Rookie question. Four rides in on my trainer and I went to unplug my kickr core after doing stage two of the tdz yesterday and it was hot. Is that normal for a trainer?
Thanks!
Yes, it’s normal, especially after a long hard climb.
It applies resistance by trying to stop you pedalling. The energy you’re putting into overcoming the resistance has to go somewhere, and it’s primarily converted to heat. So yes, totally normal.
Thanks! One less thing to worry about then.
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If you are a on the bigger side and running near 100%, the trainer is working very hard. The trainer is using a lot of brake force and with low rpms, big heat can be generated. I overheated my H3. I reduce the resistance to the 50-60% setting and it works much better as the internals get to spin at a higher rpm.
Watts are watts though, so trainer difficulty per se should have no impact on the thermal load. (But of course you may ride differently with different settings which impacts your power output, and having to use the smallest cogs results in more drivetrain losses, and what else…)
I think it has to do with the internal spin rate of the trainer…maybe a self-generated fan or something.
I do know that at 230-250 watts at 45 rpm and 103 kg that I overheated (Tower Road) using the 100% setting…twice…reducing the setting allowed 70 rpm and no overheating.
Of course, YMMV.
You are correct Chris. Lower TD will force you to use bigger gears and higher cadence. This will spin the internal trainer fan faster so it will have more cooling.
Having a fan on your trainer is also a good idea.
I’ve a kickr Core and have a small fan set up specifically aimed at the unit. It still gets warm after a decent session but I wouldn’t describe it as getting hot.
I’m sure I read somewhere that heat is the enemy of electronics so if I can keep it a little cooler and prolong it’s life I think it’s worth it.
The added air flow towards my main fan also helps to circulate the air through the room so an added bonus! 
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I’ve measured my Kickr Core’s flywheel north of 70C after an extended threshold session. Keep meaning to buy a little fan for it, always forget to though.
Heat will be generated of course, but if the trainer is overheating then it’s been badly designed, unless you’re riding in hot ambient conditions to start with.
holy moly O.o
Kinda late replying, but yes it gets hot. I bought a cheap personal desk fan from Walgreens or Walmart to cool off that flywheel on my Kickr. Seems to to the job.
If I remember correctly after doing a spin down test in the Wahoo app the results show the temp of the unit??
Would be interesting to know if that information is available anywhere else to monitor?? 
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Would a heatsink be helpful on the side?