Is my setup way off?


#1

My buddy posted his trainer rode ride on strava and I compared it to mine. Someone’s setup is way way off.
I did Augusta -
1:30:00 ride with 4, 15 min blocks at threshold which was targeted at 307w.
My numbers
Avg speed 18.9 mph (on trainer 27.5 wheel)
Dist. 28.3 miles (on trainer)
NP 289w
An hour above 300w

He did an 1:15:00 ride
Avg speed 26mph
Dist. 33 miles
NP 226w

It’s hard to say but I think my numbers are more accurate. I don’t see how anyone could hold an average speed of 26mph for an hour with only a NP of 226 watts. An average speed of 26mph is pretty dang fast. Right?

I’m going 7mph slower with a much higher NP of 289. Both on trainers. Would wheel circumference make this big of difference?

I know i know. None of this really matters comparing virtual numbers but if my setup is off it’s way off and I’d like to get it dialed in. But it seems to parallel my experience outside.

Just looked found this power to speed chart:
16 MPH = 104 Watts (+14)
17 MPH = 121 Watts (+17)
18 MPH = 140 Watts (+19)
19 MPH = 161 Watts (+21)
20 MPH = 184 Watts (+23)

21 MPH = 207 Watts (+23)
22 MPH = 235 Watts (+28)
23 MPH = 263 Watts (+28)
24 MPH = 295 Watts (+32)
25 MPH = 330 Watts (+35)

26 MPH = 368 Watts (+38)
27 MPH = 409 Watts (+41)
28 MPH = 450 Watts (+41)
29 MPH = 497 Watts (+47)
30 MPH = 547 Watts (+50)

31 MPH = 597 Watts (+50)
32 MPH = 654 Watts (+57)
33 MPH = 710 Watts (+56 lol)
34 MPH = 780 Watts (+70)

http://www.gribble.org/cycling/power_v_speed.html


#2

Speed on the trainer means nothing.


#3

Insightful.


#4

I’ve never understood why people even think about speed on a trainer? What possible use does it have?


#5

None. But it’s a number that shows up. I know it’s an estimate and has zero impact on my training but I’m still curious.


#6

Your setup isn’t off; it’s doing its job. Your friend’s setup isn’t off; it’s doing its job. My trainer (smart) reports speed based off I don’t know what, it’s always around 6mph. 90 minutes’ riding is about 8 miles. It’s fine. Miles traveled and speed achieved on the trainer means diddly squat and if it weren’t for TrainerRoad dutifully uploading those values to Strava I wouldn’t even know my trainer reports unusual numbers.


#7

It is, since the numbers ARE meaningless. Your average speed was ZERO!

Mike


#8

I assume you’re using Erg. This adjusts the trainer resistence relative to other factors, like gearing. If you ride small ring/large sprocket your wheel will be spinning more slowly and show a lower “speed”. The same workout in a large ring/small sprocket will feel the same (due to Erg adjustments) but the wheel will spin faster and show a higher “speed”. As someone has said, speed on a trainer is meaningless since you’re not actually going anywhere and reported speed is totally determined by your selected gears.


#9

To talk a little bit about the why of them being different… different trainers will have different relationships between speed and resistance. For dumb wheel on trainers, in general fluid trainers will see bigger increases in resistance for the same change in wheel speed than magnetic units. Some trainers can have adjustable resistance for the same wheel speed.

Wheel off trainers have an even more fluid relationship with ‘wheel speed.’ Smart trainers in erg mode will give you the same resistance regardless of what gear you’re in or cadence you’re using, but in theory gearing x cadence would be your wheel speed.


#10

Agreed and fully aware. Not the question I was asking.


#11

I know, but a felt like being a dick.

Mike


#12

Hahahahahaha me too. All good.


#13

Like @matthew.weigel said, most “dumb” trainers will have a somewhat meaningful reported distance because the resistance applied by the trainer scales proportionally to wheel speed at a rate that attempts to emulate a flat road. In erg mode, your gearing never changes, so your cadence is the only thing changing wheel speed. Thus 90 RPM at 100W will look just as “fast” as 90 RPM at 300W, the trainer does not attempt to estimate your distance based on your average power.


#14

Maybe that’s what it is. He’s on erg and I’m on a dumby, wheel on roller with stages crank. 1x11 34t chainring.


#15

Yeah. Gotta be it, which is why my virtual speed and distance seem to parallel outdoor conditions on dumb trainer.
But
The strangest thing I could never figure out on the dumb trainer, before I had the stages crank which calculates cadence, my kirt Kinetic rm with virtual power was tracking cadence virtually and if I was holding 250 watts at 105rpm and switched gears and held 250 watts it would show a drop in cadence to 85rpm. How could it possably know I changed gears? There’s just 1 sensor on the roller the wheel is touching and it’s only counting revolutions. This is contrary to what you are suggesting, albiet on a dumb trainer that’s actually pretty smart. I’m assuming a smart trainer is doing the same. It knows. Some how.


#16

I think Kurt Kinetic is doing a lot more analysis with their InRide; they are actually looking for torque pulses and using those to identify downstrokes. Measuring the time between those pulses allows them to estimate cadence.


#17

Had me stumped but that’s pretty amazing.


#18

The cadence on my KK inRide reads low compared to actual cadence from my power meter.


#19

I experienced the same thing. On the podcast everyone is talking about spinning at 110 and up and it had me feeling outside the norm. But with the cadence from the power meter it has evened out. Alas, I’m normal.