Evidence behind 'efficiency' of indoor training

Yes, indeed, riding outside is fun. More fun than riding a trainer.

Furthermore, I came across this:

The podcast is aimed at ultra distance runners, so some of the language is a little different and it ignores the need for sprint finishing [which is important for some of the forum members]. However, it is a really clear presentation of interval training. The take away is this:

Intervals need to be done at ~ MLSS [ie, ~ 90% of VO2 max power]. A session should accumulate 20 - 40 minutes, in intervals of 1-3 minutes or of 5-10 minutes, about once or twice every ten sessions. Intervals do not have to be the same length. The length of time between intervals is not very important, though > 2 minutes is needed for immediate recovery; it’s not until 45 minutes or more that metabolism recovers from any one of these intervals, so recoveries of 2 - 5 - 10 minutes should be all right.

The presenter really stresses the lack of really tight experimental evidence about the efficacy of specific interval lengths and recovery times. Thus, he is giving a very relaxed view of the design of good interval sessions. And: he is giving a really good explanation of why training outside may be really effective, provided that we do not fixate on precise intervals lengths and recovery times.

If the OP is aiming the question at this kind of thinking about the efficiency, then this is a really useful podcast. Of course, it’s informed opinion, rather than tight experimental evidence. If the OP is aiming the question at time in zones, TSS and suchlike, then my previous post covers that.


I belive the benefits of indoor cycling are more qualitative than quantitative thus, hard to explain only with numbers.

I didn’t detect any negativity towards outdoor training in this thread :thinking: I think the majority (including myself) would very much prefer to train outdoors if they had the time and a place to do it. It just seems to me that if you are time- and location-constrained then a good way to stay competitive is to include a substantial amount of indoor training.

Put another way 10 hours/week of indoor training while living in the city is as close as I can get to quitting my job and buying a cabin in the mountains. :laughing:


I agree. The more hours of structured training you get in the better off you’ll be.
It’s easier to do the hard yards on a trainer, but that alone won’t make you faster on the bike.

Unstructured training can still be very benificial if the training stimulus us there. That’s all.

Just as all TSS isn’t created equal, neither are all training rides. There’s no way I could find a stretch of road to do a 2x20 min over-under workout outside and there’s no way in H E :ice_hockey::ice_hockey: I’m doing a 5 hour Z2 ride on a trainer. And forget about doing actual sprint work indoors.

Which brings me to my sloppy n=1…currently engaged in “Tradition Base”, I try to 80/20 – 80% outdoor rides, 20% trainer rides (mostly for testing).

A 2hr Z2 outdoor ride will give me ~95 TSS/1300 kcal/1200 kJ/VI 1.1.
A 2hr Z2 trainer ride produces ~105TSS/ 1200 kcal/1200 kJ/VI 1.01.

Looking at those specific apples, one could say the trainer ride is ~8-10% more efficient as I’m producing more TSS with less kcal.

Then again, yesterday’s ride saw me produce a very annoying ~40% of my time doing 100w or less. So much stoppage. < pulling out hair emoji >

There may be rules of thumb, but perhaps the best way is to analyze your own data to reach your personalized degree of efficiency and apply that to different types of workouts.

And, of course, the indoor trainer is always 100% more efficient in winter. :snowman: :grimacing:


I don’t think people here are negative about outdoor training. IMHO almost all of us love riding our bikes outside. But keep in mind that the OP asked whether indoor trainers really are more efficient than training outdoors.

Moreover, most of us are busy with other life commitments such as family, so training outside is either not in the cards or we wouldn’t be as fast. I can make myself a coffee, hop on the trainer, do my hour to hour-and-a-half, take a shower and have breakfast with the family. For me rides outside, be it fun rides or training rides complement what I do indoors. Of course, I’d love to train and ride outside more often, but if I have to choose between riding less often, but mostly outdoors, and riding more often, but focussing on the indoor trainer, I’d choose the latter.

You are completely right. You don’t learn how to pace a race or a really fast ride, you can acquire bad habits (the first two out-of-saddle efforts today were really weird, because on my trainer I can’t sway my bike, I have to sway my body). On the other hand, sweet spot and threshold intervals have taught me mental fortitude that I have put to use on quite a few occasions now, and that is something I can’t really replicate outside, save for a few long climbs I’d have to commute to.


My opinion is that it is easier to accumulate TSS quicker on a trainer than riding outside due to the way inertia makes you push power on a trainer. It’s easier to control longer intervals so quality might be a player as well.

For me, however, I do prefer outside fast group rides for most training and short solo sprint workouts. I’m not as efficient building TSS but, I do way more TSS outside with three group rides a week plus recovery solo rides. Not structured but, in a way semi structured. Each ride sort of targets different systems by default of the terrain and people who show up.

I live in an area where it’s easy to ride outside all year around. If I lived in the midwest I’d be on the trainer much much more during the winter.


My comment was about ‘outdoor only’ training.
I agree whole heartedly about most of us loving outdoor rides.
I really love riding my bike for multiple hours on end without feeling like it’s a chore. TR indoor intervals helped me grind up those 30%+ sections of trail when I hadn’t been able to train outdoors very often.
I have my data that proves it. It sounds like you have yours as well.

It’s totally normal for TR to push the trainer efficiency thing. It’s their business, but it also works as described.
You do the plan and your fitness goes up. Win.
10 hrs/week gets you results that equal your previous 15 hrs/week of outdoor riding.
That could be the opposite. Maybe how easily that could be the opposite is the real question here.

This whole efficiency ratio thing doesn’t work IMO. It can never be quantified because it will always be individual to each person and ride.
SFA chance of doing well on the bike if you never noodle around outside.

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Of course fitness and training efficiency can be quantified. These are not nebulous concepts. Perhaps we can argue about which variables are most important in a given situation, but that is a far cry from “we can’t know if it works.”

If by more efficient you mean more adaptation in less time, then it is easy to quantify. Next time you do an outdoor ride, turn auto pause off and do your ride. You will likely have 30-50% of the time of your ride classified as stopped or coasting. Further, even training on a closed course on a fixed gear bike, it is very difficult to hold specific zones for recommended periods of time. It is much easier to mimic a trainer for Z2/low Z3 rides on a fixed gear bike outside, so an argument could be made that it’s a push between those two (I often do those type of rides outdoors on a fixed gear bike on a fairly flat course with minimal/no stops.

Longer Sweet spot rides are difficult to mimic outside because it’s easy to let up, whereas, on an ERG, you can’t. It forces you to hold that power. This sweet spot riding is where a lot of gains are made and doing it correctly is incredibly important.

Now, higher power efforts of 200%+ of FTP? I prefer them outside for sure. However, it’s usually only once a week that I’m doing those types of workouts.

Too funny. Is that time spent sitting in a cafe?:coffee:
You roadies get all the fun.

Seriously though, my last outdoor ride had 39 seconds of non moving time in 2hrs 40 mins. TR has coasting listed at 10.4% which means it hardly ever happened.
The ride was on similar terrain to what I race on and I pushed slightly below race pace for a PR.
Surely that ride was equal to or more benificial than the same time spent on the trainer?

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Probably not. Riding a course at close to race pace most closely resembles workouts from the specialty phase, i. e. only a tiny fraction of your structured training. And even then, IMHO the best you can get out of outdoor rides are things you can’t do on an indoor trainer, things like bike handling, riding in a group or pacing in real life. That’s what I focus on at least.

Also, the 10 % you mentioned you spent not spinning is likely a significant underrepresentation of the time you did not pedal. Bike computers auto-pause, so that the time you spend at traffic lights and such is not included.

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That’s 16 minutes of no power input, and not something to ignore, IMHO.

Even if you do some math and cut that ride in half, to 1 hour and 20 minutes (80 minutes), that is 8 minutes coasting.

Think about coasting for 8 minutes in your next TR workout of 90 minutes and decide if that’s really negligible. It is a loss of power input and is truly less efficient in the consideration of training time vs work done.


If you’re doing a 4 x 8 minutes set with three minutes rest there is virtually no difference between coasting and light pedaling. Just looking at the coasting number does not give the full picture without knowing the intent of the workout. In this case there is 9 minutes of coasting/light pedaling in a set that takes 41 minutes, excluding any warm-up.



Coasting time is not sign of weakness but is tied to the course. If you ride in the city or suburbia, its hard to find a course that does not result in at least 20% of your ride time in zone 1 no matter how hard you are riding. If you have stop lights, stop signs or sharp corners, you’re going to be doing some coasting.
On the other hand, you do get the benefit of all those little Zone 6-7 accelerations after coasting or those sharp turns so there can be a hidden benefit :wink:


I get that doing a TR workout on a trainer is 100% efficient for that workout. If you try and complete that same workout outdoors you’ll probably take longer to do so.
I don’t agree with the sentiment that you can have an easy to get ratio of efficiency for the trainer vs outdoors.

For the record, the ride I mentioned had 50 mins of non stop overs and unders to begin as it’s all up hill. The terrain dictates when it’s an over.
I have never used auto pause on a ride and I’m not sure why you would use that setting.
Aside from two very short but steep sections of asphalt, if I’m coasting in a ride it’s anything but restful. It’s either single track or cornering on rough descents. Sure your legs get a minor break. No different to doing intervals on the trainer though. Sometimes harder even.

I have plenty of other outdoor rides where I’d be happy to say they were less efficient than if I’d stayed on the trainer.

Maybe someone can ask at the church of Chad? I’d love to hear the TR crews opinion on the podcast.

Peace out boys and girls. I’m going to auto pause and grab myself a latte.:wink:

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I don’t think anyone is arguing that indoor rides are consistently X% more efficient than outdoor rides. That’s impossible. If an indoor workout is a 100, you could have perfect roads or trails outside that go up at precisely the right time and flat at the right time and get a 99.9, or city streets with a bunch of stoplights that you get a 1. But I don’t think it’s unreasonable to look at a set of data from indoor and outdoor rides and say on average, people get 1.3 times the work done on the trainer that they do outdoors.

Your first two and last sentences contradict each other.

But do you know whether 50 minutes of non-stop over-unders is actually a good idea? If you look at how TR workouts do over-unders, they are usually broken down in 12-20 minute sets with 3-6 minute breaks in between. You need the breaks to really nail the intervals, otherwise you are not doing over-unders, but rather under-unders :upside_down_face: So already here I would say you are leaving something on the table, and the outdoor interval is less efficient.

Auto pause is on by default, so unless you have disabled it, you are using it. Stops at intersections and traffic lights are thusly not counted.

The amount of coasting depends on your environment and on your pacing strategy. Perhaps it makes little sense to pedal like crazy in order to eek out the last 5 km/h on a descent. Instead, you’d use that time strategically to give your legs some rest so that you can power up the next short hill at VO2max or some such. Even during my races, I typically spend 10-20 % coasting, “doing nothing” :wink:

But those are things to train, which are complementary to what you do on a trainer.

I think you are conflating different types of training. Yes, if you are racing down a single track, your upper body does plenty of work. That can — and should be — part of your training. But this is complementary to being on an indoor trainer, and can’t really be compared with one another.


Perhaps I missed it, but for mountain bikers, there are many more benefits to being outside. My wattage is way up since starting TR, but I have to work to keep my “mtb toughness” where it needs to be, ie handling, core strength, line picking, etc. The work you do on any technical terrain cannot be duplicated inside.

More to the discussion, mtb’ers not on technical terrain, put way less zeros up than roadies (no intersections etc). Technical terrain is needed as stated above.

No evidence here, just “professional” opinion.