Just saw this - 2 for Howdens
Team BKool CycleChat
- Thread starter Peteaud
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berty bassett
Legendary Member
- Location
- I'boro
was going to do it myself as in building and theres a lot of knocking about to do - got a tame plumber and sparks lined up but 6k supply only is too steep
looked in howdens but thought it was a bit of a faff opening another account - the quote was from buildbase
went to b&q and the bloke said top of range all fitted tiled plumbed and lectrified would be about same price and the units are the same carcass !
its no good i still feel queazy
We thankfully had a mild weekend - didnt get out the previous one. Getting into a routine of heading out with a couple of club members Saturday morning where possible and then the main group ride of Sundays for 60 odd miles.
On a different note, I've got myself banned from the Facebook Bkool-English page for suggesting to others that the Bkool Pro only creates resistance of 11-12% for most people.
They were adamant that it can do 20%. Looks like they dont like me now since I cancelled my subscription. 
Bob had mentioned his now will give up to 15% but there's no change with mine. Anyone notice more resistance at high levels these days??
They actually banned you????!!
We thankfully had a mild weekend - didnt get out the previous one. Getting into a routine of heading out with a couple of club members Saturday morning where possible and then the main group ride of Sundays for 60 odd miles.
On a different note, I've got myself banned from the Facebook Bkool-English page for suggesting to others that the Bkool Pro only creates resistance of 11-12% for most people.
Bob had mentioned his now will give up to 15% but there's no change with mine. Anyone notice more resistance at high levels these days??
I had to look up that discussion - I like this comment from Bkool:
"BKOOL - English Richard, that is not true. The Bkool Pro WILL reach a maximum of 20% (no matter your weight). The Bkool Go WILL reach 8%, no matter what weight settings you put into the simulator."
Now I'm no engineer, but "no matter your weight"?! This comment alone kind of says everything about Bkool's understanding of their own product
How can it be more resistance. It is physically limited by magnets and size of flywheel. It is purely psychological as the gradient increases and speed reduces, you try harder to maintain speed. If you ignore screen and keep an even cadence it doesn't matter whether it's 9% or 15% It feels the same.
Daddy Pig
Veteran
Sounds like a load of rubbish to me. I'm 102kg and mine goes blue at 9% and the resistance stops increasing at this point. I think they need to understand what they are selling by actually using it themselves...
Spot on - every interaction with them about things like this proves they don't really use their own product. Or in this case, understand basic physics!
Just think about it for a minute, if the trainer that's limited to 8% can do that irrelevant of rider weight, then surely it would have to be capable of also replicating 20% (and more!) for lighter riders, so why would you only claim a maximum of 8%.....etc etc
Just think about it for a minute, if the trainer that's limited to 8% can do that irrelevant of rider weight, then surely it would have to be capable of also replicating 20% (and more!) for lighter riders, so why would you only claim a maximum of 8%.....etc etc
gbrown
Geoff on Bkool
- Location
- South Somerset
It also depends on the power you can produce!
As you know if you put it in ERG mode and set a power level, it is impossible to go much beyond this as the resistance is reduced as you pedal faster. The ability to produce power depends on the resistance against that power. This is Newton's third law (whenever an object pushes another object it gets pushed back in the opposite direction equally hard); if the trainer can't produce the resistance (push back) then you can't produce the power, so a powerful rider will overcome the resistance when a less powerful one could not.
The gradient it can simulate depends on the maximum resistance the magnetic brake can produce, which is limited by more laws of physics we have discussed previously. The resistance needed depends on the riders weight AND the power they are producing (and gravity which is pretty much fixed at sea level on earth).
Hence the weasel words UP TO...
This is marketing, and marketing people tend not to understand the technologies they are dealing with*, but know that they must not make it too clear that a heavy, powerful rider will see nowhere near the maximum! Common sense be damned!
* a lifetime of designing and helping market and sell high technology systems software has show this time and time again
As you know if you put it in ERG mode and set a power level, it is impossible to go much beyond this as the resistance is reduced as you pedal faster. The ability to produce power depends on the resistance against that power. This is Newton's third law (whenever an object pushes another object it gets pushed back in the opposite direction equally hard); if the trainer can't produce the resistance (push back) then you can't produce the power, so a powerful rider will overcome the resistance when a less powerful one could not.
The gradient it can simulate depends on the maximum resistance the magnetic brake can produce, which is limited by more laws of physics we have discussed previously. The resistance needed depends on the riders weight AND the power they are producing (and gravity which is pretty much fixed at sea level on earth).
Hence the weasel words UP TO...
This is marketing, and marketing people tend not to understand the technologies they are dealing with*, but know that they must not make it too clear that a heavy, powerful rider will see nowhere near the maximum! Common sense be damned!
* a lifetime of designing and helping market and sell high technology systems software has show this time and time again
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So when turbo trainer manufacturers claim their trainer replicates a slope of 20% for example, does anyone know what maximum rider weight/power they are basing this on? I'd love to find this in the smallprint of some Bkool (or other trainer manufacturer) disclaimer....
gbrown
Geoff on Bkool
- Location
- South Somerset
Since it's UP TO I would guess a pretty light and low power rider (Marketing imperative), a bit like broadband speeds based on being a foot from the cabinet/exchange that no-one acheives! If one company claims it then all the rest must do so to compete and stay in business.
Actually, since most people buying the trainer will be unfit (and wanting to get fit) low'ish power is likely, at least at first, but light weight is extremely unlikely!
It might be interesting to try and correlate maximum perceived gradient with peoples weight and FTP?
gbrown
Geoff on Bkool
- Location
- South Somerset
DC Rainmaker said this, about the Wahoo KICKR
"Power Resistance:
The unit has a maximum advertised resistance of 2,000 watts. The unit was engineered such that a 175 pound rider (at max resistance) would feel as though they were riding up a 15% grade. Due to the flywheel aspect, the unit really does feel like you’re riding on a road – very similar to how the LeMond Revolution feels like you’re actually ‘coasting’ when you stop pedaling.
Now technically they note that there’s no real limitation on resistance levels or measurement. Rather, it’s a function of speed. For example, if you’re going a pedestrian 4MPH the limitation if 600w, but at 8MPH the limitation is 1,200 watts, and at 16MPH, the limitation of 2,400 watts, and so on. Of course, if you can output that much power. The curve is linear."
This shows that the magnetic braking will increase the faster you go, thereby generating more resistance for the more powerful, faster riders. We know this from the way that eddy current braking works. This may cast doubt on my second assertion that power is a big factor, but there has to be a limit to this, as heat generation will start to affect the physics eventually.
But this also shows that the slower you go, the less resistance the unit can develop as the disc spins slower, so 2,000 Watts will only be seen in a sprint, and at typical climbing speeds the resistance will be much, much lower! If you sprint at 60 kph but climb at 10 kph the limit would be more like 333 Watts, if these things were linear.
The KICKR claims 2,000 Watts and the Bkool 1,200 Watts (60%) so implies that on Bkool Pro a 175 pound rider (c. 80 Kg) at maximum resistance would feel like they were riding up a 9% grade. This pretty much agrees with what most of us perceive in use, and when I (at 74Kg) switched from the Bkool Pro to the KICKR my maximum perceived gradient did seem to shift from just over 10% to approaching 20%, as the figures would imply.
We used to race up the Salcombe Road Hill (from Sidmouth), which maintains 18%-20% at the top and on the bkool pro I could almost keep up with Bill, but on the KICKR he destroyed me, and I could barely turn the pedals over. As I got stronger, I had a go at the Crowcombe climb (25% in places) and found that on the KICKR I could not really differentiate between the 20% and the 25% bits.
Geoff
"Power Resistance:
The unit has a maximum advertised resistance of 2,000 watts. The unit was engineered such that a 175 pound rider (at max resistance) would feel as though they were riding up a 15% grade. Due to the flywheel aspect, the unit really does feel like you’re riding on a road – very similar to how the LeMond Revolution feels like you’re actually ‘coasting’ when you stop pedaling.
Now technically they note that there’s no real limitation on resistance levels or measurement. Rather, it’s a function of speed. For example, if you’re going a pedestrian 4MPH the limitation if 600w, but at 8MPH the limitation is 1,200 watts, and at 16MPH, the limitation of 2,400 watts, and so on. Of course, if you can output that much power. The curve is linear."
This shows that the magnetic braking will increase the faster you go, thereby generating more resistance for the more powerful, faster riders. We know this from the way that eddy current braking works. This may cast doubt on my second assertion that power is a big factor, but there has to be a limit to this, as heat generation will start to affect the physics eventually.
But this also shows that the slower you go, the less resistance the unit can develop as the disc spins slower, so 2,000 Watts will only be seen in a sprint, and at typical climbing speeds the resistance will be much, much lower! If you sprint at 60 kph but climb at 10 kph the limit would be more like 333 Watts, if these things were linear.
The KICKR claims 2,000 Watts and the Bkool 1,200 Watts (60%) so implies that on Bkool Pro a 175 pound rider (c. 80 Kg) at maximum resistance would feel like they were riding up a 9% grade. This pretty much agrees with what most of us perceive in use, and when I (at 74Kg) switched from the Bkool Pro to the KICKR my maximum perceived gradient did seem to shift from just over 10% to approaching 20%, as the figures would imply.
We used to race up the Salcombe Road Hill (from Sidmouth), which maintains 18%-20% at the top and on the bkool pro I could almost keep up with Bill, but on the KICKR he destroyed me, and I could barely turn the pedals over. As I got stronger, I had a go at the Crowcombe climb (25% in places) and found that on the KICKR I could not really differentiate between the 20% and the 25% bits.
Geoff
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gbrown
Geoff on Bkool
- Location
- South Somerset
9% at 102 Kg is pretty impressive, you must be maintaining a pretty good speed!
The blue figures when climbing are a bit of a smoking gun, if they go blue isn't the Bkool simulator showing that you are not going at the speed you would in real life, and therefore implying that you are not getting the resistance you would in real life, from 9% in your case?
Thanks Geoff. I found a couple of other bits of info from Wahoo and Tacx on their trainers and the max incline related to rider weight. The first image is a graph showing the Vortex can only replicate its claimed 7% slope for a total of 75kg for rider plus bike. Unfortunately I can't find a link to the actual calculator itself any more. I also can't find any info like this for the Bkool trainers which apparently aren't constrained by rider weight at all...
