I think there's a diminishing returns on this, but on the really cheap end of things, no amount of maintenance will actually get things to work properly. You could end up with wheels that just cannot be trued, gears that never shift cleanly, etc.

Mind you, I'm thinking of BSOs, not something you'd find at your LBS.

I try to give the bikes I commute on some maintenance monthly, and take them in for a tuneup every 500-1000mi or so. I don't ride any internally geared bikes though, so I can't really say how often I feel they need service.

On a $700 hybrid with a 9 speed chain and hydraulic brakes. Fit a new chain ($30) and new tires ($55/pair) and an LBS service for the brakes+new pads ($75) twice a year. But I'm doing 50km/day (1000km/month)

The below was my summary of other answers.

I've now had my bike for 10 years and can answer from experience -- my bike is a "Kona Dr. Dew" which cost $700-$800 (when new in 2010) -- which I ride at most about 7,000 km per year.

It's aluminium with hydraulic disk brakes and maintenance is minimal:

• I have aftermarket "Marathon Plus" tires, which never flat and want replacing after 5 years (though it's been 5 years since they were last replaced and they don't seem to need it again yet, maybe the first set wore more quickly for environmental reasons, e.g. standing outside in summer sunlight or winter sub-zero).
• The chain and brake pads seem to need replacing once or twice a year -- more specifically about every 3000 km. Or the brake pads wear less quickly if you're not cycling on hills, or in city traffic (frequent braking due to traffic lights etc). After installing the new chain they check the derailleurs' adjustment.
• They often replace the cassette when they replace the chain, but I recently bought a chain gauge, so I'll see whether replacing the chain as soon as it needs it will make the cassette last longer. I think they also replaced the triple chainrings once.
• They replaced the bottom bracket after about 30,000 km, when the crankarms began to wobble a bit. The bike shop recommended a good (higher-end than the original) second-hand bottom bracket which they had in stock, so far so good.
• The only maintenance I do myself is top up the tire pressure when I can feel they're not tip-top, and add lube to the chain occasionally.

That's all! They never serviced the wheels, nor the hydraulic fluid in the brake lines.

So it's been a real pleasure. Maintenance is fairly regular, but only to replace "consumables" i.e. the chain and brake pads.

Perhaps its frame being aluminium (not steel or carbon), and no suspension, and hydraulic disk brakes, and robust (rather than "aero") 700x32 wheels, help make it low-maintenance.

This phrase from the original answer below seems quite wrong in practice (so I want to correct it):

Cost of thrice-yearly service, and new parts (pads, chain, and cassette) might be $600/year (or more if you don't do your own weekly chain cleaning, and monthly brake and gear adjustments).

Instead iirc the LBS charges $50 or $100 to replace the chain and the maybe the brake pads, so the yearly cost seems more like a bit more than $100.

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Chains

There's a lot of information here about why chains wear, how long they might last, how to tell when they need replacing, and what happens if you don't when they need it.

• 1000 km (cross-country, or all-weather abuse)
• 3-5000 km (well-maintained derailer chains)
• more than 6,000 km for perfectly groomed high-quality chains, single-gear, or hub-gear chains (preferably with a full cover chain guard)

So if you're doing 800 km/month, then you ought to replace chains maybe monthly if you don't clean and lube them every week, otherwise 2-3 times/year.

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Cassettes

There are some conversations here, here, and here about how often a cassette (i.e. rear derailleur sprockets) might need replacing.

The consensus there seems to be that a cassette must be changed approximately once for every 2 to 5 chains; and depending on how expensive the cassette is, if you're using a relatively expensive cassette then change the chains more often (to protect the cassette from being abused by a worn chain).

Other estimates suggested 10-20,000 km for a cassette.

So if you're changing the chains 2-3 times/year then expect to change the cassette once/year?

And a cassette costs maybe $80 for the part (excluding labour; if it needs changing, the LBS will probably change it when they change the chain).

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Maintenance schedule

How much maintenance (not just what type of maintenance, but how much) does a cheaper bike require?

Don't get a bike that's too cheap (a 'BSO'): no amount of tuning will be enough.

A maintenance schedule will include:

• Clean the chain weekly (otherwise, at 40 km/day, expect to replace it and maybe the cassette every month or two).

• Check the tire pressures weekly.

• Adjust the brakes and gears monthly (either yourself, or at a bike store)

• Change tires whenever necessary

• Have an in-store tune-up 2 or 3 times a year: during which they may change the chain, cassette, brake pads, and tires.

Cost of thrice-yearly service, and new parts (pads, chain, and cassette) might be $600/year (or more if you don't do your own weekly chain cleaning, and monthly brake and gear adjustments).

And/or, how much longer will more expensive components last?

An internal-geared hub should be adjusted/serviced once, after it's installed.

A 7-speed internal-geared hub from Shimano might last 3 years or so, and cost $500 to replace; it's grease-filled.

An internal-geared hub from Rohloff lasts indefinitely, but costs $1700+ to buy; it's filled with oil instead of grease (change the oil once a year).

With an internal-geared hub (unlike with derailleurs) you can fit a chain-guard around the chain: in which case the chain might last twice as long, and want cleaning every two months instead of every week.

If you have rim brakes instead of disk brakes, then you may need to replace the rims (i.e. the wheels) every two years or so. Mechanical disc are cheaper to own than hydraulic disc

There is essentially nothing in the way of maintenance on a standard bicycle that cannot be done by a competent "shade tree mechanic". It's all a matter of learning the basic techniques and acquiring a few basic tools.

The first thing to learn to do, and the most important, is of course to keep the tires properly inflated.

Repairing flats, and changing tires when they're worn is something every cyclist should know how to do.

After that, cleaning the drive train (chain and sprockets) is reasonably simple and worthwhile to do. Should be done every few hundred miles. (The "chain washers" that are now available make this task fairly easy.) Inspecting the chain for wear (with a simple inexpensive gauge) and replacing it when worn is something that can be accomplished at the same time. (Chains last roughly 2000 miles, and if not replaced when worn out will cause damage to other parts.)

Replacing worn sprockets (rear at roughly 5000 miles, front at 10-15K) is actually relatively simple, though a few specialized tools are required.

Learning how to adjust brakes and derailers is one of the keys to keeping a bike in good working order. This needs to be done every few hundred miles. It takes a modicum of skill and practice, but it's not rocket science.

Keeping your wheels true is something that is fairly easy to do and well within the capabilities of someone with reasonable mechanical ability. There's no real schedule for this -- do it when the wheel appears to be out of true. Learning to replace a broken spoke on the road is worth doing, too.

Repacking wheel bearings is something that needs to be done every 10-20K miles, and once or twice in-between the bearing adjustment may need tweaking. This is not a difficult task, but it's messy and involved, and may be where you'd prefer to defer to your LBS.

There are books that will tell you how to do much of this.

A good online reference and starting point is Park Tool. I would start there and also read up on the late Sheldon Browns web pages. If you can hold a screw driver and read a manual then the regular servicing should not be a problem. Parts replacement is easily within the scope of an average person - things like brake pads, chains and clusters (With the right tools). Where the bike shops have it is knowing just what parts are worn out, and the odd thing like a stripped thread or stuck seat post that they have the experience to deal to without breaking other stuff. ,

As far as specialized tools go, you won't need anything more than what a normal home handyman has in a tools box to start with. If you get more adventurous, You can get cheap specific bike tools kits that are OK for the odd job, but be careful as some of the tools can be low quality and damage bike parts (The Crank remover on mine "felt" too cheap for the forces needed, so I bought a Park Tool one.), or you can buy them from the LBS as needed.

From what you've described, it sounds like you are trying to achieve mutually exclusive goals.

You want to spend less AND take the bike to service less often AND have the bike feeling better (for longer) AND have parts that don't wear so much.

Indeed, you can spend less and have the bike feel better for longer by actually taking it MORE OFTEN to maintainence.

If you ride three or four times a week for EIGHTEEN MONTHS without nothing but some oil spray on the chain, no wonder your bike feels like another after you take it to shop. That is WAY TOO MUCH TIME without maintenance.

So, some simple measures would be:

• Wash the parts of your bike that move under friction if they get dirty. That is mostly drivetrain, brakes and braking surfaces. Soft brush, hose and mild soap should be fine.
• Don't wait too much before replacing the chain. A worn chain can waste good cassettes and chainrings. 1000 km is a good distance to consider replacing it, but it can last longer if you lube it and ride mostly on asphalt, and way less than it if you ride on serious muddy and/or wet conditions.
• Shifting and braking rely heavily on cables and housings being on good condition. Replacing them regularly is not expensive and have a HUGE impact on riding quality.

Beyond that, bike mechanics and shop owners also need to eat. Taking the bike to the shop more often can end up having a much better cost-benefit for you than waiting untill the bike is crappy. And even the price of each service might be smaller, since it is much less work to service a bike that is not cying for help.

Hope this is useful!

In practice (i.e. now from experience), for the riding I described in the OP, I found that I need the following maintenance.

• Fix flats (inner tubes) in the tires. After replacing the tires with reliable touring tires, no more flats ... instead the tires need replacing after about 15000 km or maybe 4 years, whichever comes first (see When does a Marathon Plus tire (not) need replacing? for more details)
• Take the bike in for service every 6 months or so (maybe expect 2 years of free service, i.e. free labour but pay for parts, included with purchase of new bike), and expect them to change the chain and cassette and maybe the hydraulic disk brake pads -- that's a few 1000 km for the chain, the same or slightly more for the brake pads. The cassette may or may not need changing with the chain, depending on how worn the chain was. Lubrication extends the life of the chain.
• After 7 years (maybe 30,000 km) the LBS replaced the whole drive chain (i.e. bottom bracket, chain ring, chain, cassette, and the wheels in the derailleur though not the derailleur itself)
• I haven't yet had to change or service the wheels or spokes (nor rims since they're disk brakes), nor the frame (including the headset), nor the hydraulic disk brake system (except the brake pads), nor the seat, nor the locks.
• Oh yes: batteries, if you're using lights.

My bike is a all-aluminium "Kona Dr. Dew" ... cost was some $800 new ... compare with cost of a yearly bus pass at $1200, for which price you could afford to replace the whole bike every year if necessary (which it isn't) ... so it is quite a good deal.

A lot depends on the design goals for the bike. High-end road bike gear often isn't terribly durable because it's designed to minimize weight at the expense of all else. Carbon is likely to be less durable in the long run than metal, especially if the bike's used for utility purposes and regularly locked up and knocked around.

A cheap fixed gear is pretty low-maintenance: in order of frequency, all you have to do is oil the chain, change the brake pads, change the tires and chain, and replace the bottom bracket and wheel bearings. After a few years, the brakes might wear through the rims. But you're giving up functionality (that you may or may not want) in exchange for less maintenance.

More expensive hand-built wheels generally are stronger than cheaper machine-built wheels.

There is a sweet spot.

Like Shimano Deore XT is going to be more reliable than an Alevio but an XTR is not necessarily more reliable than a Deore XT. At a certain point it is just about weight.

A carbon frame is not more reliable than a steel - it is just about weight.
Aluminum and steel are priced about the same - steel is more reliable and heavier

A chain with hollow pins is not more reliable - it is just about weight.

In general an $800 bike is more reliable than $600.
At that $400 - $600 range is where they tend to cheap the wheels.

But a $2200 bike may not be more reliable than a $1200 - it may just weigh 3 less pounds.

In your example that $1250 bike might not be more reliable than the $700 bike.

"better components, more durability"

This is only partially true. Firstly, the wear parts are mainly tires, brake pads and chains, to some extent cassettes. Also chainrings wear, brake rotors (if disc brakes) and rims (if rim brakes) wear too. Secondly, more money usually buys more precise shifting in the derailleurs for example but also the components that can be damaged due to an impact such as the rear derailleur are made lighterweight, so it could be possible that impact resistance would be even worse. The structural parts may also be lighter, manufactured with better methods, so it's unlikely they could bear more weight but the lighter weight could be a benefit if not done at the expense of durability.

• Tires: better bikes come with faster tires. All things being equal, faster low rolling resistance tires wear faster. Why you want to use them is that they have far lower rolling resistance. Besides, tires are a cheap upgrade so it doesn't matter what the stock tires are since you'll change them anyway. Even the thinnest road tires should last over 5000 km, possibly nearly 10000 km, if installing a new tire in the front, and when the rear tire wears, installing the old front tire to the rear and wearing it out in the rear.
• Rim brake pads: you want to test if Kool Stop salmons work without horrible squeal on your bike. If they work, use them! They are the most durable and rim friendly pads. I have never seen a bike come stock with Kool Stop salmon pads, and they're a cheap upgrade anyway so I don't think brake pads would be a reason to favor one bike over another. With good rim brake pads, you can expect nearly 10000 km dry pad life, perhaps 3000-4000 km in mixed conditions.
• Disc brake pads: usually even very expensive bikes come with resin pads. You can upgrade to metal pads if you want higher pad life (but that translates to lower rotor life). The upgrade is cheap so not a reason to favor one bike over another. I wore out a pair of front resin pads in only 2000 km.
• Chains: this is where you see some differences. A better, more expensive chain usually lasts more. However, a chain is a cheap part and changed numerous times during the lifetime of a bike, so it's not really a problem if a cheap bike comes with a cheap chain. Change it to a better one when it wears out. A good chain can last 4000 km in the dry, although in the wet the chain life can be reduced much.
• Cassettes: usually more money buys you a worse cassette. Why? Because more expensive bikes have more sprockets on the cassette. This means that practically nothing happens if you click the shifter. You need to click...click...click many times to have any impact on the gearing on a "large number of gears" cassette. On a "small number of gears" cassette, a single shift could translate to a meaningful difference in gearing. However, the lifetime of a worse (more speeds) cassette is probably about the same: you'll get 2-3 chains per cassette.
• Chainrings: this is something where a better bike will probably be very much better. Chainrings can be made from steel (but usually the steel used is very weak because steel chainrings are usually made from steel due to cost reasons). Also, chainrings can be made from many different aluminum alloys. Only aluminum alloy 7075T6 / 7075T651 is an alloy that has a very long lifetime. Changing every chainring on a bike tends to cost a lot of money, even 100 euros / dollars, so it might make sense to check if the bikes have the material marked on the chainrings. If the better bike has 7075 written on the chainring and the cheaper doesn't, then that might be a reason to pay 100 euros / dollars more. A pair of road bike chainrings can last over 100 000 km, if 7075 alloy.
• Brake rotors: some very cheap rotors might not even work with metallic pads. Thus if you want longer pad life by switching to metallic pads, you may need to change the rotors as well. Depending on the size of rotors, changing both front and rear would cost 50-100 euros / dollars. Thus, it might make sense to see if the rotors are metallic pad compatible.
• Rims: rims can wear from rim braking and wheels can fail. Some very very cheap bikes can have steel rims that have horrible braking in the wet, avoid those. Besides, steel rims are not double wall so nowhere as durable as aluminum double wall rims. Rim wear on cheap and expensive aluminum rims is about the same, if the bike has rim brakes. However, where you may see differences is the structural quality of the wheel. Very best rims have double eyelets, rims that lacks those can cause the rim to fail over 20 000 km or so due to cracking around the spoke holes. A double eyelet rim costs over 50 euros / dollars and the labor to change it costs nearly 100 euros / dollars, plus new spokes for 30 euros / dollars, so it's worth paying 180 euros / dollars more for a single double eyelet rim. Usually both front and rear rim is the same, so it's worth paying 360 euros / dollars more if the better bike has double eyelet rims. The other aspect besides double eyelets is the number of spokes in the wheel. Usually entry level bikes start with 36 (sometimes 32) spokes, the count of spokes stays the same as the bike price increases, and at some point the count of spokes crashes. Wheels with less than 36 spokes are junk (well maybe 32 might sometimes be okay for small 26" / 559mm mountain bike wheels). Replacing a junk wheel requires not only replacing the rim and spokes but also replacing the hub. Thus, it might cost 500 euros / dollars to build both a new front wheel and a new rear wheel for a bike having less than 36 spoke wheel. So you want to avoid the point where spoke count starts to reduce.

A $700 bike with derailleurs, rim brakes, and 700 wheels ... I image that this is an extremely standard, common type of bike.

• Derailleurs: easy do it yourself maintenance, albeit more frequent maintenance than with hub gears, repairing a puncture is possible without getting your hands oily in chain oil. I'd say it's a good feature for many purposes.
• Rim brakes: these are excellent for dry conditions (far better than disc brakes), the brake pads take about forever to wear. In wet weather they wear pads and rims fast and have unpredictable braking.
• 700 wheels: the most common wheel size, something to prefer

A $1250 bike with hub gears, hydraulic disc brakes, 700 wheels, and carbon forks and seat post ... these are higher-end features and it's rare to find them so cheap (and may require a much less local LBS).

• Hub gears: these may be good for someone who wants to have the bike serviced by a competent bike shop and less frequent service than with derailleurs. You can usually let the chain wear far more on a hub gear bicycle, but as a drawback then you'll need to change both sprockets with the chain. As another drawback, the hub gear system itself requires service that may be difficult to do on your own but for a LBS skilled in hub gear maintenance, it won't be an issue. Also if you get a puncture in the rear, repairing it requires lots of patience, lots of time and you end up with your fingers stained in chain oil.
• Hydraulic disc brakes: you probably want to prefer these over mechanical disc brakes as cheap mechanicals require frequent adjustment. A minor drawback of hydraulics is that roadside repairs are impossible and maintenance otherwise requires skills and tools. But if the brakes use mineral oil as the brake fluid, you get almost infinite brake fluid life (cables have a finite lifetime). As for disc brakes versus rim brakes, I wore out a set of front brake pads riding in the dry in only 2000 km. I have never seen such poor pad life with rim brakes, even if occasionally riding in the wet. So disc brakes have too frequent and costly maintenance in the dry. But in the wet they excel, and rim brakes in the wet would wear rapidly anyway.
• Carbon fork: this is something to avoid. Carbon fiber can be structurally damaged if crashing or hitting the fork at some hard sharp obstacle. Then when riding it after the structural damage, it can suddenly fail with no warning, causing you to hurt yourself. The only ways to see if a structural damage is fatal are very expensive such as X-rays.
• Carbon seat post: the same as carbon fork, although changing a fork with a compatible chromium molybdenum steel one is hard (you won't find a compatible replacement) but changing a seatpost with a compatible aluminum alloy one is easy.