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Recommended Indoor Trainers?

Old 11-05-21, 07:56 AM
  #26  
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Originally Posted by spelger View Post
you know this for sure?
I don't have your credentials on this, but it's not controversial that a heavy rider needs to put out more watts to climb the same grade than a light rider. If your trainer is simulating a grade, the software controlling it will tell it to apply more resistance if it knows you're heavy (ie, you're not Zwift-doping). I will say that I was not aware that trainers would have trouble applying enough resistance to force maximum wattage at low cadences.
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Old 11-05-21, 10:14 AM
  #27  
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Originally Posted by adamrice View Post
I don't have your credentials on this, but it's not controversial that a heavy rider needs to put out more watts to climb the same grade than a light rider. If your trainer is simulating a grade, the software controlling it will tell it to apply more resistance if it knows you're heavy (ie, you're not Zwift-doping). I will say that I was not aware that trainers would have trouble applying enough resistance to force maximum wattage at low cadences.
of course a heavier rider will need more power to climb up a given grade compared to a lighter rider...IRL. but we are talking about a trainer simulating a grade. certainly this is not the same thing, only simulation and some simulation is better than others. i only know that rider weight is not part of the FE-C spec that determines a trainer's grade simulation. Some SW could be using rider weight and altering the grade simulation sent down to the trainer because they know better. and other SW may not be doing this because they know better. i certainly do not know.

would be an easy experiment to try with some SW. ride a big hill weighing in at 40KG then do it again weighing 80KG. your power is going to be the same (or you need to make sure it is) and if the SW is altering the simulated grade based on rider mass then there should be a difference in time to the top. have not thought all this trough but it seems right.
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Old 11-05-21, 10:17 AM
  #28  
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That's a fair point. I don't use Zwift myself, but my understanding is that its modeling is pretty thorough, and even accounts for stuff like drafting effects when you're racing in a bunch. So yeah, this could vary from one app to another, but I'd be surprised if any app that's attempting to be realistic wouldn't include this in its model.
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Old 11-05-21, 10:45 AM
  #29  
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Originally Posted by spelger View Post
you know this for sure? i wrote a PC based application to control my Kicker (simple intervals and grade simulation) and there is no rider or bike weight that can be sent down to the trainer. the trainer follows the FE-C spec and those are not two parameters used for grade simulation. the only thing used for grade simulation is grade.

i know zwift takes in a rider's weight but i assumed that was strictly for a W/Kg calculation. also, zwift has that feathre called trainer difficulty that alters realism, i suppose they might take weight into consideration too to further hose things up.

i guess it depends on the SW used so i really shouldn't single out zwift.
That's interesting and has got me thinking. Obviously the physics of accurate slope simulation absolutely does need to take your weight into account. A 10% slope for a 50 kg rider is not the same physical resistance as a 10% slope for a 100 kg rider. I've always presumed Zwift etc make that background calculation and then send the appropriate resistance request to the trainer, but maybe they don't? Easy enough to check though by varying your weight massively in Zwift and seeing if a slope feels easier or harder (rather than just faster or slower avatar).
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Old 11-05-21, 01:26 PM
  #30  
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Originally Posted by adamrice View Post
That's a fair point. I don't use Zwift myself, but my understanding is that its modeling is pretty thorough, and even accounts for stuff like drafting effects when you're racing in a bunch. So yeah, this could vary from one app to another, but I'd be surprised if any app that's attempting to be realistic wouldn't include this in its model.
Originally Posted by PeteHski View Post
That's interesting and has got me thinking. Obviously the physics of accurate slope simulation absolutely does need to take your weight into account. A 10% slope for a 50 kg rider is not the same physical resistance as a 10% slope for a 100 kg rider. I've always presumed Zwift etc make that background calculation and then send the appropriate resistance request to the trainer, but maybe they don't? Easy enough to check though by varying your weight massively in Zwift and seeing if a slope feels easier or harder (rather than just faster or slower avatar).
ok, do i got to thinking and had a little look at the FE-C spec and my code once again. rider weight and bike weight *are* sent to the trainer. i just didn't remember correctly. other things that can be specified are road quality, wind resistance, and wind speed. i apparently am even sending down the weights but using the defaults for all that other stuff.

so i have to apologize for my error here. my short term memory is clearly not very good. i did recently get hit by a car on my ride this past tuesday...can i use that as an excuse?
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Old 11-05-21, 03:47 PM
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Originally Posted by spelger View Post
ok, do i got to thinking and had a little look at the FE-C spec and my code once again. rider weight and bike weight *are* sent to the trainer. i just didn't remember correctly. other things that can be specified are road quality, wind resistance, and wind speed. i apparently am even sending down the weights but using the defaults for all that other stuff.

so i have to apologize for my error here. my short term memory is clearly not very good. i did recently get hit by a car on my ride this past tuesday...can i use that as an excuse?
Honestly, no need to apologise. I thought it was actually a good question. It makes sense that weight is sent over as a direct parameter - as it's so fundamental to any kind of real life slope sim.
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Old 11-05-21, 03:59 PM
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Originally Posted by himespau View Post
Does anyone have any experience with the Elite Direto XR? It is on the Kickr Core pricing level (even cheaper if you buy from one of the European sites and don't mind waiting for shipping), but claims to have higher resistance and gradient simulation than the Kickr. At 1.5% claimed it's a bit less accurate than either of them though.
I've been using the previous Direto X for 2 years now and it has been faultless. So I would imagine the XR is even better and reviews seem to suggest it is an incremental improvement. Accuracy is a wash I think. All these higher end trainers seem plenty accurate enough. Elite use an optical torque sensor to derive power and it seems pretty consistent to me. I haven't tried a Kickr Core so can't really comment on differences in ride feel. The Direto usually gets labelled middle-of-the-road in that respect by most reviewers. To me it feels fine, not super-smooth but more than adequate. The XR has a slightly heavier flywheel, so probably a tad better. The Kickr is often seen as the benchmark for ride feel. But then the Core has a smaller flywheel, so maybe it's a notch down too.
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Old 11-05-21, 06:36 PM
  #33  
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Originally Posted by spelger View Post
of course a heavier rider will need more power to climb up a given grade compared to a lighter rider...IRL. but we are talking about a trainer simulating a grade. certainly this is not the same thing, only simulation and some simulation is better than others. i only know that rider weight is not part of the FE-C spec that determines a trainer's grade simulation. Some SW could be using rider weight and altering the grade simulation sent down to the trainer because they know better. and other SW may not be doing this because they know better. i certainly do not know.

would be an easy experiment to try with some SW. ride a big hill weighing in at 40KG then do it again weighing 80KG. your power is going to be the same (or you need to make sure it is) and if the SW is altering the simulated grade based on rider mass then there should be a difference in time to the top. have not thought all this trough but it seems right.
I believe this is how it works for the FTMS protocol, the default weight in the trainer isn't something that can be changed. Zwift sends the grade to the trainer but only uses your weight to determine the speed up the grade based on your power. The resistance that you feel from the trainer is the grade plus the default weight of the rider and bike that is programmed into the trainer. I know for Tacx Neo2 the default rider weight and bike can be changed with their app, probably similar for the Wahoo trainers.
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Old 11-06-21, 06:20 AM
  #34  
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Originally Posted by billridesbikes View Post
I believe this is how it works for the FTMS protocol, the default weight in the trainer isn't something that can be changed. Zwift sends the grade to the trainer but only uses your weight to determine the speed up the grade based on your power. The resistance that you feel from the trainer is the grade plus the default weight of the rider and bike that is programmed into the trainer. I know for Tacx Neo2 the default rider weight and bike can be changed with their app, probably similar for the Wahoo trainers.
That's a bit disappointing if true. Do you happen to know what the default rider/bike weight actually is? I guess that would depend on the trainer model. It's annoying when trainers quote a max slope simulation, but don't tell you what weight rider or what min cadence. Is there a standard they quote to or do they just make up their own?
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Old 11-06-21, 07:45 PM
  #35  
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Originally Posted by PeteHski View Post
The Kickr is often seen as the benchmark for ride feel.
My kickr feels extremely close to real world pedaling. The only difference is that I don't get as much rest/recovery after climbs because you never truly coast on an indoor trainer. And that's part of the magic.
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Old 11-07-21, 09:51 AM
  #36  
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Originally Posted by PeteHski View Post
That's a bit disappointing if true. Do you happen to know what the default rider/bike weight actually is? I guess that would depend on the trainer model. It's annoying when trainers quote a max slope simulation, but don't tell you what weight rider or what min cadence. Is there a standard they quote to or do they just make up their own?
I believe my Tacx Neo defaulted to a rider weight of 75kg and a bike weight of 7kg and they where separate things. No sure about other models.
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Old 11-07-21, 10:56 AM
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Originally Posted by billridesbikes View Post
I believe my Tacx Neo defaulted to a rider weight of 75kg and a bike weight of 7kg and they where separate things. No sure about other models.
That would be close enough for me, but it seems a bit lame not to have a variable parameter for weight in slope simulation.
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Old 11-07-21, 05:10 PM
  #38  
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because i need to take a few days off from riding to recuperate i dove into the FE-C spec again and here are some bits for those interested in the nuts and bolts of any default values our truly wonderful smart trainers use (unless overridden by the mfgr)...i've underlined the defaultsCycling Frontal Areas Bicycle and Rider Frontal Area (m2)

All-terrain (Mountain) Bike 0.57

Upright Commuting Bike 0.55

Road Bike, Touring Position 0.40

Racing Bike, Rider Crouched, Tight Clothing 0.36



Cycling Drag Coefficients Bicycle and Rider Drag Coefficient

All-terrain (Mountain) Bike, Upright 1.20

Upright Commuting Bike 1.15

Road Bike, Touring Position 1.0

Racing Bike, Rider Crouched, Tight Clothing 0.88



Wind Speed Interpretation –
Example Values
Byte 6 Value Interpreted Wind Speed

0x00 -127 km/h

0xFE +127 km/h

0x7F 0 km/h





Drafting Factor

The drafting scale factor ranges from 0.0 to 1.0, where 0.0 removes all air resistance from the simulation, and 1.0 indicates no drafting effects (e.g. cycling alone, or in the lead of a pack). Controllable fitness equipment shall assume the default drafting factor of 1.0 if…



Controllable trainers shall assume an equipment (bicycle) mass of 10kg and a user mass of 75kg if invalid values were set during configuration.



Sample Cycling Coefficients of Rolling Resistance Terrain Coefficient of Rolling Resistance

Wooden Track 0.001

Smooth Concrete 0.002

Asphalt Road 0.004

Rough Road 0.008



Wind Resistance [N] = (0.5 * Wind Resistance Coefficient * (Relative Speed / 3.6)^2) x Drafting Factor

Simulated Grade (%) = (Raw Grade Value * 0.01%) – 200.00%

Gravitational Resistance [N] = (Equipment Mass + User Mass) * Grade/100 x 9.81

Rolling Resistance [N] = (Bicycle Mass + Cyclist Mass) * Coefficient of Rolling Resistance * 9.81

Total resistance [N] = Gravitational Resistance + Rolling Resistance + Wind Resistance

the bit in red is the part was PeteHski referring to while i was fixated grade.
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Old 11-08-21, 03:30 AM
  #39  
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Originally Posted by spelger View Post


Controllable trainers shall assume an equipment (bicycle) mass of 10kg and a user mass of 75kg if invalid values were set during configuration.

Does this imply that these are merely default values if the sim software (eg. Zwift, Rouvy etc) doesn't input actual rider and bike mass?
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Old 11-08-21, 08:41 AM
  #40  
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Originally Posted by PeteHski View Post
Does this imply that these are merely default values if the sim software (eg. Zwift, Rouvy etc) doesn't input actual rider and bike mass?
Difficult to answer really. The API only allows the SW to set these values. The API does not specify a way to pull them out of the trainer. so, my assumption is that 75 and 10 are the defaults used if not set *or* if set incorrectly. i also assume they are independent of each other although they are sent to the trainer in the same data packet.

APIs that have setters but no getters are weird to me as they leave no way to verify data.
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Old 11-10-21, 08:10 AM
  #41  
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My advice, calculate the top of your budget then add 20+%. In other words get the best you possibly can. My experience has been I upgrade a little at a time, over the last 3 years I have spent more than if I got a good wheel off smart trainer to begin with but I was worried that I wouldn't use the trainer.
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