Why would I choose a bike trainer over a stationary bike?

The main difference is cost, both money and space. If you already own a bicycle then it is using up space whether you can ride it or not.

If you want to use the existing bike on a trainer then that may end up cheaper overall. And you can still unhook the trainer and go ride normally, giving you dual-service.

By comparison, a stationary bike is a fixed item and can't be used to ride outside. Its a single-purpose tool, and takes just as much space as your normal bike.

Other points to consider

• Noise - I'm not sure which is going to be louder, and this may not be an issue in your environment.
• Wear on bike - adding mileage to your real bike is hard to track when its not moving. For a stationary bike, its total distance travelled is unimportant.
• Training effect - I can't really speak to this, but there's a significant difference between any indoor bike and riding for real. The "crank inertial load" drops off much quicker on any indoor bike compared to an outdoor ride. That is, you stop pedalling and coast much longer for real. Expensive trainers can duplicate that better, but its still not ideal.
• BORING I find any static bike to be mind-numbingly boring after a while. But I've never bought into the virtual options like zwift, so that is an additional cost to consider. Turning the pedals over while reading a book or watching a movie feels quite pointless to me, you're not concentrating on the ride.

Ultimately its up to you - Do you want a bike that you can ride for real when conditions improve? Or do you want a piece of inside exercise equipment that risks being left unused after a while?

At least the bike can be used outside. The stationary bike means you still need to buy a bike for normal outside usage.

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I've just realised the suggested bike is a hardtail MTB, and presume that you intend to ride off-road with it. So there's a sub-question here about

whether the kind of bike you intend on riding, and how/where you want to ride affects the choice between stationary bike vs a bike on rollers/trainer.

I can't give a definitive answer on this point; anyone with experience is welcome to add their own answer.

The cheaper stationary bikes sold for home use tend to be "one size fits none". The better ones, with a wide range of adjustment for several parameters, are expensive.

You might be lucky. I know I'm too tall for the majority, but normal size people I know struggle as well.

We perspire. This is obvious. However, when cycling outdoors, moving air cools you considerably. Indoors, even with fans, you do drip sweat on your bike. In extreme cases, this can cause corrosion. Sweat can accumulate in your bottom bracket, or headset, or it can corrode aluminum handlebars. On carbon bikes, accumulated sweat can cause galvanic corrosion between the carbon and any aluminum fittings, like bottle cage bosses.

In theory, I suppose a stationary bike could be designed to be resistant to these issues. In particular, I think that many use enclosed chains, and the higher end ones may use carbon belt drives. Enclosing the drivetrain may also shield the bottom bracket. That said, resistant to corrosion does not mean invulnerable. Furthermore, with a traditional bike and trainer setup, you can get a bike cover and you can get additional fans to dissipate sweat. I would expect most actual cyclists would be better served by a trainer with their real bike. If your sweat is particularly acidic, it may be worth considering a stationary bike, although you will still have to wipe it down.

I have had three stationary bikes over the period of 6 years. The first two you would say were a the "normal" kind of a stationary bike. Both from the cheaper end of the spectrum. I basically bicycled on them until they broke down mechanically. The one that I have now is a more simple version, but heavy duty. A spinning bike. I dont need to plug it in electricity to activate magnetic breaks to get more resistance. There is a simple wrench where you turn to add or remove resistance. Costs a bit more then my second one did. I like it alot!

I live in Denmark where the bicycle culture is big. The whole country is also very flat so it makes it ideal. I have never tried a bike with a trainer at home, I might one day! What I like about a stationary/spinning bike is the freedom/and the time saved if you want to get a quick cardio workout, just sweat it out! Spinning bikes are made to endure alot of sweat. Perhaps if I needed to get the outdoor bike first and set it on the trainer etc.. maybe I would not bother.. I can imagin if you had a garage, then it would be very easy to just have the bike ready for for outdoor and indoor bicycling.

I would recommend a spinning bike if you like to get a quick cardio in where there is some room for faster/heavier bicycling. A "normal" stationary bike will not hold for a long time. I cant speak about the bike trainers, but I would assume there are some awsome ones out there.