ptcruiser140.6

I have been riding a staionary bike at the gym for the last few months (bad weather, no time, darkness) and was wondering how the data on a stationary bike compares to the roads.

I have been usually getting 25-27 MPH average for an hour on the stationary bike and usually average in the mid to high 200's for watts for the hour. I understand these numbers are out of wack but am wondering if anyone had any thoughts about road vs. stationary biking and how these numbers compare.

hhnngg1

Your 'speed' on a trainer or stationary bike is only an estimate. Your real-world speed doesn't only depend on your power output, but your size, aerodynamicness, gear, and terrain.

Stationary bikes that are found in a typical gym are not calibrated for typical roadies, and thus are notoriously unreliable for speed and power estimates. You can be off by 30% or more (for real) so I wouldn't read too much into translation to road.

Even the 'road calibrated' dedicated bike trainers such as Kurt Kinetic and Cycleops, which are supposed to mimic road acceleration on a flat road extremely well, are only an estimate. If you're about 140lbs and lucky, you might fit the profile so well that it works 99% well (someone posted powertap data that showed such a similar fit). But if you're 250 lbs and bulky, you will likely be surprised with how off that so-called estimate is when you hit the real road.

I know from direct measurements of speed on flats that for ME, my trainer data (cycleops2) correlates very well with my outdoor flat time-trial speed. In fact, I use this data to target my time-trial speed for a flat 40k course on the road - if I'm doing 23mph x 60min on the trainer, I know I'll be able to do that outdoors, and likely another 0.5 mph average.

I've conversely been on several gym bikes that I've done similar efforts and seen 16mph, and 30mph for pretty much the same effort.

caloso

If, and that's a HUGE if, the wattage numbers on your gym stationary bike are accurate, that's not too shabby. How much do you weigh?

hhnngg1

And actually, 200 watts will NOT get you 25-27mph on the road, unless it's on a downhill. On a flat, you're optimistically looking at 19-20mph, and that's with great aerodynamic gear. More realistically, 17-18mph on the road. And that's assuming you're actually putting out the 200 watts that the unreliable gym bike power meter is telling you.


You reallyhave to just go out and ride on the road before you can start calibrating your road speed to that particular gym bike.

climber7

what kind of stationary bike? like a cycleops or something, or just one of the life fitness-type normal gym cardio machines?

also, hhnngg1, he said mid to high 200s, as in closer to 300. that could be pretty close to 25 mph in an aero position.

canam73

Do you have any heart rate data for your road or stationary riding? That could give something to go by.

plx

200 watts = 17 mph

merlinextraligh

If:

1. you have your hands on top
2. you're 5'10"
3. you weigh 235lbs
4. the air temp is 68 degrees
5. your at sea level
6. the wind speed is zero
7. you have a typical road surface, tire, and coefficient of friction
8. your bike weighs 20.5 lbs
9. you're as aero as the hypothetical rider the calculator assumes.
10. your bike is as aero as the calculator assumes.
11. the grade is zero.
    

https://www.noping.net/english/

Some people can go a lot faster than 17 mph on 200 watts, and others might be a bit slower.

There are too many variables to say a given wattage equals a given speed.

merlinextraligh

The net net of all this is don't worry about your speed on the exercise bike at the Gym. If the power reading is accurate ( a fairly large if) use the power reading to pace your efforts and measure imprrovement.

If the power data is somewhat suspect (which is likely) take it with a grain of salt and correlate with HR data, and perceived effort.

canam73

While still not equating to an exact road speed, why do you all keep calculating for 200 watts instead of the mid to high 200's? Did you not really read the OP or climber 7 and are just talking to hear yourself?

caloso

I did. And I figure that 250W threshold power is not too shabby for anyone under 80kg. It's very good for anyone under 75, and outstanding for anyone under 70.