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What is a good power output? - Page 2

post #16 of 36
I do believe that woj did say "seated SPRINT" telling us that he was doing an all out effort. This is a rather high output for such an activity, but not unusually so. So 1500 watts is a good figure for a top amateur in a sprint especially for somebody his size (did somebody say 65kg?)

Veloflash, weight does have some effect on sprinting in that it is much easier to accelerate with less weight, thus leaving more energy to increasing the length of the sprint or to reach the top speed faster.

finally Supplesse, i am sure u would have no troubles with woj riding your bike as the top sprinters in the pro peleton would reach these figures daily. The figures u have read are averages for those activities, and woj was sprinting remember? a sprint is much shorter than climbing an Alpe.
post #17 of 36
Quote:
Veloflash, weight does have some effect on sprinting in that it is much easier to accelerate with less weight, thus leaving more energy to increasing the length of the sprint or to reach the top speed faster.
I would agree with you if the (rare) occasion occurs when a breakaway of two riders with time and distance up their sleeves play 'cat and mouse' approaching the line. Power to weight and fast twitch compositon would play a role accelerating from a low speed.

But in the real world nearly all sprints occur from high starting speeds where the bunch or a leadout have picked up the pace. The sprinters main adversary then is Mother Nature not their weight plus the bikes weight or even mechanical friction or rolling resistance.

A dedicated track sprinter's bike is beefed up and heavier than the normal track bike. If weight was a deciding factor in determining the winner then elite track sprinters would not weigh around 100kgs and have custom made heavier bikes.
post #18 of 36
Re-energizing an old thread here. I'm new to the power training concept. Purchased a Computrainer to help get through the long winter months before I can get back on the roads. I seem to hold 230-250 watts for 10-12 min. T-hold intervals (165 HR), and recover at 150-180.

I'm familiar with HR training zones, and am wondering if there is a training protocol based on power out put as well. What is "map" refered to above? I assume maximum average power, but how does this translate to traing intensity levels?
post #19 of 36
Quote:
Originally posted by mjh
Re-energizing an old thread here. I'm new to the power training concept. Purchased a Computrainer to help get through the long winter months before I can get back on the roads. I seem to hold 230-250 watts for 10-12 min. T-hold intervals (165 HR), and recover at 150-180.

I'm familiar with HR training zones, and am wondering if there is a training protocol based on power out put as well. What is "map" refered to above? I assume maximum average power, but how does this translate to traing intensity levels?
The MAP is maximal aerobic power. The zones i developed are based on this, and the protocol for testing, and the zones themselves can be found here http://www.cyclingnews.com/fitness/?id=powerstern

hope that helps, and if you want to know please ask

ric
post #20 of 36
Quote:
Originally posted by ricstern

The world record for the individual pursuit was at ~ 7.7 W/kg, whereas the hour record was ~ 6.6 W/kg

Ric
The World Pursuit Record time for 4K of 4min11.114sec was by Boardman in superbike position is 57.344473km/hr in around August 1996 at Manchester.

The World Hour Record was 56.375km/hr soon afterwards with superbike at Manchester.

The relative difference in speeds of pursuit to hour records is 57.345/56.375 or 1.72% as against W/Kg difference of 18.5%. This doesn't look right and I don't think can be explained by the 1.7% increase in speed having disproportionate effect on drag (1e 1.017 cubed is around 5%).
post #21 of 36
Quote:
Originally posted by Michuel
The World Pursuit Record time for 4K of 4min11.114sec was by Boardman in superbike position is 57.344473km/hr in around August 1996 at Manchester.

The World Hour Record was 56.375km/hr soon afterwards with superbike at Manchester.

The relative difference in speeds of pursuit to hour records is 57.345/56.375 or 1.72% as against W/Kg difference of 18.5%. This doesn't look right and I don't think can be explained by the 1.7% increase in speed having disproportionate effect on drag (1e 1.017 cubed is around 5%).
yeh, that doesn't make a lot of sense. how can a 1km/hr increase cost 100watts?
post #22 of 36
Quote:
Originally posted by velomanct
yeh, that doesn't make a lot of sense. how can a 1km/hr increase cost 100watts?
The answer is actually quite easy. There are 2 big components. A 10% power increase doesn't result in a 10% speed increase(but considerabely less. Due to how air resistance increases by increasing speed(as michuel mentions already).

And then the big one the start, they are both standing but this negative effect is spread out over 1 hour in the one case where in the other its only for 4minutes.
A kilo rider for example will be about 4 seconds slower in his first lap where if you look at the power graph his first lap has the highest average power output. For pursuit and hour the start is less explosive but say the getting to speed cost you 4 or 6 or maybe 8(I don't have eaxct data but this should be not too far off) seconds in the first 500meter if you compare it with a 500meter at the same power at speed.

This time loss will make you average drop. And simple mats 4 or 8 sec on 4 minutes and a couple of seconds means roughly 1,5% to 3% of loss where for the hour its 0,1 to 0,2%. a big difference.
Getting to speed is a waste of time and power that has a far bigger effect on the average for a pursuit

There will also energy system working explanations but I ll leave these out due too complexit and not sufficient personal knowledge.
post #23 of 36
Quote:
Originally posted by maarten
The answer is actually quite easy. There are 2 big components. A 10% power increase doesn't result in a 10% speed increase(but considerabely less. Due to how air resistance increases by increasing speed(as michuel mentions already).

And then the big one the start, they are both standing but this negative effect is spread out over 1 hour in the one case where in the other its only for 4minutes.
A kilo rider for example will be about 4 seconds slower in his first lap where if you look at the power graph his first lap has the highest average power output. For pursuit and hour the start is less explosive but say the getting to speed cost you 4 or 6 or maybe 8(I don't have eaxct data but this should be not too far off) seconds in the first 500meter if you compare it with a 500meter at the same power at speed.

This time loss will make you average drop. And simple mats 4 or 8 sec on 4 minutes and a couple of seconds means roughly 1,5% to 3% of loss where for the hour its 0,1 to 0,2%. a big difference.
Getting to speed is a waste of time and power that has a far bigger effect on the average for a pursuit

There will also energy system working explanations but I ll leave these out due too complexit and not sufficient personal knowledge.
Maarten is spot on - hadn't had a chance to answer this yet. in other words the steady state velocity of the 4-km pursuit (i.e., if you ignore the acceleration phase) requires a lot less power than originally quoted.

ric
post #24 of 36
Quote:
Originally posted by maarten
For pursuit and hour the start is less explosive but say the getting to speed cost you 4 or 6 or maybe 8....This time loss will make you average drop. And simple mats 4 or 8 sec on 4 minutes and a couple of seconds means roughly 1,5% to 3% of loss where for the hour its 0,1 to 0,2%. a big difference.
Getting to speed is a waste of time and power that has a far bigger effect on the average for a pursuit
Yes the slow start is the cause but I think it's the consequential higher speed in the following laps which contributes most to the disproportionate effect on wattage. Boardman's pursuit splits were:- first 1K 1m8s, nest 3K at a constant average of 1m0.7s. This contributes >73% to total watts as the speed relative to hour speed is (1.064 / 1.001) in km/min terms which meets the cubic expression pushing up wattage disproportionately to speed:
(1.064 / 1.001)^(~3).

The first lap peaks in wattage up to maybe around 1200W in about 12secs with staring effort before speed increases but this in itself has a much smaller effect on total watts than the next 4 minutes.

The per kg watt estimates match up for the hour record : 69kg*6.6W = 455W while most estimates are around 446W for record.

For the pursuit 69kg*7.7W = 531W. I think Boardman has reported 515kg for max power output which I believe is highest 1 min wattage in a ramp test Anybody any data on this?
post #25 of 36
Quote:
Originally posted by Michuel
Yes the slow start is the cause but I think it's the consequential higher speed in the following laps which contributes most to the disproportionate effect on wattage. Boardman's pursuit splits were:- first 1K 1m8s, nest 3K at a constant average of 1m0.7s. This contributes >73% to total watts as the speed relative to hour speed is (1.064 / 1.001) in km/min terms which meets the cubic expression pushing up wattage disproportionately to speed:
(1.064 / 1.001)^(~3).

The first lap peaks in wattage up to maybe around 1200W in about 12secs with staring effort before speed increases but this in itself has a much smaller effect on total watts than the next 4 minutes.

The per kg watt estimates match up for the hour record : 69kg*6.6W = 455W while most estimates are around 446W for record.

For the pursuit 69kg*7.7W = 531W. I think Boardman has reported 515kg for max power output which I believe is highest 1 min wattage in a ramp test Anybody any data on this?
apologies, i used the wrong data for this his mass was 68 kg and power to mass was 6.5 W/kg (442 W) and 7.6 W/kg (520 W)

The effect of the first lap acceleration adds ~ 10% to the overall power output requirement.

Boardmans, peak power has been vastly overestimated above, and significantly underestimated for his MAP. I don't believe these figures are in the public domain, so i won't bring them up.

Ric
post #26 of 36
Resistance is proportional to velocity^3, but is not watts proportional to velocity^4?
post #27 of 36
Quote:
Originally posted by 9606
Resistance is proportional to velocity^3, but is not watts proportional to velocity^4?
On the road/track watts is proportional to velocity^(~2.5->2.8). For example on track Watts is probably proportional to Velocity^(~2.6) excluding other variables, standardising conditions.
post #28 of 36
Re. the original question: to help address these sorts of queries, I've put together some tables that can be found here:

www.cyclingpeakssoftware.com/profile.html

Re. the discussion of Boardman's pursuit and hour record performances: these are, in fact, what I based the maximums for the 5 min and 20 min performances upon. To be more specific: Peter Keen has estimated that Boardman averaged 442 W during his ultimate hour record. Knowing that value, it is possible to estimate his CdA, from which you can calculate his *steady-state* power during the pursuit. To that I added a correction for the acceleration phase (based on his stored kinetic energy at the end of the race, plus some other considerations), then finally used critical power analysis to derive 5 and 20 min values from these 4 min 11 s and 60 min performances. Whew! :-)
post #29 of 36
Quote:
Originally posted by 9606
Resistance is proportional to velocity^3, but is not watts proportional to velocity^4?
Close. Wind resistance is proportional to speed^2, so power required to overcome wind resistance is proportional to speed^3. As Michuel points out, though, if you simply model things empirically using an equation of the form power = speed^X, you find that X is somewhat less than 3, due to the influence of e.g., rolling resistance (which scales with speed^1).
post #30 of 36
Quote:
Originally posted by acoggan
Re. the original question: to help address these sorts of queries, I've put together some tables that can be found here:

www.cyclingpeakssoftware.com/profile.html

It’s a very useful table and reflects the decay in watts for the few checks I’ve been able to make for strong riders from TT times. And it shows the strong relationship between loss in power and time. The only questions I’ve had are:

Is it worthwhile to extend the range to 60 minutes? Or are the 5minute and 20minute checks accurate predictors of 60 minutes. There looks like a 13% decline from 5 to 20 minutes. The limited checks in wattage I’ve done from 20min to 60minute show a further 4% decline (just for a single rider I selected apart from Boardman who seems to show no power loss). I was expecting a larger decline.

Do stronger have a reduced loss in power over time than weaker riders? In general the table shows the lower the 5sec power the bigger the percentage discrepancy between 5 or 20 min power and 5 or 60 sec power, ie Boardman shows a shallower power loss than a 4th cat. I appreciate that the 5,60, 300 and 3200sec columns are independent and different slopes between the rows may be drawn as you advise but there seems some robustness just across the rows in showing decay.
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