Without being overly supportive of the product I chose to buy and not mentioning price again you may be looking at this from the wrong direction but coming up with almost correct answers.
1. No one has ever won a bike race just by power alone, a bike race, in general, is won simply by having the highest average speed.
2. Power meters don't measure power rather they measure torque, or the result of application of toque, and they calculate power based on the torque force applied over time.
3. In order to 'calculate' what resistance to set on a Turbo trainer the best place to measure the torque force will be at the tyre.
4. Cycle torque meters in general either display the power produced at the point of measurement or adjust that to compensate for 'transmission power losses' (further calculation).
5. A direct drive turbo trainer with a power meter may also do this just like a wheel based torque meter.
6. Fit a cyclo cross tyre onto a road bike and expect to go slower for a given power at the pedals so of course tyres will make a difference and if they can make 50 watts difference on a BKool turbo it is as a result in changes of resistance at the tyre and so is effectively a good measure of how 'fast' you will go on the road and BKool only measures speed, everything else is calculated or a constant.
7. The power required to ride at a given speed is directly proportional to all of the resistant forces work against you which have often been referred to as 'the conditions'. Rider Weight, Bike Weight, road surface, tyre compound, wind, profile drag (how aero are you), skin friction (drag created on the surface of you and your machine, air density, slope, transmission losses and I'm sure I have missed a couple.
8. Quite a few of the above are 'baselined' in Turbo Trainer SW like the bike weight, wind, aero factors, skin friction, road surface i.e. they are the same for everyone all be it I do believe spending many points on a flashy kit in BKool once was supposed to reduce skin friction and aero drag.
9. Turbo Trainer SW therefore concentrates on Rider Weight, Slope and 'Drag relative to speed' as the variable conditions.
10. There is a relatively simple calculation that will tell you the power required at the wheel, and therefore torque for the accumulation of the of the above variables.
http://bikecalculator.com/ is a good example of this
11. It would be a relatively simple exercise to create a BKool 'Brake Magnet' positional map for each individual BKool trainer by using a calibrated driving motor a bit like 're-mapping' a car engine control unit.
12. In reality there is probably a common map and the trainer is calibrated by some simple adjustments to move the map into the most realistic position but this should be accurate to an acceptable degree for the purpose intended (and the price paid, oops I mentioned it).
13. However this is where the fun starts as we didn't like it when our BKool suddenly changed resistance when the slope changed because their SW did not take into account what you were doing when the slope changed i.e. what you had stored as inertia or lack of, and as a result it was not realistic. Likewise is also accelerated you you to you max descending speed immediately as the slope went down the way.
14. My view is, as said before, that this is where it all went wrong as rather than re-writing the SW they bolted on a fix which caused a problem (pro-slinging) which they then fixed with another bolt on which caused another problem (dead stopping).
15. The initial fix is still in there which is why we can skim over shorter climbs but likewise you don't immediately gain a benefit when the slope reduces (most frustrating when your on the rivet).
16. What I don't know where this SW error lies but I would not be surprised if it is part in BSim and part in the Pro FW.
17. So what is the advantage of having and on-board power measuring device?
As I don't know what the ANT FEC+ handshakes are between PC SW and Trainer FW I can't really comment but if the Trainer FW is transmitting the calculated power (and don't forget they all calculate power) to the PC then your displayed power should very close to actual at all times rather than something that is taking into the bolt FW on fixes in the trainer.
Also the SW/FW could use the Power Meter reading to tell the 'game' when the turbo resistance equals the the theoretical power required based on the conditions and thus stop it at the right setting.
18. Looking at the recent climbing stage in the WC (was it stage 8 or 9 that we did on that one same day) the stats for most riders, and I assume they are the ones using Pros with the latest FW, look pretty much OK baring the dead stop or two and the crazy power starts we still get.
The reason for this is that once the climb started there were not too may drastic changes.
I must add a this stage that you should note the speed spikes on Pep's stats as these don't shown in anyone else's ride suggesting that he is either using different FW/SW or he has learned something about dead stops that we have not or he has a fault on his turbo set up, the later we have long suspected and also assume the former.
19. Zwift has tailored its course profiles to suite Trainer SW/FW, BKool has not and last night's CG ride was a good example of a bad Trainer course as it was very saw toothed in profile.
20. So in summary:
If folk are having better experiences in Zwift with BKool Turbos then perhaps this is as a result of the better tailored courses and their PC SW algorithms are more pure i.e. have less silly bolt on's.
If your tyre makes a difference in BKooll then it should in Zwift as well.
But it may not have been the tyre that made all the difference in BKool (e.g. it was a coincidence with another change).
I still think that on a decent profile in BKool the resistance feedback is still good accepting the onset delay introduced by oversimple bolt ons.
Enough said
If you got this far, thanks for showing interest.
