Gosh

Bought a new carbon, disk brake, Di2 Giant Defy last summer. Cycled about 2,500 miles and used through winter with mud guards. Had the LBS initial service/ fixings check after 6 weeks. Apart from a sticky brake calliper which I shall clean out, there doesn’t seem to be any other problems with bearings, indexing etc. As we move into spring/summer apart from topping up tire sealant just wondering what the service advice is in my situation. Thanks.

Andrew R Stewart 

This answer depends on whether you're a reactive or a proactive rider.

If reactive then don't do more than wiping things off, lube the usual moving parts and only go deeper when the bike won't ride any longer. You'll be fine until you aren't. You'll spend nearly zero $ and be able to brag ("great bike! I haven't had to do anything to it since I bought it".

If you're a more proactive rider then you'll want to have all the parts removed from the frame and fork, clean and assess each part (replacing/lubing as needed) and reassemble about once a year. Usually done during the "off season" so to not keep from riding during the season and not to see your "nice bike" suffer from winter's harsh conditions. That's the duty of the old "nice bike" that became not nice from too little maintenance...

Real life is somewhere in between. We do what seems to make sense and is affordable when we think we need to. Unfortunately so many riders don't have the feel for what's been slowly wearing on their bike till some major amount of "badness" happens (like a broken spoke or a collapsed bearing retainer) so many bikes see far less maintenance and instead are in the shop during the nice weather due to a "JRA" issue. Andy

rm -rf

Regular checks:
chain wear. Replace the chain at or just after 0.5% wear. One of the simple chain checkers will be fine. I have the more expensive Park Tool chain checker, with a moveable lever and a wear scale, so I can see how close I'm getting to that 0.5% point.

disk brake pads. I only have rim brakes, so I don't know the procedure for checking for wear. Another rider uses an inexpensive Harbor Freight digital caliper to measure the pad wear. (and those calipers are useful for other things, too.)
disk brake fluid. Is this a maintenance item? I don't know.

tire wear -- I have Continental tires, which have two small pits in the tread. When the pits are just about worn away, it's time for a new tire. I've ridden tires with the fabric weave starting to show through the rubber, but replacing a little earlier is good.
The rear tire gets all the wear, your pedaling force wears tires way faster than the free spinning front tire gets. So I discard the worn rear, move the barely worn front to the rear, and put a new tire on the front. Otherwise the front lasts for years, accumulating cuts and cracks, etc. This is pretty easy with tube wheels, but more trouble with tubeless.

Rear shifter cable! The wire cables make a bend within the shifter body, and the flexing over this curve eventually causes the cable strands to start breaking. Cables don't seem to last more than a couple of years now. There's usually a window to see the cable at the bend. Pull back the hood to see.
Symptoms of frayed cables: the shifting seems to be less precise "I need to adjust the shifting a little". Then soon: It won't easily shift one gear, it kind of hangs up -- I'm shifting two gears, then back one gear. Then (often within the same ride!) the cable breaks and I'm stuck in the smallest cog. It can easily go from a slight problem to broken within a ride or two!

Mechanical shifting adjustment. I have Di2 now, with minimal maintenance requirements. For cable shifting, it's useful to learn how to adjust the shifting correctly. It's not hard once you understand the barrel adjustments and the limit screws. (turning things at random to try to fix isn't the way.) I would hear a slight noise from the chain being slightly off center, and fix it quite easily myself. I really like perfect shifting.

Front headset bearings: I check for play by standing over the bike, holding the front brake, and pushing forward and backward on the bars. If the play is a bit loose, I can feel it -- a slight clunk.
It's easy to readjust, but it's not obvious at all how to do it correctly. Learn the method, then it's easy to fix. Park Tool has a Repair Guide online, with step-by-step methods for all kinds of maintenance.

I spin the crankset when the chain is off, to see if the spin is smooth. If I'm not sure, I'll remove the crankset and use a finger to turn the bearings on each side. I can feel if they are rough and need replacing.

I occasionally check the wheel bearings with the wheel off the bike, hold the axle and spin it.
I had the front bearings on one wheel replaced at about 30,000 miles. They felt a little rough, but actually weren't obviously bad when the bike store gave me the old bearings to examine. Other than that, no wheel bearing problems.

Once a year, pull out the seatpost, wipe it clean. I use "carbon assembly paste" on it to increase the grip, so the clamp doesn't need to be extremely tight. Removing it is mainly to avoid any corrosion problems.

New cassette occasionally. Unfortunately, there's no good methods for measuring the wear. I think the usual way is to notice skipping on certain cogs when a new chain is installed. I think bike shops sometimes replace cassettes too early. Cassette (and tire!) wear is increased if the ride is very powerful.

What else? That's about it for me.

EDIT -- Andrew Stewart's post reminded me: Cracks at spokes, either hub or rim. A couple times a year, wipe off the rim and closely inspect the spoke holes. Aluminum rims can develop small cracks at the hole, which eventually get big enough to let the spoke pull through. Does this happen to carbon wheels? I don't know.

rm -rf

Yes, some riders just don't notice problems.

I've been on a group ride where the rider's crank was creaking quite loudly, right until the left crank fell off!

A rider got a flat, installed a tube, immediately flatted again, another tube, another flat. Rushing the change and not looking for that tiny sliver in the tire. Or maybe they pinched the tube when installing it.

Another rider stalled on a climb. Their rear shift cable had been broken for a while! Clicking to shift during the ride, and wondering why they were so "weak" -- it was stuck on the smallest cog, of course.

Gosh

Point taken. I tend to be more on the proactive side but had a nagging less is more / don’t fix if it isn’t broken

Gosh

Thanks rm-f I’ll check out those items.

blacknbluebikes 

Clean your drivetrain regularly. No need to get all scientific about it. I suggest you get a Park Tool chain cleaner thingy, simple green and some made-for-purpose chain lube. That will do you fine, and, of course, you'll find tons of 'high church' advice on other approaches. Regardless of approach, this maintenance about every 30 hours of riding is worth your time. Keep an eye on your brakes, inspect them every few rides. Again, nothing too complicated, but check for stability, accurate response, proper positioning with respect to other components. Keep your tires properly inflated. Any failed shift deserves the question: mechanical error or rider error. Address accordingly. Charge your Di2 battery the day that the front shifter won't shift and keeps you in small ring, don't delay that unless walking is also a favorite sport. Inspect regularly for loose things and address those. Congrats. You've covered it all. Rest is hobby fodder.

FBinNY 

As Andy pointed out, it's a question of how much preventive maintenance is called for. IMO 2,500 miles is too soon to be pulling things apart under normal conditions. However, winter riding is particularly hard on parts, so you're in a grey area.

FWIW, when I was much younger, I was riding 5,000+ miles per year, in all weather. As the season wound down, it was tempting to do some work, but knowing I was going to ride through the winter, I'd defer everything until late March, so I didn't have do it twice. That bike went over 50k miles on original hubs, BB and pedals, with zero on road breakdowns. Headsets died of old age (fretting), and only parts replacements were the predictable wear parts, ie. tires, chain, freewheel, etc.

So, you might follow my lead, and do some PM now, then time future PM based on season rather than miles.