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3 POWER METERS AND A TIME TRIAL
By Anthony Moran (anto.moran@gmail.com)
Jun 28, 2006
In this article we look at a club Time Trial held on an undulating course. Fortunately for us 3 riders had power meters on their bikes and agreed to allow their information to be shown here.
The three riders are club mates and all agreed before hand that they would implement a pacing strategy. This strategy would be based upon their (un)known power thresholds and this should be interesting because the lightest guy was the guinea pig for the Donegal 3 day TT and his comments at the end of the race might show if the stragetgy worked for him. The weather conditions where the same for each rider.
Rider 1 was the heaviest (90kg) and has a Functional Threshold Power (FTP) of 340w. This gives a power to weight (ptw) ratio of a mere 3.8 w/kg, the bike he used was a normal road bike with no special areo gizmos. This was a training ride more than a race for this rider.
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| Rider 1 graph |
Yellow is wattage, blue is speed, grey is torque and green is cadence.
Rider 3 is the piggy in the middle and weighs a svelte 70kg with an FTP of 310w giving us 4.4w/kg. This rider used his road bike with aero bars.
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| Rider 3 graph |
Note how he starts off at a lower wattage and builds up over the course of the test to finish very strongly.
Rider 2 is the skinny guy weighing in at a feather weight 68kg and has a FTP of 300kg giving him a a power to weight ratio of 4.3w/kg. This rider used his road bike with aero bars.
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| Rider 2 graph |
In this graph you can see that their is no rise or dropoff in the yellow power line.
This table is the vital statistics of the ride. Rider 3's Avg Power is quite high!!!
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Rider 1 |
Rider 2 |
Rider 3 |
| KG |
90 |
68 |
70 |
| Time |
24:40:00 |
24.49 |
25.3 |
| Kilojoules (kj) |
500 |
441 |
530 |
| Avg Power |
347 |
296 |
356 |
| Distance |
16.168 |
16.168 |
16.168 |
| revs per min |
84 |
95 |
87 |
| speed |
39.2 |
38.7 |
37.7 |
| avg torque |
10.8 |
9.6 |
11.3 |
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| kj per kg |
5.555556 |
6.485294 |
7.571429 |
| watts per kg |
3.855556 |
4.352941 |
5.085714 |
| watts per kj |
1.440922 |
1.489865 |
1.488764 |
| watt per rev |
4.130952 |
3.115789 |
4.091954 |
Looking at the power to weight ratio you would expect that Rider 3 would win the TT quite comfortably but this wasnt the case. The result was reversed but if we delve further into the facts the power meter gives us we can see clues as to why this happened.
The last 4 rows of the table are an analysis of the the expengy expended against the weight (kg) of each rider, the power to weight ratio , the metabolic cost of producing each watt and finally the number of watts produced per revolution of the cranks.
Rider 1: Seems to be more efficient than the other 2 riders. Remember this was done on a normal road bike with no aero gizmology and he was seperated by 1 min from Rider 3 so we can rule out environmental conditions.
Rider 3:The amazing aspect of this ride was the avg power this would rank him very highly inpower terms to his peers, however, the time is still slow but it is encouraging in that if he can train his engine to become more efficient and work on his postion it should see him move onto a higher level performance wise. This will involve more high intensity work (8-15mins) and some testing to try and get a better cadence and position on the bike.
Rider 2: This effort was the best paced effort. He has to try and improve his threshold (what else but threshold!!!) and also on the climbs he wasnt the quickest rider so that is an area that he will have to concentrate on. These climbs where big ring and therefore he could look at doing some work during long intervals where he goes above threshold and then settles back down to threshold power. Also, a block of VO2 training with big gears will help.
Rider 1 will need to improve the power to weight ratio at threshold. This could be achieved thru losing weight or just training in that zone...or better still a combination of both. The TT was a training effort and he tried to do a negative split i.e. slower on the first part and quicker over the last part but he couldnt manage this. His finishing power was the same as the 20 min efforts that he is currently doing in training.
At the end of the the TT Rider 2 said "..... matched each other second for second with a 24.57 each. I tried something new and paced the test exactly on threshold - so rode the entire race at 300w on the button. Looking back it felt a little too comfortable so the next 10 I'll just rip along and see how it compares to pacing, but it was a weird feeling to ride it and feel fresh all the way through." but that is the point you dont build up huge amounts of lactic and feel on the ragged edge throughtout the test. With a small bit of practice he should be able to go harder for the last few mmiles which will make him feel bad....but at the right time and place!
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- Updated: Oct 3rd, 2007 - 16:54:37
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