cthenn

When I upgraded my computer to a Wahoo, one of the power metrics I could display is "torque". Does anyone know what one can learn from that value? There are several variations of the metric, the one I'm using is "last lap torque", but I really don't know what I'm looking at when I see the value. I think my plan is to learn through osmosis, as I try to correlate the value to how hard I pushed on a given lap, how I felt, etc. How is torque different or comparable to power numbers? Seems to be more or less correlated, the higher the wattage, the higher the torque, more or less, but I don't know how that metric might be useful in comparison to lap power. The values are usually in the low 2 digit numbers (20s-30s) for an effort in my Z4 range, but don't even know the units lol! 20 or 30 what, and is that a lap average number? I understand the definition of the word, and obviously the more power you put into the pedals, the higher the torque value will be, but I don't quite understand how or what to take from a given effort looking at that value vs just looking at power.

tomato coupe

Simple, qualitative explanation: your power is your torque multiplied by your cadence.

pesty

Basically, it's how effective you're pedal stroke is at delivering power all the way arround. Higher is better, I want to say that 30% and higher is pretty good. If you want a really detailed write up, look here: https://www.cyclinganalytics.com/blo...dal-smoothness

tomato coupe

The OP is asking about torque -- what you referenced is completely different.

gurk700

/thread

RChung

This is true for most power meters. For Power Tap hubs, power is measured at the rear hub so power is (hub) torque multiplied by the wheel's rotation speed.

Knowing the torque can be useful for 1) checking the accuracy of your power meter, or for diagnosing problems; or 2) examining "QA" (aka pedal force and pedal speed analysis). Most riders never look at QA analyses, nor do they ever check the accuracy of their PMs, so most riders can just ignore the torque data field.

I do periodically check the accuracy of my PM, so I do like being able to get the torque value. Once I diagnosed a problem with a power meter by noticing that the product of torque and cadence (and a conversion constant) didn't quite equal the power; it turns out the cadence measurement was off.

tomato coupe

​​​​​​​That's why I emphasized qualitative -- my purpose was to give the OP a sense of how torque and power are related, without going into details.

Racing Dan

You can develop a given power, say 200w, at any RPM you like. Just "mash" the gears more or less, dependig on what gear you have chosen. The touque value is a measure of how much you mash the gears. For the same power, RPM will go up and torque go down if you choose a light geat and RPM will go down and torque up if you choose a heavy gear.

cthenn

OK, this dumbs it down enough to my level . On a short steep hill I did 300w at over 40 "torque units" while out of the saddle mashing at probably 65-70rpm whereas on other 300w efforts it can be closer to 30 if I try to spin it more. I'll probably keep the metric for a while see if it ends up having any usefulness for me.

So, what are the "torque units" shown?

redlude97

Are you measuring HR as well? If not you should be for it to be useful. See how your HR varies with the torque/cadence difference for the same avg power.

chaadster

Torque units displayed is Nm, or Newton meters.

If you're using analysis software that displays Torque Effectiveness, you might find the TE percentage useful in improving your pedaling technique. For example, a 75% TE would indicate that 75% of applied torque is going towards moving the bike, while the remaining 25% is you working against yourself by keeping pedal pressure on the upstroke. Obviously, you'd want to see as high a TE percentage as possible.

Racing Dan

There are several different ways to express torque. Pound foot, lbs ft, is common in the US, but if you set it to metric then Im betting it will display SI units. That is Newton metre, Nm. If you can make it show power, torque and RPM all at once, Im betting you quickly learn how they relate.

RChung

It depends on your power meter, and whether your head unit is set to display in SI (metric) or Imperial units. The metric unit is Nm, the Imperial unit is foot-lbs.

You don't need HR for torque information to be useful.

Here's a plot that shows cadence and crank torque for the same guy in three different types of races. The plot is from here.

Abe_Froman

Probably foot-pounds, which is a pretty simple unit. It's the amount of force exerted on a bolt by a 1 foot long wrench with a pound of weight sitting on the end of it.

cthenn

Cool, brilliant info in here, thanks! I'm gonna look more into torque effectiveness, does that require a L/R PM, because mine is left-only. I think I've experimented with that and pedal smoothness on the Wahoo data fields, and nothing shows up...

Dean V

I don't recall anyone using Horsepower as a unit for power measurement for cycling, so why would there be a readout of ft/lb?
It would be like your car speedo reading out your speed in mph and distance in kms at the same time.