With only 300 miles, your chain rings and sprocket cluster at the back should be like new.
Depending on the quality of the chain, it could need replacing in the next 100 miles or so. 225lbs ( I am 219lbs) wear a chain quicker than a 160lbs guy.
1ste Let your local bike shop reset you gears and so on, and give it a good lube and see if it improves.
With time there is wear and stretch in the shifter cables, this let the alignment of the derailleur, chain and gears go out of optimal ever so silently. This can contribute to a lot of drive train noise. I have had brand new drive-trains make irritating noises even if it works well.
Sometimes it just need that pro adjustment from someone who do it for living.
Make sure the guy at the bike shop knows his stuff. You would not let a new apprentice rebuild your Cruiser's gearbox do you?
Lastly, look at you "gear habits"
Run the biggest three gears at the back with the smallest chain-ring front.
The smallest three gears at the back with the biggest chain-ring front.
The middle six gears at the back with the middle chain-ring.
It is a worth while habit to adopt.
Keep well.
Some good advice here.. With 300 miles on your chain you should definitely be getting more life out of it than that. I probably put close to 500 to 600 miles on my chains before I start seeing degredation in performance but I am pretty anal about my maintenance. I also run a 1x10 so I use my entire range when riding. I weigh about 190-200lbs fully kitted up and I can mash on the pedals, especially in techy sections where I am searching for chain tension while going over obstacles and whatnot.
A more expensive chain may last you a bit longer but that is not a guarantee. Also look at the terrain you are riding in, if you are riding in super sandy/dusty terrain on a regular basis for long miles then that will contribute to chain wear. There are quite a few variables that can play into everything, the need to clean your chain every few rides is really not necessary unless you are leaving heavy chain lube on the chain while riding (big no no) and letting it get gunked up. Also, it is good to go in once a year to get your drivetrain adjusted, because as
@Petoors said, the shift cables will stretch a bit which causes things to not shift optimally. This is a good point to learn what you can about tuning your drivetrain, so take a 6pk of beer into the shop late one night (with their permission) and sit with one of their lead techs and have them walk you through it.
My normal process is as follows... (mind you I ride about 3-5 times a week with average ride being 10miles, longer rides being 20+)
- beginning of riding season I take bike to shop and have them do a once over on everything. (e.g. tru wheels, check bearings, etc.)
- every couple of rides, wash bike with simple green mix, wipe bike down, clean chain, re-lube chain, thoroughly clean fork/shock stanchions, regrease fork/shock stanchions
- every 100 miles or so check pressures in fork/shock, make small adjustments, check tires (tubeless), make small adjustments, thoroughly clean bike.
- every 4-6 months BIG SERVICE (depending on how hard and how much I am riding)
So for the big service normal check list is as follows...
- thoroughly wash bike, scrub junctions with soft bristle brush (e.g. crank bearing cups, major pivot points, axles, etc.)
- remove seatpost/dropper clean all surfaces and regrease stanchion
- remove wheels, regrease axles, check spokes and rim for damage, check tires for damage and wear, check Stans and top off if necessary
- remove fork and service (this normally consists of disassembling fork, checking seals, replacing seals, redoing oil levels, greasing different items, reassembling fork)
- remove shock and service (this normally is just taking the can off and checking for any stanchion wear, play and checking seals)
- remove brake pads, thoroughly clean surfaces with rubbing alcohol, bleed system (Shimano SLXs) and checking rotors to see if they are tru
- take a look a bearings and pivot points for any slop and wear and if necessary replace.
- remove jockey wheels from rear derailleur and make sure that they are clean, no damage to teeth and check bearings for slop/noise
- remove rear freehub body and check for damage, wear, etc. and regrease inside pawls if everything looks good
- while freehub body is off I take a look at the cassette and see if any teeth or rings look damaged or have excessive where and make sure it does not have more than acceptable movement while attached to freehub body
Since I run a 1x10 system I do not have to worry about my front ring as if there is an issue with it then it is pretty obvious. However, I do clean the ring and inspect, check that all ring bolts are tight and give the pedals and crank arms a quick once over. No matter what, when you are doing work to your drivetrain you want to do it in very small increments as small adjustments can make large differences. A 3x10 system is pretty complex and you will not have optimal shifting in all rings on the entire cassette, as
@Petoors said, first few (lowest) gears of the rear cassette should only be used in the big ring, then as you step in further on the cassette you wan to match those steps with shifts of the front chainrings.
(soapbox)Honestly, the need for a 3x10 system, and in some places a 2x10 system, is really not needed anymore. The gearing ratio redundancy you see is pretty major between the systems. As you get stronger you will find that the little bit of top end/bottom end that you would lose with going to a 1x system is really negligible especially with today's wide range cassettes. But like with anything else, that depends on a lot of variables (terrain, health, riding style, area, health, etc.) but I HAVE PERSONALLY found that the switch from a 2x10 to a 1x10, and previously a 2x9 system, was well worth the small amount of top end that I lost. (/soapbox)