# Track bike data on assioma

My wife has been going to the velodrome using my single sided assiomas.
She has been getting some odd data from the pedals, specifically the cadence and power. The assiomas were calibrated before the ride.,
Attached is a segment of her ride from today. The power is purple, hr is red and cadence is yellow.
This section was a sweet spot/tempo effort at a steady power and cadence.
Could single side be the cause of this, maybe because it’s a fixie? I have used these pedals in between her rides and they have worked perfectly on 2 different bikes.

Is this an outdoor velodrome? In which case with headwind/crosswind/tailwind changing every 10 seconds on a fixie would produce that kind of speed and cadence pattern.

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Nope, it’s indoors in Milton Ontario. It’s a sweet venue.

What device was this recorded on? Was it setup to recognize the Assiomas as an UNO, and not a DUO?

It was recorded on a wahoo element, the graph that I attached is training peaks, I use a wahoo bolt with the same pedals, I don’t recall having to pick single sided on wahoo but I could be wrong.

What is the problem with the data?

If you are worried about the regular fluctuations in power and cadence, thats normal. In my experience, track data always looks like that because you are accelerating and decelerating as you go from straight to turn to straight again. On a track like Milton (250m, ~42 degree banking I think) it depends where you are riding (blue line or black line) and how fast you are going, but your speed will almost always be different in the straight and the turns at a “steady pace”.

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We aren’t “worried” about the data lol, my wife says that her cadence is steady and smooth around the whole track, the attached pic was her riding on the blue line, the one little spike was her passing someone. The cadence looks like a perfect sine wave pattern which seems odd compared to our road riding experience.

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The yellow line is cadence correct? My guess is your wife can reasonably tell that she’s not fluctuating between 80 and 90 rpms. If that’s the case, I’d guess the accelerometer in the pedal is having trouble measuring cadence in the corners. If the cadence measurement isn’t working correctly you would also see the fluctuations in power.

If you really wanted to check if the Favero is doing something weird, you could get a magnet based cadence sensor and compare its data to the Favero. The magnet wouldn’t be affect by the constantly shifting forces on the bike in the velodrome, like the accelerometer in the Faveros could potentially be.

I get the exact same thing with my faveros when on the indoor velodrome in Manchester.

You just don’t get constant pressure on the pedals when your riding a fixed gear bike in a pace line going up an down the ramps in the track. It’s also really difficult to not slow down or speed up slightly going up and down in the straights. With a fixed gear speed is going to be directly related to cadence obviously.

I’d say the data is accurate

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There’s your problem …

Lol, she is a much better cyclist than I am, she is a data junkie, I actually believe her. Looking at her road data with these pedals it’s nice and smooth.

If you were to strap a speed sensor to a wheel I bet it will show the speed changing at the same time as the cadence.

I can’t quite zoom in enough to confirm myself but I assume the power is higher as the cadence decreases? Showing that she is on an upward ramp. Likewise lower when the cadence is increasing?

She talked to her coach just now and it makes sense, I think you’re bang on, cadence slows in the turns on the banks and power increases, on the straights cadence increases and power decreases.

It’s the opposite, actually, i.e., cadence is highest and power is lowest in the turns. Data from even the most experienced trackie will almost always show this pattern.

Very interesting. We’ll have to test this out this weekend.

Not sure why you would need to test it, since the effect is so well-known?

I’m being pedantic but think I’m going to have to disagree with both of you

The bends are at the highest elevation but almost all of the elevation change is in the straights.

So highest power lowest cadence approaching a corner and lowest power highest cadence coming out of a corner.

This is assuming Olympic style indoor velodrome track.

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Riding round a velodrome at a constant pace actually requires power fluctuations. The effect of the banking means that the start of each bend is essentially like going slightly uphill, with coming out of the corner like a slight downhill, even when you really closely ride the line. The impact is only small, but really adds up - its one of the things that riders who have attempted the hour record often talk about as becoming a major barrier. Holding an even cadence will require you to push slightly harder into the start or each bend

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The inside circumference of a velodrome - blue band, black measurement line - is perfectly level.

The reason you speed up in the turns is because you lean over, not because your wheels are actually going downhill.

Again, it is the opposite: your COG goes “downhill” at the start of each turn and “uphill” at the start of each straight.

ETA: This is really secondary school level maths, but if you want a reference here is a decent one.