Formula for how hard a ride is?

[Deleted member 121159]

So I know that for climbs there are formulas for estimating how hard they are, like FIETS for example. Is there a similar formula to quantify how hard whole rides are?

 

[Jameshow]

Distance x elevation

Or if your in East Anglia - distance x windspeed!

 

[ColinJ]

Distance x elevation

That kind of works, but falls down with low levels of elevation gain, and it also doesn't take into account the steepness of the climbs.

I think it should be something more like distance (km) x (1 + (average_metres_per_km_of_ascents - 5)/20). (Maybe the numbers need tweaking slightly, but the idea seems sound.)

Where average_metres_per_km_of_ascents is measured purely on the significant climbs, so trivial slopes of rolling roads don't impact the severity calculation.

That would give...

• 75 for a (mythical?!) flat 100 km ride
• 100 for a typical flattish 100 km ride with only 500 m of significant ascent
• 125 for a rolling 100 km ride with 1,000 m...
• 150 for a lumpy 100 km ride with 1,500 m...
• 175 for a hilly 100 km ride with 2,000 m...
• 200 for a very hilly 100 km ride with 2,500 m...
• Some huge number for rides so mountainous that I would run away and hide from them!

 

[Deleted member 121159]

I don't think the relationship is as linear as that. E.g., 3000m of climbing over 100 miles feels reasonable but 6000m over 50 miles sounds really tough.

 

[UphillSlowly]

I think you also need to take into account how fast you ride, how much effort you put in? Some people refer to this as Intensity of Intensity Factor (IF). Which can relate to headwind or whether you decide to push harder.

If you have a power meter or heart rate monitor you can measure the "Load" or TSS of a ride. These are based on formulas and aren't based on the road but on how hard you make the ride. Have never looked up the formulas though.

Once you have measured the load/TSS for a few rides you get a rough idea of how hard a particular ride will be in relation to your reference point.

Having said all that what @ColinJ suggests will pretty much give you your load/TSS but suspect it would be more accurate if you factor in "intensity"

 

[lazybloke]

I think you also need to take into account how fast you ride, how much effort you put in? Some people refer to this as Intensity of Intensity Factor (IF). Which can relate to headwind or whether you decide to push harder.

Yes, fatigue associated with high-intensity riding is awful. Speeds, prevailing winds, and 'aggressiveness' on climbs could all be added.

I don't want to imply Strava is an all-powerful seer, but doesn't it have such a measure already? The calculation might be documented or summarised somewhere.

 

[Ming the Merciless]

You also need to include weather in the formula as 6 hours in heavy rain at 3C with 50 mph winds is somewhat harder than 10 hours in the sun at 17C and 6 mph winds.

 

[lazybloke]

You also need to include weather in the formula as 6 hours in heavy rain at 3C with 50 mph winds is somewhat harder than 10 hours in the sun at 17C and 6 mph winds.

If rider="Ming":
Ride_hardness_index="EPIC!!"

 

[Ming the Merciless]

If rider="Ming":
Ride_hardness_index="EPIC!!"

Ride_Hardness_Index = “Merciless”

 

[Deleted member 121159]

I think you also need to take into account how fast you ride, how much effort you put in? Some people refer to this as Intensity of Intensity Factor (IF). Which can relate to headwind or whether you decide to push harder.

If you have a power meter or heart rate monitor you can measure the "Load" or TSS of a ride. These are based on formulas and aren't based on the road but on how hard you make the ride. Have never looked up the formulas though.

Once you have measured the load/TSS for a few rides you get a rough idea of how hard a particular ride will be in relation to your reference point.

Having said all that what @ColinJ suggests will pretty much give you your load/TSS but suspect it would be more accurate if you factor in "intensity"

Yes I agree the actual difficulty of the ride will depend a lot on how hard one rides, but I was wondering about a simple-ish way of determining how hard a given route will be, so not taking into account the rider. What is TSS?

 

[Deleted member 121159]

Yes, fatigue associated with high-intensity riding is awful. Speeds, prevailing winds, and 'aggressiveness' on climbs could all be added.

I don't want to imply Strava is an all-powerful seer, but doesn't it have such a measure already? The calculation might be documented or summarised somewhere.

I'm not a Strava subscriber but it still sometimes tells me that my ride was easier/harder than or the same as usual so it must be calculating this. But this is retrospective, based on my actual heart rate and I don't know if they take wind+temperature into account as well. What I wanted to know, though, was a measure like FIETS which isn't based on rider variables but purely on the route variables, so mainly just distance and elevation.

 

[Deleted member 121159]

That kind of works, but falls down with low levels of elevation gain, and it also doesn't take into account the steepness of the climbs.

I think it should be something more like distance (km) x (1 + (average_metres_per_km_of_ascents - 5)/20). (Maybe the numbers need tweaking slightly, but the idea seems sound.)

Where average_metres_per_km_of_ascents is measured purely on the significant climbs, so trivial slopes of rolling roads don't impact the severity calculation.

That would give...

• 75 for a (mythical?!) flat 100 km ride
• 100 for a typical flattish 100 km ride with only 500 m of significant ascent
• 125 for a rolling 100 km ride with 1,000 m...
• 150 for a lumpy 100 km ride with 1,500 m...
• 175 for a hilly 100 km ride with 2,000 m...
• 200 for a very hilly 100 km ride with 2,500 m...
• Some huge number for rides so mountainous that I would run away and hide from them!

elevation per mile seems key but what count as significant and what don't? Why not use elevation per mile for all climbs?

 

[UphillSlowly]

Yes I agree the actual difficulty of the ride will depend a lot on how hard one rides, but I was wondering about a simple-ish way of determining how hard a given route will be, so not taking into account the rider. What is TSS?

TSS is Training Stress Score and a way of working out how much effort a workout is. It's used by Zwift and Training Peaks. Load is used by other programmes and seems to be interchangeable. I've found it useful to use Load to plan my training.

Formula for TSS: https://www.trainingpeaks.com/learn/articles/estimating-training-stress-score-tss/

Again is retrospective, but you can use your past history to predict how hard a ride will be. You can predict how hard workouts will be so why not routes.

 

[HLaB]

Does the scale for rating how hard a ride is not go something like this:

1. Easy to Chat Continuously
2. Able to Chat at Occasionally
3. Able to say short words
4. Unable to talk at all
5. Eyeballs out
6. Sick out of the Eyeballs

I suppose you can only truly give those ratings post ride and the OP maybe wants to rate a ride in advance.

 

[Alex321]

elevation per mile seems key but what count as significant and what don't? Why not use elevation per mile for all climbs?

Because it is much harder to climb 100m in half a mile (12.5%) then ride flat for half a mile than it is to climb 100m in a mile (6.6%) of continuous climb.

The Bwlch mountain climb fairly near me is a Strava cat 3, but I find it easier than several of the cat 4s round here, because while it goes on for a long way, it is almost constant at 4-5%, while several of the cat4s peak at over 20%, with sustained stretches of 12%+

For me personally, I aim for a cadence on the flat of between 80 and 95. If I can keep that up on a hill, then it really isn't a hard enough hill to count much as making the ride harder.