Turbo training with constant power

RonB

Ok, I'm guessing it is constant - I am actually measuring speed tbh. I am using a Powertap Fluid Pro so there is a correlation between power and speed.

Anyway, for interval work I am trying to keep to a constant speed, with the anticipated HR drift, as highlighted vividly by some recent posts. A friend has suggested that I try to up my cadence from the current 80 to around 95 for a given speed and that as things get tough I can always change gear and reduce the cadence - whilst maintaining the speed (power) for the duration of the interval. I'm happy to give this a try but surely the actual effort isn't going to get any easier, and I don't really want it to anyway do I? Anyone else do this? Are there any benefits?

More generally, do folks ride at a higher cadence for indoor sessions or do you match what you get up to out on the road?

Comments welcome, Ron

GiantMike

There are a lot of difficulties in calibrating a turbo. For example, I'm not sure they maintain a constant resistance as they get hot and I doubt they are consistent from one session to the next. However, that doesn't mean you can't get something out of it.

If you use a rear wheel pick up on a cycle computer and try to minimise the changes between sessions then you MAY* be able to use speed as a substitute for power i.e. maintaining the same speed would equate to roughly the same power. It would be hard to say that half the speed was equivalent to half the power though.

To minimise variability I wouldn't touch the resistance on the turbo, just use the gears to make it harder/easier. And tyre pressure might affect it too, might not.

You'll need proper advice on the cadence though. I usually sit at around 80 on the turbo and 85 on the road (not consciously, just from my stats after the ride).

* pedants, please note the caveat in this advice. Cheers.

amaferanga

I think you can do something close to constant power, but no matter what you do it won't be exact. Not so long ago I thought my PowerTap was borked so I started looking back at some turbo sessions on my Cycleops Fluid2 turbo to compare speed/power with the intention of using speed as a proxy for power. I obviously had the advantage of being able to compare power with speed, but even then it was far from easy to relate speed to power. I did this Google spreadsheet of a number of sessions and tried to set a speed for a given session.

As you can probably see, speed varied quite a bit depending on the length of warm-up, the session that I did and the ambient temperature. I wasn't obsessive about tyre pressure, but it wasn't ever far from 100psi. The Fluid2 is probably comparable with the Jet Fluid Pro in terms of its stability and both are much better than most turbo trainers, but for a given speed there's probably still a good 20W variation in the power. More significantly, you can see that the speed actually drops off for a fixed Wattage so if you did try to hold a constant speed throughout your power would be increasing (on my turbo). That's probably better than having it fall as would be the case if you used HR.

So I guess you could do it, but you'll need to vary the speed a bit for each type of session and pay attention to the ambient temperature if it varies.

As for the cadence question - ride what feels right. As long as you can ride at varying cadence then there's nothing to worry about and you probably get a good range of cadence when you ride on the road anyway.

Alex_Simmons/RST

If you have a powertap, why are you concerned with wheel speed on the trainer?

As for cadence, as long as it's near enough to what you typically ride, that's fine. Some days you might mix it up for variety.

RonB

Alex, I should explain further, the Powertap is just the brand of my turbo, I don't have a powermeter. Apologies for any misunderstanding, thanks vmuch for all the replies.

amaferanga

RonB wrote:

Alex, I should explain further, the Powertap is just the brand of my turbo, I don't have a powermeter. Apologies for any misunderstanding, thanks vmuch for all the replies.

Its a Cycleops turbo then, not a PowerTap turbo. There is a Cycleops turbo that has an actual PowerTap within it (Powerbeam Pro), but I guess you don't have this. Is it the Jetfluid Pro you have?

Team4Luke

amaferanga wrote:

As you can probably see, speed varied quite a bit depending on the length of warm-up, the session that I did and the ambient temperature. I wasn't obsessive about tyre pressure, but it wasn't ever far from 100psi. The Fluid2 is probably comparable with the Jet Fluid Pro in terms of its stability and both are much better than most turbo trainers, but for a given speed there's probably still a good 20W variation in the power. More significantly, you can see that the speed actually drops off for a fixed Wattage so if you did try to hold a constant speed throughout your power would be increasing (on my turbo). That's probably better than having it fall as would be the case if you used HR.

does speed fluctuate up and down when holding a set power on the road, presume it does depending on the terrain/wind.

RonB

amaferanga wrote:

RonB wrote:

Alex, I should explain further, the Powertap is just the brand of my turbo, I don't have a powermeter. Apologies for any misunderstanding, thanks vmuch for all the replies.

Its a Cycleops turbo then, not a PowerTap turbo. There is a Cycleops turbo that has an actual PowerTap within it (Powerbeam Pro), but I guess you don't have this. Is it the Jetfluid Pro you have?

That's the one, I don't know what I was thinking before :roll: