Jim50Hz, Nice bikes.
I've avoided the 'fixie'/single-speed thing, though working at a university, and with a thriving local 'hipster' population, the bike racks are FULL of them.
The Giant looks nice. -Another local shop is a dealer, and they seem to be priced very well indeed... not to mention they do quite a bit of sub-contract manufacture for other name brands, so they're more pervasive than most people realize.
John,
Rear derailleur (shifter) alignment: There are bunches of YouTube videos on the subject, but before fiddling, and getting the 'feel' of what's a "big adjustment" versus a "small tweak", make sure that you learn about the two limit screws do... in particular the screw which limits the travel of the derailleur INWARDS (towards the spokes). Once those limit screws are set (and they not always are) then you should never need to touch them again, but the inward travel limit is critically important to set FIRST in my experience, because if it allows too much inward travel, then future cable tensioning experiments can drag the chain "past" the big cog, where it drops down between the cog and the spokes... chewing up the spokes if the bike is in motion. (freewheeling won't help you, if the spokes are moving, they're grinding against the chain!) -So SET THAT FIRST.
Other than the two limit screws (which there's typically no reason to ever mess with, once correctly set) then there's only two other adjustments: cable tension (where the pulleys sit in relation to each gear with the indexed "clicks") -which is the most common thing to adjust, and back-tension. (leave this one well alone for now... it's easier to mess up than set right, until you're familiar with regular use. -Again, there are plenty of "instructible" videos out there, some done by people with better understanding than others, and some done by people with better ability to communicate their understanding than others. -Certainly, you can probably assess both skills for yourself.
Be aware that staying in the smallest chain ring at the front means that the smallest cogs at the rear will probably result in a little 'chatter'... Viewed from above, when the chain is in the middle ring at the front, it's only asked to "bend" a little bit to "reach" all seven cogs at the rear... -the chain should be more or less straight and "unbending" when on the 4th (middle) cog, and in the middle front ring... and in the smallest front ring, the chain is probably pretty straight on let's say the second-largest rear cog... but if you shift all the way to the smallest rear cog, the chain links are asked to "bend" at the most severe angle as they leave the front ring, and then "bend back" as they engage with the cog at the back.
-Bear in mind that when I say "bend" here, I mean "deflect" or "deviate"... they don't actually 'bend' in terms of the metal in the chain links truly bending!
Anyhow, having the chain all the way to the left at the front (small ring) and all the way to the right at the back (small cog) is known as "cross-chaining", and is acceptable, but not ideal. -If you find that you're spending ALL your time in that combo, -or most of it- then you should shift up to the middle ring, when a similar (if not essentially identical) ratio can probably be achieved by stepping the rear cog up towards the middle. -Likewise, using the chain ring at the front all the way to the right (the big ring) when coupled with the cog all the way to the left at the rear (the low speed cog) is also an example of "cross-chaining", and it's fine for brief spells if you're using the large ring because you're zipping round everywhere... but similarly, if you find yourself spending all day in that combo, it's time to consider a spell on the middle chain ring, mated to a smaller rear cog.
Also, chain clatter noise can come from the front derailleur guide. -Since it acts on the "tight" side of the chain (not the "slack side, as does the rear derailleur) then there is no way to use a jockey wheel, so it has to form a narrow 'gate' through which the chain passes. -Its job is to forcibly "drag" the chain over to the next ring when you need to shift, but to then sit in a position which -ideally- doesn't 'rub' against the chain sides... This is often a 'compromise' since the 'deflection' of the chain as you switch rear cogs, and the chain 'bends' and changes path, often causes the chain to rub slightly, again most commonly at 'cross-chain' combinations.
DO NOT fiddle with any adjustments on the front derailleur. -Not until you're at least well familiar with other adjustments. Instead, you MIGHT find that your FRONT shifter controls (be they twist-grip, paddle-shift, or 'trigger and thumb-lever' types) may have small "in between" clicks among the main indexes... -If so, these are to allow you to "trim" the position of the front derailleur to quiet chain-rub during cross-chain combinations.
Anyhow, that's probably more than you need to know right now, but certainly, the rear shifting is generally just a matter adjusting of the cable tension. There should usually be one thumbscrew at the cable entry to the rear derailleur, and also one at the shifter end of the cable... they both do the same thing, so don't worry. -The difference is that you can only reach the shifter one when you're riding, so it's common for a shop-tech to 'center' the front one to allow for adjustment both ways, then to make the 'basis' adjustment at the rear thumbscrew, while the bike is on the stand.
Some bikes have plastic "spoke protector discs" (also known as "dork discs") to protect against spoke-grinding from misadjusted rear limit screws and over-adventurous thumbscrew-twiddling. some people remove them because they get dirty/cloudy/nasty looking. If you have one, do not remove it unless you've checked that the inner limit screw is set so that your chain CANNOT drop over towards the spokes.
My son actually managed third place in the Miami triathlon this weekend... first place was the national champion, so I'm inclined to let that slide... but he thinks he wants to up his training to see if he can claim that second place... -I'm game!
