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Cycling indoors: How to use indoor training for your outdoor cycling goals

Cycling indoors
(Image credit: Wattbike)

If you’re preparing for a big event on the bike, cycling indoors is the most efficient way to build your fitness and fine-tune your form for the months ahead.

Cycling indoors was once considered a necessary evil for cyclists, reserved for the cold, dark months of winter. However, the advent of smart turbo trainers and smart bikes, alongside interactive apps including Zwift, TrainerRoad and Rouvy, has changed the way riders view indoor cycling. Dare we say it, indoor training is fun and the training benefits are plain to see.

“Indoor training allows you to follow a specific training plan far closer,” says Pav Bryan of Spokes Personal Performance Coaching. “When you’re riding out on the road, traffic, weather and unsuitable terrain can all become barriers to completing a quality training session.

That’s good news if you want to fast-track your fitness. Cycling indoors will remove the external variables and distractions found outside, and ensure you can fit a quality session into a considerably shorter period of time.

Today's best turbo trainers or smart bikes also measure your power, allowing you to train much more intelligently, and are compatible with apps that allow you to measure and track your fitness through a series of tests. Taking a fitness test will also enable you to determine your Functional Threshold Power (the maximum power you can sustain for an hour).

Understanding FTP

The ramp test is widely accepted as one of the best ways to test fitness and set training zones (Image credit: TrainerRoad)

From there, you can set prescribed power targets for each session based on the area of fitness being targeted, with the trainer then requiring you to hold that power so you can complete quality intervals without the temptation to slack off or ride too hard.

“That means you have specificity in training,” adds Bryan. “You can really target certain power outputs to give a specific fitness adaptation, whether that’s focussing on your endurance or climbing.”

Ultimately, by incorporating indoor training into your riding schedule, you can put the building blocks in place to achieve your outdoor riding goals. After all, who doesn’t want to be stronger and faster on the road?

Training indoors for short, steep climbs

If you’ve got your sights set on a local Strava KOM, Ian Jenner of Rule 5 Cycling Coaching recommends high-intensity intervals to train for punchy climbs. After a ten-minute warm-up, complete four to eight x two-minute intervals at maximum intensity, with two minutes recovery between each.

If you are using a smart turbo trainer or smart bike, these intervals should be conducted at approximately 110 to 120 per cent of your Functional Threshold Power. Once you’ve completed your efforts, cool down for ten minutes.

“This is a great workout if you’re short on time and will improve your body’s ability to carry oxygen to your muscles when working really hard,” says Jenner.

Cycling indoors for improved endurance

Indoor training might not sound like the best way to improve your endurance - after all, surely three hours on the road is better than one hour indoors? Once again, however, you’re devoid of distractions - and the opportunity to freewheel - and you can use ‘sweet spot’ intervals to make big endurance gains in a smaller amount of time.

“Sweet spot is generally considered to achieve positive adaptations without placing too much stress on your body, so you can repeat these intervals regularly,” says Bryan.

Your endurance sweet spot is between 83 and 97 per cent of your Functional Threshold Power (FTP) and a typical training session should include two or three intervals of 10 to 20 minutes, with a 10-minute break between each interval.

Zwift KISS Super League

Racing on the Zwift platform is a great way to train your top end fitness (Image credit: Zwift)

Sprint training indoors

While sweet spot intervals can be used to improve your endurance, short sprints can be used to boost your top-end speed. “Start by warming up for 15 minutes, then do five x 15-second, all-out sprint efforts, with five minutes of spinning between each,” says Jenner. “The goal of this session is to improve peak power output.”

Start each sprint from a standstill, Jenner adds, and try to keep your cadence high throughout, without needing to change gears too soon (or at all). Because your sprints should be all-out efforts, this session shouldn’t be completed to a prescribed power - empty the tank each time. Finish with a 15-minute cooldown.

How to fuel for a cycling race

Use your time cycling indoors to trial fuelling strategies ahead of your goal event (Image credit: Getty Images)

Fuelling tips for cycling indoors

When cycling indoors, your fuelling needs are going to be somewhat similar to your outdoor fuelling strategy, however, training on a turbo trainer is an altogether different climate to outdoors, and this can mean fuelling adjustments are required to ensure you get the most out of every session. 

Individual preferences will vary but these eating and drinking guidelines apply to every cyclist.

Performing well on the bike is as much about fuelling correctly as it is about ensuring you’ve done the training. Riders often forget that the body is an engine and needs to be fuelled in order to perform at its optimum.

Sometimes it’s easy to get caught up in the hype of racing – particularly at the start when riders are jostling for position and the peloton is sorting itself out – but it’s here, in the first hour, where fuelling is most critical.

Failure to ensure a steady flow of energy to the muscles will have a direct impact on your performance and, more often than not, result in low blood-sugar levels and eventually the dreaded bonk. Here are five tips to ensure that you never hit the wall again.

1. Pre-ride

The goal here is to replenish your liver glycogen stores. The body utilises the liver glycogen stores during sleep to maintain glucose balance.

For short sessions, an easily digestible food source is ideal to ensure that there’s nothing sitting in the stomach and small intestine when you start training. Try two slices of white bread (toasted, if you like) with jam or honey, a banana and 500ml of commercial energy drink will suffice.

Muesli and uncooked oats, nuts and seeds can take anywhere between 8 and 12 hours to fully digest and are more suited for longer sessions, or post-ride replenishment. You should aim to eat 90-120 minutes before your session. 

2. During the session

The amount of carbohydrates required depends on the duration of the session. As a guideline, for any ride over 2 hours, aim to consume between 60-90 grams of carbohydrates, as well as 500ml of fluid, per hour.

With your carbohydrates, you'll need a mix of 2/3 maltodextrin and 1/3 fructose, as this is proven to be the best way to get the 90 grams of carbohydrates per hour, as it recruits two different transporters. Fluid absorption and gastric emptying peak at around 500ml of fluid per hour – any more than this will pool in the gut and possibly lead to an upset stomach. 

3. Bars, gels or fluid?

A combination of a commercial energy drink, bars or gels can be easiest to get through without palate fatigue, but everyone will be different. What's important is to consume the correct quantities of macronutrients. 

While cycling indoors, try to experiment with your fuelling so that it is perfected come event day. A good starting point is to try and get around 50g of carbohydrate within your 500ml of energy drink, and use gels or bars to make up the remaining 10-40g.

4. Caffeine timing

Caffeine is widely known to improve performance. We don't recommend high doses every time you train, but as with fuelling, try to use your time cycling indoors to experiment with how your gut reacts to caffeine prior to - and during - exercise, and optimise your strategy ahead of race day. 

Having a coffee roughly one hour before the start of a race and topping up after 2-3 hours with a caffeine gel/bar can be a useful strategy.

5. Use the time to train the gut

Your gut needs to be trained to consume high levels of carbohydrates during intense exercise. You should therefore never experiment with anything new come race day, and instead stick to the same nutrition used throughout your training. Use the time indoors to control your carbohydrate and fluid intake to see what yields the greatest performance. 

Develop mental fortitude

Although the traditional environmental and mechanical issues are absent with an indoor trainer, the most significant barrier to accessing your peak potential, is mental. Indoor cycling apps have come a long way to provide productive mental stimuli, but training in any guise is hard work. 

Riders need to develop the discipline to avoid digital distraction when cycling indoors. Devices should be set to aid training, instead of streaming potentially disturbing media sources. To access the immense potential that a quality indoor training programme and bike can provide, riders must develop an appropriate calibre of mindfulness.  This state of mental fortitude can then be transferred into outdoor cycling, to aid with concentration during a time trial, or an extra bit of grit when the going gets tough.

Remember you're cycling indoors for an outdoor cycling goal

Cycling indoors removes many of the variables from your cycling. In your living room, there is no wind, only a fan which you control for cooling. There are no bad road surfaces generating greater rolling resistance, nor is there rain or the risk of traffic management. Draining environmental or fatiguing mechanical issues don’t exist with a modern indoor trainer. 

If ever you are going to establish where your peak performance outputs are, it will be on an indoor trainer. It might be ironic, but an indoor trainer is perhaps the purest form of cycling and truest reflection of your inherent ability. 

When it comes to your outdoor cycling goals, these variables will return to the equation and it's important to account for them. You can use indoor training to increase your fitness, FTP, VO2 max and any other quantifiable metric, but don't forget that bike handling skills, bunch riding dynamics, crosswinds, or even a simple puncture could affect your event performance. A big engine will help you put in a strong performance, but it's not the only part of the equation.