.
I did this as I had 10 thousand miles on that chain. I damaged the rear sprocket high gear sprocket when one day, I decided to try climbing a steep grade from water level, in the big sprocket and 10th gear. And damaged the teeth in the process, creating a skipping whenever I was in high gear on flat roads. Lesson learned: replace that chain every few thousand miles....not at 10 thousand!
Here's the reason why; note the wear on the teeth of the original versus the brand new:
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