# Naismith's rule? - but for cyclists?



## PpPete (13 Apr 2010)

Hillwalkers amongst you may be familiar with "Naismith's rule" which is a handy guide for working out time to complete a given walking route:

In it's original version:
20 minutes per mile + 30 minutes per 1000 ft ascent.

Or in metric units:
12 minutes per km + 10 minutes per 100 m 

Personally I find that "generous" so long as the path is reasonable, whereas over Pennine peat groughs it's tough going, but with modifications its a useful planning tool.

However.... does anyone know of anything similar for cyclists? Or have a 'pet' method of their own?


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## on the road (13 Apr 2010)

When I'm planning a ride, I estimate the time based on my typical average speed and then add 20 minutes for stoppages like traffic lights, other junctions and anything else I might come across.


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## jimboalee (13 Apr 2010)

Jimbo's rule.

Work out the time based on unhindered, flat travel.

Add on 1% for every 'stop junction' and upward contour ( 10m ) more than down contours.

A 'stop junction' is anywhere where you may have to stop to give way to other traffic.


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## PpPete (13 Apr 2010)

jimboalee said:


> Jimbo's rule.
> 
> Work out the time based on unhindered, flat travel.
> 
> ...




So if you have an equal number of up and down contours (which you must have if route is circular) then you make no allowance for climbing?

Better legs than me then !
I'm sure I slow down more on the ups than I speed up on the downs.


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## Hont (13 Apr 2010)

I've never thought about this, but it would be interesting to look into (if you're a stats obsessive like me that is). The problem is there are a few extra variables, as you point out with walking the terrain itself can make a difference and the same is true with cycling and road surface. Wind is also a factor as is bike type, rider weight and fitness. So it'll be difficult to get a general rule that fits everyone.


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## jimboalee (13 Apr 2010)

porkypete said:


> So if you have an equal number of up and down contours (which you must have if route is circular) then you make no allowance for climbing?
> 
> Better legs than me then !
> I'm sure I slow down more on the ups than I speed up on the downs.



Well spotted, and if one would like to be precise.....

I've found I won't need to stop at every junction.
I've found my psychological effort dismisses the climbing theory.

I've found it's almost impossible to predict the time of a bicycle ride.


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## gaz (13 Apr 2010)

jimboalee said:


> I've found it's almost impossible to predict the time of a bicycle ride.


This! well said.


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## kewb (13 Apr 2010)

avg speed , distance = time approximation which is what naismiths rule is ,
i check my distance to the turning point then my average speed , factor in stuff like lights ,
and i can estimate to within 15 /20 minutes how long return journeys will be (accurate enough for me ),
on a new route i just estimate based on a familiar route which usually works out .


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## PpPete (13 Apr 2010)

jimboalee said:


> Well spotted, and if one would like to be precise.....
> 
> I've found I won't need to stop at every junction.
> I've found my psychological effort dismisses the climbing theory.
> ...




ALthough junctions and road surfaces will have a non-negligible impact I suppose I was expecting a "read-across" from walking and the ascent to be the major factor apart from the distance.


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## Oldlegs (13 Apr 2010)

My digital map (Tracklogs) has a Naismith road cycling calculator built in. 

The user setup requires speeds for flat, 1:10 ascending and descending and something called the Trantor correction. Cannot see the algorithm but it's doubtless more complicated than the walking one.

After a bit of fiddling with the variables it gives pretty accurate results.


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## piedwagtail91 (13 Apr 2010)

Oldlegs said:


> My digital map (Tracklogs) has a Naismith road cycling calculator built in.
> 
> The user setup requires speeds for flat, 1:10 ascending and descending and something called the Trantor correction. Cannot see the algorithm but it's doubtless more complicated than the walking one.
> 
> After a bit of fiddling with the variables it gives pretty accurate results.


i'll second the tracklogs one, it's pretty accurate once set up.


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## jimboalee (14 Apr 2010)

Garmin's 'ETA' function has something built in.

Country speed predictions are always faster than city speed predictions, which indicates to me junctions are compensated for.

I haven't assessed whether Garmin compensates for hills if Topo GB is installed.
NO CHANCE if City Navigator is installed.....


I have my own calcs sheet which compensates for temperature, wind direction and wind strength.
It gets the 'Trip duration' to within 2 minutes in an hour's trip; 10 minutes on a 100km Brevet Pop, and 20 minutes on a Rando 200km.

As I said, NO accuracy when predicting bike rides.


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## hubbike (25 Aug 2010)

Naismith rule is that 1 unit of vertical travel is equivilent to 7.92 units of horizontal. (use miles, kms, feet, inches, bananas as you wish.)

Analysis of cycling data suggests a similar rule (1:8.2) for cycling on mountainous roads and tracks.

So going up 2000m is equivalent to adding an extra 16km. no matter how steep. 

However, going down speeds you up much more on a bike than on foot and this is unaccounted for in Naismith.

any help?


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## snorri (25 Aug 2010)

I use the rule 'if it takes one hour in a car, it'll take one day on the bike'


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## HLaB (25 Aug 2010)

snorri said:


> I use the rule 'if it takes one hour in a car, it'll take one day on the bike'


That rule wouldn't work here  Going to Edinburgh takes half an hour in the car, add parking etc and it can take longer; I can cycle it in under an hour. Fully laid down with pannier it still only takes an 1h and 1/2.


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## Tigerbiten (25 Aug 2010)

On tour with my full trailer over the hills, I was working on taking 1.5 hours to cover 10 miles.
On the flat I could get upto 10mph average.
If it was very hilly it could drop as low as 6 mph.

Luck ...........


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## Ticktockmy (25 Aug 2010)

porkypete said:


> Hillwalkers amongst you may be familiar with "Naismith's rule" which is a handy guide for working out time to complete a given walking route:
> 
> In it's original version:
> 20 minutes per mile + 30 minutes per 1000 ft ascent.
> ...



Tranter's Corrections allow for the bad sections like grough, etc.

I am not sure, if anyone has written a "Cycle Naismith rule" but as it a rule I guess some wise soul out there has done so.


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## jimboalee (25 Aug 2010)

Another aspect of bicycle riding which the online calculators are sadly lacking is....

They don't know where the newsagents and Tesco Metros are, and how long the cyclist waits in the queue to buy a can of Coke.


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## HLaB (25 Aug 2010)

I've never really paid attention to it but Memory Map has got some sort of journey time planner built in; it concerns average speed the number of minutes added per 10m of climb and the number of minutes lost per 10m of climb. To get it accurate though you've got to accurately plot the route via every twist in the road.


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## jimboalee (25 Aug 2010)

HLaB said:


> I've never really paid attention to it but Memory Map has got some sort of journey time planner built in; it concerns average speed the number of minutes added per 10m of climb and the number of minutes lost per 10m of climb. To get it accurate though you've got to accurately plot the route via every twist in the road.



So you tell the sofware how fast you can ride on the flat. How does it know how determined you are and how much extra effort you are willing to give climbing a hill? Will it know I am a lazy B and get off and walk at the first molehill?


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## Sheffield_Tiger (25 Aug 2010)

Need to account for the concave hill effect.....you know, when you've just done a longish climb and you are barrelling along glad to be on the flat...then you realise that you're actually still climbing


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## jimboalee (25 Aug 2010)

Sheffield_Tiger said:


> Need to account for the concave hill effect.....you know, when you've just done a longish climb and you are barrelling along glad to be on the flat...then you realise that you're actually still climbing



That's called a 'False flat'.


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## Sheffield_Tiger (25 Aug 2010)

jimboalee said:


> That's called a 'False flat'.



Whatever it's called, I love it


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## HLaB (25 Aug 2010)

jimboalee said:


> So you tell the sofware how fast you can ride on the flat. How does it know how determined you are and how much extra effort you are willing to give climbing a hill? Will it know I am a lazy B and get off and walk at the first molehill?



LOL, If you're honest and say that every 10m on average takes you 10 minutes longer it might work, as long as you are consistent


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## PpPete (25 Aug 2010)

hubbike said:


> Naismith rule is that 1 unit of vertical travel is equivilent to 7.92 units of horizontal. (use miles, kms, feet, inches, bananas as you wish.)
> 
> Analysis of cycling data suggests a similar rule (1:8.2) for cycling on mountainous roads and tracks.
> 
> ...



Interesting stuff hubbike, thanks for the link.
the difference between 1:7.92 and 1:8.2 is probably irrelevant in view of the inconsistency in descending speed. After all, most of us are happy enough at 50 kph on a long straight downhill with good surface & good visibility, but with twists & turns we might be pumping the brakes trying to hold it down to 20 kph.

And these are Average values too... different people will have different ratios for sure. 

Interestingly... walking on the level my wife & I are similar speeds, uphill she goes away from me easily.
Cycling I'm a tadge faster on the flats, she gets up hills faster 
so maybe there is good read across

I'll have to go away & analyze some tracklog data see if I can work what our own particular ratios are.


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## jimboalee (26 Aug 2010)

At 16kmh, I'll cover 16km in an hour.

Give me a 10" gear and I'll climb a 50% gradient at 1 kmh. To rise 2000m up a 50% is a 4 km road.

4 km at 1 kmh is four hours.

If I rode the 16 km flat road at 4 kmh, it would take me four hours.

BUT, riding at 4 kmh on the flat requires 20 kCals/hour. Riding up a 50% hill at 1 kmh requires 480 kCals/hour.

Half way up the hill, I would be gagging for some sandwiches and drink, so I will stop which would take ½ hour, so the theory is flawed by human endurance capacity.

As I said earlier, the calculations don't take into account stopping for refreshments.


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## snorri (26 Aug 2010)

HLaB said:


> That rule wouldn't work here


 You're right of course, I was thinking rural.


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## Globalti (27 Aug 2010)

Not completely irrelevant to this discussion: a good way of estimating distance from an OS map is to follow your route counting every time it crosses a blue grid line. This means EVERY time so even if the road dives across a grid line then back again that counts as two. Then halve the total and you have the distance in miles. The further you go the more accurate it is; don't ask me how it works but it does.


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