time trialing on a turbo

[ayceejay]

The very nature of time trialling is testing ones self to measure improvements (or otherwise) over a given distance against the clock. A turbo trainer will not measure distance in the same way and is a poor indicator as a measure against performance on the road but can offer information to compare with similar performance on the turbo.

 

[Joshua Plumtree]

Agree. Not having access to a power metre, I use a heart rate monitor to identify if I'm working at the correct intensity on the turbo. I then try to monitor any improvements in power output by using average speed readings over time. Not ideal, I know, but beggars etc etc.

 

[Rob3rt]

@Joshua Plumtree

Depending on your turbo trainer and your willingness to do stuff methodically (pump tyre to the same pressure, ensure same number of turns when engaging the resistance unit against the tyre etc), you can work off of turbo speed. Provided you have a turbo trainer that has a repeatable power profile and you do a bit of speed profiling, this is a better training intensity metric than heart rate IMO.

For a given power on my turbo (Cyclops Fluid2), I generally get the same speed (comparing average power and average speed over a set duration) within 0.1 mph. If I compare heart rate and power, the variance is far larger percentage wise, to the point I could be swinging 20+W either way of target power, if I ride to maintain a target heart rate value. The 0.1 mph speed variation is representative of a smaller power variance <10W. I would say, on average, based on speed I could peg my power output on my turbo trainer to within about 5-8W.

 

[Rob3rt]

To be very clear, in the above I am talking about seeing the same speed for the same power, on the same turbo trainer, between sessions or for intervals within a session, speed vs power is simple not comparable between road and turbo.

 

[Joshua Plumtree]

To be very clear, in the above I am talking about seeing the same speed for the same power, on the same turbo trainer, between sessions or for intervals within a session, speed vs power is simple not comparable between road and turbo.

Thanks for that Robert. I know that road and turbo are not comparable, it just seems a slightly better way to gauge any improvements I might be making rather than relying purely on guesswork or instinct.

 

[Rob3rt]

If you have a suitable turbo trainer, you can gauge improvements over various durations by simply doing a maximal effort over said duration and noting the average speed. For this you do not need anything other than a (suitable) turbo trainer and the same set up procedure each time. Provided the turbo is as I said, suitable i.e. it has a repeatable resistance curve (power vs speed) then an increase in average speed will indicate an increase in power. You won't know how many watts you have improved by, but you will know you have improved and be detecting fairly small, realistic gains.

If you don't have a suitable turbo trainer, you can't really do this, except to detect gross, unrealistic or long term (large) changes since any indication of improved fitness over any sort of short term (small changes in fitness) may well be hidden within the noise created by the unrepeatable resistance curve.

 

[Hip Priest]

That's what Graeme Obree suggests in his book. Set up your bike on a turbo, eliminate all variables (to an incredibly precise degree, in his case), and seek to improve your average speed.