Well to be honest I never yet came across a gradient on bkool that it couldn't cope with. You have to push hard of course if its a 12% gradient. Anything over 12% doesn't seem to get any harder for some reason.
I was reading up and trying to understand the differences between the max resistance on the Bkool and the KICKR. On the Bkool, as you say, when it gets much above 12% it doesn't really get any harder, I found I could just push through and the resistance seemed to give a little, allowing me to make decent progress. On the KICKR this does not happen, and at 17% I almost ground to a halt, had no choice but to change down, slow down and push really hard, eventually having to stand up and grind it out.
I'll try Crowcombe at some point and see how it simulates 24%, or at least see if I can still keep moving the pedals.
I read up on the max wattage of the trainers, and the KICKR claims 2000W to Bkool's 1200W, but it sounds like 1200W should be more than enough, unless there is something I don't understand (very likely).
I suspect the rating should actually be for Torque (N m) rather than Power, and hence the gearing effects the torque you are putting into the trainer. Marketing will always overcome accuracy in these kind of things.
Purely speculation on my part, but high wattages are generally for sprinting, in which case you are in a very high gear and hence the torque applied to the trainer is lowered by the gearing. This may mean that 1200W in top gear is not equivalent to 1200W in bottom gear, not even close. In the lowest gear, the torque that can be applied at the rear wheel is much greater. When I calibrated the powertap, they suggested putting the bike in the lowest gear to ensure the highest torque reading at the rear wheel.
My best guess is therefore that the Marketing is all about the highest sprint power the trainers can cope with, and at the opposite end of the gearing, climbing steeply in a low gear, they are overcome by much lower power figures. After wall, the figure quoted is just a maximum wattage, not a minimum, which means it can cope with that wattage in an ideal situation, but perhaps only when the highest gear is used.
This would also suggest that by using a lower gear you can overcome the trainers resistance easier, so a 32 tooth sprocket is even more of a benefit than a 25 than just the higher cadence would suggest, as it would amplify the torque on the trainer and exceed the maximum resistance sooner. So everyone rush out and get a 32 tooth sprocket and get spinning up those mountains ...
So if 1200W is the max in the Bkool, to apply this to a gradient would require adjustment for weight, drag, resistance AND gearing, and seems to top out at around 12%. All else being equal, the 2000W KICKR should therefore be able to properly simulate around 20%.
Of course, this could all be rubbish, based on poorly remembered A level physics from 35 years ago ...
Geoff
