Team BKool CycleChat

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bridgy

Legendary Member
Location
Cheddar
@gbrown - I'm just thinking, based on what you posted earlier, and that graph for the Tacx vortex I posted, would it be possible for Bkool to claim that in theory the trainer could in fact replicate a 20% slope for any rider weight if the rider was going slow enough?
 

RickB

professional procrastinator
Location
Norn Iron
Agreed - the limitations of the Bkool we've been talking about apply to other trainers as well. It's just that other manufacturers are a bit more open about what rider weight/speed they are basing their max gradient claims on!

I actually think the Bkool Pro is a pretty good piece of kit for the price. But I really don't like the fact Bkool are claiming it will replicate the resistance of a 20% incline for ANY rider weight, and banning Rick from their Facebook page for disagreeing

Spot on Paul. The Bkool trainer is a great piece of kit for the money - just a pity the company that makes it is full of muppets. I vote that everyone posts similar about the resistance on their page and see if everyone gets blocked! :laugh:
 

Whorty

Gets free watts from the Atom ;)
Location
Wiltshire
Managed to get a day working from home today :laugh: so up for a goat or chaingang tonight. Anyone else fancy a ride? 6.30 ish? Could do 6 if that suits better?
 

Bored Man

Upstanding Member
Location
Arrochar
Tell me about it! I keep having to put in a performance to remind the selectors:hello: I think Kipster is doing some serious base work keeping his powder dry so to speak ^_^ Adam will arrive on the dot!

thinking about it we could have back up members for specific courses, Perky, Breedon, Berty are stronger on climbs, than me and would say Tommy, so we could be domestique riders burying ourselves for an early tow then pulling off? Ssssh Geoff its our little secret on tactics

Oooooh matron...:whistle:
 

theboxers

TheBoxers on Cycle Sim sw
Fatties Versus Thinnies ftp test
What we need is someone like @AAAC, @bridgy, @BILL S or @TurboTommy, or all of them, to do a set of short sessions at increasingly steeper gradients at increasingly higher weights. Say from 50-130kg, @ 5 or 10kg steps and then telling us when the trainer resistance maxes out for them at each weight.

For me, 127kg, with my power, about 200w, I feel I get max resistance @ just under 6%. Anything above that and the resistance level does not appear to get harder for me.
 

gbrown

Geoff on Bkool
Location
South Somerset
@gbrown - I'm just thinking, based on what you posted earlier, and that graph for the Tacx vortex I posted, would it be possible for Bkool to claim that in theory the trainer could in fact replicate a 20% slope for any rider weight if the rider was going slow enough?

Possibly, but one problem would be that at low speeds very little resistance is generated, as the magnetic eddy currents that provide the resistance depend on the speed of the disc rotating between the magnets. But if you go faster, it needs to generate even more resistance to oppose the greater torque force being applied to the roller.

Hence the blue triangle showing resistance as linear in relation to speed, but the curves for gradient showing the force as exponential.

I guess at a low enough speed, approaching zero, the resistance needed would also approach zero, and even though the magnetic braking would approach zero it could be claimed to "simulate" the gradient at that speed. I believe the term is asymptotic! Near the zero access of your graph, most gradient curves will likely drop into the blue triangle denoting the operational range. However, in reality simulating a gradient only at almost zero speed is just about as far from the truth as a downright falsehood!

I have seen it stated, that to have any validity any claim must state the assumptions used to make the claim. These assumptions can then be validated as meaningful or not. Hence to be meaningful, a maximum gradient must state what weight, speed, etc., is needed to attain it.

Without this, such claims are meaningless! They can't even be compared, as different assumptions may have been made for each figure.

Unbiased testimony usually gives a better sense of the truth, hence we know from our own shared experiences that for a rider of around average weight, say around 80 Kg, riding at around average speed on a steep incline, say around 5-8 mph, that the Bkool Pro can simulate gradients just into double figures, which is pretty good for the price and much better than many competitors, unless they cost considerably more!
 

gbrown

Geoff on Bkool
Location
South Somerset
For me, 127kg, with my power, about 200w, I feel I get max resistance @ just under 6%. Anything above that and the resistance level does not appear to get harder for me.

Which kind of fits our rough idea of where it should be; 80 Kg = c.10%-12% so 127 Kg = c.6-7%

Do you then get the blue speed numbers, or has bkool backed that out of this version of the simulator?

If the blue numbers do appear, that would be a good way of quantifying the max resistances, by adjusting weights and gradients on a sequence of steady inclines and slowly increasing speed until numbers turn blue. A range of weights, speeds and gradients would give a 3 dimensional graph of their relationships.
 

theboxers

TheBoxers on Cycle Sim sw
Which kind of fits our rough idea of where it should be; 80 Kg = c.10%-12% so 127 Kg = c.6-7%

Do you then get the blue speed numbers, or has bkool backed that out of this version of the simulator?

If the blue numbers do appear, that would be a good way of quantifying the max resistances, by adjusting weights and gradients on a sequence of steady inclines and slowly increasing speed until numbers turn blue. A range of weights, speeds and gradients would give a 3 dimensional graph of their relationships.
I can get blue numbers if I manage to get the pedals going a bit quicker than normal, usually after a bit of slightly less steep pedalling.Even then it is only 0.2-0.4 mph more than my speed sensor reading

That is why we need some of the power monsters to do these tests. At different weights, gradients and power levels. My 6% @200w @ 65rpm on a 36 chain ring x 32 cassette cog. I may be able to pedal a bit quicker at this point but I am at my max and gone through the red into the black and can't say for certain that I am not getting weaker rather than the resistance getting harder
 

bridgy

Legendary Member
Location
Cheddar
Possibly, but one problem would be that at low speeds very little resistance is generated, as the magnetic eddy currents that provide the resistance depend on the speed of the disc rotating between the magnets. But if you go faster, it needs to generate even more resistance to oppose the greater torque force being applied to the roller.

Hence the blue triangle showing resistance as linear in relation to speed, but the curves for gradient showing the force as exponential.

I guess at a low enough speed, approaching zero, the resistance needed would also approach zero, and even though the magnetic braking would approach zero it could be claimed to "simulate" the gradient at that speed. I believe the term is asymptotic! Near the zero access of your graph, most gradient curves will likely drop into the blue triangle denoting the operational range. However, in reality simulating a gradient only at almost zero speed is just about as far from the truth as a downright falsehood!

I have seen it stated, that to have any validity any claim must state the assumptions used to make the claim. These assumptions can then be validated as meaningful or not. Hence to be meaningful, a maximum gradient must state what weight, speed, etc., is needed to attain it.

Without this, such claims are meaningless! They can't even be compared, as different assumptions may have been made for each figure.

Unbiased testimony usually gives a better sense of the truth, hence we know from our own shared experiences that for a rider of around average weight, say around 80 Kg, riding at around average speed on a steep incline, say around 5-8 mph, that the Bkool Pro can simulate gradients just into double figures, which is pretty good for the price and much better than many competitors, unless they cost considerably more!
My brain hurts now :wacko:

Thanks Geoff - I think I understand the basic gist of what you're saying and it's what I thought - they can claim it can simulate 20% for any weight but it's a meaningless claim not relevant to the real world, as the speed would have to be stupidly low for a rider over a certain weight. Hence other manufacturers clarifying their max gradient claim as based on a certain rider weight and speed. And in the real world we're finding that we max out at between 6-10% gradient depending on rider weight. Which ironically, despite their claims, is proved by the blue numbers thing Bkool themselves have built into the simulator!

I'm still Team Rick!
 

<Tommy>

Illegitimi non carborundum
Location
Camden, London
@TurboTommy What happened to you last night? Looked like you got a puncture and tried to limp to the end.
As for me, I killed myself trying to catch and then stay with Bridgy as far as the first hill.

Throwing up was probably the final nail in the coffin!

Well first my fan fell off the pile of LP's it was balanced on. I tried to re-jig it but gave up pretty quickly, so from then on I didn't have a fan. Bob was off in the distance so I buried myself trying to catch back up. I managed it but I'd badly over cooked it by then, and at that point the orange I'd eaten in the warmup and the pizza I had 40 odd minutes before hand had a bit of a clash of personalities!

You can probably just replace that whole paragraph with 'I'm an idiot!' To be fair...

Luckily the bin I'd used for the orange peel was next to me when my dinner came back to say hello so the carpet didn't take the brunt of it, and the missus will never have to know!

To be honest I think Bridgy was going to pass me at some point anyway and Bob looked very strong so the result may of been the same. I figured you'd had a bit of a blow up of your own when you started cruising. It's quite nice just pottering along sometimes to be fair.
 

Daddy Pig

Veteran
Throwing up was probably the final nail in the coffin!

Well first my fan fell off the pile of LP's it was balanced on. I tried to re-jig it but gave up pretty quickly, so from then on I didn't have a fan. Bob was off in the distance so I buried myself trying to catch back up. I managed it but I'd badly over cooked it by then, and at that point the orange I'd eaten in the warmup and the pizza I had 40 odd minutes before hand had a bit of a clash of personalities!

You can probably just replace that whole paragraph with 'I'm an idiot!' To be fair...

Luckily the bin I'd used for the orange peel was next to me when my dinner came back to say hello so the carpet didn't take the brunt of it, and the missus will never have to know!

To be honest I think Bridgy was going to pass me at some point anyway and Bob looked very strong so the result may of been the same. I figured you'd had a bit of a blow up of your own when you started cruising. It's quite nice just pottering along sometimes to be fair.
At least you got to enjoy the pizza twice...xx(
 

bobinski

Legendary Member
Location
Tulse Hill
Throwing up was probably the final nail in the coffin!

Well first my fan fell off the pile of LP's it was balanced on. I tried to re-jig it but gave up pretty quickly, so from then on I didn't have a fan. Bob was off in the distance so I buried myself trying to catch back up. I managed it but I'd badly over cooked it by then, and at that point the orange I'd eaten in the warmup and the pizza I had 40 odd minutes before hand had a bit of a clash of personalities!

You can probably just replace that whole paragraph with 'I'm an idiot!' To be fair...

Luckily the bin I'd used for the orange peel was next to me when my dinner came back to say hello so the carpet didn't take the brunt of it, and the missus will never have to know!

To be honest I think Bridgy was going to pass me at some point anyway and Bob looked very strong so the result may of been the same. I figured you'd had a bit of a blow up of your own when you started cruising. It's quite nice just pottering along sometimes to be fair.

:laugh:

I thought you might have puked given your warning post TT. We have all been there! I had eaten curry, rice and dahl and 2 slices of lemon tart, but at 5-30 so whilst it sat a little heavily in my stomach and prompted the odd burp there was never any risk of reaching for a bin! But it did make it a little harder to get in the drops for the descents:rolleyes:
I enjoyed our tustle and did slow a few times for you to latch on so we could draft but once i knew you were not at your recent best i had to plough on. I slowed, almost to a pootle at one point, in the final half though and could have done with you chasing or more likely me chasing to get a better time.
 
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