Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Training & Nutrition (https://www.bikeforums.net/forumdisplay.php?f=148)
-   -   Mileage on Wahoo Kickr Core (https://www.bikeforums.net/showthread.php?t=1220636)

Het Volk 01-01-21 01:50 PM

Mileage on Wahoo Kickr Core
 
Not sure if everyone else has observed this, but when in ERG mode, your wattage is obviously the same regardless of gear ratio. So when riding in say, the small ring, putting out the same wattage, the speed and distance will be dramatically different than when in the big ring.

It definitely screws up morale if in the big ring up front and smaller rear COG because the Wahoo Kickr (or the app) is thinking you are going faster even though you are putting out the same power.

caloso 01-01-21 02:02 PM

On an indoor trainer your speed and distance will always be zero.

gregf83 01-01-21 02:10 PM


Originally Posted by caloso (Post 21858077)
On an indoor trainer your speed and distance will always be zero.

Yes, it's best to ignore distance and keep track of time when indoors. Riding with zwift also tends to create unrealistic speed & distance numbers. I prefer to do my intervals in the big ring so the speed/distance are reasonably close.

Iride01 01-01-21 02:37 PM

I don't do trainers yet, but do get on a stationary bike some. I've always disliked the idea of speed and distance on all of these things. Between all the indoor riding devices it's going to be a more arguable metric than Calories derived from HR monitors.

Time and power to me seem the better things to worry about and use for comparison to actual cycling.

Carbonfiberboy 01-01-21 05:46 PM

If I counted distance, I could probably include my roller time because my roller's power curve seems very close to my outdoor power curve w/r to speed. But I don't. It does matter to some tiny extent how fast you go because that affects flywheel inertia. And some erg trainers do vary the resistance with speed, especially dropping below some critical speed. You might look that up as see if that's true of yours. If there is a critical lower speed, I'd say ride as close to it as is practical for steady-state work, to keep flywheel momentum down. Makes it harder, harder is good. One would probably have to ride an erg with a power meter to see what's really going on.

For time, I think in erg mode you can figure you get your training done in about 3/4 the time you'd spend outdoors doing it. Erg mode never eases off.

zen_ 01-01-21 07:41 PM

I have not used the Wahoo app, but the virtual speed on most apps is based on your power, or power to weight ratio (w/kg).

The only things that actually changes when shifting gears in ERG mode since the power is theoretically, and in practice mostly the same is peddling dynamics (it's worth the 7 minutes to watch this video).


Het Volk 01-02-21 11:34 AM


Originally Posted by zen_ (Post 21858503)
I have not used the Wahoo app, but the virtual speed on most apps is based on your power, or power to weight ratio (w/kg).

The only things that actually changes when shifting gears in ERG mode since the power is theoretically, and in practice mostly the same is peddling dynamics (it's worth the 7 minutes to watch this video).

https://www.youtube.com/watch?v=uHUOhmG04M8

I will put it this way: When I look at my Wahoo APP while riding in ERG Mode, and switch the gear ratio, my speed changes, but power remains the same.

Iride01 01-02-21 01:57 PM

That's what ERG mode is supposed to do isn't it? Keep your power output the same regardless of gear or cadence?

zen_ 01-02-21 02:08 PM


Originally Posted by Het Volk (Post 21859141)
I will put it this way: When I look at my Wahoo APP while riding in ERG Mode, and switch the gear ratio, my speed changes, but power remains the same.

Are you using a wheel speed sensor?

Again, I don't know how the Wahoo app calculates (virtual) speed. The three ways it can be calculated on an indoor trainer are wheel speed (usually used when power is not available), power alone (e.g. TrainerRoad, w/o simulated climbing or drafting), or power-to-weight (e.g. Zwift /w simulated climbs). The latter is probably closest to to real world speed (assuming you don't draft in a blob of riders or weigh 20 pounds less online), but they are are virtual numbers at the end of the day. The only number that matters for training inside is power, and heart rate to some degree to keep track of fitness and fatigue.

Het Volk 01-02-21 11:34 PM


Originally Posted by zen_ (Post 21859313)
Are you using a wheel speed sensor?

Again, I don't know how the Wahoo app calculates (virtual) speed. The three ways it can be calculated on an indoor trainer are wheel speed (usually used when power is not available), power alone (e.g. TrainerRoad, w/o simulated climbing or drafting), or power-to-weight (e.g. Zwift /w simulated climbs). The latter is probably closest to to real world speed (assuming you don't draft in a blob of riders or weigh 20 pounds less online), but they are are virtual numbers at the end of the day. The only number that matters for training inside is power, and heart rate to some degree to keep track of fitness and fatigue.


The Wahoo Kickr Core provides data based on I am guessing, some form of algorithm based on the combination of speed and force on the magnetic device? Otherwise, no other speed sensor involved.

rubiksoval 01-05-21 11:30 AM


Originally Posted by Het Volk (Post 21858061)

It definitely screws up morale if in the big ring up front and smaller rear COG because the Wahoo Kickr (or the app) is thinking you are going faster even though you are putting out the same power.

Screws up morale, like, makes you feel better because you're going further and faster? Or worse?

In erg mode, I try to pick a gear that allows for a similar average speed to what I maintain outside. I don't want time and mileage messed up too muich indoors since climbing already is. :D

genejockey 01-05-21 01:56 PM


Originally Posted by Het Volk (Post 21859860)
The Wahoo Kickr Core provides data based on I am guessing, some form of algorithm based on the combination of speed and force on the magnetic device? Otherwise, no other speed sensor involved.

I'd assume it's measuring power output and yes, using an algorithm that calculates what your speed on the road would be for that power output, given your mass, the virtual slope, and estimated wind and rolling resistance. In Erg mode your wheel speed is meaningless because you could theoretically be spinning 39x30 or 53x11 at the same cadence and putting out the same power, but on the actual road you might be going 9 mph with one and 34 in the other.

spelger 01-05-21 02:28 PM


Originally Posted by genejockey (Post 21863850)
I'd assume it's measuring power output and yes, using an algorithm that calculates what your speed on the road would be for that power output, given your mass, the virtual slope, and estimated wind and rolling resistance. In Erg mode your wheel speed is meaningless because you could theoretically be spinning 39x30 or 53x11 at the same cadence and putting out the same power, but on the actual road you might be going 9 mph with one and 34 in the other.

that does not seem right to me. i will be riding tonight and will be sure to test that since it is pretty easy to do.

spelger 01-05-21 02:32 PM


Originally Posted by Het Volk (Post 21859860)
The Wahoo Kickr Core provides data based on I am guessing, some form of algorithm based on the combination of speed and force on the magnetic device? Otherwise, no other speed sensor involved.

it has a speed sensor built in. the number of rear wheel rotations is counted per some unit of time (can't recall what the units are). its all quite meaningless outside of an indoor metric.

jadocs 01-05-21 02:45 PM


Originally Posted by spelger (Post 21863902)
that does not seem right to me. i will be riding tonight and will be sure to test that since it is pretty easy to do.

Think riding uphill vs. on the flat. Both riding the same wattage....the guy on the flat is going to go faster and further.

genejockey 01-05-21 02:57 PM


Originally Posted by spelger (Post 21863902)
that does not seem right to me. i will be riding tonight and will be sure to test that since it is pretty easy to do.

There may be limitations to this based on the possible ranges of resistance inherent in the trainer itself, but you can definitely be turning the same cadence at the same power in a range of gears in Erg mode. That's kind of the whole point.

spelger 01-05-21 04:07 PM


Originally Posted by genejockey (Post 21863947)
There may be limitations to this based on the possible ranges of resistance inherent in the trainer itself, but you can definitely be turning the same cadence at the same power in a range of gears in Erg mode. That's kind of the whole point.

i may have misunderstood what you were saying. certainly in ERG mode power is to be controlled at the target power level regardless of cadence. i thought you were inferring that speed would be the same and that is what i did not think was quite right...

by the way, does anyone know what ERG stands for? my search turns up ERG to be short for Ergometer. but what is that exactly? speedometer...speed, altimeter...altitude, tensiometer...tension, but what is the ERG in Ergometer? if i recall erg is a unit of energy but i though that was a unit for atomic scaled particles.

spelger 01-05-21 04:08 PM


Originally Posted by jadocs (Post 21863924)
Think riding uphill vs. on the flat. Both riding the same wattage....the guy on the flat is going to go faster and further.

thanks, not having trouble knowing what ERG mode is. :thumb:

genejockey 01-05-21 05:09 PM


Originally Posted by spelger (Post 21864040)
i may have misunderstood what you were saying. certainly in ERG mode power is to be controlled at the target power level regardless of cadence. i thought you were inferring that speed would be the same and that is what i did not think was quite right...

by the way, does anyone know what ERG stands for? my search turns up ERG to be short for Ergometer. but what is that exactly? speedometer...speed, altimeter...altitude, tensiometer...tension, but what is the ERG in Ergometer? if i recall erg is a unit of energy but i though that was a unit for atomic scaled particles.

No, what I meant was that on a trainer in erg mode, "speed" would be a meaningless concept, because no matter what gear or cadence, the power output is the same. I haven't played around with the Wahoo ap for my Snap to know whether they do a power-based virtual speed calculation, like Zwift and others do, but Erg mode makes that meaningless anyhow.


All times are GMT -6. The time now is 06:28 PM.


Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.