What to get? How do I know whether what I'm looking at is a BSO? (Bicycle Shaped Object); what should I do about the multiple chainrings?

Both have 700×35c stock tyres and can accommodate 38c tyres as well.

Good! Although if your area has a real winter, it might be a bit limiting to fit studded tires in. Is this 35c / 38c tire clearance with or without mudguards?

If I choose to buy a Mach City Munich 21 speed, I'd also like to know if I should simply remove two chainrings of three (if they're detachable, which I am yet to find out) to help "ease" my riding?

No, no, a thousand times no, unless you're planning to retain the front derailleur and the shifter.

I have removed the small ring on a 26T/36T/48T crankset because it's just so ridiculously small for my uses. But it wouldn't be a crime to retain it.

If you have only one chainring, the chain is prone to drop off the chainring, requiring you to get your hands dirty in chain oil whenever that happens. It's a major annoyance.

There are three conditions that allow chain drop to be a non-issue:

1. If you have a front derailleur and the front shifter, the chain is unlikely to drop, and when it drops, you can operate the front derailleur to re-raise the chain on the chainring.

2. If you have a chainguide, the chain is very unlikely to drop. This may depend on the design of the chainguide: some are better than others and there is no standard for chainguides.

3. If you have a narrow/wide chainring (needs to have an even tooth count for it to be possible) AND a clutch-type rear derailleur (e.g. Shimano Shadow Plus) AND you have enabled the clutch by turning the switch on the rear derailleur, the chain is very unlikely to drop. Note that the clutch needs to be disabled to easily remove the wheel and re-enabled after installing the wheel. A clutch-type rear derailleur and a narrow/wide chainring will not help at all if the clutch is disabled, as I have found.

I've currently understood that I should be getting a helmet

It's debatable. Bicycle helmets are very weak, much weaker than motorcycle helmets. Due to the ventilation needs, they may not be strong enough to prevent brain injury. However, if you choose to select a helmet, run through this checklist:

1. The helmet should be an in-mold type, i.e. it should have a polycarbonate structural part that is molded in to the expanded polystyrene. Cheap helmets don't have the polycarbonate structural part molded in.

2. The helmet should have MIPS protection to prevent rotational brain injury. If it doesn't, you may be putting yourself in more danger when wearing a helmet than when not: a helmet increases the likelihood the head rotates violently when crashing, thus making it possible to get rotational injury.

3. The helmet should be Snell certified as only Snell certified helmets are dropped from 2.2 meter height. United States CPSC certified helmets are only dropped from 2.0 meter height and European EN-1078 certified helmets for (oh the horror!) 1.5 meter height. Note here that the actual height of your head does not matter, because the constant angular momentum puts more linear momentum in your head than in your toes. Thus, because of this constant angular momentum, your head is effectively dropped from 1.5 times of its actual height, when falling. So if your head is at 1.8 meter height, ideally the helmet would be tested by dropping from 2.7 meter height.

a good quality lock

Select the smallest quality U-lock you can find. Smaller locks are harder to get a hydraulic jack in, and harder to find space to run an angle grinder without damaging the bicycle itself. Smaller locks are lighterweight, too. For me, my choice is the Kryptonite Evolution Mini 5 lock.

mud-guards that cover the whole wheel (we actually have a monsoon season)

I recommend Hebie Wingee. They combine mudguards and 8+8kg capacity pannier rack to the same lightweight part, and are very sturdy. It's much lighterweight to mount the panniers directly to the rear mudguard. Note that when driving in the rain, the water spray from your front tire will still make your toes wet even if having a mudguard.

a bottle stand

Not necessary. I used to ride 50 km rides, and never once needed water. If the theoretically unlikely occurrence of needing water happens, you are usually less than 10 km away from a grocery store. So replace the bottle stand with a credit card, unless you are riding in very remote locations.

a bell

Yes! Don't forget lights and reflectors. German law requires (I follow the German law even though I'm not in Germany):

• at least two red rear reflectors
• at least one white front reflector -- I use two
• tubular spoke reflectors in every spoke OR at least two yellow side reflectors per wheel OR a reflective strip around the tire -- I prefer the tubular spoke reflectors in every spoke
• yellow pedal reflectors facing front and rear on both pedals
• a non-blinking red light to the rear
• a non-blinking white light to the front with a beam pattern that produces useful visibility and vision without blinding oncoming traffic

I won't be buying lights because I am not thinking about riding in the dark.

Note most jurisdictions make reflectors mandatory even if not riding in the dark, and there are jurisdictions that make lights mandatory even if not riding in the dark. Also, you may find yourself needing those nevertheless.

I want the bike to last as long as it can, so should I also get a chainstay protector?

Unnecessary. It is not a reasonable failure mode preventible with a chainstay protector for a chainstay to fail.

Anything else that I should be getting?

You need the most important things to bring on a ride. Plus a floor pump you keep at home, because it's a pain to inflate tires with a mini pump.

If you need to park the bicycle standing often, consider a kickstand.

If you transport stuff with the bike, consider quality panniers (Ortlieb is one good manufacturer).

A cyclocomputer would be useful but not a necessity.

Bicycling shoes, preferably of the types that attach to the pedals AND that you can walk in out of the bike. So this pretty much limits you to SPD shoes. They require SPD pedals; I prefer Shimano PD-T8000 as the PD-T8000 has reflectors and at the same time allows you to ride the bike in regular shoes.

Bicycling clothes for all kinds of weather you're planning to ride in and gloves are heavily recommended. The clothes should be synthetic, because cotton holds a lot of water (i.e. sweat), making you cold when sweaty.

The saddle should fit to your anatomy. For most, it means around 14 .. 15 cm wide saddle that is fairly hard. A soft saddle or a too wide saddle means you're sitting on the muscles that propel you forward, which is not a good situation in the long run. Any saddle hurts a lot if not being accustomed to bicycling. Ride 300-500 km and the saddle pain goes away.

If you maintain the bike yourself, tools plus an inventory of the most common spare parts.

How do I know something is a BSO (Bicycle Shaped Object)?

Look at the hubs. They should be Shimano. Other hubs are likely to fail early, and hub is the second most difficult component to change in the bike.

Look at the rims. They should be aluminum, and have eyelets around the spoke holes. Ideally, they would have double eyelets. However, I wouldn't call something a BSO just because the rims lack eyelets around the spoke holes, if it's otherwise a good bicycle.

Ideally the front and rear wheel would both have 36 stainless steel spokes, triple-butted (2.34mm at head, 1.8mm middle, 2.0mm at threaded end) and the nipples would have a spherical seat (e.g. DT Swiss Pro Head), but if I labeled this as a recommendation of a bicycle as opposed to a BSO, I would be heavily downvoted. (I still may be, as I dared to question the usefulness of less than 36 spokes per wheel.)

Look at the frame specs. If it says "hi-ten steel" it's a BSO. Quality frames are butted chromium-molybdenum steel or hydroformed aluminum. The frame is the most difficult component to change in the bike.

Look at the fork. If it's a cheap suspension fork, it's a BSO as opposed to a bicycle. Suspension forks have their place in more expensive mountain bikes, but unless you're planning to spend a lot of money on the fork (and thus the bicycle), a rigid chromium molybdenum steel fork is a much better choice.

Look at the seatpost. If it has a cheap clamp with finite adjustment positions, or a clamp separate from the seatpost, it's a BSO. (However, if this is the only problem making the object a BSO as opposed to a bicycle, it's easy to remedy -- replace the cheap seatpost and clamp with a good quality two-bolt infinitely adjustable seatpost.)

That Munich "21-speed" is really a 7-speed. It doesn't have a triple chainring or front derailleur (and doesn't seem to have a planetary-gear rear hub). Not sure why they call it that.

Both bikes seem pretty comparable. Decathlon is well-known in Europe as selling cheap but decent products. I've never heard of Mach City. If a brand's reputation is worth anything, that's something to consider.

One of the hallmarks of terrible BSOs that I've seen in the USA is thin stamped dropouts with tubes that are pinched onto them (see below). Neither the Mach City nor the Decathlon bike seem have this kind of construction. Another hallmark is the one-piece crank.

Regarding the term "BSO" for bicycle-shaped object: in a city where some bicyclists can afford top-quality bikes, if you were to make a list of models of new bicycles for sale locally and sort by price, there would be a few models that are very expensive, several that cost much less, and typically not very models in between. The term "BSO" is an insulting term for the models in the lowest group.

I rode BSOs for years and depended on them as my primary mode of transportation, and learned to love bicycles in the process. I would recommend that you not waste much time trying to figure out if the label applies to a particular bicycle. Just understand that the term as used here applies to lower-quality bikes. Even cheap bikes can provide efficient and reliable service for years if they are used carefully and maintained well.

Here's my advice:

• Buy the best quality bike that you can afford.
• If you don't know much about bicycles, a knowledgeable friend can be very valuable when buying a bicycle, especially if the bicycle is used.
• Buy essential accessories at the same time you buy the bicycle, so factor the cost of the accessories when you calculate what you can afford.
• Don't skimp on safety, unless you have absolutely no other alternative.
• For non-essential accessories, consider riding the bike for a while first before buying the accessories so that you get a better understanding about what might be worth the money.
• Advice from people who understand your specific situation is worth more than advice from people who live in different climates and different situations.
• If you are at all mechanically-inclined, learn to maintain and repair your own bicycle.
• Having friends that you can learn from and share tools with is a good thing.

Both look like perfectly decent bikes for low requirement riding, like commuting or recreational riding.

I would take into consideration two things: fit and the reseller. For fit, it sounds like you can try both. Typically Decathlon will allow fitting the bike (even if only in the shop) and the local bike shop might even allow you to ride it outside.

As to the reseller: if the local bike shop selling the Mach has a good reputation, you might have a bit more recourse on the shop if a problem occurs. I also think it's good to support a LBS by buying a bike and accessories from them.

Decathlon on the other hand sells tons of accessories that are typically compatible with the bikes they sell. That means you can always buy parts later on. That also makes it more suitable if you intend to do most of the maintenance on the bike yourself.

Good luck and enjoy the riding!