More power on some turbo trainers compared to others?

neeb

Just wondering if other people have found that they can generate a little more power on some turbo trainers compared to others (with power measured using the same power meter, a Powertap hub in my case).

I've been using a Kinetic Road Machine recently which bobs and rocks around a little more than the tacx trainers I've used before and power at FTP seems a little down. Could this sort of thing, combined with the different pedal actions of different machines, account for slight differences in ability to generate power? I'm talking in the 5%-ish range.

Alex_Simmons/RST

I had a trainer once on which I could only manage to ride at nearly 2 power training levels below what I could sustain on another. They can be chalk and cheese, or have subtle differences.

Also, check how your torque zero behaves while fixed in the trainer's clamps.

neeb

That's interesting and reassuring. Pretty sure I'm not quite as unfit as my power figures on this trainer would imply..

I've always wondered whether to zero the meter before or after clamping the dropouts and/or pushing the roller against the wheel. Presumably in theory the "zero" state should be as the thing is setup with no force being applied to the pedals, i.e. with the wheel clamped? I have checked to see if there's a diference in the callibration number and in general there doesn't seem to be (there seems to be more of a difference just from turning the wheel).

Roberto di Velo

My feeling is that trainer power measures are a bit like bathroom scales, in that they all measure you a bit differently, but if you stick with one then it will give you an idea of whether you are improving or not.

For your reference, I went from using a magnetic TacX trainer to an Elite fluid one, and my estimated power went waaaaay down. What I hadn't realised is that using it in an unheated shed in winter (where it was cold) would have a significant effect on the fluid.

neeb

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19744449#p19744449]Roberto di Velo[/url] wrote:

My feeling is that trainer power measures are a bit like bathroom scales, in that they all measure you a bit differently, but if you stick with one then it will give you an idea of whether you are improving or not.

For your reference, I went from using a magnetic TacX trainer to an Elite fluid one, and my estimated power went waaaaay down. What I hadn't realised is that using it in an unheated shed in winter (where it was cold) would have a significant effect on the fluid.

In my case though I'm measuring power with the same separate powermeter (powertap), not the trainer. I genuinely seem to be generating less power (as measured at the hub at least) on average on one trainer as opposed to the other.

Not sure if it's energy being wasted due to the bouncier/wobblier turbo frame or if it's just that I can't apply as much power on average given the dymamics of the different pedalling actions.

The tacx was electronically controlled so on, say, a 20 min interval session the resistance was constant (even if my power and cadence might vary a little), whereas the elite is a fluid trainer that increases resistance with force applied. I wonder if that has something to do with it, or perhaps it's the resistance variation over the course of the pedal cycle.

AK_jnr

Yeah I wondered this at first as well with my powertap but it seems to of been consistent so far, and matches the outside world. Havent tried it with a different trainer though.