Team BKool CycleChat

[gbrown]

Geoff, my assumption is that the resistance regarding the power read out would be the limitation and I believe the Classic is limited to 1200 watts.
This is because it is effectively a magnetic brake and therefore the max braking effect is when the magnets are 100% exposed to the flywheel at the circumferance of the flywheel, any futher in and the breaking effect will be reduce unless the magnets move closer to the flywheel as they move toward the centre.
An alogorithimn is used to position the magnets and create the required resitance for your forward speed and vertical speed.
Forgetting descending, which BKools don't do well because they have no motor.
Forward speed resistance is nearly all as a result of the calculated drag and weight has very little impact.
Your vertical speed is litteraly all to do with weight.
Calculating both as vectors will give you the total restance required to overcome your forward and vertical speed and is displayed in Watts. Unless the algorithmn limits are inside of the power required to go uphill toward the vertical and the foward limits are inside of say 70mph then I see no reason why any trainer cannot set resistance for any slope and speed up to the maximum watts (i.e. resistance) that can be generated and therefore the limitation on the Vortex is perhaps not 7% but would equate too a average weight rider riding at and average sustained power which ends up equating to 7% ish.
Saying that I don't know how the vortex generates drag as may trainers have a fan that assists in creating the V squared drag (i.e.) forward speed and then a second resistance creator like the magnets on the BKool.

I believe that the resistance should be quoted as torque rather than power, and the maximum 1200 Watt figure is another "optimised" Marketing claim, calculated using the maximum possible rpm and therefore only applicable at very high speeds. On steep climbs, the speed and therefore roller rpm will be much lower and therefore the maximum torque will be reached at a much lower power figure, more like 250-300 Watts (if speed is around a quarter of max or less).

The Bkool Pro uses magnetic Eddy Current Circular Braking, hence my understanding that resistance should be specified as torque. I did speculate more about this back last February, although my expertise is software engineering rather than physics, so I expect I was somewhat out of my depth and winging it slightly ...

Team BKool CycleChat

Given the complexity of the simulation, the range of trainers and weights and abilities of the riders and the variation of terrain over which the rides take place, it is hard to see how any unifying formula could be calculated. On a relentless steep climb I guess you could get close, but on anything with any decent descent the bkool pro has such a massive advantage no one else can get close.

I still can't believe that Bkool have not addressed the coasting issue in over a year ...

I presume that the software measures the wheel speed and also calculates a speed due to weight and gravity and when the latter exceeds the former it just uses the latter (and seems to colour the speed blue). Unless and until you can spin the wheel faster than the gravity calculation you may as well coast.

I can see no reason why this calculation could not be done for any type of trainer, they either don't see it as a problem, actually prefer to advantage the bkool trainers or just are too busy ...

We have asked repeatedly for this to be fixed or for some explanation of why it cannot be, but nothing is forthcoming.

Geoff

 

[A.Loki]

Hi I have requested to join the mountain goat and top 100 climbs.
Username: Loki

Thanks!

 

[BILL S]

Sorry to insist, but as an ultralight rider with a vortex my main issue is lack of downhill speed boost and ability to coast. You see, with the vortex the speed is the actual wheel speed reported by the trainer, whereas with the bkool this speed is multiplied by a factor depending on the rider weight and down slope. The result is that even if vortex riders had a slight advantage due to lack of resistance simulating >7% uphill (which I doubt), the disadvantage on the downs overcompensates. Bkool virtual speed on a descent is >60-70 kmh whereas on a vortex it is the same that you can make on the flats, in my case about 40kmh pedalling hard and not resting. A vortex rider easily gives 1 min per min, all-out, to any bkool rider coasting. I doubt that I can get to my favor a few seconds per minute on the steepest climbs against a bkool rider of similar weight and condition.

So,.... if you manage to find the formula to slow us on the climbs, don't forget to speed us up on the downs!

Hi Baldo. I totally understand your and others frustration about the lack of freewheel ability and slowness on the descents if you have anything other than a bkool unit. Classics and Pros are both fast downhill compared to anything else although bkool seem to have slowed them somewhat in the most recent updates. It seems less worthwhile pedalling downhill now and might as well just coast.
I also agree that there may be some league stages in the chain gang where an adjustment in favour of the vortex rider may be appropriate if we could find an approximate and appropriate adjustment based on the average gradient of the ride. I think I suggested a factor that could be both less than, equal to, or more than (gradient dependant) when I suggested this in one of my previous posts.
The main problem is that (weight and power dependant) the vortex can allow you to climb a mountain with unrealistic speed due to the lower resistance so again (weight and power dependant) it can cause a problem with the mountain goat league. There are generally no downhill or flat parts to these stages and therefore there is no advantage to be had with the bkool over the vortex. I am still watching the performances with curiosity and would rather see a sample of different stages before looking to try and work out a factor that could even things out.

 

[BILL S]

@BILL S - Do you have a link to Ryan's effort? Maybe we can analyse that data to see if a specific part of the climb I was a lot quicker.

I assume you are referring to Alpe d'Huez so here is Ryans effort from the mountain goat league a few months back:
http://www.bkool.com/bkoolSessionHistory/showSessionSummary?sessionSummaryId=1426465
http://www.bkool.com/classification/showIndividualStageClassification/3936

I'm guessing you were quicker everywhere because of the steepness.

Sorry Ryan, hope you don't mind us comparing your ride to Robs to see if we can come up with a solution for the Vortex's in the mountain goat league.

 

[Goldwolfie]

It's the slowest rider's time plus 5% that you're given if you miss a stage according to Bkool - http://www.bkool.com/help/leagues

Which would normally equate to my time plus 5% as I'm usually the 'tail end Charlie' in the Chain Gang stages - so there is an obvious incentive to complete in all stages if you don't want to suffer from my level of unfitness.

However, I have to say I feel as though I am making decent progress, for a near OAP and being over weight as well.

 

[Rob_H]

I assume you are referring to Alpe d'Huez so here is Ryans effort from the mountain goat league a few months back:
http://www.bkool.com/bkoolSessionHistory/showSessionSummary?sessionSummaryId=1426465
http://www.bkool.com/classification/showIndividualStageClassification/3936

I'm guessing you were quicker everywhere because of the steepness.

Sorry Ryan, hope you don't mind us comparing your ride to Robs to see if we can come up with a solution for the Vortex's in the mountain goat league.

Thanks @BILL S I'm now getting more and more confused There is a very big difference in my time and Ryan's and he was producing a bigger w/kg so there is clearly a big problem..But then you did Alpe d'Huez yesterday in 40.16? I'm not sure where to see your watts/kg, were they greater than Ryan's 5.04? I think the segments might be slightly different, is that the case?

 

[Baldo Mero]

I presume that the software measures the wheel speed and also calculates a speed due to weight and gravity and when the latter exceeds the former it just uses the latter (and seems to colour the speed blue). Unless and until you can spin the wheel faster than the gravity calculation you may as well coast.

I can see no reason why this calculation could not be done for any type of trainer, they either don't see it as a problem, actually prefer to advantage the bkool trainers or just are too busy ...

We have asked repeatedly for this to be fixed or for some explanation of why it cannot be, but nothing is forthcoming.

Geoff

I presume this is possibly related to the fact that Bkool trainers do not broadcast speed data by ANT+ whereas tacx trainers do. Can this be related somehow? I have heard that Elite trainers get virtual speed with Bsim and they do not broadcast the speed data either.

 

[BILL S]

Thanks @BILL S I'm now getting more and more confused There is a very big difference in my time and Ryan's and he was producing a bigger w/kg so there is clearly a big problem..But then you did Alpe d'Huez yesterday in 40.16? I'm not sure where to see your watts/kg, were they greater than Ryan's 5.04? I think the segments might be slightly different, is that the case?

I wish I had Rob. You're new to this game so you don't know the old joke about people going up Alpe d'Huez and cutting it short to 30 mins ( Mine was 30 mins + the 10 min warmup that you saw on my wall). Alpe d'Huez seems to help to make a little bit more power than other rides so is often chosen instead of doing an FTP. I managed to get 330 watts over the first 30 mins so that was it. Job Done!

 

[Baldo Mero]

The main problem is that (weight and power dependant) the vortex can allow you to climb a mountain with unrealistic speed due to the lower resistance so again (weight and power dependant) it can cause a problem with the mountain goat league. There are generally no downhill or flat parts to these stages and therefore there is no advantage to be had with the bkool over the vortex. I am still watching the performances with curiosity and would rather see a sample of different stages before looking to try and work out a factor that could even things out.

I totally understand Bill, thanks for the explanation. I guess that one way to know each rider's handicap (or lack of) would be to compare that rider's results in a given real climb with those of the same virtual ride with similar %FTP effort. If done on a range of steep climbing efforts in which the lack of resistance could be reached, that could give you a rough figure to use as a compensating guide. But anyway, in sustained climbs the W/Kg ratio multiplied by the % effort should give a very close prediction of the final position, shouldn't it?

 

[Rob_H]

I wish I had Rob. You're new to this game so you don't know the old joke about people going up Alpe d'Huez and cutting it short to 30 mins ( Mine was 30 mins + the 10 min warmup that you saw on my wall). Alpe d'Huez seems to help to make a little bit more power than other rides so is often chosen instead of doing an FTP. I managed to get 330 watts over the first 30 mins so that was it. Job Done!

I'm so pleased you said that...I was thinking BKool was totatlly broken I look forward to giving it a lash on the BKool when my friend gets it.

 

[Rob_H]

Thanks @BILL S I'm now getting more and more confused There is a very big difference in my time and Ryan's and he was producing a bigger w/kg so there is clearly a big problem..But then you did Alpe d'Huez yesterday in 40.16? I'm not sure where to see your watts/kg, were they greater than Ryan's 5.04? I think the segments might be slightly different, is that the case?

Sorry for all the questions, just trying to get a grip of how BKool works. I thought everything was clear and then.....on that link you sent Gareth beats Ryan by 2 minutes but produces 3.95 w/kg vs Ryan's 5.04? What am I missing?

 

[JLaw]

Anyone want to buy a barely used KICKR at a good discount off the new price?

Geoff

If you're serious about the kickr, I might be interested -- particularly if you're on my side of the pond. I can't imagine what the shipping costs for that monster would be.

 

[bridgy]

Sorry for all the questions, just trying to get a grip of how BKool works. I thought everything was clear and then.....on that link you sent Gareth beats Ryan by 2 minutes but produces 3.95 w/kg vs Ryan's 5.04? What am I missing?

You're right that is odd! From what I can see, Ryan produces considerably higher average watts AND is lighter, but still goes slower than Gareth? I have noticed similar anomalies before which can be explained by the faster rider producing fewer watts having made good use of drafting, but not sure this would work going up Alpe D'huez?

The other thing that might explain it is that it appears Gareth used a Bkool Classic 2 and Ryan a Pro, so maybe it's the different models of trainers behaving differently?

 

[rob01792]

how is it possible that I beat bill s on stage 1 of the mountain goats my time 33.59 watts normalized 178 max 668. bills time 35.55 watts normalized 289 max 844
the way I rode it was to power on then quick breather of a few seconds as the wheel start to slow down power on again I'm running a compact keeping on big ring front middle ish rear @BILL S @AAAC 76C

 

[bobinski]

I wish I had Rob. You're new to this game so you don't know the old joke about people going up Alpe d'Huez and cutting it short to 30 mins ( Mine was 30 mins + the 10 min warmup that you saw on my wall). Alpe d'Huez seems to help to make a little bit more power than other rides so is often chosen instead of doing an FTP. I managed to get 330 watts over the first 30 mins so that was it. Job Done!

Bill,
Do you realise that was your 25th attempt at d'Huez?!? You deserve respect for that alone Even if you have not finished many of them ( i fear i may be doing the same thing this weekend to try and get back up to Active 8)
On a more serious note, and trainer issues aside, another handicap race built would be great fun!