Indoor Vs Outdoor Cycling - different muscles?

Hi everyone,

I’m noticing that my thighs are getting cooked a lot more on the indoor trainer than they are outdoors?

Is this usual or am I doing something different/wrong?

My immediate thought is that if you cycle outdoors then you are not always peddling, going downhill stopping at traffic lights etc. Indoors there are no breaks just continuous cycling. So outdoors your quads get occasional rests

The other possibly is that you ride harder indoors. I might have an hour to do an indoor session so try to make it count by pushing it a little. If I go for an outdoor 3 hour ride then there is not the same level of intensity; I am perhaps enjoying the ride more

Just a couple of thoughts

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You’ll be out of the saddle more outdoors too, so hamstrings etc. The upper body works more outdoors too. So yes, certainly different.

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Indoor cycling is completely different in the area of inertia, the inertia indoors is significantly lower - dumb trainers particularly, but even todays “smart” trainers whiich don’t need to be anywhere near as low are default configured to the least aerodynamic bicycle around in quite slow air conditions. As others have said, it also doesn’t change at all during your time, completely different to outdoors.

What does the inertia difference mean? Well it means that everything slows down on each pedal stroke so you’re accellerating the pedals and wheel much more on each stroke, this is slightly different pedalling dymanics - just like cycling with a tailwind is different to cycling with a headwind. Some people don’t notice it at all, others notice it a lot - you are probably someone noticing it a lot.


What’s the real world implications of this then Jim? Would it mean your pedalling technique is simply not optimised when you head outside or are there more subtle challenges that may arise as a result? Or is it the opposite, in that you will see strength/endurance gains from working ‘against’ the physics, rather than benefitting from?

Or am i missing the point?


Specificity matters of course, but cycling is ultimately not limited by leg muscles in any way really, so in the end, it shouldn’t matter much at all, your central adaptations to cycling will happen either way.

However, if you struggle in the low inertia situations, you may well take a long time to adapt to them such that your training indoors whilst you do is much more compromised - you’ll see this situation if you struggle to get the heart rate up in doors compared to outdoors - especially for those of us in cool climates where the extra heat training indoors should make that easier. So the indoor training will not give you the same benefit as outdoor, and you’ll be trading fatigue just for indoor adaptation rather than performance gains.

If you want strength gains - go to the gym, don’t do it on an aerobic workout, the aerobic workouts are just too important.


So low cadence work isn’t useful? Or am I reading your post wrong>?

I used to have this a lot when I had a Road Machine, had to be working really hard to get HR above 140 when I do easy runs at 165. Find getting HR up on the Kickr much much easier.

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I’m in the notice it ALOT camp.

I cannot ride into a headwind; completely destroys any technique/fluidity.
And for whatever reason I’ve adapted to turbo far better than outside. Just something about the consistent power application (which I’ve always felt is linked to inertia but never really understood it enough).


I do not personally see any sane reason to do low cadence work, unless your event has specific times when you require it - which should never be the case in a triathlon - you change your gears.


I’d agree, but I’d say it as being far more efficient to do actual weightlifting.

A bit of grinding practice is okay if that’s your natural cadence on steep climbs but not if the sim is to get stronger really.

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It helps to short circuit training and provides a similar firing pattern to that which you would wish to use in competition…