Tacx Flow and First MAP - FAILED!

tuney

Hi Guys

After 2 months of just riding to get fit to train I've finally decided to sort my training program and do a MAP test and the like.


I set up an Imagic Route which used increments in power from 100watts and increases every 30 second by 10 watts. This was the minimum granularity I could get from the IMagic Editor.

Q1: Should I be using the Power session type? or should I use a constant grade and simply ride faster myself.


Anyway, I got on the bike and did a quick warm up... I just wanted to check that things would work ok before doing the MAP in a couple of days so did a quick test map.


I started the test MAP.

When I hit 360 watts the power leveled off, even though the Imagic was saying it was upping the power... this went on for about a minute/minute and a half... and 360watts aint easy ... so I decided not to stick around to see what happend next... and cooled down.

The imagic should have gone up ~30 watts but i had no increase.

Im sure my back wheel wasnt slipping... its as if the imagic wasnt compensating enough.

A bit of a bugger really, Im wondering if anyone has any experience with this, or how I could get around it.


Thanks in advance
Chris

Ive attached a pic of the PT file.

tuney

PT File

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tuney

As you can see... goes a bit un-linear

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Markster

Were you reaching the resistance limits of the unit? If you were using a low gear then the unit may not be capable of generating enough resistance at a low wheel speed. Changing into higher gears as the test continues will increase the wheel speed and make it easier for the unit to generate the necessary resistance.

m.

tuney

Hi Markster

I had the resistance about half way... so probably slop 0/1/2 nothing which should have effected anything....

I was also cracking on at about 25mph at 95rpm or so.
Ive attached the Analyser Display as a comparison.

I think it may be that the Tacx just is not linear at High power values...

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ric_stern/RST

i often see this type of problem with some trainers -- one's that don't increase resistance automatically, with increasing power/speed.

thus, if i was testing someone on something like a Tacx, i'd do a little trial prior to the test at the power i might expect them to finish and make sure the resistance at the tyre/roller interface is high enough -- from memory i've had to use something like 5% on a tacx for most.

ric

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tuney

Thanks Ric, So you think it could be a Tyre/Roller friction Issue?

Ill do some testing tonight and try making the roller push a bit more on teh tyre.

Markster

Yeah, sounds like your wheel speed was high enough (I should have looked more closely at your attachments!).

If you can't get this problem sorted, and you decide to control the power using your gears and cadence, I strongly recommend you get someone to help you out. I did an MAP test by myself a short while ago, and while it was okay keeping to the wattage/time schedule at lower powers, as I neared the end of the test it was just too much to think about. Trying to balance gearing and cadence while watching the power, time, and reading the schedule I'd stuck to my stem was way too much at higher intensities - I hadn't got enough mental capacity left to really dig in at the end. Next time I'll get my girlfriend with a stopwatch to shout powers at me, so all I have to focus on is holding that power. Someone there to pick me up off the floor too!

m.