The effect of going up big hills?

Me, climbing on the ‘Cinglés du Mont-Ventoux’ ride in October 2015. My all-time favourite mountain

With apologies for ‘nerdiness’ …

OK – I know the short answers to this question, largely based around ‘slower’, ‘tougher’, ‘exhaustion’ ‘pain’ etc – but what I’m talking about is how much time big hills add to a ride, recognising that the loss of time going up is never fully compensated for by the additional speed going down the other side.

Of course, I also recognise that this is very subjective – it entirely depends on the type of rider, the nature of the slope, bravery on the descent, fitness levels, the weight of the rider and the bike and a dozen more factors but, in general, can it be said what effect going up hill has on a ride?

I’ve wondered if there is a formula for it – ‘x metres of climbing adds y minutes to a ride, compared to a flat ride of the same distance’.

I have a friend who goes by an extra hour for 1,000 metres (3300 feet) of climbing – but I can’t really validate that from my experience. Also, it seems a bit simplistic as it depends greatly on whether it’s a mountain top finish (like my Etape d’Tour back in 2013 which finished at the top of Mont Semnoz overlooking Annecy) or if the climb comes with a good descent.

Looking at my stats from riding up Mont Ventoux, ‘everesting’ last summer, my Etape, various hilly sportives, and a lot of climbs in the alps, I think the following seems to apply – to me, at least.

If I ride up a mountain, but don’t include coming back down it, I think something like 1,300 metres (about 4,300 feet) of climbing adds an hour to the time it would have taken me to do the same distance on the flat.

If I climb and have a good descent, I think it’s around 1,600 metres (c.5,300 feet) of climbing that adds an hour to my time to cover that distance on the flat. This seems to make some sense as the fast descent balances out the extra climbing.

Does any of this make sense to anyone else?

The purpose of this? It’s linked with route planning for the ride to the alps in the summer:

• first it helps answer the question ‘how much shorter does a hillier route have to be to justify the extra climbing’? It seems to suggest that 1000m (3300 feet) of climbing should be compensated by about 20 km (12.5 miles) of saved distance.
• secondly it helps work out how long it might take me to do each of the first two days which are about 280km (175 miles) with 700m (2300 feet) of climbing – about 11.5 hours in good conditions and on good roads?

Not surprisingly, this might not apply to every 1000 metres of climbing. I think this probably works for ‘sensible’ gradients in the range 3% to 10% (?) but accumulating fatigue on a very long and mountainous ride like the etape is likely to mean that the first 1000 metres of climbing is quicker than the third, or fourth …!