Mont Ventoux Power calculation

frenchyge

Another way to say it is that gearing doesn't affect the power required to climb, if the speed is held constant. What changes is the cadence of the pedals and the force required to push them down each time (ie, spinning easily or mashing).

The way I think of it is that lower gearing allows you to climb *slower* (ie, with less power) while still maintaining a comfortable cadence which doesn't kill the knees. After all, the reason we have low gears is because we lack the power needed to fly up some hills.

2laps

Your wright frenchyge, going from 3 to 4 doesn't seem much but infact it does constitutes a 33% increase in speed. It seems i overlooked that one.

I now have downloaded a profile from the Mont Ventoux the southern approach. I have a new problem !
How would i simulate this route on my tacx flow trainer. I can not program this trainer, what i can do, is changing the needed power on a given time.
The profile is devided in segments of a 1000m each with the slope.
Should i calculate the power needed for each segment keeping my speed constant and change that power every 330sec (if i want my speed at 3m/s)??

frenchyge

That should work to simulate the actual ride on your trainer. You can asume 3 m/s and determine the power requirement for each section based on that speed, but what's really going to happen on your ride is that your speed will naturally vary depending on the steepness of each road section, right? In other words, if there's a very steep section of road, then you wouldn't blow yourself up trying to maintain 3m/s, you'd crawl up at whatever speed you could manage given the power you had available. So, when you calculate the power requirement for each 1000m section of road, place a limit on how much power you're willing to expend. If the required power at 3 m/s exceeds that limit on certain sections, then calculate the max speed on those sections based on your power limit, and adjust those particular interval durations based on riding 1000m at that new, calculated max speed (ie, 400 sec at 2.5m/s, 500 at 2m/s).

That seems pretty complicated, but hopefully you can save your power profile once you've built it. That'll certainly give you a nice benchmark ride to test yourself. I don't have those capabilities on my trainer, so the simpler approach I'd take is to just ride long intervals above the average power needed for the ride (235W, in your case) in hopes of raising my 2 hr power as high as possible. If you can't hold 235W for 2 hrs, then that just means you'll climb a little slower during your ride. You'll still make it to the top. The only thing to worry about is having too little power to climb at a pace that maintains a comfortable cadence given your gearing. That's what will shut you down.

rikoshea

---------------------------0----------
You will need to average ~190W for two hour

I am assuming that you are starting from Bedoin. Which is the hardest side - and the the one that you should do :-).

The road surface is fairly good and rolling resistance isn't an issue at the speed you will be going at anyway. You're biggest problem is your gearing; with a low of 39-21 you are going to be in big trouble unless you like to climb out of the saddle A LOT! Your cadence at this speed would be less than 50 rpm. There are two very hard sections over 10% which at this speed would require a 280 W effort - more realisticly you would need to travel at 7.5 km/h on these sections and with you current gearing would require a cadence of 32 rpm.

So to summarize, you need either a triple or a 32 cog or a pair of comfortable cycling shoes (for walking). 190 W for two hour will do OK.

Here are the details:

Input Parameters
================
Cyclist
-------
Height [m] ............................. 1.72
Mass [kg] .............................. 64.00
A (Frontal area) [m^2] ............ 0.4392
A as % BSA ........................... 25.00
CD (Drag coefficient) ............... 0.850
CDA [m^2] ............................ 0.3733

Course
------
Velocity [km/h] ........................ 11.350
Distance [km] .......................... 22.7
Time [h:m:s] ........................... 2:0:0
Slope (%) (Rise/run * 100) ........ 7.1
Wind Vel [km/h] ........................ 0
Wind Angle [0-180 degree] .......... 0
Altitude [m] (average)................. 1000
Acclimatized .............................. No

Atmosphere
-----------
Sea Level Corrected Air Pressure [mb] .. 1013.25
Air Pressure [mb] ...................... 901.16
Relative Humidity (%) .................. 55.00
Air Temp [deg C] ....................... 15
Air Density [kg/m^3] ................... 1.0852

Equipment
---------
Bike+Clothing Mass [kg] ................ 9
Drive Efficiency (%) ................... 97.50
Crr (Rolling resistance coefficient) ... 0.0045
Chainring (teeth) ...................... 39
Cog (teeth) ............................ 21
Wheel Circumference [mm] ............... 2096
Cadence (Rev/min) ...................... 48.6


Results
=======
Mechanical Power
----------------
Total [W] .............................. 181.3
Air Resistance [W] ................... 6.3 3.5%
Rolling Resistance [W] .............. 10.2 5.6%
Slope Resistance [W] ................. 160.2 88.4%
Drive Train [W] ........................ 4.5 2.5%

Power/Mass [W/kg] ...................... 2.83
Power/CDA [W/m^2] ...................... 486

Sea Level Aerobic Power
-----------------------
Total [W]............................... 190.8

Available Aerobic Power (%) ............ 95.0

Power/Mass [W/kg] ...................... 2.98
Power/CDA [W/m^2] ...................... 511

Energy Requirements
-------------------
Total [kjoule] ......................... 1864
Cycling [kjoule] ....................... 1304
Basal [kjoule] ......................... 559

rikoshea

---------------------------0----------
You will need to average ~190W for two hour

I am assuming that you are starting from Bedoin. Which is the hardest side - and the the one that you should do :-).

The road surface is fairly good and rolling resistance isn't an issue at the speed you will be going at anyway. You're biggest problem is your gearing; with a low of 39-21 you are going to be in big trouble unless you like to climb out of the saddle A LOT! Your cadence at this speed would be less than 50 rpm. There are two very hard sections over 10% which at this speed would require a 280 W effort - more realisticly you would need to travel at 7.5 km/h on these sections and with you current gearing would require a cadence of 32 rpm.

So to summarize, you need either a triple or a 32 cog or a pair of comfortable cycling shoes (for walking). 190 W for two hour will do OK.

Here are the details:

Input Parameters
================
Cyclist
-------
Height [m] ............................. 1.72
Mass [kg] .............................. 64.00
A (Frontal area) [m^2] ............ 0.4392
A as % BSA ........................... 25.00
CD (Drag coefficient) ............... 0.850
CDA [m^2] ............................ 0.3733

Course
------
Velocity [km/h] ........................ 11.350
Distance [km] .......................... 22.7
Time [h:m:s] ........................... 2:0:0
Slope (%) (Rise/run * 100) ........ 7.1
Wind Vel [km/h] ........................ 0
Wind Angle [0-180 degree] .......... 0
Altitude [m] (average)................. 1000
Acclimatized .............................. No

Atmosphere
-----------
Sea Level Corrected Air Pressure [mb] .. 1013.25
Air Pressure [mb] ...................... 901.16
Relative Humidity (%) .................. 55.00
Air Temp [deg C] ....................... 15
Air Density [kg/m^3] ................... 1.0852

Equipment
---------
Bike+Clothing Mass [kg] ................ 9
Drive Efficiency (%) ................... 97.50
Crr (Rolling resistance coefficient) ... 0.0045
Chainring (teeth) ...................... 39
Cog (teeth) ............................ 21
Wheel Circumference [mm] ............... 2096
Cadence (Rev/min) ...................... 48.6


Results
=======
Mechanical Power
----------------
Total [W] .............................. 181.3
Air Resistance [W] ................... 6.3 3.5%
Rolling Resistance [W] .............. 10.2 5.6%
Slope Resistance [W] ................. 160.2 88.4%
Drive Train [W] ........................ 4.5 2.5%

Power/Mass [W/kg] ...................... 2.83
Power/CDA [W/m^2] ...................... 486

Sea Level Aerobic Power
-----------------------
Total [W]............................... 190.8

Available Aerobic Power (%) ............ 95.0

Power/Mass [W/kg] ...................... 2.98
Power/CDA [W/m^2] ...................... 511

Energy Requirements
-------------------
Total [kjoule] ......................... 1864
Cycling [kjoule] ....................... 1304
Basal [kjoule] ......................... 559

velomanct

Don't forget that Mt. Ventoux is very windy, which will lower your speed for a given power output. add 10% more wattage to be safe.

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ric_stern/RST

2laps, it's worth bearing in mind that your Tacx may not be accurate for the purposes of power output. While i have *never* used a Tacx Flow, i have used several other Tacx trainer (Elite, Grand Elite and another) and the power they reported was somewhat different to my PT and SRM. Additionally, each one reported different power values when riding at a constant PT/SRM power. In other words one unit reported higher figures, another reported lower figures, etc.

Ric

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2laps

In the manual they already stated something like that, but i have nothing to compare with, but it seems you did. Would you say there is a avg 10% deviation in power values between the different trainers?

2laps

In belgium we had a great weekend of the 21 july so i could not reply sooner.
I did calculate the power needed for the Km sections starting from Bedoin.
The first time i tried it, i had to stop just before Km 10. Was very dissapointed. Next day tried again and went the whole way. Triumph! or not?!
The thing is at the higher power settings 250W - 270W i had to keep a cadence of at least 70rpm otherwise my trainer couldnot prevent my wheel from slipping. Now i am worried that with the higher rpm it felt a little bit better than it would if i was riding at a cadence of 60rpm like i was supposed to do. Anyway i will try to insert my settings here:
Each section of 1Km had a timeframe of 5m30s

Km slope% height m power W
1 3 311 84
2 2.5 338 73
3 3.5 375 96
4 5 426 131
5 5.5 482 143
6 4.5 527 120
7 6.5 592 166
8 10 690 248
9 9 781 225
10 10.5 884 260
11 9.5 977 236
12 10 1076 248
13 9.5 1172 236
14 9.5 1266 236
15 9 1356 225
16 7.5 1429 190
17 7 1500 178
18 6.5 1564 166
19 7 1635 178
20 8 1712 201
21 8.5 1799 213
22 11 1909 272

tomUK

I have both a Tacx Flow and Power-Tap Pro (which I've check the calibration of) and to be quite honest, the figure shown on the Wattage figure shown on the flow is so far out it's not even usable. I've calibrate the Flow as described in the manual, however, this still produces wild readings.

Also, FWIW (old news here), producing 200W on the trainer feels about 50% harder than producing that same wattage out on the open road.

2laps

tomUK, this comes as a shock to me. You are now telling me that i will not be able to simulate the montoux on my Flow because i can not rely on the Wattage figures it gives me. So my trainer is practically useless for this kind of stuff. I'm stunned. You think the Power-Tap is accurate? (i will have to get one, but i dont know much about it). You also say that the trainer feels harder than the same thing on the road? Do you mean it just 'feels' like it or is it actually harder (more wattage)?

And i thought i climbed the mountain

ric_stern/RST

2laps, as i suggested in my previous post, it's unlikely that your Flow will be accurate.

The Power Tap is as accurate (if not more so) than the SRM Pro, as has been discussed in quite a few threads previously. The SRM Amateur is less accurate.

Some people find riding a trainer at the same power harder than the road. On the other hand i find it considerably easier than the road (and can generate ~10% more power in a 1-hr TT on the trainer)

Ric

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2laps

Yes, you did tell me the flow was not accurate enough but still i had some hope (could live with a 10% deviation) but the way tomUK presented it, there does not even seem to be any logic in it not being accurate.

If i would to calculate the speed outcome for the given power settings on a flat road, and then train on the flat road for the given speeds, would that give me a good training for the ventoux? Suppose not because my cadence would be much higher?

I just spend money on new gipiemme wheels with campa gears (9s veloce), not even sure if i could still use them if i'm going to buy a power-tap. Ohoh what a setback, i keep spending money and i'm not getting anywhere.

ric_stern/RST

As i mentioned earlier i have *no* experience of a Flow, but have used and own a Tacx Basic and Excel (or Grand Excel). These units are not accurate. I do not know if they are the same flywheel, and computers as the Flow.

However, on the Wattage list, someone, maybe a year ago reported that the Flow was not accurate and was possibly less accurate than the Basic and Excel units in comparison to an SRM unit.



Environmental conditions will affect your velocity/power relationship to, too much extent.



The Power Tap gets built into an entire wheel, so some or all of your new Gipiemme wheels would be redundant if you purchased a PT.

However, it is possible to train (well) without the use of a power meter (although having a power meter makes your training much more accurate and specific, and cuts down on wasted time). Good coaching (and training) will improve your fitness, which is what you need to aim to do (increase fitness) if you want to ride up Ventoux or other climbs either at a faster pace or at the same pace as before and feel more comfortable.

You need to concentrate on building your sustainable power output, and maximal aerobic power. This can be done in several ways from longish, quality rides, to flat out time trialling, to short (~4-min) nasty intervals. This will help you increase your fitness, and thus travel at a faster rate up Ventoux (or any other climb, and of course on flat roads). In the training section of this forum, there's quite a lot of threads on these subjects. Additionally, our coaching group (RST; www.cyclecoach.com) who sponsors the forum can help you with these issues if you so desire, and of course there's several other coaches on this forum who would also be able to help.

I see you're in Belgium, do you read "Het Nieuwsblad"? I'm trying to translate an interview i did with them... If you are able to help, i'd be most grateful,

cheers
ric

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