NomadVW said:Quite simply, you're not doing real 537 TSS points. It's just not possible.
Let's assume you rode in exactly 6 hours (mileage doesn't matter). Your Intensity Factor (IF) would have to be .94 for the entire ride. If the critical power model has any validity at all, you're 6 hour power should be closer to low 80's% for an ALL OUT effort for the entire duration.
For a large percentage of us, on a normal training load - holding 94% for our 2x20's could be a hard day in the saddle.
Your FT is probably above 200, and maybe even around 220.
I just have a hard time reconciling your indoor trainer workouts of 150-160 W and those 5-6 hour rides you've noted that generate 400-550 TSS. Maybe you aren't used to the indoor trainer yet? Or perhaps you need a better setup in terms of cooling/fan, etc and that definitely makes a difference.
Another thing, you noted your cadence being over 105 RPM's? Is that your preferred cadence, or rather, what you use when riding outdoors? While power is power, if you are riding at a radically different cadence than you typically use then that might account for why you find the indoor work so hard.
Oh and TSS of 537? That really strikes me as being rather unrealistic. Not that I doubt you - I'm sure you did the ride and what not, but rather I think your estimated number/value for FT is way, way too low.
I've seen TSS values for mid-pack TDF riders on Alpine stages and even then, you are talking 300-400 TSS, but not 500+.
I'd up that FT estimate by a good bit. Like Nomad says, at least to 200 W, if not more.
Have you tried doing 2x20's outside on nice steady grade (sans lights, etc)? Something tells me you'd easily surpass your indoor figures and if you do, then you know the difference in power outdoors vis-a-vis indoors, is entirely based on environment, flywheel, etc.