Turbo Trainer Advice

But still his aim is to get better at a 2 hour climb. So steady state intervals on the turbo are perfect. When he can't get out on the road, as he said that's what he want's the turbo for.

What do you class a hill repeat? For me that's VO2 work. Not threshold work.

That's exactly what I said to use the turbo for.

Climbing actual mountains/hills is still better in terms of muscle groups specificity.

Hill repeats can be used for any intensity. It's only VO2 if you're riding them pretty hard. Likely over here as we only have short stuff. But if you ride hills at threshold or a little over repeatedly you are more closely simulating actual long climbs. Depends what you have near your house innit.