This may help . A buddy of mine has the Halfords bike hut turbo trainer and used it for a while on Zwift with Wahoo speed sensor and a Wahoo cadence sensor. It was obvious to me that his power figures on Zwift were way optimistic.
This weekend I borrowed his wheel and trainer and calibrated using my TT bike which had a Quarq D Zero crank based power meter.
I found resistance level 3 gave way over optimistic power numbers whilst resistance level 4 was a bit pessimistic. The solution was to fine tune it using the barrel adjuster at the trainer end of the control cable. With about 5mm of the knurled bit protruding and resistance at level 4 it is now in agreement with my power meter. I recorded a 10km run and compared the Zwift power curve with the power meter curve using the analysis tool in Zwiftpower. Accuracy was spot on. Not all trainers will be exactly the same but use the same adjustments and you may not be far off. Incidentally I inflated the tyre to 100 psi and warmed it up by riding for 15 minutes before recording anything. A cold tyre gave higher power numbers until it warmed up.
This is an amazing bit of work thank you Outlaw! You need more recognition.
I’m sure there’s a lot of people out there using this exact same turbo trainer (guessing there’s a factory somewhere rebranding the same trainer for countless different places)
I saw your post on a different thread where you said to select a certain trainer, which one was this?
currently using the “not on the list” option, on setting 4, got 300 watts on the ramp test…i’m a competent enough cyclist but nowhere near in that realm! Realistically I’d say 230-240 could even be an overestimate for my FTP.
Thanks again for your hard work! hopefully Zwift can add this to their recognised trainer list.
You are too kind Adam. I can’t link to the other post but if you search for ‘bike hut’ it comes up under the feature request category.
In the pairing screen I selected the option for ‘Lifeline TT01’ mag trainer because it, at least visually, closely resembles the Halfords trainer.
TBH I don’t think Zwift will add the Halfords trainer to the options list without carrying out their own calibration test.
The thing with some of these trainers is you can “calibrate” one but then the next one is different. that is why they differ in cost, it comes down to manufacturing tolerance and QA.
But if you have access to a power meter you can “calibrate” your own trainer. I have done it for a few friends.
Just a note to say after changing to Lifeline TT01 my FTP has dropped to about 200, went from CAT B to being dropped by CAT C… and successfully destroyed my ego 
But in all seriousness it’s nice to be getting more real world results.
Oh dear. I know how it feels.
Originally I had a Tacx vortex and if I calibrated it with the Zwift facility my FTP was 220.
If I calibrated it with the Tacx app (recommended) it was 210.
Then I upgraded to the accurate Taxc Neo and discovered my FTP was really only 209.
To make things worse I had a bout of illness recently and my FTP dropped to 188! Recovered now and it is picking up a bit.
You can get a pretty good idea of your real FTP by doing a max effort over your local 10 mile TT course and recording it on Strava. I find Strava’s estimated power is pretty close to or the same as my power meter.
There’s no easy way to boost your FTP - just have to a training plan on Zwift or at least keep doing an over and under session. My mate gets good results just repeating ‘Emily’s Short Mix’ - seems to have worked for him as he’s closer to and sometimes beating me in races now.
Outlaw, Thankyou for your efforts with this, its much appreciated!! 
I recently bought the Halfords turbo, with speed/cadence sensor. I run very basic figures on cadence/speed same gear ratio, low wind, flat road etc. I found resistance 4 to be as close as I could get. Now a few months on Resistance 4 I’m completing a lap of Watopia with avg 295watts. That seems high to me, iv switched to resistance 5 now and I’m avg 235. After getting annoyed maxing out 400watts sprints with unlisted trainer, iv changed to TT-01 trainer still on resistance 5 and I’m avg 250watts.
What I’m after establishing is, am I way over with my FTP still? The reason I suspect this may be the case is my Strava Avg ride is usually between 150-170watts, where my HR is usually higher. (I know not the most accurate comparison to have!). Just after some pointers to get as close as possible so I can start to enter races without smoking people who are probably miles fitter than I am, thus annoying the zwift community 
If you search Zwiftinsider for 'FTP without a powermeter you should find his article with this useful table in it:
(sorry link posting not allowed)
Here are rough estimates of the power needed for a solo road cyclist to hold various speeds:
- 25kph (15 mph) – 92 watts
- 30kph (18-19 mph) – 143 watts
- 35kph (21-22 mph) – 212 watts
- 37.5kph (23-24 mph) – 254 watts
- 40kph (24-25 mph) – 301 watts
- 45kph (28 mph) – 415 watts
So if you’re unsure if your power numbers are accurate in Zwift, just find the speed above that you can hold outdoors on a flat ride going all-out for 20+ minutes. Then see if that wattage matches what you see in Zwift when you’re giving it everything you’ve got for that same amount of time.
This is the only way I would recommend without access to a powermeter.
@Outlaw_Hobbs why have I never seen this before!!, its really helpful. Again thankyou for your help, I will have a search and find the article 