gbrown
Geoff on Bkool
- Location
- South Somerset
Short answer ... it depends (largely on your weight) but I would expect it to be harder in real life, much harder if you are a heavier rider!
Long answer (please excuse my tendency to waffle on) ...
Lots of different opinions on this, as it depends on so many factors, but in general you are unlikely to be able to exactly replicate your bkool performance in the real world. Some of this is down to inevitable inaccuracies in the simulation, and some down to the environmental differences between indoor and outdoor rides. It's harder to give your all in a real ride outdoors, as you must deal with road surface conditions, weather, traffic, balance the bike, save some energy to get home again, etc.. You can't just fall exhausted off the trainer onto the bedroom floor!
As for the accuracy of the trainer, that depends on so many factors. All trainers have a limit to the resistance they can apply, usually quoted in watts but as I understand it, in reality it is limited in torque, and therefore depends on speed (rpm). Hence high power figures are quoted but are only applicable at high rpm, when climbing rpm is much lower so max torque resistance is reached at a much lower power figure (power is torque multiplied by rpm). Gearing also complicates things. If you want to experience this, try pushing hard at the bottom of a hill, just as a climb starts, when speed is high and the resistance suddenly increases. You will see power figures shoot up towards 1,000 Watts before your speed falls away. Then try and hit 1,000 Watts, even briefly, when your speed is down to single figures, part way up a steep climb. I expect you will not get anywhere near.
Bkool quotes 1200W resistance for their Pro trainer, and claims UP TO 20%. In reality this would depend so much on your weight, as a heavy person would need much higher resistance to simulate a 20% gradient compared to a lighter person. If the Bkool Pro can simulate 20% for a 60Kg rider, it would be much nearer 10% for a 120Kg rider! If your trainer is one that quotes resistance up to a much lower figure, say 7%, it may be that their marketing people are more honest, but the trainer is likely to be able to apply a much lower level of resistance that the Bkool, and hence for any weight the simulation will break down at a lower gradient.
The Wahoo KICKR, and other expensive direct drive trainers, quote higher figures, e.g. the KICKR quotes 2000W. This means that it should be able to continue increasing resistance at gradients up to 2/3 higher than when the bkool pro max's out. So for a rider with moderate or low mass, it will be able to simulate quite steep gradients very accurately.
It is not only down to the resistance the trainer can apply, but also down to the calibration of the trainer, so it will vary from one trainer to another, even of the same make. The Bkool Pro only estimates resistance being applied and hence speed measured from the back wheel or calculated from estimated resistance/power will vary from one bkool pro to another, even without differences in weight. Expensive trainers with power meters will be more accurate, as they attempt to actually measure power being generated and so resistance is likely to be closer to what you would experience in the real world, but it will still max out, especially for heavy riders.
The simulation of the ride also presumes many factors that in reality would vary greatly in the real world, for example, drag and rolling resistance. Drag will depend on wind speed (including gusts), speed and aerodynamic efficiency. Different riders vary greatly in size and position, and using a single figure for drag will leads to a large range of variance between simulation and real world. Rolling resistance would be the same, with tyre make and condition, pressure and temperature and road conditions making huge differences. These would both be less of a factor on slow climbs, I guess, but would still make differences between the experiences of different riders.
Because of the numerous and large variances in factors, I would say that it is impossible to say if the simulation is accurate or not for any individual set of factors from theoretical analysis, so practical comparisons are needed. Many people here have compared simulated rides with real world ones, with a greater or lesser degree of thoroughness. Some feel that it is easier in "real life" but I think most would say that it is harder.
I would expect a very light rider to find the simulation much close to the real world than a very heavy rider.
Personally I have never been able to equal or beat my performances on bkool in the real world, although I have got close at times. I am pretty sure that even at my fittest I would find the likes of Mont Ventoux or Alpr d'Huez much more challenging in real life than I did here. However, after training on these climbs I did become confident I could actually complete them, even if it would likely have taken considerably longer to do so!
Apologies for any inevitable inaccuracies in my understanding of the above, feel free to prove me wrong ...
We did once moot a Cyclechat chaingang ride up Alpe d'Huez in reality, it would be very interesting to compare performances to the simulated rides here!
Geoff
Or at least not until I am at a more sensible weight.
only joking Randy, well deserved as I know you put the times into the goat sessions.
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