New toy just arrived...

Power tap Pro.
Looks a bit like an SL, but its not.
Compare
The Saris guys are amazing. They certainly stand by their product. Awesome to know this when you live thousands of miles away from their HQ. These babies look totally different inside to the old yellow model pro. It has little hearing aid type batteries instead of the bigger half AA sized ones.


The weight is very similar to the old yellow pro though, despite the shiney carbon : ) - well, it was on my kitchen scale.

Read More

DIY aero testing

DIY aero testing.

The goal.
To see if there is a measurable difference in "aero-ness" between using my new aero lid, and using my old standard helmet.

An increase in "aero-ness" is crudely defined as the ability to do the same speed for less watts.

The location.
Outdoor velodrome at Haitaitai, Wellington NZ.
333 metre concrete track. (Bumpy).
Wind . Nil.
Temperature. 9-11 degrees.
From around 8am onwards.
Barometric pressure 1026 hpa.
Humidity 80%

The format.
8 runs. Completed in 1 hour and 15 mins with very little resting or downtime, apart from swapping helmets and noting temperature. Aero means Aero helmet, non-aero means non-aero helmet.
4 x 5 mins at 34 kmh. Aero, non-aero, aero, non-aero
2 x 5 mins at 40 kmh Non-aero, aero,
2 x 10 mins at 35 kmh. Aero, non-aero(35kmh seemed easier to do than 34 kmh)

The difficulities.
1. Getting the track to myself. (No problems)
2. Getting consistant wind . (No problems)
3. Getting consistant temperature. Pretty good.
4. Riding at a consistant speed. Way better than a previous attempt. The trick was to ride by feel (cadence?), rather than obsess on watching the computer.
5. Getting a smooth line. I rode on the sprinters line because it was way smoother than the bumpier pursuiting line. I guess this means I am less vertical than I could have been.

The equipment:

1. Bianchi d2 chrono TT bike and Power tap. Deep front rim. Weight around 9kgs
2. Carrera Dragon Fly helmet (Non-aero)
3. Louis Garneu Rocket helmet. (Aero)
4. Rider about 71 kgs. Add another 3 kgs for kit at least.


The "raw results"" are as follows, and have had no factors applied to them. They are listed in the order that they were undertaken.

Run number:

----------------------------------------------------
1. Aero.      5mins    34.6kmh  191 watts  temp 9.3
2. Non-aero   5mins    34.5kmh  194 watts  temp 9.9
----------------------------------------------------
3. Aero       5mins    34.7kmh  196 watts  temp 9.4
4. Non-aero   5mins    34.5kmh  197 watts  temp 9.8
----------------------------------------------------
5. Non-aero   5mins    40.2kmh  280 watts  temp 9.9
6. Aero       5mins    40.5kmh  270 watts  temp 10.9
----------------------------------------------------
7. Aero       10mins   35.1kmh  195 watts  temp 11.4
8. Non-aero   10mins   35.3kmh  197 watts  temp 11.4
----------------------------------------------------

To try to get an smooth transitition from start to finish, I would set my timer off for 5 mins, take two laps to settle in, then go another 2 laps after my time had elapsed, and stop pedaling on the line.

At the end of the day, after downloading this data, I would then "select" 5 mins worth of data, back from that coasting point, so all tests at least stopped in the same place.

The differences I recorded in the 40kmh test were pretty major, compared to the lower speeds, but I guess I would have to do it a couple of times to see if they were consistant and not some kind of an aberration. I think the last two runs are the least impressive as far as being decisive in any way, as the last run was actually faster than the one before it. If I am doing it right, I get a CdA of .233 using Alex Simmon's spread sheet. I am not sure if that is good or not.

Read More

Pacing with the Power Tap in a series of short TT's

Here is a bit of a timeline on my first serious efforts at racing, (rather than training) with my Power Tap on. I almost always go back to my race wheel (Corimma disc) rather than using my Power Tap wheel, which is a Mavic Open Pro with a Wheel cover.

In the interests of self betterment I decided to use the PT wheel and see if I could use it for pacing, even in short events like our Wednesday night 24km Time Trials.
Coming from a background as a Mountainbiker I am used to starting at maximum watts to be the first into the single track !
Old habits die hard, there is no single-track on our course, and we are starting at 1 minute intervals, so maybe I could slow down a bit?

Race 1. I pretty much raced as I always did, hard out of the blocks.
Its a 4 lap course. Up one side of the main drag, usually into a strong northerly, ever so slightly climbing, and back down the other side over about 4 rollers, no more than 5-10 metres in height.
Watch as my lap times got slower and slower.

Liverton road 4 laps (5.85kms)34-08 mins
1, 8.21 mins 307 watts, 168 bpm, cad 94, 42.3 kmh
2, 8.26 mins 301 watts, 179 bpm, cad 90, 42.2 kmh
3, 8.36 mins 284 watts, 179 bpm, cad 90, 41.0 kmh
4, 8.46 mins 292 watts, 179 bpm, cad 90, 41.0 kmh

Average power 296, Normalised Power 303
20 min power, 307 average , 312 Normalised power.

Out and back speed differentials on a very windy northerly
39.2 / 46.1 kmh
38.8 / 46.1 kmh
37.3 / 45.2 kmh
37.3 / 45.1 kmh


Race 2. I decided to use my 20 minute power of 307 watts as an upper ceiling to try not to go over. This had a good pacing effect on my first lap.
At the end of the TT, my 2nd and last laps were the same, a very good thing... my average power was up 8 watts and my NP was up 6 watts.
I was also 30 odd seconds faster.

Liverton road 4 laps (5.85kms) 33.26 mins
1, 8.24 mins 307 watts, 168 bpm, cad 94, 42.5 kmh
2, 8.18 mins 303 watts, 179 bpm, cad 89, 42.9 kmh
3, 8.26 mins 304 watts, 179 bpm, cad 90, 42.1 kmh
4, 8.18 mins 300 watts, 179 bpm, cad 90, 42.3 kmh
Average power 304, normalised power 309
20 min power, 310 average , 313 Normalised power.

Out and back differentials on another very windy northerly
40.1 / 45.2 kmh
40.6 / 45.7 kmh
39.0 / 45.9 kmh
39.7 / 45.4 kmh


Race 3. The same plan as the previous week. But at last some good conditions, a lighter southerly. The speed differential between out an back legs would be less.
I had done some pretty hard workouts only 2 days previous, so I would be tired, but the chance to have a go at the course record was to good too turn down. I was supposd to be peaking for a 40km TT the next weekend (3 days away).

Liverton road 4 laps (5.85kms) 31.30 mins. A new allcomers record, and vets record by 1 minute 20.
1, 7.51 mins 306 watts 167 hr 95 cad 45.0 kmh speed differential 46.0 / 43.7
2, 7.53 mins 299 watts 177 hr 96 cad 45.2 kmh speed differential 46.7 / 43.7
3, 7.56 mins 300 watts 180 hr 96 cad 44.8 kmh speed differential 46.1 / 43.5
4, 7.51 mins 301 watts 181 hr 97 cad 45.6 kmh speed differential 45.6 / 45.5

Average power 302, normalised power 306
20 min power 304, 307 normalised.

Watts were down about 2 in average and normalised power, probably due to tiredness, but the better conditions meant I went 2 minutes faster.

A speed differential of only 2-3 kmh, as opposed to 6-8kmh of the previous two weeks races, meant I was able to get maximum value out of my efforts.
Keeping a lid on my watts on the first couple of laps was essential to a good time..

Read More