Turbo with accurate power

gingerflash1975

I currently have a Tacx Vortex smart turbo trainer which I used with The Sufferfest. I have my winter bike on it in summer and my summer bike (with an old rear wheel) on it in winter. Whichever bike is not on the turbo has my Garmin Vector power meter pedals. I have used the Vortex with the Vectors occasionally, to check the accuracy of the power data. It is awful.

It seems to be a warming up issue, in that the resistance is too great for the first 15 minutes, then it's about right for a while, then starts to tail off. In the first period, the trainer produces figures about 15-20% lower than the pedals. So the trainer/app say I'm doing say 200W whereas the Vector says it's 230-240w . Later on, it's the reverse. Pedals are measuring 300w while the trainer/app say it's 350w. In short, warm-ups are too hard and the session gets easier as it goes on. I can kind of fix this if i stop the session and recalibrate, but this would need doing every 10-15 minutes or so, which isn't really practical.

I want a new trainer and am looking for one with a reliable power meter, that is accurate from start to finish.

I realise that if Sufferfest did powermatching, then i could stick with this turbo and get a second power meter, so the app would take power from the meter rather than from the trainer, but at present they don't offer it.

So, does anyone have a trainer, i assume a direct drive one, that has reliable power figures right from the off?

Thank you.

dannbodge

Tacx Neo
Shane Miller uses that for his power meter comparisons.

wongataa

A lot of the direct drive trainers have a stated max error in the region of ±2-2.5%. The more expensive ones such as the Neo have greater accuracy. You would probably be OK with any decent direct drive smart trainer in reality. Check out the DC Rainmaker & GPLama reviews. They will call out any accuracy issues.

gingerflash1975

2% I can live with! 300w would be 294 to 306. That's good enough.

Do the direct drive ones have no warm-up issues? I'm not sure if the warm-up factor is just tyre vs roller or whether it's elements with the resistance unit having to get to temperature as well.

mariamartinez

the first rule of turbotrainer club is don't talk about TTclub
the second rule of turbotrainer club is use the highest reading power you can find
the third rule of turbotrainer club is buy at least three power meters to triangulate
the fourth rule of turbotrainer club is don't talk about TTclub

StillGoing

As some one that made the mistake of going for a few low to mid range turbos before biting the bullet and buying a NEO, don't waste your money and just get a NEO. I've had a Bushido Smart that was utter garbage, an Elite Kura fluid that was not really smart and very hard to use and an Elite Direto that was prone to drop outs and very slow responding to resistance changes making short sprint intervals impossible to do correctly. The NEO has been a revelation. Accurate, quick response even for short sprint intervals and I can't hear it over the chain noise.

dannbodge

gingerflash1975 wrote:

2% I can live with! 300w would be 294 to 306. That's good enough.

Do the direct drive ones have no warm-up issues? I'm not sure if the warm-up factor is just tyre vs roller or whether it's elements with the resistance unit having to get to temperature as well.

Nope
You can't calibrate a Neo and it all works on magnets so has no moving parts inside to warm up.

Just jump on a ride.

Just remember to not compare your vectors to it, you'll find they don't match and be annoyed (hardly any powermeters ever match each other, alternatively you could calibrate/offset your vectors to match the Neo)

StillGoing

Dannbodge wrote:

gingerflash1975 wrote:

2% I can live with! 300w would be 294 to 306. That's good enough.

Do the direct drive ones have no warm-up issues? I'm not sure if the warm-up factor is just tyre vs roller or whether it's elements with the resistance unit having to get to temperature as well.

Nope
You can't calibrate a Neo and it all works on magnets so has no moving parts inside to warm up.

Just jump on a ride.

Just remember to not compare your vectors to it, you'll find they don't match and be annoyed (hardly any powermeters ever match each other, alternatively you could calibrate/offset your vectors to match the Neo)

The NEO doesn't require calibration to be more specific.

ric/rstsport

I have a Neo. It's accurate. It matched perfectly (within maybe a watt or two) of my Infocranks. And within 5 Watts of my SRM.

FatTed

Ric/RSTSport wrote:

I have a Neo. It's accurate. It matched perfectly (within maybe a watt or two) of my Infocranks. And within 5 Watts of my SRM.

And almost the same as my Quarq.

daniel_b

Dannbodge wrote:

you could calibrate/offset your vectors to match the Neo)

Intrigued, is this something you have done / know the mechanics of?

dannbodge

Daniel B wrote:

Dannbodge wrote:

you could calibrate/offset your vectors to match the Neo)

Intrigued, is this something you have done / know the mechanics of?

Nope.
Just something I've seen mentioned (Maybe Shane Miller on youtube/facebook groups could help)

StillGoing

FatTed wrote:

Ric/RSTSport wrote:

I have a Neo. It's accurate. It matched perfectly (within maybe a watt or two) of my Infocranks. And within 5 Watts of my SRM.

And almost the same as my Quarq.

And my P2M Type S.

gingerflash1975

Thanks for the replies.

I don't need/expect an exact match between the trainer and my Vectors, but i don't want it to be 10%+ out either. I just want TrainingPeaks to be able to make something useful of the data from my trainer sessions. At present, my best 5 min power on the trainer is way higher (like 40w higher) than anything I've ever done on the road.

I'd expect the trainer power do be a few watts lower as it's measuring at the other end of the drivetrain and there'll be some loss between the two.

CptKernow

The Elite Direto is supposed to be around 2.5% accuracy and has good reviews (incl DC Rainmaker).

I actually have a borrowed one in the garage at the moment. Only tried it once, didn't feel hugely better than my Tacx Bushido, but I'm assuming the accuracy (once calibrated) is way better. The Tacx was giving almost 20% difference to my PM at higher watts...

On my Bushido I actually tweak the turbo to match the PM at around threshold. It still reads over or under depending on the power, but it's the best solution without a new trainer.

Edit: Have just tried the Direto with Zwift on a workout and erg mode was pretty shocking. Had read there were some issues but you really don't want a trainer to not lower the resistance quickly after a sprint interval...

MiddleRinger

My Tacx NEO (first gen) reads within 1-2% of my Assioma pedals.

chris_bass

gingerflash1975 wrote:

2% I can live with! 300w would be 294 to 306. That's good enough.

That's assuming your vectors are 100% accurate which is incredibly unlikely!