Smart Turbo and resistance changes

blackwater

Hi All,

I am currently using a CycleOps Mag+ 'dumb' trainer with Zwift and I am not convinced that 'virtual power' is very accurate.

Additionally I am using the training plans on Zwift and sometimes can't find a gear that gives me the exact instructed power output at the recommended cadence. Not a huge issue I know but slightly annoying.

So I am considering a smart trainer, but was wondering how the resistance changes on a Smart Trainer work. Let me explain, on my CycleOps Mag+ I can via an adjuster switch through 5 resistance levels.(Although I leave on level 5 for Zwift) Will a smart Trainer have a similar crude range of adjustment (albeit controlled by Zwift) or does the resistance vary smoothly in very small steps across the range?

ie would a Smart trainer in ERG mode always be able to perfectly set the appropriate resistance for the recommended cadence to achieve the target power output?

Many thanks

grenw

Can only speak for my KickR but it's 'exact' to the individual watt. Used with Trainerroad the output line will pretty much exactly follows the workout. No need for gears just find the comfortable cadence that allows you to keep up the power output required. It will keep the power the same whether you pedal slowly or quicker.

The Wahoo app also allows you to control the resistance in either % (so 100 breaks) or in individual watts.

markhewitt1978

I've ridden a Bushido Smart and Tacx Neo I don't know what the exact granularity of the changes is but they've always seemed very smooth to me, imperceptable even. Certainly not only 5 resistance levels.

jgsi

Matching the cadence to the power target.. is never going to be easy with your setup.
I take it you have tried a lesser resistance setting?
To get to target, are you having grind or really spin up?

Never forget that Zwift is trying to be everything to everybody - sometimes it works sometimes it dont.

markhewitt1978

The thing I've noticed with ERG mode both on Trainer Road and Zwift is that say you're targeting 200W it may seem to vary on screen between 180W and 220W but then if you look at your power output graph on Strava afterwards it's always a near enough straight line, so it does a good job.

markhewitt1978

You can see from the graph here where I went into ERG mode (in this case using the Tacx iPhone app but recorded on Zwift)

blackwater

Thanks all for the feedback.

It sounds like the Smart trainers are able to alter the resistance in many very small steps so as to be realistic and therefore offer a better experience with the likes of Zwift.

lbmxj560

GrenW wrote:

Can only speak for my KickR but it's 'exact' to the individual watt. Used with Trainerroad the output line will pretty much exactly follows the workout. No need for gears just find the comfortable cadence that allows you to keep up the power output required. It will keep the power the same whether you pedal slowly or quicker.

The Wahoo app also allows you to control the resistance in either % (so 100 breaks) or in individual watts.

Strictly speak that is not true at all. If you use a Kickr the wattage shown on screen in Trainerroad is the wattage that the Kickr says it is putting out, not the wattage that it is actually putting out. DC Rainmaker did a very good post on this. If you use the Kickr and a power meter and record the power meter output separately you will see the standard variations over an under the target power. The "perfection" is just how Wahoo has decided to transmit and display the data.

With regard to the original question, smart trainers are very smooth. You will not feel big "jumps" as wattage changes, it will take place over a handful of seconds to avoid that feeling of hitting a wattage wall. Do bear in mind, though, that in erg mode, once your cadence starts dropping you can very easily end up in a downward spiral as, to keep power the same (wattage = force x speed) it has to add more force (resistance). This means that you feel like you are pedaling harder, which makes it even harder to hold the cadence.