I’ve just bought a cadence meter which has made my intervals so much more precise.

for e.g. 4x8mins threshold – after the first set I find out what gear & cadence gets me into the correct zone (threshold)

then for the next set I simply drop the gears and get into the correct cadence – 90secs later I’m in the zone.

If I keep the cadence the same throughout the set – what extra benefit would a power meter be?

just wondering as this seems to take a lot of the guess work out or going too hard too early in the set to raise the Heart rate too quickly.

Dunno, but I too have fitted both a HRM and Cadence via an Edge 810 and the first 110ks ride out on Sat with it all linked up looked madly phsycotic on the chart when I’d downloaded the route.
I’m keen too to train efficiently but until I unlearn all the roadie riding I’ve done in the last 25years and sensations in my legs I get I think a power meter is a little too far over the “try too hard” threshold for me syndrome.
I’ve clearly got some reading up to do.

Best of luck though, not a fat lot of help my comments, sorry!

How do you know whether you’re in the zone; HR? HR is affected by factors other than power output (it can go up when you’re hot, for example), power is constant and unaffected by outside factors.

That said, HR is fine if you’re doing it for fitness, ‘pleasure’ and I’m sure, many people manage just fine with HR for competing too. Mind you, I’m in the fitness / pleasure category and a power meter is on my shopping list, but that’s cos I get off on the stats and I know that I have more focused and therefore beneficial sessions when I have a computer telling me that I’m slacking off 🙂

Power measurement is a lot more accurate in terms of exactly how much force you’re applying to the pedals. Power is a combination of force and speed, so just pedalling in a certain gear at a certain cadence works until the gradient of the road changes! Try doing 100rpm on a downhill in 53/12 and then the same on a 7% gradient. It won’t be the same power…

but for the training example I have given (on a turbo) would power aid or give me more accurate readings to work from?

I presume you’re on the turbo?

If so then there’s probably little difference. But I’ve got mine hooked upto trainerroad and it’s supprising how a little change in cadence (without changing geer) changes the power. If you want to get geeky with numbers without splashing too much cash, it’s the way to go.

If you’re on the turbo and have cadence/speed then use TrainerRoad to estimate your power.

As an actual power number its somewhat off, but as a training tool to force you to work at the right levels its excellent.

I use a power meter as I came to cycling from running and whilst I could run intervals at any given pace on the track and be spot on with my splits, I had no experience of perceived effort in cycling terms, so a power meter was a great help. Now I’ve had two seasons of using it, I can gauge my efforts better and use it less often in the summer months.

Have a look on the Sufferfest thread about Trainerroad, but be aware that different tyre pressures, different tyres and how tight the turbo is on your rear wheel will affect your virtual power differently.

no power in garage

You don’t really need cadence. On a turbo, speed alone should be a pretty good indicator of power – this is all trainnerroad does. A power meter would take out the other variables, such as tyre pressure, roller clamping force, temperature, but if you take a bit of effort to keep these the same, you can get some pretty consistent figures.

You don’t really need cadence. On a turbo, speed alone should be a pretty good indicator of power – this is all trainnerroad does. A power meter would take out the other variables, such as tyre pressure, roller clamping force, temperature, but if you take a bit of effort to keep these the same, you can get some pretty consistent figures.

This!

Training by cadence is a bit of a daft idea as you have you remember what gear you are in and how fast to pedal for every effort and every zone which is a really longwinded way to try and get the right speed (and in turn vitual power) the same for each interval which is what matters on the Turbo. Also, there would be no provision for mixing up the cadence which can be quite useful as you might not always be able to climb at 90-100rpm for example.

Much simpler to choose one resistance setting and use speed to hit your desired intensity (look in to 8 minute and 20 minute tests to predict your Threshold value). If you find your Threshold to be 16mph on a given resistance setting then you can now scale this based on the session. Let’s say you want to do some longer “Sweetpot” intervals at 90% FTP then you just need to ride at 0.9×16 = 14.4mph at any cadence you like. All you need is a speed sensor that fits to the rear wheel.

Note though that you need to check your turbo has a linear speed/power relationship for any of this to make sense.

Alternatively, just sign up to Trainerroad for next to nothing and have your riding revolutionised 😀

thanks guys,

so lets say the first set I find out that 16mph gets me into threshold.

would any gear as long as I’m reaching 16mph will get me into threshold?

no trainer road – no power or smartphone.

would any gear as long as I’m reaching 16mph will get me into threshold?

Yes.

Scaling from that based Threshold speed to work out other zones (use power zones top determine the % scaling) only works if you turbo has a linear speed/power relationship. The trainer website should give you that info.

Also, do an 8 minute or 20 minute test rather than try and guess stuff from HR or other intervals when setting your Threshold Speed. As other have said make sure absolutely everything is consistent day to day in your set up.

no trainer road – no power or smartphone

Take a laptop to the garage? Works for me. No need for power. Trainerroad is really far too awesome to be finding excuses not to 😀

Take a laptop to the garage? Works for me. No need for power. Trainerroad is really far too awesome to be finding excuses not to

+1, laptops best as you’ll need to plug the ANT+ dongle into it.

Speed = Power for your turbo. Just find the callibration for your favourite resistance setting.

Power = Force x Velocity and
Velocity = Crank length x Cadence (in appropriate units).

So Power = Force x Cadence, which means that there will be mulitple combinations of gear choice and cadence that give you the same power. I’m a spinner so run at 100-110 RPM. That’s because I have chicken legs 😉 . A masher will up the Force for lower cadence. But it is POWER that determines speed out on the road.

I’d just tape the speed vs. power conversion to the stem, or better, calibrate a rear sensing speedo to about 0.7x normal diameter and read off watts as XX.X mph

+1 for Trainerroad + Sufferfest!

+2 for Trainerroad and Sufferfest

(then get a power meter)

+2 for Trainerroad and Sufferfest

(then get a power meter)

Actually, thinking about it… the only reason to not start using Trainerroad is because you’ll soon realise how much simpler getting faster can be with power and start trying to justify the huge expense of a Power Meter 😀