[ianrobo]

Not been on the trainer for a while and I am changing my training to do more on it.

so today went to do a 20 min FTP test and something was wrong.Basically doing 80RPM in a middle gear and with a vector PM was showing 220W and I was at 180HR. Something wrong there as 220 is just outside my endurance zone.

I then took the bike on the road for 5 mins on the flat and same gear, same rev gave me a power reading of 360W which is more like it.

Nothing changed with the Vector positioning at all, so can you think of any reason for this? I have a Kurt Kinetic Road machine and tried different pressures on the fly wheel and no difference.

Any thoughts on the massive difference ?

Topic

[ianrobo]

No chance of a power tap one
No chance of a power tap one at all. I have decided to split my training and use the virtual power readings for indoors and outside use the vector.

Would mean having two different FTP’s but no real issue there.

[KirinChris]

I do quite a few hours on the
I do quite a few hours on the trainer and this beats me. With the power being measured at the pedals it shouldn’t make any difference.

I wouldn’t take the HR as the benchmark but I’m sure you can feel the difference between 280 and 360 watts and if you couldn’t get over 280 on the trainer that is very odd.

The only thing I can think of is that there is some slippage or something going on in the trainer which just isn’t giving you enough resistance to reach your higher power levels. Although I would expect that you would feel that if it was causing such a huge problem.

I go inside and outside with big temperature differentials but still get pretty consistent figures from my Powertap wheels and also a Stages meter. The suggestion of trying a Powertap to see if there is any variation is a good one.

[Anonymous]

It may also be worth seeing
It may also be worth seeing if you can borrow a Powertap wheel, and do a comparison, as a PT is easy to just slot in and compare.

That way at least you know if it is an equipment based issue or not.

[Anonymous]

The power is measured at the
The power is measured at the pedal, so I can’t see a situation where the type of resistance at the wheel could affect the amount of power being put through the pedal.

As a note though, even if the trainer is outside, you need a big fan, as you are in still air as opposed to a 20 mph wind blowing you cool on an actual ride. Your ability to create power and also your perceived exertion will be quite well skewed by being too hot.

I know quite a few riders who just cannot reach their power figures they are used to on he road when on their trainers. I am one of the odd ones it seems, who generally do better on a trainer, but I am odd in that I can spend hours on a turbo without wanting to kill myself!

Sounds like you are best finding a good stretch of road for your FTP tests, long steady hills often seem the best option as it is easier to settle in to a good hard rhythm.

[ianrobo]

Thanks DaSy
I was actually
Thanks DaSy

I was actually outside doing this test and the strange thing I was going as hard as I could and registering just under 280W. The effort I was putting in was massive ….

the PM should have been registering at least double that

[Anonymous]

I often do my FTP tests on
I often do my FTP tests on rollers, and the gear I’m in is irrelevant. It certainly isn’t going to equate to outdoor riding with the added rolling resistance, wind resistance and gradient variation.

I generally end up near the end of the block, and the key is just go as hard as you can for the time. HR can be affected by heat, so if you are indoors with insufficient cooling this could account for the (presumably) higher HR for the same effort. I have a massive industrial type fan when on the rollers, and even at FTP I rarely have any visible sweat as this thing blows hard!

I have a resistance unit on my rollers, and if I get to the point where I cannot hit the power required without spinning out in my biggest gear, I just up the resistance by one notch and that sorts it out.

Don’t try to compare the indoor and outdoor efforts in particular gears, just ride as hard as you can in whatever gear gets you to exhaustion in 20 mins or an hour etc, but do pay attention to cooling when indoors.

[Author]

Replies