SHIMANOXTR Fc-M9100-1 Crankarms - Boost

It definitely looks cleaner than the older XTR 9100 on my other bike. However, I'm not out there to just 'look good'. Let's talk about the practical aspects. It's exactly 454 grams w/o the chainring (nice). It's not hard to put on; you need a special tool to secure the chainring, other than that it's pretty similar to the usual Hollowtech II design. However, two issues that prevent me from giving it 5 stars. First, the XTR direct-mount chainrings are ridiculously expensive. I instead got am SLX 32t for about $45 and it's fine but...it weighs a lot, around 115 grams. It will probably last a long time but there are aftermarket chainrings out there for $10 that are perfectly fine, weigh 1/2 that much, and last 1000+ miles. There just are not any for direct mount...yet. Second, and more important, there is some weird-assed preload dial on the left side (other side from the chainring) that's attached to the crank. The crank is put on with an M10 hex key (easy), but then if your bottom bracket is not exactly right for this crank, the left crank will slowly loosen. You need to dial off the preload tension first, turn the hex key very tight for the crank to attach to the arm acceptor, then tighten preload dial until that's firm. You have to do this every 100 miles or so because it will eventually loosen again. If the left crank starts to feel floppy / too easy to pedal compared with the right crank, get off the bike immediately and loosen/tighten as above. Or it will fall off. I don't know if this problem still occurs with the correct bottom bracket or not, I have an Alivio BB and it works "OK" with that, but others have had similar issues with the left crank and the probably have a more correct BB than that one. Just be warned. Other than that it's fine, it was still worth the purchase. But just saying...the XTR M9100 never, ever had a problem with the left crank falling off. The older Alivio one did. Just some trivial info. for you.