It's pretty cool to run through the streets of the cities on Sundays. I ran in Bogota one Sunday when I was traveling.

https://en.m.wikipedia.org/wiki/Ciclovía

Manizales area is good and the route to nevado del ruiz is great . Plenty of mtb ers too in that area

Bogotá is a bad idea, unless you want to jog a few hundred meters in oxygen debt before you're rammed by an errant cyclist, inline skater, walker, or STROLLER. The Sunday Ciclovía in Bogotá is a good idea if you're in for a little outing with your family and a half-million Colombian recreants... who still have to stop at Stop Lights.

Plus, Bogotá is 8,000 FEET elevation and its air is very, very polluted (even on weekends).

FWIW, I live 53 miles from Bogotá. And there is more to a nice place to live than just a "temperate climate".

I hear the Darien Gap is great for MTB and trail running (pink).

Look into Colombia's Eje Cafetero, which is the area where a lot of Colombia's coffee is grown within a temperate climate with little pollution in the shadows of towering, green mountains. This area does not have major cities, but they do have most every amenity you might expect when traveling to South América. Paved roads are very well maintained (for Colombia) and most have safe shoulders. Getting off the pavement means riding into agricultural roads along the outskirts of banana plantations, which is as much of an adventure as most foreigners would ever desire.

Armenia and Pereira (cities) and Salento (a village) are gems. Right above Armenia is the craziest, sickest, longest road cycling climb (paved) you could ever imagine. That climb is part of a route known as La Linea. But most routes are down in the valleys and yet still having major climbs and descents within them. El Eje Cafetero is never flat.

The Valle de Cocora sits a few hundred meters below the village of Salento. The one-way road ends at a trailhead that would make an incredible trail run or runs up its multiple trails into the clouds hugging the hillsides stacked with 120-foot palm trees. Before global warming (it is said), the trails dead-ended up into a permanent snow pack. The whole area is jaw-dropping beautiful. Think summer in Switzerland!

Most elevations are around 4,000 feet above sea level.

Thanks for your suggestions. The coffee-growing region sounds awesome.
Altitude is not an issue -- I have just spent 2 weeks in Ecuador mostly above
3000m.

A while back, there was an article in the Financial Times about the
climb on Alto de Letras:
https://www.ft.com/...e5-b072-006d8d362ba3
Is this something that you would recommend?

No, I had not heard of Alto de Letras before now. But I have driven through roughly that part of Colombia. Looks epic and even doable. Yet, there are plenty of other great cycling destinations. Alto de Letras would be a great, final-day ride for a tour.

As a starting point, Mariquita is kind'a "out there", even for Colombia. All driving distances in Colombia are in HOURS (not miles) and not even in kilometers. Driving routes are slow, slower, and even stopped... for hours. All those small cities and villages get all of their products delivered on snail-like trucks. And so, as when on the bicycle, one just has to roll with it.

I can confirm that Eje Cafetero (around Pereira, Manizales) is a great place
for cycling. I also did Alto de Letras starting from Mariquita (80K climb, 3800m
vertical climb), very long climb. There are many roads (paved and unpaved)
that offer great cycling.

Few notes:
- it's difficult to find a place to rent a road bike
- there are some places where you can rent a mountain bike

Running trails are harder to find. Many people run on roads.