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Smart trainer and real world resistance

Posted: Wed Dec 05, 2018 5:59 pm
by wheelsONfire
When you ride on a smart trainer (ex Tacx Neo), does it compensate for rolling resistance (tire to tarmac) and a pre-set wind resistance value?
If yes, what are these based on?

Smart trainer and real world resistance

Posted: Wed Dec 05, 2018 5:59 pm
by Weenie

Re: Smart trainer and real world resistance

Posted: Wed Dec 05, 2018 9:12 pm
by VTR1000SP2
Sounds like a question for Shane Miller or DCRainmaker


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Re: Smart trainer and real world resistance

Posted: Wed Dec 05, 2018 10:11 pm
by TobinHatesYou
wheelsONfire wrote:
Wed Dec 05, 2018 5:59 pm
When you ride on a smart trainer (ex Tacx Neo), does it compensate for rolling resistance (tire to tarmac) and a pre-set wind resistance value?
If yes, what are these based on?

A smart trainer controls resistance. Period. If the application/client chooses to simulate windspeed and wind direction, that is entirely up to a software developer. But yes, apps like Zwift approximate the gravity, rolling resistance, air density, etc. in a rudimentary fashion to aid in the simulation of realistic riding conditions. Zwift doesn’t have wind, temperature, or air density changes though.

Re: Smart trainer and real world resistance

Posted: Wed Dec 05, 2018 11:08 pm
by jfranci3
Zwift or whatever would tell the trainer a number. Your speed in the app has nothing to do with real world speed. Without the app, I'd assume the trainer would drop to the wattage floor or a pre-programmed resistance.

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 12:10 am
by bikeboy1tr
I follow Shane Miller on Strava and he had a pic from a bike show were the bike fork attached to a lifting device which I gather is to simulate the angles of a hill when climbing. So the lift raises on incline to avoid any pulling on the rear dropouts when attached to a smart trainer obviously. Its quite the sight.

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 1:03 am
by TobinHatesYou
bikeboy1tr wrote:
Thu Dec 06, 2018 12:10 am
I follow Shane Miller on Strava and he had a pic from a bike show were the bike fork attached to a lifting device which I gather is to simulate the angles of a hill when climbing. So the lift raises on incline to avoid any pulling on the rear dropouts when attached to a smart trainer obviously. Its quite the sight.

Actually without special considerations for the KICKR Climb device, you risk damaging your bike's dropouts. That's why the KICKR Climb is only compatible with 2017 and later versions of the KICKR. They had to create a free spinning endcap for both the NDS and DS "hub shells."

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 2:59 am
by bikeboy1tr
TobinHatesYou wrote:
Thu Dec 06, 2018 1:03 am
bikeboy1tr wrote:
Thu Dec 06, 2018 12:10 am
I follow Shane Miller on Strava and he had a pic from a bike show were the bike fork attached to a lifting device which I gather is to simulate the angles of a hill when climbing. So the lift raises on incline to avoid any pulling on the rear dropouts when attached to a smart trainer obviously. Its quite the sight.

Actually without special considerations for the KICKR Climb device, you risk damaging your bike's dropouts. That's why the KICKR Climb is only compatible with 2017 and later versions of the KICKR. They had to create a free spinning endcap for both the NDS and DS "hub shells."
Thats kind of scary thought to put your frame in a torture device that may end in tears. I havent made the conversion to smart trainers yet and not to sure I will anytime soon. My next purchase in that department will be Elite E Motion Rollers with resistance before the smart trainer.

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 3:18 am
by wheelsONfire
I read around alot before i bought a new smart trainer. Rollers were my first, shall we say pre-choice.
But then i read somewhere that they deemed Neo as the least noisy trainer. Kickr 2018 came second.
The option that was absolutely loudest were rollers. Needless to say perhaps, but the rollers scored lower value than any trainer.
Since i live in an apartment, aswell as hate noise, i went for Neo.

As for the question, start of this thread. I was contemplating if it's common people actually get higher speeds on their trainers vs real cycling?
I have no idea really since i almost never used my old Tacx. I can't use Neo now, since my new frameset isn't here yet.

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 7:05 am
by TobinHatesYou
The KICKR18 is quieter than the Neo at higher speeds where the Neo develops an electronic hum. It's a close contest so I'd just call it a tie. Rollers are fine if you're doing base, but most are only capable of putting up ~700W worth of resistance at big ring speeds. The Neo has a few advantages...it doesn't require spindowns, it doesn't require mains power, it has built-in flex in the legs. The disadvantage is it still has non-native thru-axle support and it doesn't have a real physical flywheel. Its "road feel" suffers a tiny bit as a result. The KICKR is of course compatible with the KICKR CLIMB and it can do clever things like power matching / bridging a power meter. The silliest thing about the KICKR is it doesn't provide torque based cadence. Wahoo just chucks one of their separate cadence sensors in the box for you to install on your crank. Every other high-end trainer provides cadence estimation based on torque / drivetrain micro-acceleration.

As for metrics to care about indoors...speed is not one of them. The only metrics that matter are power and training load.

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 9:52 am
by mattr
wheelsONfire wrote:
Thu Dec 06, 2018 3:18 am
The option that was absolutely loudest were rollers.
Never used a fan trainer then....... Mine used to leave me with ringing ears after even a short interval session.
wheelsONfire wrote:
Thu Dec 06, 2018 3:18 am
As for the question, start of this thread. I was contemplating if it's common people actually get higher speeds on their trainers vs real cycling?
TBH, the Neo paired with Zwift gives me "close enough". Obviously it's not right, as it's a generated number. But it's not like i look at the screen and think WTF when i see the speed. It fairly well mirrors the effort i'm putting in, and what i'd expect to get on the open road.

And TBH, i get more noise from driveline, breathing, music and the zwift environment than i do from the actual trainer. Even at well north of 500W.
My previous Flux was slightly louder, but still not loud enough for me to think "this is loud". (Didn't need to turn the TV volume up)

Re: Smart trainer and real world resistance

Posted: Thu Dec 06, 2018 10:59 am
by Jugi

wheelsONfire wrote: As for the question, start of this thread. I was contemplating if it's common people actually get higher speeds on their trainers vs real cycling?
There is no practical purpose for "speed" on interactive trainers, as it is completely abstract. The Neo is a good example on this - it does transmit a "speed" value to a head unit just because it is possible. At the same time, if Zwift is controlling the trainer, Zwift will actually record a differing speed value inside the simulated environment. In my opinion both speed values are in the right ballpark for evaluating drivetrain wear etc. in the long run, but neither is realistic or accurate.

Zwift has a "realism" setting which alters how hard ascending is and how easy descending is, but Zwift's biggest departure from realism is the lack of need for braking while descending. You can push up a 6% climb at "realistic" 15km/h average speed, and then roll down at a constant 65km/h on the other side of the climb. That'll have a significant effect on the overall average speed.

Re: Smart trainer and real world resistance

Posted: Sat Dec 08, 2018 12:04 am
by packetloss
Jugi wrote:
Thu Dec 06, 2018 10:59 am
wheelsONfire wrote: As for the question, start of this thread. I was contemplating if it's common people actually get higher speeds on their trainers vs real cycling?
There is no practical purpose for "speed" on interactive trainers, as it is completely abstract. The Neo is a good example on this - it does transmit a "speed" value to a head unit just because it is possible. At the same time, if Zwift is controlling the trainer, Zwift will actually record a differing speed value inside the simulated environment. In my opinion both speed values are in the right ballpark for evaluating drivetrain wear etc. in the long run, but neither is realistic or accurate.

Zwift has a "realism" setting which alters how hard ascending is and how easy descending is, but Zwift's biggest departure from realism is the lack of need for braking while descending. You can push up a 6% climb at "realistic" 15km/h average speed, and then roll down at a constant 65km/h on the other side of the climb. That'll have a significant effect on the overall average speed.
Also to add to this, gradient on a trainer is just an excercise in shifting. Basically in Zwift they take your power output and based on your weight and the gradient they determine your speed. So if you use the Zwift setting to make climbs easier, all they are doing is setting a lower slope on your trainer (i.e. less resistence) but if you do the same power output (albeit in a different gear between the 2 modes) you will go the same speed up the hill in zwift. Is it really easier? No, you will just be in a different gear and possibly won't have to shift as much.

Re: Smart trainer and real world resistance

Posted: Sat Dec 08, 2018 1:08 am
by TobinHatesYou
packetloss wrote:
Sat Dec 08, 2018 12:04 am

Also to add to this, gradient on a trainer is just an excercise in shifting. Basically in Zwift they take your power output and based on your weight and the gradient they determine your speed. So if you use the Zwift setting to make climbs easier, all they are doing is setting a lower slope on your trainer (i.e. less resistence) but if you do the same power output (albeit in a different gear between the 2 modes) you will go the same speed up the hill in zwift. Is it really easier? No, you will just be in a different gear and possibly won't have to shift as much.

There is actually one key difference between climbing up a 20% grade with 100% trainer difficulty or less (like 0%.) Flywheel speed will be much lower, and thus the inertia will affect your pedaling technique. With a 0% setting, the momentum keeping the flywheel in motion will allow you to focus on your peak power phases while allowing your feet to glide through the dead spot in your stroke. With a higher setting, the inertia works against you forcing your to put effort through the dead spot and return to keep a smoother/circular pedal stroke, more like climbing IRL.

So yes, the power requirements and "virtual speed" will be the same, but muscle recruitment will differ.

This is also why wheel-on trainers with tiny flywheels tend to feel like you're pedaling through mud, and why something like the Hammer has a better road feel than the Neo with its virtual flywheel.

Re: Smart trainer and real world resistance

Posted: Sat Dec 08, 2018 10:35 am
by wheelsONfire
It seems as with most things, testing is the best way.
I have not yet got my new frameset, so no Neo tested.

A buddy of mine got a crack on his frameset, at the BB, from sprinting on his trainer.
Luckily i'm more or less a typically seated rider.
I would never stress my frameset sprinting on the trainer.

Re: Smart trainer and real world resistance

Posted: Sat Dec 08, 2018 10:35 am
by Weenie

Re: Smart trainer and real world resistance

Posted: Sat Dec 08, 2018 10:50 am
by TobinHatesYou
Sounds like a frame defect. I know tons of people who sprint pretty hard on the trainer and they don’t break their bikes. I sprint on the trainer all the time.