Team BKool CycleChat
- Thread starter Peteaud
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adammada33
Active Member
I will have a go at Finestre on tuesday or wednesday evening - will do a screen dump of stats just incase. Over the weekend I've had 3 stages from Liga Multiplayer 2015 discounted because I changed my weight by 1kg during the league. You put so much effort in its quite a blow, even though I know I got the exercise and that was the point!
Rob H
Eat, Sleep, Climb, Repeat
ITs terrible really, what has strava and other data loggers done to us!!! but... that being said... im a little reluctant to have another crack and it not upload or crash
I think you should ride it one more time just to be sure Bill....
Stranger things have happened
(Mont Ventoux for example)
gbrown
Geoff on Bkool
- Location
- South Somerset
If you are still on 3.2 firmware, I think it was quite wayward with the power, and if you are using the bkool it for cadence 3.2 was rubbish. I think things really settled down with 3.3 and then 3.4 (they obviously had issues with 3.3 to withdraw it, but they have left a bunch of people using it!
I have to say, if you find it much easier to get a high average power on the steep climbs rather than the 2% FTP test, that speaks for itself.
I'm delaying doing the FTP test at the moment, as I know doing it on the KICKR will put me down several levels, even though I seem to have got stronger in the last few weeks and also lost a bit more weight. I did a fixed 2% climb this week, for 20 minutes, to see what average I would get and it was 247 Watts, compared to 269 Watts at the end of December on the Bkool.
Both were done on a steady 2% slope so the difference must be down to calibration of my Bkool.
This would put me down from Active 4 to Active 2, even though I am lighter and feel stronger. Back in December I suspect I would have dropped back into Amateur.
Geoff
gbrown
Geoff on Bkool
- Location
- South Somerset
Ok so in desperation to get on my KICKR last night I ordered another ANT+ stick from Snow & Rock via their click and collect service as it was showing as in stock. Having just rang them they are not in stock and need to be ordered in, I can collect it Monday, so Monday I will have 2 ANT+ sticks.
Any sign of either of the ANT+ sticks?
I've had a few issues with my KICKR and bkool as I get used to how to use them together. I guess it's only sense that the Bkool trainer is the simplest way to use the Bkool simulator.
I've found that it is not a good idea to have the Wahoo Fitness app running at the same time as the Bkool Simulator. Do a spindown calibration with the Wahoo app on a phone or tablet using Bluetooth, then make sure you close the app completely (swipe it out of the task list), before you start the Bkool simulator. When I ran both at the same time, the KICKR ended up in a fixed level (standard mode) resistance while the bkool thought it was in erg (power) mode and I could ride up any gradient at 28 mph! Might allow me to keep up with Bill, the Adam's, etc.
Sometime the bkool simulator doesn't pick up the KICKR properly and shows it as a power meter and therefore a virtual trainer. I found exiting and restarting the simulator fixed this.
Stopping pedalling to start a session is tricky as well, as it takes about 30 seconds to stop spinning, and then sometimes it shows the countdown for a split second before going straight back to telling you to stop pedalling. It seems to get a little bounce as it get to a stand still and it thinks to have started pedalling again. But it sits at zero asking you to stop pedalling, so you have to pedal again enough to get it to register, before trying the whole process of stopping again. This really is too difficult, and I'm going to email bkool with a screen image of it sitting at all zeros asking me to stop pedalling.
Hope you enjoy the KICKR, it really is a lovely bit of kit.
Geoff
gbrown
Geoff on Bkool
- Location
- South Somerset
It is possible that Bill is producing more force at the wheel than you (and me) and therefore overcomes the resistance at a lower gradient.
Differences between trainers and firmware and calibration will affect this. I think there is no doubt that the trainers can't simulate the very highest gradients, say over 20%, so the theory seems sound, it's probably just a matter of the force you are pushing through it and the individual trainer's tolerances.
Interestingly, even at 2% or 0% I was finding that at higher wattages my Bkool showed higher power figures than my powertap, and now the KICKR, so actual resistance must have been lower than that used in the Bkool calculations.
At lower wattages it actually showed lower figures, so that must just be a calibration issue, even though Bkool calibrated the trainer for me just a few weeks ago when they upgraded the firmware.
Bkool did say to me that they expect a variation up to around 10% between the trainer and any power meters, and that would be plus or minus 10% so a variation of 20% between trainers is within specification. They only showed concern when I got differences of up to 30%, and after calibration this dropped to 10%-15%, depending on power output.
Geoff
gbrown
Geoff on Bkool
- Location
- South Somerset
I couldn't resist reading up about magnetic Eddy Current Circular Braking (http://www.explainthatstuff.com/eddy-current-brakes.html) and gearing and torque ratios (http://en.wikipedia.org/wiki/Gear_ratio).
Please indulge me in thinking out loud again, it may all be wrong ...
It seems the electro-magnetic resistance units (like the KICKR and I believe Bkool) use fixed electro magnets floating a short distance from the surface of the conducting flywheel, which rotates within the magnetic field. When the electro magnets are on, the magnetic fields generate electric current in the conducting flywheel, which can't go anywhere so manifest as eddy currents, which align in order to create their own magnetic field to resist the electro magnetic (conservation of energy, etc.). This causes the resistive force, and the stronger the current to the electro magnets the stronger the resistive force.
The KICKR has the electro magnets fixed in place on a strain gauge, which measures the rotational force applied on the electro magnets by the flywheel trying to drag them around with it. Since forces are equal and opposite this equals the force you are applying to the flywheel by pedalling, i.e. the rotational force (torque) at the back wheel hub (KICKR) or tyre (bkool). (http://www.bikerumor.com/2012/11/08...-smartphone-powered-cycling-trainer-computer/)
The torque at the back wheel in a lower gear is higher than in a higher gear due to the mechanical advantage of the gearing, in ratio to the gear ratio, as torque ratio is equal to gear ratio (http://en.wikipedia.org/wiki/Gear_ratio).
This torque is converted to a power reading using the rpm of the flywheel, which is the same as the rpm of the rear hub/wheel, to get a wattage. Therefore the higher the speed the higher the wattage (Power = Rotational Force (Torque) times RPM). So for the same wattage, if the RPM is lower then the torque (rotational force) must be higher (as torque equals Power divided by RPM). This means that doing 300W in lower gear (with a lower wheel RPM) at say 7mph will produce twice the torque than doing 300W in a higher gear at 14mph would, and four times the torque that doing 300W at 28mph would. Since the resistance unit has to resist this torque (rotation force) it has to apply a force two or four times higher to be equal and opposite.
Hence, given the same power, it's maximum resistance will be exceeded at a lower speed when in low gear (high torque, low wheel rpm/speed) than when in a higher gear (low torque, high wheel rpm/speed). That is to say, a max resistance (torque) that equates to 500W at say 30 Kmph would only equate to 250W at 15 Kmph or 200W at 10 Kmph.
Individual trainers will have differences in the resistance generated by the same current due to the differences between the tolerances of the electro magnets, the structure of the flywheel, the gaps between them, the heat they generate and can dissipate and probably loads of other factors, but the maximum resistance of each unit will be equal to the rotational force they can generate between the flywheels rotation and the opposition of the magnetic forces due to the eddy currents resisting the opposite magnetic forces in the electro magnets.
To get this maximum resistive torque specified in watts they must assume an RPM or rotational speed of the flywheel and hence the rear wheel/hub.
To get this maximum resistive torque specified as a gradient they must assume a wheel/hub speed and the weight of the rider (along with possible factors for assume air drag, rolling resistance, etc. which would apply on a real cycle and gradient).
This would seem to be born out by the Elite web site for the Real Tour trainer, which quotes a maximum gradient, AND specifies a speed and a weight.
This states that it can resist an 85kg rider doing 30Km/h or 18.75 mph, so if the same 85 kg rider uses the gears to get a rear wheel speed of 15 km/h, while producing the same power, they also would reach the maximum torque resistance of the unit.
If the 85Kg rider can exceed 9.375 mph up a 6% gradient they will overcome the maximum resistance of the unit, so if the gradient goes up to 7%, 12% or indeed 24% there will be no more resistance from the trainer and they can continue pedalling at the same force to continue at 9.375 mph.
Since the Bkool simulator thinks they are doing this speed at 15% they will go up the steeper slope at the same speed they could a 6% slope, and therefore in the same time.
Again, this seems to be born out in practice as an Elite Real Tour rider could ride up the incline on Cothelstone at around 11 kmph, regardless of whether the gradient was 10% or 17%, while on the Wahoo KICKR it showed fluctuating speed, in line with the fluctuating gradient.
Elite RealTour (speed stays level on the two steeper sections)
Wahoo KICKR (speed dips on the two steeper sections)
Since the max gradient is a factor of the maximum resistive torque, the maximum power therefore depends on gearing and speed and the maximum gradient also depends on the simulated weight, drag, rolling resistance and wind, as well as speed and gearing, as well as the differences between the individual trainers, and possibly the firmware and calibration, it is impossible to say at what gradient any rider and trainer will be limited
However, we can estimate that quoted at 1200W it seems the bkool would be limited at around 2.4 times the RealTour's 6% (i.e. 14% to 15%) depending on gearing, speed, weight, etc.
the KICKR is quoted at 2000W so could go as high as 24%, again depending on gearing, speed, weight, etc.
And my wife says I over analyse everything ...
Geoff
Please indulge me in thinking out loud again, it may all be wrong ...
It seems the electro-magnetic resistance units (like the KICKR and I believe Bkool) use fixed electro magnets floating a short distance from the surface of the conducting flywheel, which rotates within the magnetic field. When the electro magnets are on, the magnetic fields generate electric current in the conducting flywheel, which can't go anywhere so manifest as eddy currents, which align in order to create their own magnetic field to resist the electro magnetic (conservation of energy, etc.). This causes the resistive force, and the stronger the current to the electro magnets the stronger the resistive force.
The KICKR has the electro magnets fixed in place on a strain gauge, which measures the rotational force applied on the electro magnets by the flywheel trying to drag them around with it. Since forces are equal and opposite this equals the force you are applying to the flywheel by pedalling, i.e. the rotational force (torque) at the back wheel hub (KICKR) or tyre (bkool). (http://www.bikerumor.com/2012/11/08...-smartphone-powered-cycling-trainer-computer/)
The torque at the back wheel in a lower gear is higher than in a higher gear due to the mechanical advantage of the gearing, in ratio to the gear ratio, as torque ratio is equal to gear ratio (http://en.wikipedia.org/wiki/Gear_ratio).
This torque is converted to a power reading using the rpm of the flywheel, which is the same as the rpm of the rear hub/wheel, to get a wattage. Therefore the higher the speed the higher the wattage (Power = Rotational Force (Torque) times RPM). So for the same wattage, if the RPM is lower then the torque (rotational force) must be higher (as torque equals Power divided by RPM). This means that doing 300W in lower gear (with a lower wheel RPM) at say 7mph will produce twice the torque than doing 300W in a higher gear at 14mph would, and four times the torque that doing 300W at 28mph would. Since the resistance unit has to resist this torque (rotation force) it has to apply a force two or four times higher to be equal and opposite.
Hence, given the same power, it's maximum resistance will be exceeded at a lower speed when in low gear (high torque, low wheel rpm/speed) than when in a higher gear (low torque, high wheel rpm/speed). That is to say, a max resistance (torque) that equates to 500W at say 30 Kmph would only equate to 250W at 15 Kmph or 200W at 10 Kmph.
Individual trainers will have differences in the resistance generated by the same current due to the differences between the tolerances of the electro magnets, the structure of the flywheel, the gaps between them, the heat they generate and can dissipate and probably loads of other factors, but the maximum resistance of each unit will be equal to the rotational force they can generate between the flywheels rotation and the opposition of the magnetic forces due to the eddy currents resisting the opposite magnetic forces in the electro magnets.
To get this maximum resistive torque specified in watts they must assume an RPM or rotational speed of the flywheel and hence the rear wheel/hub.
To get this maximum resistive torque specified as a gradient they must assume a wheel/hub speed and the weight of the rider (along with possible factors for assume air drag, rolling resistance, etc. which would apply on a real cycle and gradient).
This would seem to be born out by the Elite web site for the Real Tour trainer, which quotes a maximum gradient, AND specifies a speed and a weight.
Electronically managed resistance unit with maximum slope of 6% (500W at 30 Km/h)
The electronically managed resistance unit, one of the best performers on the market, develops up to 500 W (on an average 85Kg rider's weight and 30Km/h speed).
The electronically managed resistance unit, one of the best performers on the market, develops up to 500 W (on an average 85Kg rider's weight and 30Km/h speed).
This states that it can resist an 85kg rider doing 30Km/h or 18.75 mph, so if the same 85 kg rider uses the gears to get a rear wheel speed of 15 km/h, while producing the same power, they also would reach the maximum torque resistance of the unit.
If the 85Kg rider can exceed 9.375 mph up a 6% gradient they will overcome the maximum resistance of the unit, so if the gradient goes up to 7%, 12% or indeed 24% there will be no more resistance from the trainer and they can continue pedalling at the same force to continue at 9.375 mph.
Since the Bkool simulator thinks they are doing this speed at 15% they will go up the steeper slope at the same speed they could a 6% slope, and therefore in the same time.
Again, this seems to be born out in practice as an Elite Real Tour rider could ride up the incline on Cothelstone at around 11 kmph, regardless of whether the gradient was 10% or 17%, while on the Wahoo KICKR it showed fluctuating speed, in line with the fluctuating gradient.
Elite RealTour (speed stays level on the two steeper sections)
Wahoo KICKR (speed dips on the two steeper sections)
Since the max gradient is a factor of the maximum resistive torque, the maximum power therefore depends on gearing and speed and the maximum gradient also depends on the simulated weight, drag, rolling resistance and wind, as well as speed and gearing, as well as the differences between the individual trainers, and possibly the firmware and calibration, it is impossible to say at what gradient any rider and trainer will be limited
However, we can estimate that quoted at 1200W it seems the bkool would be limited at around 2.4 times the RealTour's 6% (i.e. 14% to 15%) depending on gearing, speed, weight, etc.
the KICKR is quoted at 2000W so could go as high as 24%, again depending on gearing, speed, weight, etc.
And my wife says I over analyse everything ...
Geoff
Last edited:
gbrown
Geoff on Bkool
- Location
- South Somerset
I just noticed the power figures for the RealTour are around half what they are for the KICKR, even though the speed and weight are much the same. It's as though the bkool simulator knows the gradient simulation is around half what it should be and has taken this into account when calculating the power, but not compensated by adjusting the speed to match the desired gradient.
I don't think I've seen this effect with the Bkool. Does the Elite RealTour transmit power to the Bkool simulator?
Geoff
Hi Geoff. I did read all that and I do very much appreciate your efforts but I do only have an HND when what I really need is a PHD. My brain is hurting trying to understand and I feel like I need to have a lie down. But thanks. What do you reckon about the file size being too large on the league rides not showing up? Cheers.
You doing Finestre tonight?
You doing Finestre tonight?
Rob H
Eat, Sleep, Climb, Repeat
You doing Finestre tonight?
Is that one that showed up from today or the 'missing one'
Runexeter
Senior Member
- Location
- Exeter, Devon, United Kingdom
I don't know if its the distance though Bill, Darryn does 48 mile rides and he don't seen to have a problem with them uploading.
