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Everything you need to know about indoor trainers for cycling

There are so many questions and decisions to make when it comes to picking an indoor trainer. We give you all the info you need to know before taking the plunge

Indoor training has become massively popular with cyclists in recent years. Riding indoors has been seen as a safe way to exercise in the current climate; but before that, time-crunched cyclists were seeing the benefits of being able to do structured sessions that could be more easily fitted around family time and work commitments than traditional training.

There is one thing that you’re going to need before you start training indoors, and that is an indoor trainer. We’re going to take a look at the different types of indoor trainer, with some cracking examples from Saris to help us explain the differences and what you might want to look for when you go to buy one.

Wheel-on vs Direct drive

Indoor trainers can be split into a number of categories, but the biggest split and the easiest to identify is the wheel-on vs wheel-off trainer. This is also where there is a split in price.

Wheel-on trainers are generally the simpler and often cheaper option, but if you’re looking to get on Zwift then you’ll be happy to know that you can still get connected to apps with wheel-on trainers.

For the majority of general cyclists, these wheel-on trainers offer plenty of power, allowing you to smash the pedals. Modern wheel-on trainers have (thankfully) come a long way from the budget trainers of old, and the newer models have a realistic road feel which is a massive factor in making the experience enjoyable. That being said, these trainers can suffer from power fade when the tyre heats up, and that heat isn’t the kindest to road tyres. If you’re going to spending a good amount of time on your trainer, a specific trainer tyre is a good idea.

> Review: Saris H3 Direct Drive Smart Trainer

The best thing about wheel-on trainers is that you can just bolt the bike onto the trainer and get on with your session. The lower price also means they’re more accessible to recreational riders too.

A direct drive, or wheel-off trainer is a step up in certain performance aspects, but the most noticeable difference is that these trainers are quite a bit quieter than their wheel-on counterparts. We’ll take a deeper look at noise later, but if you’re looking for a quiet ride, a direct-drive trainer is the one you want.

In most cases, direct drive trainers also deliver a more realistic road feel. This is because they feature larger and heavier flywheels that better mimic the feeling of inertia that you get when riding outside. This realistic road feel is very important for lots of riders, as it helps to make the experience more immersive. 

Many third-party apps offer virtual climbs, and gradient simulation is a big feature of an indoor trainer. Direct-drive units take this to the extreme, replicating some of the world’s steepest climbs. The H3, for example, will replicate a savage 20% incline. 

While all of this sounds great, you do have to remove the rear wheel every time you want to put the bike on the trainer, and that can mean you’ll need to re-index the shifting. These trainers are also more expensive, though we are seeing trainers with impressive performance coming down in price.

Power Measurement

Whether a trainer will measure the power that your legs produce, and the accuracy that it will measure it with, depends on the trainer that you buy. Power measurement is almost ubiquitous on direct drive trainers. It’s not just the domain of the direct drive trainer though; the Saris M2 is a wheel-on trainer with a power meter built in. That’s great if you’re on a tighter budget or you simply don’t want to spend loads of money. 

Trainers without a power meter can still give you a power reading. Take the Saris Fluid 2 for example; the resistance that the trainer provides is known at any given speed, so by using a speed sensor on the rear wheel you can get an estimated power reading for your favourite training app.



Noise is a big concern for many, regardless of whether you live in a detached house or a flat. As a considerate neighbour or family member, you don’t want to be annoying the people around you. Leave that to your questionable music choices!

The common thinking is that wheel-on trainers are the noisiest, while the quietest option is a direct drive trainer. This is generally true as the tyre-roller interface causes more noise than the drivetrain of your bike which is, pretty much, the only noise associated with a direct drive system.

Besides the noise from the trainer, you’ll also need to think about the surface that the trainer sits on. A hard wooden floor is a recipe for lots of vibrations that anyone living a floor below you will hear. Thankfully, you can combat the noise with a thick mat or some carpet.

Noise is one of the key features that brands like Saris will highlight as one of the features of their trainers. The H3, for example, is claimed to produce just 59 decibels when riding at 20mph. For context, your drivetrain is probably going to be louder.

Smart resistance vs progressive resistance vs manual adjustable resistance

The type of resistance that an indoor trainer provides will determine the ride experience that you’ll get from a trainer, especially when using one with a training app like Rouvy and Zwift.

Fixed or manually adjustable resistance

The simplest resistance method is a fixed resistance, where the resistance level of the trainer is not adjustable and you can fine-tune that resistance with your bike’s gears. The cheapest trainers work like this, and use a metal plate spinning through a magnetic current to generate the resistance. 

The next step up is to make the resistance adjustable, which basically involves moving the magnets closer to, or further away from, the braking disc. That can be a lever on the trainer, or like the Saris Mag plus here, a handlebar-mounted control lever so that you don’t have to get off the bike to adjust the resistance. 

The resistance tends to increase in a linear fashion, so the harder you pedal, the more resistance there will be, but the maximum resistance is low compared to more expensive trainers, so they’re good for steady-state riding but less so for sprint efforts.

Progressive resistance

Progressive resistance takes this to another level with a non-linear increase in resistance. The resistance ramps up as you go harder. That’s more like riding outdoors because that’s how air resistance works when you go faster. On a progressive trainer, spinning your legs during a warm-up will feel really easy, and smashing the pedals in an all-out sprint will feel very hard. 

One common way to get a resistance curve like that is to use fluid resistance, rather than magnets, to provide the resistance. That’s how the Saris Fluid 2 trainer works: inside the resistance unit there’s an impeller - kind of like a steamboat paddle - pushing oil around.

Smart resistance

Saris competition - 04 - H3 trainer.jpg

Smart resistance is the one that you want for the fully immersive experience on third-party apps like Zwift and Rouvy. This allows the app to control the resistance based on an in-app metric like gradient. It can also fine-tune the resistance if you’re riding in a virtual group by reducing the resistance to mimic the feeling of being in a rider’s slipstream. 

A smart trainer can also work in what’s usually known as ERG mode, where the trainer will adjust the resistance based on your cadence and gear to hit a set power target. This makes trainers with smart resistance the best for virtual racing and training. 

Smart trainers commonly use magnetic resistance, often in the form of electromagnets, that can be easily controlled and the resistance changed quickly. Both of the Saris smart trainers - the wheel-on Saris M2 and the direct drive Saris H3 - have an electromagnetic resistance unit.

The Practical Bits

Saris H3 Direct Drive Smart Trainer - folded end.jpg

Those are the techy things, but what about the practicalities of living with an indoor trainer? Thankfully, unlike an exercise bike, an indoor trainer can be folded up for easier storage. That, combined with the fact that you still have a bike that can be ridden outdoors, be that for leisure or commuting, makes an indoor trainer a more sensible option, especially if you don’t have much room at home.


Indoor trainers are generally made of strong stuff. They’re meant to provide a solid base under the rider and they need to cope with a lot of force, so don’t expect them to be a lightweight item. The H3, for example, gets a beefy 20lbs flywheel for that realistic road feel that we mentioned earlier. Then inside the body of the trainer, the H3 has its own cooling system, power meter parts that deliver a claimed accuracy of +/-2% and sensors for speed and cadence too. Add that to the metal legs and you’re looking at a total weight of over 21kg.

Attaching the bike

Attaching the bike is a simple case of securing the rear end of the bike to the trainer. Most trainers will use the quick-release skewer or thru-axle that is in your bike, or one that is specific to the trainer will be provided. There will be instructions included with your trainer,  and it's important to follow them. Most modern trainers feature swappable end caps so you can fit bikes with quick release wheels or through-axles.

Making indoor training fun

Saris Trainer Lifestyle

Staring at a blank wall for a few hours with sweat dripping into your eyes isn’t the best fun, but as we mentioned a little earlier, indoor training can be made a lot more interesting through apps like Rouvy and Zwift. These will immerse you in a virtual world, allowing you to ride famous roads or race with your friends, all with data supplied by a connected trainer. The best trainers for this immersive experience are the smart trainers, so while they cost more, it could be worth investing if you’re planning on spending a lot of time riding indoors.

Saris Rocker Trek

If you really want to take your indoor riding to the next level, you can even buy something like the MP1 Nfinity Trainer Platform from Saris which is designed to give you a more realistic road feel. This comes with a price tag, but it allows the bike to move underneath you like it would in real life. A trainer platform can make indoor riding more realistic, and also more comfortable; the movement of the platform can relieve pressure on your saddle, your feet, your wrists and your arms. You’ll have to engage your core a bit more too, which makes your workout more immersive and helps to exercise more of the muscles you’ll need when you’re outdoors.

There are quite a few options out there for rocker plates that move from side-to-side, but platforms like the MP1, which also moves a whopping 24cm forwards to backwards, are a lot less common.

Well, that should give you a good idea of what you’re looking at when you go to buy an indoor trainer for your bike. These things really are a cracking way to get fit quickly to pack more quality training into a busy life!

Son of a Marathon runner, Nephew of a National 24hr Champion, the racing genetics have completely passed him by. After joining the staff in 2016 as a reviewer, Liam quickly started writing feature articles and news pieces. After a little time living in Canada, where he spent most of his time eating poutine, Liam returned with the launch of DealClincher, taking over the Editor role at the start of 2018. At the weekend, Liam can be found racing on the road both in the UK and abroad, though he prefers the muddy fields of cyclocross. To date, his biggest race win is to the front of the cafe queue.

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