Not accurate. Pushing 200 watts to go 16.5/17 mph needs some sort of correction. Where? How? Nothing on the website. Trying to connect to support keeps failing as there is a bug in the software. Frustrated as I rode the rock (Computrainer) for years without issues like this.
What app are you connected to? Most will determine a virtual speed based on your physical parameters, the route parameters (i.e. slope), and your power output.
Wahoo fitness and Rouvy are the primary “apps/software” I utilize. Sometimes I ride without these apps/software and just with my Garmin 820 monitoring. When I do this, the speed is still off and…the trainer resistance is terrible #1 is like riding down a 20% grade regardless of what gear you are in, #2 is like riding downhill on a 10% grade and this is the kickr default setting, #3 finally makes some sense but produces a little too much resistance for the speed that is being recorded. Performing a power calibration doesn’t solve the issue. I have had the Kickr Core for a year now. I hate this issue and much prefer the Computrainer for the more realistic feel and accuracy.
In what mode?
There are 4 modes on the kickr:
- level 0-9 (9 simulates a 4.5% grade).
- resistance 0-100% (0 easy > 100 hard)
- ERG you set the resistance in W
- SIM (you configure slope and headwind, CdA and crr)
SIM is the only mode where speed makes some sense - although those CdA / crr presets are totally bullshit (CdA of 0.6 and Crr 0.0033 for a road bike and 0.345 / 0.0033 for a tribike).
In what mode?
There are 4 modes on the kickr:
- level 0-9 (9 simulates a 4.5% grade).
- resistance 0-100% (0 easy > 100 hard)
- ERG you set the resistance in W
- SIM (you configure slope and headwind, CdA and crr)
SIM is the only mode where speed makes some sense - although those CdA / crr presets are totally bullshit (CdA of 0.6 and Crr 0.0033 for a road bike and 0.345 / 0.0033 for a tribike).
Photos? Some of us have no concept of what you are talking about?
The alternate answer is that the concept of speed is irrelevant with a smart trainer. The whole point of the trainer is that it dynamically adjusts resistance to either force you to maintain a target power or simulate a route. I ride my bike in the small CR and 19 cog for a straight-ish chainline and quieter drivetrain noise. It thinks I am going 15 MPH, even when I am dropping 350W. However, If I shifted to my 52-11, it would think I was going 35 MPH, even when recovering at 100W.
This is the wahoo app. Scroll right from the initial screen to get to this one. See the Level, Resist, Erg and Sim tabs on top - those are the modes I’m talking about.
This is the wahoo app. Scroll right from the initial screen to get to this one. See the Level, Resist, Erg and Sim tabs on top - those are the modes I’m talking about.
Where did you find this? the Black Wahoo software/app does not have it. The Wahoo utilities just finds the sensors. Accuracy stinks when riding without software in like ero mode. Rode 250 watt intervals at all 17.3-6 mph. Not accurate.
Already mentioned above, but exactly what do you hope to learn from the “speed”? You are stationary and not moving. Your speed is zero. It is telling you power which is actually useful information.
Consider this: outside on smooth roads, light tailwind and an aero bike, your 200W will push you 25+ mph. Those same 200W on a gravel bike with knobs up a bumpy climb will bring you to a standstill. Speed is not a training parameter which makes any sense unless you have no better metric, like say…power.
Bringing it full circle: the answer to why Wahoo put way more thought/effort into power than speed is all that above. It is just an arbitrary guess based on some calculation using your power and some random values for crr, cda, weight, slope, etc. Why not just use the power, man and forget about speed?
Black app. After you start the workout swipe left. That’s how you move to the next page…
This is the wahoo app. Scroll right from the initial screen to get to this one. See the Level, Resist, Erg and Sim tabs on top - those are the modes I’m talking about.
Where did you find this? the Black Wahoo software/app does not have it. The Wahoo utilities just finds the sensors. Accuracy stinks when riding without software in like ero mode. Rode 250 watt intervals at all 17.3-6 mph. Not accurate.
I don’t disagree that other metrics are superior training guides than speed on a trainer. Zwift (and other ride simulators) have, at their core, a need to estimate speed. This is done, as others have pointed out, using measured power and a physics model based on rider and environmental characteristics. But I disagree with some who have claimed in this thread that speed measurement is something impossible or irrelevant indoors. The rear wheel is spinning, no? The diameter of that wheel can be measured, no? Ok, the simplest math in the world gets you a ‘speed’ based on the rotational velocity and size of the rear wheel. This is what every ‘bike computer’ used to do before we all went GPS. So, why care? Well, maybe you’re tracking ‘distance’ (speed x time) as a surrogate for maintenance intervals (chain lube, tire replacement, cog wear, etc.). Maybe you have a historical record of annual cycling distance and you hate to see that suddenly end, or not be even remotely comparable with current ‘distance’ (although annual hours might be a useful surrogate). In any case, getting ‘speed’ (and ‘distance’) from a trainer should be easy. I actually have a old school, non-GPS bike computer connected to the rear wheel of my trainer bike. Maybe that is the best solution for the OP, or a cadence/speed sensor that generates a signal readable by the OP’s recording device…
Speed (without knowledge of the resistance) is arbitrary for indoor training. As others have said, for a given resistance, the speed is entirely based on your gear choice. It’s entirely possible to generate a speed (Wahoo does this) and it’s not a very meaningful metric. The current crop of direct drive smart trainers are focused on accurate resistance across a wide range of speeds so they can work for simulating a flat TT sprint or a climb up at 10% grade.
This is different than something like a Kurt Kinetic fluid trainer where resistance goes up the faster the wheel in the resistance unit spins. With that model, the only way to get more resistance is to make your rear wheel spin faster (i.e., change gears). Kurt matches this curve to roughly be in line with what riding speed outside are like - https://www.kurtkinetic.com/fluid-resistance In this case, speed is super relevant because it roughly lines up with power using their curve (this is how their inride unit and zwift give you power numbers from a Kinetic).
If I take that same Kurt trainer and don’t tighten the resistance unit to the wheel, I can record some way higher speeds in 53x11 than I will at 36x25 for the ~same, minimal, input power. The same applies against any fixed (wattage) resistance load.
I know you want speed to mean something, but it really doesn’t unless you’re in something like Zwift as discussed above. You can mess with the “speed” simply by changing gears. Seriously, try it. Put out 200 watts in your small chainring and then put out 200 watts in your large chainring. You’ll notice a huge difference in “speed”.
Not accurate. Pushing 200 watts to go 16.5/17 mph needs some sort of correction. Where? How? Nothing on the website. Trying to connect to support keeps failing as there is a bug in the software. Frustrated as I rode the rock (Computrainer) for years without issues like this.
I feel your pain and I’m glad you posted this. I have the same “problem†and I’ve looked at Settings (wondering if I put in the wrong wheel type) and searched online to no avail. I get the exact same results you do. I know what it feels like to ride at 20 or 22 mph and to see that display telling me I averaged 16.5 for a workout is super annoying.
Like others have mentioned, I try to run a straight chain line from the small chainring to the middle of the cassette to reduce wear and tear on my equipment. I’m not going to stop doing that.
I try to ignore speed at this point and focus on workout time and watts and use watts for interval training. Would I like to get “credit†for 21 miles if I ride for an hour and a proper reflection of mileage over months of training? Yes. Do I think that’s going to happen? No. I’ve given up on that and focus on other metrics, like getting in X hours per week.
Not accurate. Pushing 200 watts to go 16.5/17 mph needs some sort of correction. Where? How? Nothing on the website. Trying to connect to support keeps failing as there is a bug in the software. Frustrated as I rode the rock (Computrainer) for years without issues like this.
I feel your pain and I’m glad you posted this. I have the same “problem†and I’ve looked at Settings (wondering if I put in the wrong wheel type) and searched online to no avail. I get the exact same results you do. I know what it feels like to ride at 20 or 22 mph and to see that display telling me I averaged 16.5 for a workout is super annoying.
Like others have mentioned, I try to run a straight chain line from the small chainring to the middle of the cassette to reduce wear and tear on my equipment. I’m not going to stop doing that.
I try to ignore speed at this point and focus on workout time and watts and use watts for interval training. Would I like to get “credit†for 21 miles if I ride for an hour and a proper reflection of mileage over months of training? Yes. Do I think that’s going to happen? No. I’ve given up on that and focus on other metrics, like getting in X hours per week.
What you are seeing here is something that other posters have tried to explain without getting to the fundamentals of the issue. The ‘speed’ you are seeing is wheel speed as measured by the trainer. All the trainer is doing is measuring how fast you are rotating the cassette. Trainers do this because it is an essential part of the spin down calibration process (changes in cassette speed are related to resistance so you can correct for resistance drift if you can very accurately measure changes in wheel speed) and not because it is a useful training metric. Fundamentally you are trying to interpret real-world speed based on a value not intended as an indicator of real world speed.
The more common frustration people voice over the same issue is that at 80-90 rpm they are forced to push 300 watts on the trainer even though the same gear/RPM combo equates to modest speed and wattage outside. This is very true but isn’t a problem with the trainer. Indoors you will always push a smaller gear (and hence maintain a lower speed) to hit a target wattage and RPM than you would outside.
You have a speed number but feel it is inaccurate - Fair enough
But what do you want it to mean? Without knowing that it’s impossible to understand your complaint.
I don’t believe there is anything wrong with your trainer. It’s unfair to criticise it by comparison to your computrainer when the problem appears to be that you don’t yet understand it.
“Speed” on a trainer can mean two things. The first is wheel speed, when using a wheel on trainer. The second is a notional equivalent riding speed you’d be doing IF you were travelling based on the power you are producing. The former is only useful if the resistance curve is understood. The latter depends entirely on the criteria used to convert power to “speed”. There is no a “correct” conversion, because you don’t have any real circumstance you are representing. You have to choose those circumstances for the typical riding conditions you want to represent. What sort of bike with what sort of tyre on what sort of surface and on what gradient, while weighing how much and wearing what, with what exact riding position? And that’s not even a full list. This isn’t being pedantic, each of those are fundamental to coming up with a figure that means any more than one you would pick out of thin air. Even assuming everyone wants an equivalent speed for a level road with good quality tarmac, with no wind…the remaining parameters are sufficient to make any default figure provided irrelevant.
Train to power. If you keep track of training volume using distance, like I once did, switch to hours, calories or TSS. They’re all more useful and will work both indoors and out if you have a power meter on the bike. If the trainer is your only source of power data, use hours. I currently track hours as my single figure for volume as I only have power on my tri bike and ride my road bike most of the time outdoors.
Riding software that simulates the course you ride outdoors should be the standard for the software. If not, why should I buy it? I can ride in erg mode at targeted power levels without an issue. If I purchase the software for say the Lake Placid bike course, I want that software to accurately produce what I will experience outdoors. It is that simple.
Riding software that simulates the course you ride outdoors should be the standard for the software. If not, why should I buy it?Have you tried this with Zwift yet? This is what Zwift does and does well. The Wahoo app is free; it is is likely they did not invest much in outdoor simulation, because that is an unlikely use case for a basic app. Or, it is just as likely that you do not have the correct rolling resistance, drag, weight, slope, and windspeed entered for you and your bike.
https://www.bestbikesplit.com/case-study-offseason covers some of the options for simulating riding a course with a FE-C ANT+ compatible trainer (which the Kickr is). The speeds probably still won’t line up 100% due to all the factors mentioned in the thread (cda, crr, weight) but if your goal is to simulate riding courses ala the computrainer setup, you need additional software. The base Wahoo software (and really from most companies) is pretty barebones since a lot of the value of these trainers is being able to hook into a variety of third party software (zwift, trainer road, etc.)
I don’t disagree that other metrics are superior training guides than speed on a trainer. Zwift (and other ride simulators) have, at their core, a need to estimate speed. This is done, as others have pointed out, using measured power and a physics model based on rider and environmental characteristics. But I disagree with some who have claimed in this thread that speed measurement is something impossible or irrelevant indoors. The rear wheel is spinning, no? The diameter of that wheel can be measured, no? Ok, the simplest math in the world gets you a ‘speed’ based on the rotational velocity and size of the rear wheel. This is what every ‘bike computer’ used to do before we all went GPS. So, why care? Well, maybe you’re tracking ‘distance’ (speed x time) as a surrogate for maintenance intervals (chain lube, tire replacement, cog wear, etc.). Maybe you have a historical record of annual cycling distance and you hate to see that suddenly end, or not be even remotely comparable with current ‘distance’ (although annual hours might be a useful surrogate). In any case, getting ‘speed’ (and ‘distance’) from a trainer should be easy. I actually have a old school, non-GPS bike computer connected to the rear wheel of my trainer bike. Maybe that is the best solution for the OP, or a cadence/speed sensor that generates a signal readable by the OP’s recording device…
It is always good when a poster answers his own questions.
Btw, I don’t think a speed sensor is the best solution for a Kickr Core.