Ming the Merciless
There is no mercy
- Location
- Inside my skull
Nope a friend on same ride has similar figures. Your calculator is making incorrect assumptions about real world.
Are these times any good for a beginner.
- Thread starter philthecat
- Start date
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Nope a friend on same ride has similar figures. Your calculator is making incorrect assumptions about real world.
Ming the Merciless
There is no mercy
- Location
- Inside my skull
Your friend is clearly the problem. Remember 85% of that is air resistance of rider. He might have nice bike but must be sitting rather upright and / or be wearing flappy clothes. Is he a big fella?
Nope his average 6ft and what you expect from someone who has a few KOMs.
You are right your data doesn't match mine, nor people I know, or what online calculators predict, so clearly lots of variation in powermeter reading...Good thing power readings are what so many people base their training on
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Ming the Merciless
There is no mercy
- Location
- Inside my skull
Nope his average 6ft and what you expect from someone who has a few KOMs.
You are right your data doesn't match mine, nor people I know, or what online calculators predict, so clearly lots of variation in powermeter reading...Good thing power readings are what so many people base their training on
But not compare with others.
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Its interesting to see all this, I do know the readings on the eBike is consistent across rides, so for the purposes of fitness a repeat run in a few months will tell and be representative of fitness levels rather than using average speeds.
cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
Heres my stats from today , gives me about 2.5 watts per kg if its any help
IanSmithCSE
Guru
- Location
- Worcester, Worcestershire
Good afternoon,
Thanks for the feedback @Ming the Merciless on the numbers.
The problem when calculating the numbers for a general statement rather than using live data is that you have to make a very large number of assumptions.
If you allow me to go through the numbers assuming no wind, putting exactly 18.6mph through my calculation comes up 231Watts
Taking the initial value of 215 watts for a hybrid at 18mph and making some changes to the calculation
The rolling resistance of the tyres is affected quite significantly by the road surface, it is clearly unlikely that a real ride would be on as good as surface as concrete but this does indicate the range of possible variations.
A hybrid bike is a very broad term, so it covers a very wide range of tyres including some pretty cheap, nasty and slow ones.
Again wind resistance is something that is impossible to assume and get right for a specific instance, dropping the drag by 10%-20% show very large savings in the power requirement.
So by making some different reasonable assumptions I have reduced the power required by 67 Watts or nearly 30%.
Remember that for the increased power requirement shown in the wind tables there will also be a similar reduced power consumption table for riding with a tail wind.
So I see no problems with a measured 209 Watts at 18.6mph and it is well within my acceptable tolerance for my generalised tables.
GCN went a bit OTT recently and put one rider on a hybrid and another on a road bike and rode the hybrid faster than the road bike by riding the hybrid in a simulated tribar type position.
Bye
Ian
Thanks for the feedback @Ming the Merciless on the numbers.
The problem when calculating the numbers for a general statement rather than using live data is that you have to make a very large number of assumptions.
If you allow me to go through the numbers assuming no wind, putting exactly 18.6mph through my calculation comes up 231Watts
Taking the initial value of 215 watts for a hybrid at 18mph and making some changes to the calculation
| Change (just the change specified not the total of all changes) | New Power Requirement |
| Altering the rolling resistance of the road from asphalt to concrete | 166 Watts - Down by 49 Watts |
| Decrease the rolling resistance of the tyre by 10% | 207 Watts - Down by 8 Watts |
| Decrease the rolling resistance of the tyre by 20% | 199 Watts - Down by 16 Watts |
| Decrease the aero drag for the body position by 10% | 201 Watts - Down by 14 Watts |
| Decrease the aero drag for the body position by 20% | 188 Watts - Down by 27 Watts |
| Altering the rolling resistance of the road from asphalt to concrete Decrease the aero drag by 10% Decrease the rolling resistance of the tyre by 10% | 149 Watts - Down by 67 Watts |
The rolling resistance of the tyres is affected quite significantly by the road surface, it is clearly unlikely that a real ride would be on as good as surface as concrete but this does indicate the range of possible variations.
A hybrid bike is a very broad term, so it covers a very wide range of tyres including some pretty cheap, nasty and slow ones.
Again wind resistance is something that is impossible to assume and get right for a specific instance, dropping the drag by 10%-20% show very large savings in the power requirement.
So by making some different reasonable assumptions I have reduced the power required by 67 Watts or nearly 30%.
Remember that for the increased power requirement shown in the wind tables there will also be a similar reduced power consumption table for riding with a tail wind.
So I see no problems with a measured 209 Watts at 18.6mph and it is well within my acceptable tolerance for my generalised tables.
GCN went a bit OTT recently and put one rider on a hybrid and another on a road bike and rode the hybrid faster than the road bike by riding the hybrid in a simulated tribar type position.
Bye
Ian
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SkipdiverJohn
Deplorable Brexiteer
- Location
- London
Most people seem shocked at the thought of riding over 10 miles in a day. My guvnor had a problem in that he needed a vehicle delivered for maintenance, but officially staff are not supposed to give each other lifts at work in case someone infects someone else with the virus.
So I said I'd take it. He said "that's great, you can get an Uber cab back home and claim it back on expenses". I told him I don't use Uber, but I would deliver it on a decent weather day and ride back so long as he gave me the remainder of the afternoon off. "How far it it?", he says. Shortest route is about 16 miles I replied. "you're seriously going to ride 16 miles on a push bike?" he exclaims. When I pointed out I often ride 25 or 30 miles in one hit at the weekend just for fun, he looked totally confused!
Ming the Merciless
There is no mercy
- Location
- Inside my skull
It’s what comes of living in a sedentary society where people won’t think anything of driving 2 miles for something cause it’s too far to walk / cycle etc.
cyberknight
As long as I breathe, I attack.
- Location
- Land of confusion
My neighbours will drive down to the local corner shop , its less than a 5 min walk even if they only need some milk etc
philthecat
New Member
That’s exactly it “once a wheeler”.
rogerzilla
Legendary Member
My old Tacx turbo trainer (a real turbo, fan resistance only) was pretty accurately sized. If I could hold that speed on the turbo, I could do it on a flat road in still summer* conditions.
Trainers with variable resistance need calibrating by the user, really.
*the extra air density between a freezing January morning and a warm July evening knocks 1mph off. And that's ignoring the fact that you'll also be down in power due to cold legs and seasonal drop-off.
Trainers with variable resistance need calibrating by the user, really.
*the extra air density between a freezing January morning and a warm July evening knocks 1mph off. And that's ignoring the fact that you'll also be down in power due to cold legs and seasonal drop-off.
I went on a ride Saturday- 16 mph average, 1300ft of climbing over 28 miles- average power 147 watts, normalised power 165 watts. My FTP is only 190 watts (which I can reliably hold for an hour). On my TT bike that will see me hold an average speed of 23-24mph. On my road bike 17-18mph. Maybe 19 on a good day.
Twilkes
Guru
1300 feet is very different from 1500 metres, not sure what difference that makes to the calculations but it's significant as it's less than 400 metres climbing.
Look at the ride lengths- the 1500m of climbing was over 135km (4200 ft of climbing over 84 miles roughly= 50ft climbing per mile). My 1200 feet of climbing was over 28 miles, roughly 46 feet of climbing per mile- there isn't much in it.
But the point it is- FTP alone doesn't indicate speed. There are a lot more factors to consider: bike choice, rider size and weight, tyre choice, clothing choice, how aero or not someone is, wind speed and direction, wheel choice, terrain etc.
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