I have a brand new bike, brand new Ultegra SL. Shimano # FC-6601-G (53-39 rings). After a couple hundred miles, while cleaning chain and spinning pedals backwards, I noticed a a sound almost like a bit of sand stuck between surfaces. Could be the chain needs to be finished cleaning, but figured I'd bring bike to LBS, get opinion. The LBS guy said that he thought there should be a spacer between left crank and left adapter, and that because the crank was (maybe) touching the adapter, that sand might be in between, causing sound. He seemed quite sure of the spacer deal. So, I checked the Shimano Service Instructions, removed the left crankarm, cleaned it up (there was a tiny bit of damned winter sand), reinstalled. And then cleaned the chain, which solved the problem. MY issue is, the LBS guru swears that there should be a spacer, while the Service Instructions state there should be a spacer for the FC-6603 and 6604-G. Should I trust the specs?? Or the LBS human??

Trust the manual.

Trust the manual.

Indeed, why even ask...

One could usually assume that the bike shop owner might actually be knowledgable. My bad. One less bike shop to go to!

It doesn't at all mean he isn't knowledgeable. He's probably a bright guy and is used to seeing the spacer on other gruppos.

But, I would bet Shimano knows their equipment better than the LBS guy.

Never trust a hippy... huh... a shop mechanic that is...

For all of you that are now criticizing the bike mechanic, would you know any better. Do you know every spec on every single part made since 1975. If you do, feel free to criticize, if not shut the hell up.
I'm tired of seeing people rag on mechanics for missing the slightest detail, they are human just like everyone else.
The shop probably didn't even install the crank if it was a new bike, it was probably put on in Taiwan or China were the bike was made and the parts placed on it, boxed up and ended up at the bike shop to be assembled many months later. A small spacer like that is easily overlooked especially if you are assembling the bike. Mistakes happen, its part of being human.

i work in a bike shop and we have been known to make assumptions from time to time, we are right almost all the time but well not always I would trust the manual, the shop employee is used to seeing the spacers and assumes all cranks need it, but shimano does not make the stuff up in the tech manual, it's there for a reason

For all of you that are now criticizing the bike mechanic, would you know any better. Do you know every spec on every single part made since 1975. If you do, feel free to criticize, if not shut the hell up.
I'm tired of seeing people rag on mechanics for missing the slightest detail, they are human just like everyone else.
The shop probably didn't even install the crank if it was a new bike, it was probably put on in Taiwan or China were the bike was made and the parts placed on it, boxed up and ended up at the bike shop to be assembled many months later. A small spacer like that is easily overlooked especially if you are assembling the bike. Mistakes happen, its part of being human.

It's ragging on a mechanic to say "Trust the manual" or "No question, trust the tech manual"?

The manual will be superior to the mechanic's knowledge.
That does not mean the mechanic knows less. It just means the manual knows more.
There IS a difference.

I've installed three Hollowtech II double cranks and have never installed a spacer. It's never been provided.

You (and the manual) are correct. The spacers are for the triple cranks.

Thank you, Doctor!

FWIW, my LBS diagnosed the same noise on my Ultegra 10sp cranks as road grit. Comes (sometimes) from riding in the rain. In fact, my cranks are afflicted with this annoying problem right now. No big deal.

For all of you that are now criticizing the bike mechanic, would you know any better. Do you know every spec on every single part made since 1975. If you do, feel free to criticize, if not shut the hell up.
I'm tired of seeing people rag on mechanics for missing the slightest detail, they are human just like everyone else.
The shop probably didn't even install the crank if it was a new bike, it was probably put on in Taiwan or China were the bike was made and the parts placed on it, boxed up and ended up at the bike shop to be assembled many months later. A small spacer like that is easily overlooked especially if you are assembling the bike. Mistakes happen, its part of being human.

Ok so here are my rare experiences with mechanics. Note that these were enough to prevent me for handling my bike to anybody but myself :

1) On my first MTB, I had to change the front derailleur. Had it installed at the shop. When I got the bike back I noticed I couldn't get on the big ring because the derailleur had been installed too low on the seat stay that it was rubbing the big ring. Great so I paid for that idiot to install my FD and he didn't even try shifting with it installed.

2) A couple of times I went to LBS for some small advice. Every time I got a rude answer of the "bring it to us, we'll do it" type with no further explanation. Of course you want me to pay 50 to install a damn chain guide right?

So yes I complain about shop mechanics because I have always had better experience setting things up myself. Plus most of the time it's cheaper to simply buy the tool (and therefore DIY multiple times) rather than paying to having it done once. And that's without counting the added knowledge you gain by working on your own bike. I don't think I would have ever learned to build wheels if I had not learned to setup a derailleur first... Thanks to that incompetent mechanic for forcing me to get my hands dirty.

Pissed, I like your reply. Decided to get the tools to take apart and inspect the BB myself. Now I can do it any time I want. The way to go for cyclists who rack up any kind of mileage!